View Full Version : ESE's works engine tuner
Frits Overmars
27th June 2015, 18:57
well when we" english" started the industrial revolution...Which reminds me of an antiquarian's convention. One of them had brought a vase and everybody started guessing about its origin. Some suggested Greek, others proposed Mesopotamian or Etruscan, until one of them took a look under the bottom and read "Made in Birmingham". Whereupon all reacted: "That old?"
ken seeber
27th June 2015, 19:51
anybody heard of the "middle power flush (http://www.google.com/patents/DE102010056258A1?cl=en)", could the Ryger rely on this? except from using the crankcase and instead connecting the transfers directly to the Reed valve in BDC. Therefore the piston builds up higher to contain the connection ports. So the thick alloy plate is not only to block the transfers from the crankcase but also to compensate the increased piston height?
There was/is a dude in Oz called Arthur James Fahy, who was a prolific inventor. He also had a vey similar idea to this, the focus at this time was to gain more transfer port area. I believe he also made up samples for Kenny Roberts. In unsuccessfully searching for this, I came across http://www.google.com.ar/patents/WO1992003645A1?cl=en If you click on espacenet in the title block, you can get a pic to match the text. This is a variable transfer port height control, coming down from the top. As with the “middle power flush patent” here by Gleich, both these patents have lapsed, so free for all to play with. Funny that Harry didn't show any ports in the bore pic.
richban
27th June 2015, 20:24
A little off the current topic. Wob you might be interested, Its great making lots of power but when the clutch on the engine was designed to handle a lot less hp, it does mess with your racing. Now the 300 is making good hp the clutch is the first weak link. The MC21 dry clutch with 5 fibre's that is. What we are doing is running 2mm steels instead of the 2.9 factory steels. This should allow 6 friction plates and hopefully no more clutch slip. I am keen to try anodised ali as a replacement to the steels.
These bike are now well sorted. In the right hands they are class winning. Bring on summer.
speedpro
27th June 2015, 23:16
I hope you have only thinned the friction surface of the steel plates and not the fingers(?) that engage with the clutch hub. Typically you can lose a bit off the friction surface of the clutch parts that clamp the plates together. The idea being that the finished clutch assembly with the extra "pair" of plates has the exact same assembled height as the original. You need to add an extra steel and an extra fibre to make an improvement. The trick is machining everything dead true with no chattering. Not easy for a beginner on a lathe.
While you have the clutch out check the cush drive as well. If the engine is making more power at not many more revs then the torque must be greater. Go far enough and you can overpower the cush drive and if it's bad enough smash springs(if you have them) and even start to shear off the rivets that holds the assembly together.
husaberg
27th June 2015, 23:50
A little off the current topic. Wob you might be interested, Its great making lots of power but when the clutch on the engine was designed to handle a lot less hp, it does mess with your racing. Now the 300 is making good hp the clutch is the first weak link. The MC21 dry clutch with 5 fibre's that is. What we are doing is running 2mm steels instead of the 2.9 factory steels. This should allow 6 friction plates and hopefully no more clutch slip. I am keen to try anodised ali as a replacement to the steels.
These bike are now well sorted. In the right hands they are class winning. Bring on summer.
According to the NSR the dry clutch would have one 2mm steel on the inside an upgrade is to replace this one thin plate with a std 2.9. For more preload.
It also says EBC and JHa do upgraded springs.http://nsr-world.com/tuning/250-tuning/engine/
It looks like the Tyga kit replicates this set up.http://tyga-performance.com/site/product_info.php?products_id=1178
Ps your bike looks great.
that the German version was not exactly faultless either. An hour wasted; what a start of my Saturday.
sorry Frits :laugh: so you mean the idea didn't even work in the first place? which would explain why I couldn't find any engine built like this... :rolleyes:
breezy
28th June 2015, 06:03
Which reminds me of an antiquarian's convention. One of them had brought a vase and everybody started guessing about its origin. Some suggested Greek, others Mesopotamian or Etruscan, until one of them took a look under the bottom and read "Made in Birmingham". Whereupon all reacted: "That old?"
:clap::clap::clap::killingme... yeah but ...old but gold...:woohoo:
Frits Overmars
28th June 2015, 08:55
so you mean the idea didn't even work in the first place? which would explain why I couldn't find any engine built like this... Most patents don't substantiate their claims; most patented engines are never even built.
breezy
28th June 2015, 09:09
Most patents don't substantiate their claims; most patented engines are never even built.
well, having looked through the patents for variable length
t
conrods , it makes you think, is their a new version which isnt coverd by an existing idea.....:confused:
lodgernz
28th June 2015, 11:20
Wobbly, can I ask your advice please.
You'll remember that senso posted photos of his CRM50 cylinder that he cut up to see how close the water jacket was to the ports (see photo).
I also have one of these engines, which I've started modifying.
Upon measuring the exhaust port, I find that the narrow bit you see in the photo has an area only 73% of the standard port area. Obviously that will be worse when I increase the port area.
I plan to make an insert to reduce the flange area as you suggested to senso.
My question is: Should I try and make this restriction equal in area to the port, or could I begin the 90% area from this point out to the flange?
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wobbly
28th June 2015, 12:10
My immediate question is to establish if the restriction is 73% of the EFFECTIVE port area ie The measured port area X the Cosine of the down angle.
And subsequently the answer is that the duct should be as smoothly transitioned down to 90% at the exit as is possible.
lodgernz
28th June 2015, 12:19
My immediate question is to establish if the restriction is 73% of the EFFECTIVE port area ie The measured port area X the Cosine of the down angle.
And subsequently the answer is that the duct should be as smoothly transitioned down to 90% at the exit as is possible.
Yes that 73% is using the cos of the port down angle of 23*.
So I read it that I need to make that restriction maybe 96% of port area and then an insert to continue it down to 90% at the flange?
Thanks for your help Wobbly.
richban
28th June 2015, 14:55
I hope you have only thinned the friction surface of the steel plates and not the fingers(?) that engage with the clutch hub. Typically you can lose a bit off the friction surface of the clutch parts that clamp the plates together. The idea being that the finished clutch assembly with the extra "pair" of plates has the exact same assembled height as the original. You need to add an extra steel and an extra fibre to make an improvement. The trick is machining everything dead true with no chattering. Not easy for a beginner on a lathe.
No thinning, no lathes. We will have Laser cut new ones. They are the same as Honda RS250, 2mm steels. Ali is an option as well.
Neal
28th June 2015, 16:22
No thinning, no lathes. We will have Laser cut new ones. They are the same as Honda RS250, 2mm steels. Ali is an option as well.
Rich ,
Have you looked at using other primary gear ratios ? I have been using the mc28 combination .
My next mod is to get straight cut primaries with the f3 ratios .
I have ally plates to use but have not tested them yet .
wobbly
28th June 2015, 16:56
You cant use ally plates in a dry clutch - they warp instantly from heat stress.
lodgernz
28th June 2015, 17:04
One last question please Wobbly. The insert I make for the cast-iron CRM50 cylinder: Can it be just mild steel? Is Aluminium alloy an option?
If neither is good, can you advise what is?
Sorry, that's 4 questions. Never could count...
Neal
28th June 2015, 17:23
You cant use ally plates in a dry clutch - they warp instantly from heat stress.
Even these ones ? http://www.thetuningworks.co.uk/store/product_info.php?cPath=21_124&products_id=1159
richban
28th June 2015, 17:25
You cant use ally plates in a dry clutch - they warp instantly from heat stress.
I know they don't last long but plenty for sale for the rs250's
richban
28th June 2015, 18:01
Rich ,
Have you looked at using other primary gear ratios ? I have been using the mc28 combination .
My next mod is to get straight cut primaries with the f3 ratios .
I have ally plates to use but have not tested them yet .
Nah not going to go that far. The bike is way fast how it is.
wobbly
28th June 2015, 19:06
Yea, well as the advert says Standard VJ22 clutch. not SP or F3 ie they are for an oil bath.
I have tried Hinson cryo'd plates for Banshee in a TZ350 and they were fucked the first hard start thrashing they got.
Re the insert of the Ex duct - make it in ally and give it a real heavy press fit to help the heat transfer path
lodgernz
28th June 2015, 21:06
Re the insert of the Ex duct - make it in ally and give it a real heavy press fit to help the heat transfer path
Thanks again Wobbly.
speedpro
28th June 2015, 22:37
No thinning, no lathes. We will have Laser cut new ones. They are the same as Honda RS250, 2mm steels. Ali is an option as well.
I think that is a mistake. Where the plates drive the inner hub will be the same thickness, 2mm. This will accelerate the wear and you will end up with ripples sooner which will inhibit clutch action as the plates will want to stay where they are, with the fingers in the ripple, rather than sliding freely to their disengaged position.
If I was getting some cut I would go for 3mm or maybe even thicker then machine the friction surface down to the required thickness. You end up with 2mm at the friction surface so your stack of plates can include the extra pair and remain at the correct stack height, but you also have the fingers at 3mm which will reduce load and wear where they contact the hub.
I've done something similar on the MB clutches. With standard springs they are good for 27hp and feel just like a standard clutch. Try and avoid big springs. They are hard work and make the clutch feel funny, in my experience anyway. Malcolm has one of mine, and Dave. If you ask nicely I could probably turn your plates down for you, for a fee.
Sketchy_Racer
28th June 2015, 23:49
I think that is a mistake. Where the plates drive the inner hub will be the same thickness, 2mm. This will accelerate the wear and you will end up with ripples sooner which will inhibit clutch action as the plates will want to stay where they are, with the fingers in the ripple, rather than sliding freely to their disengaged position.
Well, yeah i would agree normally but it's a little different on the NSR clutch
On the NSR clutches it is the clutch outer which is the problem for "finger wear" Which is where the clutch fibres are engaging, which we are keeping the same thickness on the fibres but increasing the plate count by 20% reducing the load on each plate by the same amount which = less wear. Unfortunately we will be losing 19.3% clutch basket contact area on the steel plates even when fitting an additional plate which is not optimal. But then I go back to two observations on that which is that 1. it is not a street bike so the amount of time that the clutch spends chattering around is much less, and I feel that a lot of the wear would come from clutch chatter as opposed to continuous load. 2. RS250s run 2mm clutch plates in the same configuration and it seems to work just fine for them.
I could also be hopelessly wrong and we'll be filling our clutch baskets after every race haha
husaberg
29th June 2015, 09:26
Well, yeah i would agree normally but it's a little different on the NSR clutch
On the NSR clutches it is the clutch outer which is the problem for "finger wear" Which is where the clutch fibres are engaging, which we are keeping the same thickness on the fibres but increasing the plate count by 20% reducing the load on each plate by the same amount which = less wear. Unfortunately we will be losing 19.3% clutch basket contact area on the steel plates even when fitting an additional plate which is not optimal. But then I go back to two observations on that which is that 1. it is not a street bike so the amount of time that the clutch spends chattering around is much less, and I feel that a lot of the wear would come from clutch chatter as opposed to continuous load. 2. RS250s run 2mm clutch plates in the same configuration and it seems to work just fine for them.
I could also be hopelessly wrong and we'll be filling our clutch baskets after every race haha
As I mentioned (a couple of days ago) the stock std steel plate closest to the engine on a std Honda NSR250 with a dry clutch ie se sp. Is 2mm.
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nick gill
29th June 2015, 11:35
Hello forum gang.
This is my first post, but I've been lurking, absorbing, disseminating, and note taking for a few years now so hopefully I won't be wasting anyone's time.
A question for Wobbly:
I have an Iame small cage reed block in a cylinder-reed application. The engine is now of a much greater bore x stroke than an Iame Sudam for which the reed was designed, but for packaging reasons I cannot use the larger reed version, or any larger reed.
Is there a general rule for altering reed stiffness, that as the flow demands increase you need to stiffen/soften the petals reed thickness? How does this tunability pan out in real life?
Sorry if this was covered 900 pages ago, my memory is only human ;)
Sketchy_Racer
29th June 2015, 12:35
As I mentioned (a couple of days ago) the stock std steel plate closest to the engine on a std Honda NSR250 with a dry clutch ie se sp. Is 2mm.
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Yep but they are significantly more expensive than 2.58 per plate to get them later cut
husaberg
29th June 2015, 12:38
Yep but they are significantly more expensive than 2.58 per plate to get them later cut
Fair enough, I tried to find a parts book for a 87 NF5 but couldn't find one. I did notice though that the later models RS250's seemed to have a fibre plate on the inside.
lodgernz
29th June 2015, 12:56
Yep but they are significantly more expensive than 2.58 per plate to get them later cut
Is that $2.58 per plate to get them laser cut? Sounds cheap
wobbly
29th June 2015, 13:20
In a word - NO.
The only way to get greater performance from a reed that is essentially too small is to the vary the petal frequency such that it
is resonant within the powerband.
EngMod gives the primary frequency that coincides with a particular rpm.
But then it gets real murky if you start to use soft patals and add revplates and then extra backups.
This cant really be modeled, but all you can do is follow the general advise on how to do this I gave in here ages ago, and test a bunch of
setups on the dyno.
Here is an example where I have done just that, in a SKUSA CR125 where the carb is sitting up high on a manifold bent at 30* to the flow.
All the air was trying to go thru the top,RH petal.
2 days of testing and here are the best few against the stock Honda carbons.
nick gill
29th June 2015, 14:07
The only way to get greater performance from a reed that is essentially too small is to the vary the petal frequency such that it
is resonant within the powerband.
Thanks Wobbly for the reply. That has informed the direction I will take. Cheers.
Sketchy_Racer
29th June 2015, 15:08
Is that $2.58 per plate to get them laser cut? Sounds cheap
We get quite a lot of laser cutting done through work so we get good prices. My clutch plates accidentally sneaked into one of the orders
peewee
29th June 2015, 15:08
frits a couple pages back you showed a pic of 20* radial aux ports. i thought that was a old pic. reason is because didnt jan say eventually he extended the aux window to almost center bore ? there must be a updated pic somewhere :laugh:
Frits Overmars
29th June 2015, 19:31
frits a couple pages back you showed a pic of 20* radial aux ports. i thought that was a old pic. reason is because didnt jan say eventually he extended the aux window to almost center bore ? there must be a updated pic somewhere.I've been waiting for this question to come up. Those 20° do not indicate the position of the port, but only the difference between its positional radius and its direction.
By the way, I can't remember what Jan did or didn't write, but I do know what he did: he extended the positional trailing angle of the auxiliary exhaust port to 8° past the center of the bore. This, combined with my 20° difference gives a directional trailing flank that exits the cylinder, pointing 12° forward.
The picture below is really a scavenging concept, but it may clarify the above-used expressions positional angle and directional angle.
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Tim Ey
29th June 2015, 20:17
In a word - NO.
...
But then it gets real murky if you start to use soft patals and add revplates and then extra backups.
This cant really be modeled, but all you can do is follow the general advise on how to do this I gave in here ages ago, and test a bunch of
setups on the dyno.
I modified my daily driver reed with a splitter, as your advice was in #16420, but the 0,25 carbon plate tends to brake right away - so I would be VERY interested what a "revplate" is :-)
(I suggest a second reed petal mounted on top of the first?!)
Just searched my arse off - but I can not find it...
TZ ? :-D
husaberg
29th June 2015, 20:32
I modified my daily driver reed with a splitter, as your advice was in #16420, but the 0,25 carbon plate tends to brake right away - so I would be VERY interested what a "revplate" is :-)
(I suggest a second reed petal mounted on top of the first?!)
Just searched my arse off - but I can not find it...
TZ ? :-D
Rev plate is a generic term think what Boyesen used to sell to put in place of the std reed stopper. look under the screws
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Muciek
29th June 2015, 21:32
Use the softest carbons you can.
Make a " rev plate " from the old reed 0.5mm material ie a strip say 6mm wide, this sits on top of the carbon under the screws.
Then take the original thin fibre reeds, cut them to 1/2 length then cut them to make 3 pointed hats,these are backups that sit on top of the 0.5mm spacer.
Next take the old radius plate and cut it to 1/3 its original length,this sits on top of the backups with the screws going thru all 4 elements.
Best reed setup known to man.
The backups are tapered from full width at the clamp, to a point with a small rad on the end.
These pointed backup plates are 1/2 the reed petal length.
I have tested several full width petal plates, and some made better power - I believe due to the fact they were slightly stiffer than the original petals
and this is what was needed.
Yes, but I think the 0.5mm material from the original reed is too thick to use as a backup.
Those are Wobbly posts combined into one about this idea
Here are a pictures related to this
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286633&d=1376961178
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286727&d=1377310333
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286632&d=1376959399
husaberg
29th June 2015, 21:37
Those are Wobbly posts combined into one about this idea
Here are a pictures related to this
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286633&d=1376961178
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286727&d=1377310333
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286632&d=1376959399
Buggered if I know what you did there Muciek
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286633&d=1376961178
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286727&d=1377310333
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=286632&d=1376959399
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seattle smitty
30th June 2015, 04:25
To anyone, why do Frits' .pnf attachments take forever to load? They take so long that I never have the patience to wait them out. Any way I can speed this up?
The US has been trying to change to the metric sytem since 1893 . . .
No, SOME un-American fools, having been talked into believing the claims of certain socialist pinko bedwetter Europeans that their measurement system is inherently superior, have been messing with our perfectly good system. Why is a decimal system of measurement better than a fractional one that's easily divides into 12, 64, and 360, evenly. Sometimes decimals are more useful, sometimes fractions are, neither is superior all the time. This same bunch of fools convinced automakers that sideways-mounted engines and transaxles with CV joints that soon have an inch (an INCH, dammit!) of accumulated lash is the way to go. Try to swing a wrench in one of these miserable vehicles!! Good old American cars had the engine here, the transmission there, and the differential back there, so you could work on any of them relatively easily.
Metric system, aargh! I learned to work with it fifty years ago when I raced German Konig outboards, but still don't see a reason we should change. Y'all can change!!:bleh:
Frits Overmars
30th June 2015, 07:49
I could say a lot about it Smitty, but I won't; American car manufacturers have it tough enough as it is, fighting a loosing battle against the German and Japanese metric level of quality. I have just one question: why did a redbloodyblooded American like yourself race German König outboards, eh? What was wrong with Johnson, Mercury, Evinrude?
Before I forget (to be honest I am usually trying to forget it): I once owned a true American car: a Dodge. Never again!
It gave a whole new meaning to the expression "get the hell out of Dodge".
F5 Dave
30th June 2015, 07:56
. . . Why is a decimal system of measurement better than a fractional one that's easily divides into 12, 64, and 360, evenly. . . !
Yeah `cause that's what I want to do Every time I pick up a socket. Maths. So I can work out if a 1/5th is bigger or smaller than a 12/73rd.
Oh yeah you use IE as a browser and its a dog for images.
Tim Ey
30th June 2015, 08:06
Yeah `cause that's what I want to do Every time I pick up a socket. Maths. So I can work out if a 1/5th is bigger or smaller than a 12/73rd.
Oh yeah you use IE as a browser and its a dog for images.
Also quite funny when it comes to really small measurements like piston-clearance : 0,05mm equals 0.0019685".
Thanks a lot Muciek and husa :clap:
Flettner
30th June 2015, 08:35
We make rotorheads (autogyro) for the US market, all inch measurments and bolts but rotorhead main bearing is metric. Bit of a bugger when all the engine parts and gearboxes we make are metric, also for the US market, Just how it is. Another example, prop flange PCD is 4" but bolts that fit the drive lugs (on the 4" PCD) are 8mm with lugs being 13mm???
wobbly
30th June 2015, 08:57
Yes, rev plates are a term used for a spacer between the main petal and the backup reed ie just a packer plate.
The thickness of this spacer and the backup modify the resonant frequency of the main reed, but more importantly allows the use of very soft reeds
that would normally flutter all over the place like a mad womans shit at the wrong time.
Thus they open quickly, then as the lift increases the tension gradually increases as well.
In the CR125 example I gave the main petals were different top to bottom, to rebias the vertical flow anomaly, but also the backups
were biased in length left/right to rebias the sideways flow angle anomaly.
On the flow bench pulling 60Cfm, the velocity thru all the 6 ports was the same.
ken seeber
30th June 2015, 09:16
:
Before I forget (to be honest I am usually trying to forget it): I once owned a true American car: a Dodge. Never again!
It gave a whole new meaning to the expression "get the hell out of Dodge".
My grandma used to say:
"If you can't afford a Dodge, dodge a Ford"
FOS over. Saw the V8 Moto Guzzi, but it was out of action, so no sound. Saw a Trabant though, but it was also stationary.
F5 Dave
30th June 2015, 09:31
One of the funniest car stories was in a mate's lockup (it was huge) he shared with a chap Matt who owned among other things a dirty big A'mercan car, was some collectors item & supposed to be aerodynamic which means they extended the heck out of it and it was called the Roadrunner I think, had a picture of the cartoon on it. No WileeCoyote though. [did a google, maybe it was a superbird roadrunner)
But the amusing thing was under the bonnet there was a big horn & the adjusting screw was some strange arrangement so they actually had a label.
"Do not lose this screw" something about "you won't find another" or words to that effect.
It was metric. Hilarimouse.
TZ350
30th June 2015, 11:30
Page ....... 1220
Can you use any of the commercially available air-fuel O2 meters with crankcase-lubricated 2-stroke race motors, or does the lube confuse (and foul) the sensor too quickly? I just got one of these (from Innovate) to dial-in automotive engines.
313564
Provided that you don't mount it too close to the cylinder, where it would be hit by washed-through unburnt mixture (between the cylinder and the sensor there should be room in the header for at least once the cylinder capacity), that you use only unleaded fuel, and that you switch on the sensor's internal heating element and bring it up to working (=self-cleaning) temperature before starting the engine.
As Frits has alluded to you can use a Lambda in a 2T.
I have been using one for ages on the dyno that screws into a fitting on the front of a muffler cap.
It must be pre heated before use and will be killed quickly by lead, or being covered in oil as when warming up or running in slowly.
But at the end of the day an egt will tell you all you need to know about whats going on, including things the A/F ignores like deto onset.
You simply cant use any info from 4T sources and try to translate this to a 2T scenario.
A 4T can easily be rpm limited by materials technology, but this has been helped a lot in recent times by the short strokes NEEDED to allow a big bore to fit in
the huge valve area requirement for the power predicted.
A 2T is much more limited by the bore size and the area that can be fitted into that specific circumference,and THEN becomes limited by the mechanical issues of exceeding the 26M/Sec
that has become the currently accepted allowable max mean speed.
There appears to be NO reason at all to not run a long rod, well above 2:1 ratio, as its been proven that the tradeoffs between friction/case vol/angle area are
biased in favour of the longer version.
Aprilia did it for years, then Honda decided they agreed and went longer on the final champ winning RS250 going from 105 to 109.
The other issue is that there "could" possibly be an argument that a slightly undersquare engine might ultimately prove to be superior to the current accepted practice
of "square is best".
This has been playing on my mind, I couldn't reconcile what I had read about not removing the step in the exhaust duct. Why would the A kit not have the step if it's supposed to reduce power. Clearly I don't properly understand the function of the step.
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So no steps at the flange is better, so why does the NX4 RS125 lose power when the steps are cut out? Is this a function of the duct entry to exit ratio changing?
Cutting the steps out increases the duct volume, which is bad. Filling in the steps until there is a smooth transition to the header is good.
Removing the step in the old Honda engine makes its duct a bit like the IAME shown a few pages back.
The duct looses all its velocity well before it approaches the header - exactly the opposite to what is needed, so of course it looses power.
Fill in the spigot shape on any 3 port or T port Honda and power goes up - proven time and time again.
The trend has been to progressively reduce the duct volume, and at Aprilia this was started up at the port by lifting the floor and then filling
in the bottom corner radi, both reducing A port short circuiting as well as increasing blowdown velocity.
Later as Frits has said the exit area was progressively reduced as the floor and roof were machined closer to the center line thus reducing total volume again in the duct.
But we have never seen an Aprilia picture with this late version duct, so also cant tell if the flange entry was modified as well to eliminate the steps.
IF it was done that way then I can guarantee that it made better power.
Honda did this for years on the A Kit and RS250 factory bikes with a nice cast piece that transitioned from the very flattened oval to the round header diameter.
As I have said before, I developed a new T port cylinder that started with a 40 by 35 oval, with steps, and this evolved into a 41 by 32 oval with no steps and the power
increased with both the smaller exit area and the new CNC transition piece.
Then look at a new design like the TM KZ10B, this has a quite small exit area with small steps, modify this by welding the spigot to match the cylinder, then grind the Aux
ducts all the way from big 1/2 moons at the flange face ,tapering smoothly down to nothing at the header and it pics up a couple of Hp at peak,but revs on with something like 6Hp more at 14,000.
What is better?Step between exhaust duct and exhaust pipe or not? And if the exhaust duct exit is round like a lot of production motorcycles should be a step also there?
And one more,i'm sure mr Jan Thiel have already try this but I have to ask :whistle: .You said that Aprilia couldn't make max power with more than 13000rpm because of the insufficient blowdown angle-area.What would be the results if the exhaust port was raised into 204* or the B&C tranfer ports were lowered into 130*?Loss of power maybe? Cheers!!
So here it is as simple as can it be made - NO STEP IS BEST - but this does NOT mean grind the duct to make it round OR bigger in any way.
If its a 3 port or a T port, then the duct exit should be around 75% of the total effective Ex area, then the spigot should transition to 100% round diameter.
If its a single port, the duct should be around 90% exit area, with no step and the header the same diameter if its round.
If you have a really dumb 3 port or T port with a round exit, THEN CHANGE IT.
Re the angle area of the RSA.
The answer is all to do with finely balancing all the variables to optimize the end result.
Do you REALLY think that if going to 204* was actually better then why the hell wouldnt Jan do exactly that.
We have had the same question on here about the pipe dimensions,why not simply make it shorter and fatter, well if that was better
do you really think that it would not have been done.
I have been running thru pipe designs for a 250 KTM for a road racing kart, and discovered in the sim that going over 132mm belly diameter makes
NO MORE power.
Aprilia under Jan would have actually thought about this and built the pipe - I dont need to waste my time, its called diminishing returns, proven easily now
by a major step forward in computing ability.
Attached is the pathetic dyno result for my Honda 50 that I used to think ran really well..
I'd appreciate any ideas as to why the curve is such a strange shape.
The engine is stock except for small Boyesen ports and 2-stage Boyesen reeds.
I wondered if this could be reed flutter. The exhaust is the standard muffler with the guts ripped out.
Apologies for the quality of the screenshot.
313625
To have 3 peaks there has to be serious interaction of a couple of elements that are not even remotely matched to make power
in the same bandwidth. The Boyesens are rubbish anyway so dump them to start with, but i would suspect the pipe is out of sync with the port as well as the ignition curve.
The cylinder pressure at exhaust opening can be as high as 7 bar.
TZ350
30th June 2015, 13:57
Team ESE have been busy working on developing our RG50's.
Currently our RG's are about 13-14 rwhp so this picture of a 50cc AM6 converted to RV and pumper carb making 17 rwhp is very interesting, hope to be there ourselves soon(ish).
313224313225
Grumph
30th June 2015, 14:02
One of the funniest car stories was in a mate's lockup (it was huge) he shared with a chap Matt who owned among other things a dirty big A'mercan car, was some collectors item & supposed to be aerodynamic which means they extended the heck out of it and it was called the Roadrunner I think, had a picture of the cartoon on it. No WileeCoyote though. [did a google, maybe it was a superbird roadrunner)
But the amusing thing was under the bonnet there was a big horn & the adjusting screw was some strange arrangement so they actually had a label.
"Do not lose this screw" something about "you won't find another" or words to that effect.
It was metric. Hilarimouse.
That would have been Matt Gibbons. Owned two of the huge things at one point I believe...Ex bike racer, mate and teammate of Dale Wylie. Only rider i've ever come across who rode on track by braille - riding against him, you always lost paint.
Larry Wiechman
30th June 2015, 14:17
Frits, if you look up the word "dodge' in the dictionary the definition is "to avoid".
F5 Dave
30th June 2015, 15:43
yeah that's right. Said he had a 750 triple he was going to restore but never saw that. Bit of a character but seemed a good guy.
cotswold
30th June 2015, 18:06
[QUOTE=TZ350;1130878503]Team ESE have been busy working on developing our RG50's.
Currently our RG's are about 13-14 rwhp
13-14 rwhp is plenty, if you get 17 I will have to get rid of my Honda iron cylinder and spend some money on an aluminium (unobtainium) cylinder out of Europe, I'll let you explain that to mrs. Cotswold
peewee
30th June 2015, 18:30
welded some ears on this manifold tonight. as it sits the outer wall of the aux tunell will join the manifold at a larger angle than i would like. thought about using a 6mm spacer between the manifold and cylinder exit ,as this would let the aux tunell outer wall enter the main tunell more gradual but i think it might throw my pipe brackets way off and the front tire dam near rubbed the pipe as it was. maybe ill have a look tomorow. since the spacer would be before the beginning of the pipe would it affect how the pipe works ? i havent even got around the putting any of this in engmod yet so maybe the spacer might help. i was just thinking maybe i could shorten the manifold and pipe flange that goes over the manifold to compensate for the spacer
wobbly
30th June 2015, 18:35
So if its not been checked in EngMod how do you know that the CR500 spigot ID isn't miles too big ?
peewee
30th June 2015, 18:50
well it may be slightly big but i was hoping its close enough. other wise i have to get a new pipe. im already going broke because this :eek:. old cylinder on this bottom end was 3mm bigger piston and called for nearly 48mm but it didnt have any where near the amount of blowdown area this one will have. cr5 is 50mm so i should be in the ballpark. ill consult with engmod and decide from there
Grumph
30th June 2015, 19:50
yeah that's right. Said he had a 750 triple he was going to restore but never saw that. Bit of a character but seemed a good guy.
Ah, something possibly relevant to this thread...The last thing Matt built in ChCh before going home to Wgtn where you met him, was an H2 750 kawasaki.
I remember him saying it was the same bore and stroke as the 250 Bultaco singles and he'd got the port timings and pipe specs for them...
I don't think he actually ran it before moving North so i never saw it run.
In the absence of anything like Engmod, that still strikes me as quite a sensible start to development.
Frits Overmars
30th June 2015, 20:36
Frits, if you look up the word "dodge' in the dictionary the definition is "to avoid".You're telling me now, Larry...
My grandma used to say: "If you can't afford a Dodge, dodge a Ford".
FOS over. Saw the V8 Moto Guzzi, but it was out of action, so no sound. Saw a Trabant though, but it was also stationary.Too bad you could not make it to the Sachsenring, Ken. I saw, heard and smelled the Moto Guzzi V8 in anger. It sounded almost like a two-stroke.
Saw a fleet of Trabants that were far from stationary; watched two Trabant races together with my mate Frank Ziprian, also known as world's best Trabant tuner (changing 26 HP into 80+ HP).
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Flettner
1st July 2015, 02:54
Is Ryger taking water injection to a whole new level? Super clean piston and exhaust (steam clean). Now the crank case is sealed off from the rod and crankshaft allsorts can be done under the piston, how does the piston not melt, how does detonation not ruin the piston? How is higher pressure made in the crank case (under piston) to overcome lack of blowdown time, how come when the Kart does 113 laps endurance the power has to be dropped off, perhaps lack of water storage for the long trip? I think under piston water injection might play some part in this engines performance. Perhaps?
seattle smitty
1st July 2015, 04:09
I remember someone advocating switching to the metric system in a class long (very!!) ago, in a contemptuous tone, saying that, "Our system has the inch based on the width of old King Harry's thumb, the foot based on Harry's foot, and so on; how unscientific!! The metric system is based on the wavelength of particular light spectra in a vacuum; entirely scientific." Yes, said I, but of what practical use is that? The width of your thumb, your foot, your pace, etc., are, as any Boy Scout (which I was at the time) learns, immediately USEFUL!! King Harry was right.
Frits, I can top your Dodge as an appropriately named car, for a little while in my youth I was driving and maintaining a Plymouth . . . a Plymouth Fury . . . .
OTOH, some years later I owned a '73 Dodge Swinger (a sort of sporty Dart, Dodge's econo car) with a built Slant Six. Not only reliable and economical, but versatile; these Dodges had torsion-bar front suspensions, and if desired you could get under and quickly adjust the front-end ride height up or down. I completed this adjustability with a set of air-shocks in back (and had the battery mounted in the truck for more traction). I was occasionally called on to serve as a chase-car driver for a couple of friends who were hang-glider pilots. With both ends of my Swinger adjusted for max ground clearance, and snow/mud tires installed, I amazed all the other chase drivers with their high-dollar four-wheel-drive rigs, who could hardly believe that a mere CAR, a 2WD coupe, had made it up the mountain over the steep, deeply-rutted trail, carrying two hanggliders on my home-welded rack.
No company manufacturing motor vehicles was better at finding good names for their products than Hodaka. You had to love a "Road Toad," a "Wombat,' or if racing, a "Combat Wombat." Sounds like bucket material to me.
+ Reply to Thread
peewee
1st July 2015, 05:53
years ago i had a chrysler car with over 300K miles but back then they were using mitsubishi engines :laugh:
136kg136ps
1st July 2015, 06:51
In defense of US technology, there are still some exceptional things being done using our antiquarian systems of measurement and tools.NASCAR takes the cake in the spirit of bucketeering.Take a POS sedan with a motor designed in the 40s and get 14 bar bmep(granted they cost a bit). We also do good with weapon delivery systems.I do have to apologize for Harley and all the other American "Iron"
RE:Ryger...to what effect would ceramic bearings and possibly rings have on an engine's ability to rev?Also as the oil doesn' need to burn we could use some exotics in the crankcase.
Flettner
1st July 2015, 08:25
RE:Ryger...to what effect would ceramic bearings and possibly rings have on an engine's ability to rev?Also as the oil doesn' need to burn we could use some exotics in the crankcase.
Emulsified fuel / water? Ceramics would be useful for this.
Partially a steam engine?
F5 Dave
1st July 2015, 09:10
Flux capacitor?
wobbly
1st July 2015, 09:24
Only reason I ask about the CR500 spigot is that I am doing a KTM250 for roadracing in a kart and its making around 75crank Hp.
That will have a 42mm header dia = around 75% of the Ex effective total area - 50mm is absolutely enormous for any 250 cylinder.
peewee
1st July 2015, 14:21
wob this engine is 510cc 89x82. im hoping the cr5 spigot will be close enough to work fine but ill get around to loading it in engmod and figure it out from there
made a mold of the transfers today. i think what im going to do is run a bead or two on the outside of the cylinder and then use devcon on the inside wall so i can get a nice big radius through the duct. the plate attached to the cylinder bottom was nothing more than a half ass heat sink in hopes the gasket surface wouldnt pull down. one side stayed pretty flat. the other side sunk about .16mm (which is good enough for me) for you metric folks. i guess it should be more like the blue line
peewee
1st July 2015, 16:28
anybody used one of these 3in1 untis ? really considering one for cutting head chambers, making intake manifolds and such. oh ya i got thinking afterwards about that cylinder plate. maybe i better put a tack weld in the center to keep the gasket surface from moving any further. why dont i ever think of this shit until later on :facepalm:
http://www.smithy.com/graniteCLASSIC
wobbly
2nd July 2015, 08:39
Sorry, wrong end of the stick re being a 250 cylinder.
Re the 3:1 mill/lathe.
I had a cheaper Smithy for 20 years and it worked really well, but the big issue was that the swing height was " just " too low to machine
twin heads like RZ350/Banshee etc.
So I sold it and got a very similar machine that seems to be copied by various Taiwanese company's that has a much higher swing.
Only issue is I couldnt get one at the time with powered cross feed, big mistake - sure to be one now I would think.
peewee
2nd July 2015, 16:55
im assuming you were using the lathe function to machine the chambers. the engine head was contacting the mill head ? i know on most of the new smithys the mill head swings 360* so it can be moved out of the way but im wondering if a twin cyl head wouldnt hit at the bottom where the table is. website says they have power feed on x and y axis. i would defintaly have to machine twin cyl heads
anyways one more day of build up and it should be good enough. thinking it would be warped to buggery if i didnt attach the two plates. it broke one of the tack welds and started pulling down. ill probly weld the plates on alittle stronger tomorow
wobbly
2nd July 2015, 17:40
The Smithy machine you showed has a swing of 12", not enough.
The other machines with greater swing to the bed have 16" - plenty.
Yes you have to be able to center on one spark plug hole, and on a Banshee the head will hit the bed of a 12" swing machine..
nick gill
2nd July 2015, 22:43
313217
Really interesting 'hack' there that I'm going to take to my next dyno session.
A question about the placement of piston windows for cylinder/reed engines:
If flow velocity and mass transfer into the cylinder is maximal at BDC, then does that also mean crankcase induction through the reed is also maximal at BDC, and therefore windows ahould be made to this optimisation ?
It could be the difference between modifying Windows, a Skirt, or both...
husaberg
2nd July 2015, 22:47
Really interesting 'hack' there that I'm going to take to my next dyno session.
A question about the placement of piston windows for cylinder/reed engines:
If flow velocity and mass transfer into the cylinder is maximal at BDC, then does that also mean crankcase induction through the reed is also maximal at BDC, and therefore windows ahould be made to this optimisation ?
It could be the difference between modifying Windows, a Skirt, or both...
No idea maybe Wob will chime in the Robinson Book has a bit on reed frequency with some dyno results.
Frits Overmars
2nd July 2015, 23:34
If flow velocity and mass transfer into the cylinder is maximal at BDC, then does that also mean crankcase induction through the reed is also maximal at BDC, and therefore windows should be made to this optimisation ?The flow velocity from the crankcase to the cylinder will increase as long as the crankcase pressure is higher than the cylinder pressure.
At max.torque rpm the flow velocity reaches its maximum at roughly 10° to 20° after BDC; then the crankcase pressure and the cylinder pressure are equal, and they are also roughly equal to atmospheric pressure. The reed will only start to open when the crankcase pressure drops below atmospheric pressure, so it won't even begin to open until after BDC.
jasonu
3rd July 2015, 04:48
To anyone, why do Frits' .pnf attachments take forever to load? They take so long that I never have the patience to wait them out. Any way I can speed this up?
No, SOME un-American fools, having been talked into believing the claims of certain socialist pinko bedwetter Europeans that their measurement system is inherently superior, have been messing with our perfectly good system. Why is a decimal system of measurement better than a fractional one that's easily divides into 12, 64, and 360, evenly. Sometimes decimals are more useful, sometimes fractions are, neither is superior all the time. This same bunch of fools convinced automakers that sideways-mounted engines and transaxles with CV joints that soon have an inch (an INCH, dammit!) of accumulated lash is the way to go. Try to swing a wrench in one of these miserable vehicles!! Good old American cars had the engine here, the transmission there, and the differential back there, so you could work on any of them relatively easily.
Metric system, aargh! I learned to work with it fifty years ago when I raced German Konig outboards, but still don't see a reason we should change. Y'all can change!!:bleh:
There are around 400 million yanks using the standard system. Why should they change?
Mind you, my 1989 Chev pick up (ute) has both standard and metric bolts on it which is a real pain when you crawl under it with a 12mm socket only to find the bolt is 1/2 inch...
Yow Ling
3rd July 2015, 08:16
There are around 400 million yanks using the standard system. Why should they change?
Mind you, my 1989 Chev pick up (ute) has both standard and metric bolts on it which is a real pain when you crawl under it with a 12mm socket only to find the bolt is 1/2 inch...
population of America is 319 million, I guess you must have included the mexicans
jasonu
3rd July 2015, 08:26
population of America is 319 million, I guess you must have included the mexicans
It is hard not to...
HAPPY INDEPENDENCE DAY TO ALL THE SEPTIC TANKS THAT LURK AROUND KB!!!
wobbly
3rd July 2015, 09:10
The reeds opening and thus initiating case inflow is as Frits detailed, dependent upon the pressure differential
across them.
In this typical example that does have critical intake tuning - ie where the intake length is arranged such that as the case goes negative,the bounced off atmosphere
intake wave is arriving as a coincident + wave that opens the petals quickly, there is no significant reed inflow till the transfers are starting to close.
There is certainly no flow around BDC, so this will obviously affect your thinking as to what will be important re shaping the rear of
the liner and piston cutaways etc that are in the way ie the position of the bottom timing edge of the piston has alot more affect on power than do skirt windows
on the inflow of a cylinder reed - as do the shape and area of so called Boyesen ports.
nick gill
3rd July 2015, 15:01
Frits + Wobbly Love your work !!
Thanks for short cutting what would take me a very long time to discover in isolation.
peewee
3rd July 2015, 17:32
wob i got these pistons back finally :Punk:. i think what ill do is cut the sleeves out and put the aux exh ports in then reinstall some new sleeves. pretty sure the casting will pull miles away from the sleeve otherwise
nick gill
3rd July 2015, 17:50
Is that a Blaster Piston Peewee?
I just bought a Banshee piston in 66mm because the compression height suits me better than a blaster. I bought a Namura piston because of all I learned from Jan and Frits - it is cast not forged, skirt coated, and anodised dome to harden it without effecting it thermally. Problem is Namura thought they'd do us all a favour and lighten it by shortening the skirt 10mm to 60mm. Well my stroke is 62mm, so Dang! It will sit on the shelf for years....:weep:
peewee
3rd July 2015, 18:38
the pistons jan and frits used werent made by namura. namura i believe is taiwan or china, i dont have much faith in either place
Frits Overmars
3rd July 2015, 20:52
Namura thought they'd do us all a favour and lighten it by shortening the skirt 10mm to 60mm. Well my stroke is 62mm...Well, maybe Namura (first time I've heard of it) did do you a favour. The skirt length is not determined by the stroke but by the distance from TDC to exhaust port bottom. If you raise that bottom (TZ350 posted lots of how-to pictures) you can use your pistons and you may also be in for a pleasant surprise, power-wise.
Frits Overmars
3rd July 2015, 21:30
I just came across this link in the kiwibiker bucket foundry. It impressed me enough to decide posting it here as well.
http://www.brewracingframes.com/safety-alert-brake-cleaner--phosgene-gas.html
husaberg
3rd July 2015, 21:47
I just came across this link in the kiwibiker bucket foundry. It impressed me enough to decide posting it here as well.
http://www.brewracingframes.com/safety-alert-brake-cleaner--phosgene-gas.html
Frits it looks like its is the chlorinated solvents that are the cause, it seems most brake cleaners now no longer contain them.
Keep Solvents Away From Flames and Heat Do not use or store chlorinated solvents near open flames or excessive heat (such as ovens, furnaces, space heaters, welding operations and pilot lights). When solvent vapors are exposed to extreme heat, they can decompose, yielding highly corrosive or toxic products such as hydrogen chloride, carbon dioxide, carbon monoxide and chlorine, which can create greater hazards than the solvent itself, including metal corrosion in the workplace and toxicity to employees. Under certain conditions such as welding, very low levels of phosgene may form.http://www.dow.com/webapps/lit/litorder.asp?filepath=gco/pdfs/noreg/100-06901.pdf&pdf=true
Frits Overmars
3rd July 2015, 21:55
Frits it looks like its is the chlorinated solvents that are the cause, it seems most brake cleaners now no longer contain them.I don't intend to find out....
husaberg
3rd July 2015, 21:57
I don't intend to find out....
Smells like fresh cut grass apparently. That fresh cut gas smell. I don't intend to be trying to create any either.
41juergen
3rd July 2015, 23:49
About carbon reeds:
Wob I believe you mentioned for using carbon reeds (together with the rev and stopper plates) "take the thinnest you can get".... The thinnest I found is a set of 0.42mm carbon reeds, is that what you had in mind or do you use more thinner material (for a 125 ccm reving to approx. 12.500 rpm)....
cheers
Juergen
Lef16
4th July 2015, 00:18
Hey Wob,as you say the rule of 75% at the exhaust port exit works well with tripple exhaust ports,with oval shape and an oval to round adapter to the header(which starts at full 100% of exhaust port window eff dia).
Does it apply to round exhaust port exit?And then what?A round to round adapter which starts at 75% eff diameter and ends with 100% in the header? And what about its length?
Also,did you try it to single exhaust port,like a lot of production 2 strokes?I dont think that this 75% apply there..
Thank you..
Cheers!
Tim Ey
4th July 2015, 00:57
@Juergen, have a look here:
http://www.lambretta-teile.de/Membranplatte-Polini-Carbon-2-Stk-110x110mm-025mm?ac=polini%20membranp
there are also 0,3 and 0,35mm plates.
@Lef16:
I remember reading about 90% of the Area with a single exhaust port.
I have a question on that topic as well:
313393
This is a picture, stolen from an IAME Homolgation Paper.
Is the reduction allready made in the cylinder, right as the auxiliary exhaustports joins the main?
An other question:
If I got a single exhaust port with 100%, go linear to 90% at the flange, how shall I design the 25mm long adaptor to go back to 100%? Tangential coming from the flange with the upper angle kept straight?
41juergen
4th July 2015, 01:29
@Tim: thank's a lot, I saw them by accident but I'm wondering what the minimum thinkness might be before they might fail under high revs...
FastFred
4th July 2015, 07:25
<iframe width="560" height="315" src="https://www.youtube.com/embed/TsX0nuGCNRE" frameborder="0" allowfullscreen></iframe>
Last lap pass ....
<iframe width="560" height="315" src="https://www.youtube.com/embed/-ZF3l22lIbQ" frameborder="0" allowfullscreen></iframe>
On my Knees.....
Muciek
4th July 2015, 08:55
Question about port angles.
For street use would it be good to use 25*A 10*B (non PV so A 1st then B and C) axial angles or some others would give wider powerband?
Also would it work converting old Yamaha porting (wide A port , small B , A flat , B angled up B ports limited by mounting holed ) into more modern eg A 25* B 10* ?
Here's a picture.
313394
wobbly
4th July 2015, 10:19
I tested a huge number of reed combinations for the SKUSA Stock Honda 125 project I have just completed.
This also revs to 12500 so the result would be similar, but of course depends upon the intake geometry.
I ended up with a 0.35mm top carbon petal with straight cuts between ports.
The bottom petal was 0.295mm and had a 1/2 round reduction in width each side at the clamp point to make it softer.
The backups were 0.35 fibreglass as were the rev plates.
Backups seem to work better with the glass material,as its softer and also has a different natural resonant frequency than the carbon main petal.
I also added a rev plate under the stopper plate as this cannot be cut or modified.
I tried a 0.285 top with a 0.276 bottom ie softer again, but in this case it did pump up the mid by 1.5 Hp, but lost all the very valuable over power
at 12500 I was looking for.
Using backups with a rev plate means there is no issue with soft petals failing due to rev induced flutter.
Re the area guides for 3 port or T port.
In a 125 size the best oval shape was 41 wide by 32 high for the T port, the Aprilia shape works best for a 3 port with 75% area at the spigot face.
Both then need the 100% area at the header start.
For a single port the 90% area works fine with the header the same size, going back out to 100% does not make more power.
Re the old Yamha port setup.The B ports can be widened alot despite the stud holes as these drillings are smaller where the port goes around the corner.
But with no PV the A port at around 25* and stock width, with the B port lower at 10* as wide as you can get it ( watch the ring pins ) will always work alot better
but usually needs welding of the B port roof to get enough material for this angle.
Of course the A port can simply be epoxied up to for the 25* angle.
The boost port is easily re-angled to 55*.
Old model RS125 cylinders had 28* and 15* but I dont know if this really made more mid power or not.
Re the IAME duct.
You can see that the designer has added material to the floor to reduce the area where the Aux ducts are widest, then reduced the ski jump height as it approaches the exit.
This is WRONG.
The Aux ducts should be extended right up to the exit face, making two 1/2 moon shapes on each side, then slowly tapering to nothing inside the spigot as it approaches the header.
This promotes the blowdown flow running down these additional ducts right into the header.
To keep the area down at the exit face the floor should be lifted ( filled in ) to maintain the correct area ratio.
peewee
4th July 2015, 13:31
like wobbly said check the location of your ring pegs. you may or may not need to relocate them depending where theyre at. i just had some relocated and its a easy process for a experienced machinist if you can find one. then again maybe you have the tools to do it yourself.
to add to what wobbly said about reversing the flat A and steep B. once you flaten out the B, you may need some epoxy on the inner wall radius closest to the bore. reason is because often times that inner radius was cast at a steep angle to coincide with the steep outer wall
peewee
4th July 2015, 13:43
I just came across this link in the kiwibiker bucket foundry. It impressed me enough to decide posting it here as well.
http://www.brewracingframes.com/safety-alert-brake-cleaner--phosgene-gas.html
typically its recomended to use acetone for the preweld cleaning of alloy. i have a can in the garage but never bothered to check the ingredients. ill assume it wont make phosegene as im still alive but maybe i should take a look
nick gill
4th July 2015, 16:18
Well, maybe Namura (first time I've heard of it) did do you a favour. The skirt length is not determined by the stroke but by the distance from TDC to exhaust port bottom. If you raise that bottom (TZ350 posted lots of how-to pictures) you can use your pistons and you may also be in for a pleasant surprise, power-wise.
I'd love to Frits, but this particular cylinder is cast iron, or should I say 'pig iron'
Frits Overmars
4th July 2015, 19:19
If you raise that bottom (TZ350 posted lots of how-to pictures) you can use your pistons and you may also be in for a pleasant surprise, power-wise.
I'd love to Frits, but this particular cylinder is cast ironSo?
313417 313423
peewee
5th July 2015, 03:06
frits is that a piece of alloy with small bolts holding it to the exh floor ? i wouldnt mind doing something like the picture to a old sleeved honda cylinder i have
senso
5th July 2015, 05:18
If I recall correctly its an experimental exhaust damn made by TZ.
breezy
5th July 2015, 05:25
Words for today nonsmoking 125cc 2t 70HP @ 17-18k rpm
Here's picture 312083
Frits could shed some light on it , but like he said other place he have a confidentiality clause.
Muciek, after starting this bomb shell, have you been able to find out any more about this engine:sherlock:
Muciek
5th July 2015, 07:00
Not much more , there is their "official" FB I think, https://www.facebook.com/mcd.twist.9/videos/2046265392136991/?pnref=story here is video of running but you can't see much and hear too...
nick gill
5th July 2015, 13:24
So?
313423
Hi Frits.
Yes I have been thinking along these lines for a couple of years actually but I'm a bit too chicken to try it to date.
In fact I was thinking of attempting my own method: plugging the cylinder bore with copper billet bar, then pouring a molten aluminium floor into the cast iron exh port, then retain with high tensile screws as per your image. The cylinder would be rebored and the aluminium dressed away from the rings. I figure that unless its a fantastic fit, eventually a floor plate/stuffer would work loose and 'fukushima' the cylinder.
F5 Dave
5th July 2015, 14:34
If it were cast iron could you not fill it with brazing rod? That's probably more of a question I have no real experience in that area and aren't about to take on iron barrels any time soon.
Grumph
5th July 2015, 16:20
If it were cast iron could you not fill it with brazing rod? That's probably more of a question I have no real experience in that area and aren't about to take on iron barrels any time soon.
Yep, just a case of using the right flux. Some very good nickel bronze rods about now too though historically the original non nickel rods work well on iron.
nick gill
5th July 2015, 21:14
If it were cast iron could you not fill it with brazing rod? ...
In the past my cylinder welding guy said to braze cast iron you'd have to get it cherry red, so the metal has a phase change and the bronze can link interstitialy. He thought this amount of pre-heating could crack the cylinder. I've had iron exhaust ports metal sprayed before, but you can only build up a about 1-2 mm this way and it's more of a crust than parent material.
Frits Overmars
5th July 2015, 22:54
TZ350 did it without any welding or casting. It won't hurt to go back to his descriptions.
peewee
6th July 2015, 05:07
i found the brazing process isnt all that permanent, not much more than epoxy. brazing does have the advantage of being more resistant to chemicals than epoxy but your still not melting the parent underlying material so your bond is relying on surface grip strength.
maybe tz can chime in with how he holds the dam in place. appears to be some screws or something fastening it to the exh floor ?
Grumph
6th July 2015, 06:30
In the past my cylinder welding guy said to braze cast iron you'd have to get it cherry red, so the metal has a phase change and the bronze can link interstitialy. He thought this amount of pre-heating could crack the cylinder. I've had iron exhaust ports metal sprayed before, but you can only build up a about 1-2 mm this way and it's more of a crust than parent material.
Because iron doesn't conduct heat well, it's usually only a local hot spot which gets that hot. I've repaired a lot of fins in my time, successfully too.
As I said, it's finding the right flux to get a good bond on clean metal.
But as Frits says, if you don't want to bronze, fix it in place mechanically.
peewee
6th July 2015, 11:46
wob what you think. should be able to put some nice tea cups in now. lost count of how much filler was used but i think it was somewhere around 7 or 8 rods at 3' x 3.15mm. also took some molds of another cylinder so i have a 3D visual guide on how to make the radius twist on the front side of A as ill do a similar window shape with this other cylinder
wobbly
6th July 2015, 13:36
The brazing I do when building say a Post Classic chassis in chrome molly tube is stronger than the base material when using gas flux
thru the torch.
Any brazing process when done properly becomes a molecular bond - hugely stronger than any epoxys surface grip.
And the dozens of KT100 cylinders that I have seen metal sprayed first on the cast liner, then on the alloy top face to change the deck height
dont have any issues with it "not sticking " either - again if the process is done properly.
Peewee, the cylinder is looking better every post.
I want to see the Engmod results of course before you even think about doing any grinding on it.
Flettner
6th July 2015, 14:58
Not much more , there is their "official" FB I think, https://www.facebook.com/mcd.twist.9/videos/2046265392136991/?pnref=story here is video of running but you can't see much and hear too...
Yes it's all gone a bit quiet. But lets recap, for charge to flow from the crank case to the cylinder at speeds that would normally stall the transfer charge (not enough blow down time) there must be a method of "super" charging the crank case (I don't suggest mechanical) crank case pressure must be increased before transfer takes place. How is this done? That is the key, suggestions anyone.
wobbly
6th July 2015, 17:20
A bottle of Nitrous with a T,one line into the carb the other into Frits helmet.
Thats where all the perceived performance enhancement comes from - easy.
peewee
6th July 2015, 17:52
i hope by the weekend ill be able to start on engmod. still i need to get to the local machinist and have the bore skimmed of all the excess weld so the piston can fit. assuming the rsw drawings are still up to date then i figure i could just make some templates of those transfer wall radiuses and use that somewhat as a guide ?
Frits Overmars
6th July 2015, 22:56
A bottle of Nitrous with a T, one line into the carb the other into Frits helmet.Love you too, Wob. But like you, I prefer a single malt to a draught of N2O.
husaberg
6th July 2015, 23:17
Yes it's all gone a bit quiet. But lets recap, for charge to flow from the crank case to the cylinder at speeds that would normally stall the transfer charge (not enough blow down time) there must be a method of "super" charging the crank case (I don't suggest mechanical) crank case pressure must be increased before transfer takes place. How is this done? That is the key, suggestions anyone.
I also think it must pre-compress the inducted volume to a larger degree, which allows for more actual mass of flow to occur.
It might also allow for some direct flow into the cylinder driven by the inertia and speed of the inrushing pre compressed mixture.(think venture or ram jet)
I still muse it has a variable crankcase size
Frits Overmars
6th July 2015, 23:54
I still muse it has a variable crankcase sizeWith a crankshaft at one end and a reciprocating piston at the other, I dare you to mechanically connect the two without having a variable crankcase size. I don't see a way.
husaberg
7th July 2015, 00:25
With a crankshaft at one end and a reciprocating piston at the other, I dare you to mechanically connect the two without having a variable crankcase size. I don't see a way.
Yes very true :2thumbsup I was meaning being able to vary the size beyond these actual parameters. Thus to be able vary the initial size according to the engine speed.
Yes it's all gone a bit quiet. But lets recap, for charge to flow from the crank case to the cylinder at speeds that would normally stall the transfer charge (not enough blow down time) there must be a method of "super" charging the crank case (I don't suggest mechanical) crank case pressure must be increased before transfer takes place. How is this done? That is the key, suggestions anyone.
It actually can't be the crank case, because it runs on fuel only, no oil mixed. The crank is probably lubricated by that dry sump oil can with the filter on top mounted at the side.
Frits Overmars
7th July 2015, 01:37
I was meaning being able to vary the size beyond these actual parameters. Thus to be able vary the initial size according to the engine speed.That's possible.
313540
Wobbly will no doubt recognize this patent drawing from his hero Helmut Fath. But compared to a conventional two-stroke I would not really call it simple.
husaberg
7th July 2015, 01:57
That's possible.
313540
Wobbly will no doubt recognize this patent drawing from his hero Helmut Fath. But compared to a conventional two-stroke I would not really call it simple.
I was musing something less mechanical more pneumatic as a side note. More in the reed cavity area, more a bypass.
One of the guys that used to work with Helmet was Ferry Brouwer (not sure of the spelling) he allegedly used to remove so much of the rear skirt of the piston on the (I think TR2) that the inlet closing became simultaneous with the transfer opening, this was pre reed days of course. Not sure what would make of the inlet duration or the primary compression on piston ports.
Frits Overmars
7th July 2015, 02:13
One of the guys that used to work with Helmet was Ferry Brouwer (not sure of the spelling)My old mate Ferry spells his name the same way you do, but I doubt if the late Helmut Fath would trade his first name for a headgear description.
Ferry allegedly used to remove so much of the rear skirt of the piston on the (I think TR2) that the inlet closing became simultaneous with the transfer opening, this was pre reed days of course. Not sure what would make of the inlet duration or the primary compression on piston ports.Ferry and I did a lot of silly things. With about 134° transfer timing his piston shortening would give an inlet timing of 226°.
It was not uncommon in those days; Bultaco did it too on their TSS250. Remember: back then the carburettors were tiny by current standards.
A more drastic mod by Ferry was raising the inlet ports until they opened at BDC. That's right: C-transfer ports directly connected to the carbs; no reed interference (but quite a lot of Read interference; dear Phil MBE was not the easiest person to get along with).
seattle smitty
7th July 2015, 04:09
Just catching up here; FWIW, the new, supposedly eco-friendly brake cleaner (comes in a green can, naturally), is acetone: highly flammable, but no chlorine and evaporates fast. Traditional brake cleaner (which is much better for brake work IMHO) still comes in, usually, red cans. Appreciate that link, Frits; hope the poor guy has fully recovered.
Also, somebody commented on my metric system rant quoting my crack about Euro-socialist-yakkety-yak. Hope it was understood that the rant came from occasional minor irritation at mixed measuring systems, and that the crack was made in jest. To be serious, I rather admire the French in particular, as contrarians by nature, and I wish our recent idiot leader from Texas had taken French advice instead of getting us into a two-front war, creating new terrorists by the thousands (and now ISIS) and putting this country deeply in debt to the Chinese . . . (end serious rant).
Foundry story from decades ago: Paid a visit to a tech school where I had taken a couple of quarters of basic machining classes. The instructor said, "Come take a look, we're just getting ready to start a metal casting section and we did a test-pour last night." We went into a side room with some shiny new gear and he handed me a chunk of aluminum. I couldn't even tell what they had been trying to make; the metal was utterly shredded and distorted. I handed it back and went over and picked up a handful of the casting sand. With no experience one might have considered the sand to be dry, but by foundry standards it was soggy! "Steam," I said. This was a classic case of how if you know a very little when the others know even less, you can appear to be a real tech-whiz and cover yourself in glory.:rolleyes:
AndreasL
7th July 2015, 10:23
A more drastic mod by Ferry was raising the inlet ports until they opened at BDC. That's right: C-transfer ports directly connected to the carbs; no reed interference (but quite a lot of Read interference; dear Phil MBE was not the easiest person to get along with).
I have tried to get my head around what happens when having a C-transfer in a non reed engine but cant get any further then its not good...
Or does it have some kind of benefit at all?
AndreasL
7th July 2015, 10:35
Talking about brazing cast iron cyliders.
What do you think is the best method and rod for the job?
A welder I have spoken to was thinking about "TIG brazing" with https://www.castolin.com/product/castotig-45703-w
Pros and cons are welcomend.
husaberg
7th July 2015, 12:42
My old mate Ferry spells his name the same way you do, but I doubt if the late Helmut Fath would trade his first name for a headgear description.
Ferry and I did a lot of silly things. With about 134° transfer timing his piston shortening would give an inlet timing of 226°.
It was not uncommon in those days; Bultaco did it too on their TSS250. Remember: back then the carburettors were tiny by current standards.
A more drastic mod by Ferry was raising the inlet ports until they opened at BDC. That's right: C-transfer ports directly connected to the carbs; no reed interference (but quite a lot of Read interference; dear Phil MBE was not the easiest person to get along with).
Bill Ivy wasn't a fan of Phil.I guess that was mutual though.:girlfight:
I was musing the inlet would have been more degrees with such drastically shorterned skirts.
So according to your last post the conventional reed inlet was not opening until?
The flow velocity from the crankcase to the cylinder will increase as long as the crankcase pressure is higher than the cylinder pressure.
At max.torque rpm the flow velocity reaches its maximum at roughly 10° to 20° after BDC; then the crankcase pressure and the cylinder pressure are equal, and they are also roughly equal to atmospheric pressure. The reed will only start to open when the crankcase pressure drops below atmospheric pressure, so it won't even begin to open until after BDC.
Grumph
7th July 2015, 13:43
Talking about brazing cast iron cyliders.
What do you think is the best method and rod for the job?
A welder I have spoken to was thinking about "TIG brazing" with https://www.castolin.com/product/castotig-45703-w
Pros and cons are welcomend.
I've not used that method personally but I'd guess that better control of just where you're heating and a cleaner working area would make it better overall.
Better than oxy acetylene at least...
Yow Ling
7th July 2015, 17:37
Frits, on the Ryger facebook they write this
"and yes ! we do have 70 bhp and 30k rpm and 80% less emissions....it is the result of 10 years of development and a lot of hard work.
BUT ! it is NOT about rpm or horsepower it is about a clean twostroke engine with superb characteristics !"
Are you able to confirm these are all from the same engine or from several different engines
mr bucketracer
7th July 2015, 18:08
Frits, on the Ryger facebook they write this
"and yes ! we do have 70 bhp and 30k rpm and 80% less emissions....it is the result of 10 years of development and a lot of hard work.
BUT ! it is NOT about rpm or horsepower it is about a clean twostroke engine with superb characteristics !"
Are you able to confirm these are all from the same engine or from several different enginesand also it will last 5 mins:innocent:
Frits Overmars
7th July 2015, 18:46
Frits, on the Ryger facebook they write this: "and yes ! we do have 70 bhp and 30k rpm and 80% less emissions....it is the result of 10 years of development and a lot of hard work. BUT ! it is NOT about rpm or horsepower it is about a clean twostroke engine with superb characteristics !" Are you able to confirm these are all from the same engine or from several different enginesWhen Facebook announced they would disrespect all privacy rules as of 01-01-2015, I stopped logging in, so I haven't got a clue what is going on there nowadays.
I do know that avoiding facebook saves me over an hour, every day, so I do not intend to go back there.
Who wrote the lines you are quoting? If it was Harry Ryger, you can take his word. And yes, the power, the revs and the emission values are all from the same engine.
husaberg
7th July 2015, 22:48
When Facebook announced they would disrespect all privacy rules as of 01-01-2015, I stopped logging in, so I haven't got a clue what is going on there nowadays.
I do know that avoiding facebook saves me over an hour, every day, so I do not intend to go back there.
Who wrote the lines you are quoting? If it was Harry Ryger, you can take his word. And yes, the power, the revs and the emission values are all from the same engine.
Frits has anyone done any work in the field of using the cylinder pressure present (prior to the exhaust port opening) to pressurise the crankcase. two birds one stone.
Frits Overmars
7th July 2015, 23:14
Frits has anyone done any work in the field of using the cylinder pressure present (prior to the exhaust port opening) to pressurise the crankcase. two birds one stone.Not too long ago I posted drawings from the Curtil-patent ( http://www.freepatentsonline.com/4091775.pdf ) wherein cylinder pressure was employed to stimulate transfer. Suzuki tried something similar in their 50 cc RM62 racer, with a B-transfer port that had the same timing as the exhaust port.
I tried to find that post back via the search function and as usual I failed, so you'll have to do the searching yourself, Husa.
husaberg
7th July 2015, 23:49
Not too long ago I posted drawings from the Curtil-patent ( http://www.freepatentsonline.com/4091775.pdf ) wherein cylinder pressure was employed to stimulate transfer. Suzuki tried something similar in their 50 cc RM62 racer, with a B-transfer port that had the same timing as the exhaust port.
I tried to find that post back via the search function and as usual I failed, so you'll have to do the searching yourself, Husa.
In 1962 Suzuki even gave the B-port (there were only two A-transfer ports and one B-port) the same timing as the exhaust port.
312434
I was meaning more modern and perhaps more indirect to keep the pressure but not transfer the unwanted heat.
edit looked at the patent I think I understand it?
Muciek
8th July 2015, 11:32
Re the old Yamha port setup.The B ports can be widened alot despite the stud holes as these drillings are smaller where the port goes around the corner.
But with no PV the A port at around 25* and stock width, with the B port lower at 10* as wide as you can get it ( watch the ring pins ) will always work alot better
but usually needs welding of the B port roof to get enough material for this angle.
Of course the A port can simply be epoxied up to for the 25* angle.
The boost port is easily re-angled to 55*.
Old model RS125 cylinders had 28* and 15* but I dont know if this really made more mid power or not.
Forgot to ask, in this combination B ports should "look" straight at each other or should I try put there some "kicker" so they are pointed downwards at 1/2 bore (no way of doing proper radius because of stud hole).
peewee
8th July 2015, 16:07
Not too long ago I posted drawings from the Curtil-patent ( http://www.freepatentsonline.com/4091775.pdf ) wherein cylinder pressure was employed to stimulate transfer. Suzuki tried something similar in their 50 cc RM62 racer, with a B-transfer port that had the same timing as the exhaust port.
I tried to find that post back via the search function and as usual I failed, so you'll have to do the searching yourself, Husa.
frits have you looked through some of them patents ? all kinds of crazy ideas. pnumatic valves and sliding sleeves over the piston and all kinds of other stuff. http://www.freepatentsonline.com/5205245.pdf
peewee
8th July 2015, 16:38
muciek i think a sharp kicker is not the best idea. besides that, if you look at the drawing frits has posted many times it has the rear wall of B aimed more about 3/4 bore. do you have another photo from the top side to see how long the stud is and where the nut is ? its difficult to say but maybe you can have the tunell go up and then reach over the top of the stud.
Muciek
8th July 2015, 20:29
muciek i think a sharp kicker is not the best idea. besides that, if you look at the drawing frits has posted many times it has the rear wall of B aimed more about 3/4 bore. do you have another photo from the top side to see how long the stud is and where the nut is ? its difficult to say but maybe you can have the tunell go up and then reach over the top of the stud.
Bolt goes from the bottom of cylinder to the top and it uses ordinary nut at the top of the head, not like that special ones from other yamahas. There is approx 3mm between hole and port channel. Aiming for 1/2 I got find in other Wobbly post:
Easy - double the A and B port axial angles.
Move the B port front edge as far forward as you can to make a narrow bridge - and grind it perpendicular to the front/rear axis.
Move the B port rear wall around as far as you can ( limited by the ring pins generally ) and get a hook in there pointing 1/2 way to bore centre.
Frits Overmars
8th July 2015, 20:34
frits have you looked through some of them patents ?Some? Thousands. It's part of the job. You never know when you'll find a gold nugget in the mud. I haven't found many nuggets yet....
Lef16
8th July 2015, 22:14
Hey guys.
I design (amateur) exhaust pipes for a while.
My question is about the temp on the exhaust pipe.Untill now I calculated this number by luck.Do I need an EGT?I think I need one.
However I design an exhaust pipe for a 130cc bike now and for 14000rpm.But the engine is not a full racing engine,so in my mind that means lower temp.
EngMod suggests 500-700c.
I will go 650 for the moment wich makes the tuned length about 740mm..it seems too short to me
What't the way to find the right temp?
Enlightenment please :rolleyes:
Frits Overmars
8th July 2015, 22:53
My question is about the temp on the exhaust pipe.Untill now I calculated this number by luck.Do I need an EGT?I think I need one. However I design an exhaust pipe for a 130cc bike now and for 14000rpm.But the engine is not a full racing engine,so in my mind that means lower temp.
EngMod suggests 500-700c. I will go 650 for the moment wich makes the tuned length about 740mm. it seems too short to me. What't the way to find the right temp?A 130 cc bike won't do 14000 rpm unless it's full-race spec, Lef16. And I assume the 14000 rpm is your maximum rpm, not the rpm of maximum power.
It would also help if you told us what you told EngMod: port timings, areas and directions, compression ratio, ignition timing, that sort of stuff.
For starters you can use the simple concept shown below, where I left out most of the variables I just mentioned. You will only need to enter the exhaust timing
(from your 740 mm I gather that you entered about 180°, but that is way too low for the revs you have in mind) and estimate the speed of sound.
650 m/s will probably be too high, but it will result in a relatively long pipe, so maximum power will be developed at a more moderate rpm that may be in synch with your angle.areas. And once you know where the engine produces its max.power, it's fairly simple to find the actual speed of sound by reverse calculation.
313561
Lef16
8th July 2015, 23:42
Frits all I can say is that the exhaust timing is 203*(I think its low because its an oversquare engine) with 17/1 comp ratio,unfortunately the bike it's not mine,so I can't share info without permission :shutup:
My inptup in EngMod for max power rpm was 14000 and the temperature 650 celsius.
The engine is designed for drag racing but it have some characteristics from the factory that dont help to reach 14000 at all.Maybe I should try something like 13000 or 13500..
Also I dont want a fat pipe because the transfers and crankcase volume is relatively low,so the pipe/engine volume ratio is about 22.5/1.
What wave speed should I start with as a benchmark?
Cheers!
Frits Overmars
9th July 2015, 01:10
The engine is designed for drag racing but it have some characteristics from the factory that dont help to reach 14000 at all. Maybe I should try something like 13000 or 13500.EngMod can tell you what to try; in the absence of relevant data I can only guess.
Think of it this way. A 125 cc state of the art engine produces its max.power at 13000 rpm. Yours has a bigger cylinder capacity, it's short-stroke (undesirable for a two-stroke) and the specific angle.areas probably won't come close to state of the art, so I'd aim for max.power at 11.000 to 11.500 rpm. More revs will only give less power.
What wave speed should I start with as a benchmark?Try 500 to 550 m/s.
But I wonder: you say the engine is designed for drag racing, but earlier you wrote 'the engine is not a full racing engine'. They don't come any fuller than drag racing...
Lef16
9th July 2015, 04:11
The engine is designed for drag racing but as I say earlier it have some disadvantages like small transfer port and crankcase volume from the factory.You can increase that volume but still you're under some restrictions from the engine manufactor!
Also,I don't say that it will make more power than the Aprilia's(I would be crazy if I told so)..not even close.But because it is an oversquare engine at 14000rpm the piston velocity is less than 25m/s so I think it's possible with this speed,but maybe unpossible from the port anle/areas......
The pipe looks like Honda-KTM-Derbi style in Motogp,but with steepest angles in the header and first diffusor,and relatively smaller baffle(~115mm) than it should(?),because im thinking that bigger diameter here and bigger volume won't cooperate with the small(and maybe not with the right direction) tranfer ports.
seattle smitty
9th July 2015, 04:32
I have read of tuners looking for evidence (burned paint, etc.) of the hottest point on the header pipe, as a guide to estimating wave speed. I wonder if you could do this sort of thing using the temperature-graded indicators that welders use. One company that has made these products for years is Tempil, and they have wax crayons with which you mark a line on your metal, and when it reaches the selected temperature, the wax liquefies. They are accurate to plus or minus 25F degrees (and are also marked for Celcius); I believe the same company also has a paint-on indicator substance, but I've never used that. The crayons are inexpensive, and maybe you could have a set of them with different target temperatures for various tuning purposes. (The only race-engine-related use I've ever used one of these temp-sticks for was pre-heating an old cast iron Konig outboard cylinder for welding, long ago).
Frits Overmars
9th July 2015, 04:38
...because it is an oversquare engine at 14000rpm the piston velocity is less than 25m/s so I think it's possible with this speed, but maybe unpossible from the port angle/areas...That's right. Piston velocity is not a limiting factor in a two-stroke; angle.areas are. And oversquare, or short-stroke engines are at a disadvantage.
Imagine an engine with a bore and stroke of 40 x 40 mm. Make the bore twice as big, and all port widths can be doubled. But doubling the bore means that the stroke has to be made 4 times smaller in order to keep the cylinder capacity unchanged. And dividing the stroke by 4 means that for a given timing all ports will become 4 times lower. So all port areas and angle.areas will be halved! That low piston velocity won't do you any good...
Frits Overmars
9th July 2015, 04:54
I have read of tuners looking for evidence (burned paint, etc.) of the hottest point on the header pipe, as a guide to estimating wave speed. I wonder if you could do this sort of thing using the temperature-graded indicators that welders use.No way Smitty. Those indicators will tell us the outside temperature of the pipe, not the temperature of the gas inside, which can be hugely different.
One lifetime ago I worked on pipe lines so I'm not unfamiliar with pre-heating high-grade steel pipes prior to welding.
I'll admit I did 'borrow' those indicators for use on crankcases, brake drums, etc, but never on exhaust pipes.
seattle smitty
9th July 2015, 05:02
Can you use any of the commercially available air-fuel O2 meters with crankcase-lubricated 2-stroke race motors, or does the lube confuse (and foul) the sensor too quickly? I just got one of these (from Innovate) to dial-in automotive engines.
Haufen
9th July 2015, 05:05
That's right. Piston velocity is not a limiting factor in a two-stroke; angle.areas are. And oversquare, or short-stroke engines are at a disadvantage.
Imagine an engine with a bore and stroke of 40 x 40 mm. Make the bore twice as big, and all port widths can be doubled. But doubling the bore means that the stroke has to be made 4 times smaller in order to keep the cylinder capacity unchanged. And dividing the stroke by 4 means that for a given timing all ports will become 4 times lower. So all port areas and angle.areas will be halved! That low piston velocity won't do you any good...
I am wondering why all these racing engines are "only" square and not long-stroke. What do you think?
Muciek
9th July 2015, 05:40
I think this answers Your question
Dont need to spend hours trying to get the numbers to work in the sim
The short stroker is capable of mechanically going to 15,500 @ 26M/Sec but the port STA is simply unable of supporting any power up there.
Yamaha tried forever to make it happen, but finally gave in with a square engine and won the 250 title with Olivier Jaques around 2000.
Going the other way the 52 by 58.5 is able to generate the STA needed but with the longer stroke is only capable of 13500 rpm absolute peak rpm
whereas the square engine runs out at 14500 when stressed to 26M/sec mean piston speed, as has been proven to be reliable with an Aprilia.
The extra 1000 rpm would easily blow away an equally tuned setup simply due to the gearing torque available for an equal terminal speed.
Frits Overmars
9th July 2015, 06:16
Can you use any of the commercially available air-fuel O2 meters with crankcase-lubricated 2-stroke race motors, or does the lube confuse (and foul) the sensor too quickly?313564
Provided that you don't mount it too close to the cylinder, where it would be hit by washed-through unburnt mixture (between the cylinder and the sensor there should be room in the header for at least once the cylinder capacity), that you use only unleaded fuel, and that you switch on the sensor's internal heating element and bring it up to working (=self-cleaning) temperature before starting the engine.
breezy
9th July 2015, 06:42
I am wondering why all these racing engines are "only" square and not long-stroke. What do you think?
didnt it used to be something about pisiton speeds? although with todays better quality materials perhaps thats no longer a problem. better torque but poor rpm levels?? although a friend of mine noted a recent moto cross engine ( may have been ktm 125) had a longer stroke but produced good power.:sherlock:
Haufen
9th July 2015, 07:01
I think this answers Your question
Well, as Frits just recently mentioned that piston velocity is NOT a limiting factor (any more?), there should be nothing in the way of going from square to long stroke for hunting max hp figures, or is it?
breezy
9th July 2015, 07:47
Yes it's all gone a bit quiet. But lets recap, for charge to flow from the crank case to the cylinder at speeds that would normally stall the transfer charge (not enough blow down time) there must be a method of "super" charging the crank case (I don't suggest mechanical) crank case pressure must be increased before transfer takes place. How is this done? That is the key, suggestions anyone.
May be exhaust returning wave, which stuffs fuel back via the exhaust port, also effects a transfer boost port via a reed valve to increase the cylinder filling?
breezy
9th July 2015, 08:44
Well, as Frits just recently mentioned that piston velocity is NOT a limiting factor (any more?), there should be nothing in the way of going from square to long stroke for hunting max hp figures, or is it?
"Shrinking the bore and increasing the stroke provide more opportunities for favorable compromise, but doing so requires exotic materials if the 18,000-rpm revving ability is to be maintained"
this passage was taken from a web site talking about 4 stroke ferrari f1 engine... so it looks like longer strokes are know less piston speed hinderd..
peewee
9th July 2015, 15:36
frits maybe im wrong on this but isnt the port timing of a modern 2t engine mostly useless numbers as its only the point where the window opens and closes relative to crankshaft degrees with no regard to time area or angle area ? you could have a tall window and still a small angle area
was there ever a usa 2t racing team worth mentioning ? it seems as if the usa tuners are 100 miles behind the rest of the worlds tuners. advancements in recent 2t development dont seem to be associated in any way with usa. im trying to think of one thing they could take credit for. even with some fairly modern designs like ktm to look at, they seem oblivious to the fact they could apply some of those ideas to older engines. maybe they like being stuck in 1980 with short rods, over sqaure pistons and small crankcases :laugh:
F5 Dave
9th July 2015, 16:27
was there ever? Well the evil empire & of course Erv could hold their heads up at the time.
wobbly
9th July 2015, 16:31
As Frits has alluded to you can use a Lambda in a 2T.
I have been using one for ages on the dyno that screws into a fitting on the front of a muffler cap.
It must be pre heated before use and will be killed quickly by lead, or being covered in oil as when warming up or running in slowly.
But at the end of the day an egt will tell you all you need to know about whats going on, including things the A/F ignores like deto onset.
You simply cant use any info from 4T sources and try to translate this to a 2T scenario.
A 4T can easily be rpm limited by materials technology, but this has been helped alot in recent times by the short strokes NEEDED to allow a big bore to fit in
the huge valve area requirement for the power predicted.
A 2T is much more limited by the bore size and the area that can be fitted into that specific circumference,and THEN becomes limited by the mechanical issues of exceeding the 26M/Sec
that has become the currently accepted allowable max mean speed.
This is why a 50.6 stroke in a 125 is just as flawed from the outset as a 58.5 for the reasons I outlined in the quote shown above.
Yes, quoting port timing is a completely useless exercise without the analysis needed to compute the STA available - as this takes into consideration all the
important variables of swept vol/time/area
There are plenty of examples of well engineered USA engines we hear little about, in the SKI sports for example.
But most companies are dealing with aftermarket add ons to existing very flawed designs, the Banshee being the best example where say CPI produce exquisitely done
castings that do have square bore/stroke setups available, but usually cater for the Yank obsession with " if in doubt - bore it out " huge customer base.
And if you want to look deeper, of course you can't go past the efforts that the Roberts Team went to when trying to drag Yamaha GP kicking and screaming into new technology for
Wayne R to win races and titles.
They were one of the first to use the Czech flow visualizing technology that Yamaha finally got on board with when it was all too late in early 2000s.
husaberg
9th July 2015, 16:40
was there ever? Well the evil empire & of course Erv could hold their heads up at the time.
That Bud Aksland did all right, surprised you forgot about him Dave.
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Center of the Pic, propping up Kenny Roberts.
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peewee
9th July 2015, 17:17
unfortunatly i reside in the land of yanks but want no part of their ' in doubt bore it out mentality'. for pete sake theyre still using 115 rods on 64mm crankshafts. dont bother trying to tell them any different as they wont hear of it
anyways on to something worth talking about. pretty sure it was frits who posted this some time ago. does anyone know something about it ? looks like a great idea but why dont we here more about it http://www.zeroshift.com/
husaberg
9th July 2015, 17:38
unfortunatly i reside in the land of yanks but want no part of their ' in doubt bore it out mentality'. for pete sake theyre still using 115 rods on 64mm crankshafts. dont bother trying to tell them any different as they wont hear of it
What size is that KTM again?:whistle:
peewee
9th July 2015, 17:54
i reduced the bore 3mm and lengthened the conrod 4mm :niceone:. far as i know theres no longer conrods available to the public
husaberg
9th July 2015, 19:49
i reduced the bore 3mm and lengthened the conrod 4mm :niceone:. far as i know theres no longer conrods available to the public
Kawasaki KX500 is a tad longer and I think the Husky rod is longer again, assuming you are using the CR500 rod.
It still started life as a KTM550.:2thumbsup
F5 Dave
9th July 2015, 21:43
That Bud Aksland did all right, surprised you forgot about him Dave.
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Center of the Pic, propping up Kenny Roberts.
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I thought i did by association. Evil Empire being Kennys crew.
husaberg
9th July 2015, 21:48
I thought i did by association. Evil Empire being Kennys crew.
Isn't that HONDA crowd normally the evil empire.
F5 Dave
9th July 2015, 22:28
That was later but for a while Kenny's team had all the best riders and most cancer stick money, biggest transporters etc hence the pit moniker. Or so the magazines put it. I of course wasn't there.
Frits Overmars
9th July 2015, 23:47
frits maybe im wrong on this but isnt the port timing of a modern 2t engine mostly useless numbers as its only the point where the window opens and closes relative to crankshaft degrees with no regard to time area or angle area ? you could have a tall window and still a small angle area.If the timing of a port would be a useless number, then so would be the port width, wouldn't it? I'd say neither is useless, but only together are they meaningful.
was there ever a usa 2t racing team worth mentioning ? it seems as if the usa tuners are 100 miles behind the rest of the worlds tuners. advancements in recent 2t development dont seem to be associated in any way with usa. im trying to think of one thing they could take credit for. even with some fairly modern designs like ktm to look at, they seem oblivious to the fact they could apply some of those ideas to older engines. maybe they like being stuck in 1980 with short rods, over sqaure pistons and small crankcases :laugh:There are quite a few capable two-stroke specialists in the USA but their names are not generally well-known, as opposed to the 1970s and 80s when we had Erv Kanemoto (100% American in spite of his oriental-sounding name), Kevin Cameron (still a highly appreciated technical editor), Don Vesco, Bob Work, Kell Carruthers (originally an Aussie who became chief whip in Kenny Roberts' team after having been a 250 cc world champion himself), Bud Aksland, and many others.
seattle smitty
10th July 2015, 05:04
unfortunatly i reside in the land of yanks
So sorry for you . . .
AndreasL
10th July 2015, 09:02
I've not used that method personally but I'd guess that better control of just where you're heating and a cleaner working area would make it better overall.
Better than oxy acetylene at least...
Thanks Grumph!
2T Institute
10th July 2015, 11:27
was there ever a usa 2t racing team worth mentioning ? it seems as if the usa tuners are 100 miles behind the rest of the worlds tuners. advancements in recent 2t development dont seem to be associated in any way with usa. im trying to think of one thing they could take credit for. even with some fairly modern designs like ktm to look at, they seem oblivious to the fact they could apply some of those ideas to older engines. maybe they like being stuck in 1980 with short rods, over sqaure pistons and small crankcases :laugh:
There are some very good US 2T tuners like not that well known like Eric Gorr, then there are the slippery "salesman" types like Pro Circuits Mitch Payten, who still knife edges transfer dividers and charges as much as a small family car.
Erv Kanemoto was as good with frames and fabrication as he was with tuning engines.
peewee
10th July 2015, 12:58
Kawasaki KX500 is a tad longer
yes 1mm but if i recall it has a odd wristpin at 19mm where as the honda is 20mm and it just so happens the honda piston fits right in the 500 ktm cylinder. the last husky 500 i know of was around 1987 or so. parts must be rare as hens teeth by now.
It still started life as a KTM550.:2thumbsup
it may have started there but it ended somewhere else :Punk:. the aux exh ports poped open under the piston at tdc, the rod and piston were very short, case ratio around 1.5:1 from what i remember. i dont know why anyone would bother with those headaches
back to the 'when in doubt bore it out' theme for a moment. those same yanks might be the only folks selecting fuels based on static cylinder pressure. i thought about it a few times and couldnt find any connection between fuel type and cylinder pressure at 300rpm. last i heard, compression gauges were used when buying second hand cars :laugh:
2T institute, most everyone over here is still knife edging all the dividers, yes even the yamaha twin cylinders. dont ask me why as i have no answer
jonny quest
10th July 2015, 14:10
Angle areas are not the limiting factor in a two stroke. Friction is.
F5 Dave
10th July 2015, 16:02
Ahh well you need to use Amsoil
(1200 pages & I'm going to crash it now by turning it into the dreaded oil thread:innocent:)
Here come the zealots, run!!
husaberg
10th July 2015, 16:11
Angle areas are not the limiting factor in a two stroke. Friction is.
Here is me thinking it would be thermodynamics or physics.
peewee
10th July 2015, 16:18
didnt wob say one time the piston skirts fell off after using amsoil :laugh:
Grumph
10th July 2015, 19:56
Here is me thinking it would be thermodynamics or physics.
Nah, the only limitation is money....The laws of thermodynamics and physics can both be at least bent a little given sufficient money....
F5 Dave
10th July 2015, 22:18
I hereby recant my sins and only prescribe apricot oil.
At 70:1
Continue.
Frits Overmars
10th July 2015, 22:31
Angle areas are not the limiting factor in a two stroke. Friction is.Care to enlighten us Jonny?
Haufen
11th July 2015, 03:59
That's right. Piston velocity is not a limiting factor in a two-stroke; angle.areas are. And oversquare, or short-stroke engines are at a disadvantage.
Imagine an engine with a bore and stroke of 40 x 40 mm. Make the bore twice as big, and all port widths can be doubled. But doubling the bore means that the stroke has to be made 4 times smaller in order to keep the cylinder capacity unchanged. And dividing the stroke by 4 means that for a given timing all ports will become 4 times lower. So all port areas and angle.areas will be halved! That low piston velocity won't do you any good...
Would you be so kind and share your thoughts regarding long-stroke racing engines with us, Frits? Wobbly already did, and I would be very interested to hear your opinion on this subject, too.
Personally, I think a longer stroke RSA would have had the potential for even more hp, and the increased piston velocity would not have been much of an issue.
jonny quest
11th July 2015, 05:06
How much angle area is lost with a longer rod? How much power is gained by less side loading of longer rod?
Frits Overmars
11th July 2015, 05:25
Would you be so kind and share your thoughts regarding long-stroke racing engines with us, Frits? Wobbly already did, and I would be very interested to hear your opinion on this subject, too. Personally, I think a longer stroke RSA would have had the potential for even more hp, and the increased piston velocity would not have been much of an issue.Increased piston velocity would have been no issue at all in the RSA; the crankshaft was bulletproof.
There have been experiments with a smaller bore for the RSA, but only with 52,8 mm instead of 54 mm, because the special small-bore piston had to be made out of a standard forging. Making a special piston forging was considered too expensive (in a period where millions of euros were wasted on development of the three-cylinder foul-stroke MotoGP engine).
Changing something in a highly-developed engine will almost invariably lead to a power loss and it will take quite some development to establish whether the change was worthwhile, but Jan Thiel did not get the opportunity to carry out this small-bore development because it was aborted by the Great Leader when there was no immediate improvement.
I expect that at the very least the axial scavenging angles would have to be adapted to the altered bore/stroke-ratio.
seattle smitty
11th July 2015, 05:49
With the port contours and entry angles optimized for the "square" engine, wouldn't you expect to have to revisit those contours and angles to get the most out of the smaller bore? In other words, maybe the engine that is somewhat undersquare would ultimately work even better than the square version but only IF there was the same painstaking development program specifically for it. This is something that makes me wonder whether all the folks who are trying their best to reproduce Mr. Thiel's ports in engines with different specifications might not quite get the results they hope for. To reproduce his results in a non-identical engine, I'd think unless you got real lucky you'd have to reproduce his development program: long hard labor by someone who knows what he's doing. No free lunch, alas.
Frits Overmars
11th July 2015, 06:03
Angle areas are not the limiting factor in a two stroke. Friction is.
Care to enlighten us Jonny?
How much angle area is lost with a longer rod? How much power is gained by less side loading of longer rod?I was really hoping you'd give us an answer Jonny, instead of reverberating a question that I already answered: http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1207?p=1130874798#post1130874798
jonny quest
11th July 2015, 07:52
I mentioned that rod length because you gave up angle area. If a 2 stroke is angle area limited. .. why give any of it up?
Piston skirt friction is in the area of 20 to 30%, around 10% for rings, around 15% for crank bearings.
Will you gain 50% more power with ultimate ports?
wobbly
11th July 2015, 09:36
I think we have two streams of thought going concurrently.
There would appear to be NO reason at all to not run a long rod, well above 2:1 ratio, as its been proven that the tradeoffs between friction/case vol/angle area are
biased in favour of the longer version.
Aprilia did it for years, then Honda decided they agreed and went longer on the final champ winning RS250 going from 105 to 109.
The other issue is that there "could" possibly be an argument that a slightly undersquare engine might ultimately prove to be superior to the current accepted practice
of "square is best".
But this argument really is moot for anyone on this forum, as no one has the time/money/need/or knowledge to prove this one way or the other in anything like the detail needed
to make a water tight conclusion.
First you would have to replicate ( or improve upon ) the result gained by Jan Thiel with a square engine ( yea dream on ) to prove that you actually knew what you were doing
and then go into the same micro details of the small bore engine with the resources that 100 R&D employees at Aprilia had.
Only then could anyone say with any conviction that the theoretical advantage of a slightly improved angle area Vs the reduced rpm capability of the longer stroke was a trade off worth pursuing.
As it stands it HAS been conclusively proven that with our current knowledge " square is best ".
Proving otherwise is simply not going to happen in our lifetime, so discussing it in any detail thinking this might have some relevance to buckets or any other minor racing class I think is a waste of energy.
Ive just spent 3 days on the dyno testing air filters and mufflers,and gained 2.4Hp in 40, changing nothing else - thats not a waste of energy, as no theoretical musing with no useful end use is involved.
twotempi
11th July 2015, 10:51
"There would appear to be NO reason at all to not run a long rod, well above 2:1 ratio"
Is there a reasonable upper limit for this.
A Yamaha TA125 has a stroke of 43mm and a rod of 98mm which gives a ratio of 2.28 although I think this was more of a dimensional "make things fit" decision rather than a technical design one.
What other engines have a high rod to stroke ratio ??
breezy
11th July 2015, 18:35
"There would appear to be NO reason at all to not run a long rod, well above 2:1 ratio"
Is there a reasonable upper limit for this.
A Yamaha TA125 has a stroke of 43mm and a rod of 98mm which gives a ratio of 2.28 although I think this was more of a dimensional "make things fit" decision rather than a technical design one.
What other engines have a high rod to stroke ratio ??
the mighty" BSA BANTAM 125" 58mm stroke 125mm conrod;)
breezy
11th July 2015, 18:42
Here is me thinking it would be thermodynamics or physics.
husaberg, have you come across any 2 stroke engine designs that in corporate reed controlled transfer ports, with the transfer ports high in the cylinder above the exhaust port/s. transfer ports connected directly to the inlet and not through a crankcase?:sherlock:
husaberg
11th July 2015, 18:42
the mighty" BSA BANTAM 125" 58mm stroke 125mm conrod;)
The villiers as well but to be fair the poms needed such long rods because the piston skirts were so long and the piston pins so low.
The cooking MZ's had very long rods as well.
husaberg, have you come across any 2 stroke engine designs that in corporate reed controlled transfer ports, with the transfer ports high in the cylinder above the exhaust port/s. transfer ports connected directly to the inlet and not through a crankcase?:sherlock:
I may have yes, but I am not at liberty to divulge where.
breezy
11th July 2015, 19:04
Wobbly, would you think that if transfer ports could be controlled at the cylinder/face/ wall( reed type valve) that having the transfer ports high in the cylinder would enable the filling of the cylinder to be more efficient, using the the opening of the exhaust port to both expell combusted fuel and pull a fresh charge in behind it, with the transfers being open to atmospheric pressure while open? could this lessen the amount of fresh charge being pulled straight out the exhaust port as in the way transfers are positioned in the cylinders we have now? with this in mind if the piston was used only to compress the fresh charge and was not using the return to bcd to influence the goings on below wouldnt this enable the piston to move more freely?
TZ350
11th July 2015, 20:55
Page 1230 ......
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ESE's number 1 works rider has scored herself a ride at Suzuka on board this Beast, moonlighting must be ok
Ken Oconnor racing has a good video on rebuilding tin can cranks,he cuts the rod and pin in half for easy removal..
https://www.youtube.com/watch?v=hs5Au5rrlUw
Compression Ratio
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TeeZee I dont understand why you would spec a combustion chamber with a huge squish - 0.8mm when 0.65 is fine.
And no squish width, that gives no squish velocity at all at 18.7M/Sec - this is just throwing away alot of power everywhere in the useable band.???.
As the Ex height has a big influence upon the trapped dynamic com, I use the trapped ratio. For your air cooled 125 on AvGas a ratio of 7.4 will work reliably no matter where the port is.
Here is the output with the Ex at 82*, double the squish velocity, and near on the same pumping pressure prediction.
Wobbly, can I assume the trapped ratio you refer to is the CR calculated from exhaust closing rather than the simple geometric CR based solely on swept volume?
If so, do you have a guideline for a water cooled 100 on 98 pump gas?
The trapped ratio takes account of radical differences in Ex port height, but when dealing with your normal race engines the Ex port is usually in a fairly small window of timing.
Thus your 100 on Avgas could quite happily go around 16.5 full stroke CR (geometric CR based solely on swept volume), 98 pump would be pretty much maxed out at 15.5.
Exhaust port Duct length and Shape.
The optimum transition length. There will be a direct relationship to how long the well cooled duct wall is, to the length of the A/F slug sitting outside the port waiting to be shoved in by the returning wave front.
All I can say is that in any normally dimensioned cylinder we usually end up with a duct and spigot around 2X bore length, and that a slip joint
spigot is usually around 1/2 bore - and that works.
Technically correct as Frits has pointed out, would be to derive a relationship between duct exit area and the blowdown needed to develop the target bmep. But in any scenario keeping the duct volume down by lifting the floor and filling in the bottom corners, then restricting the exit and connecting that to a transition WITH NO STEPS will make better power than any other solution that has actually been tested to date.
This has been playing on my mind I couldn't reconcile this with what I had read about not removing the step in the exhaust duct. Why would the A kit not have the step if it's supposed to reduce power. Clearly I don't properly understand the function of the step.
313615313616
So I went back and tried to connect the dots from the bits I remembered from the ESE thread: so no steps at the flange is better, so why does the NX4 RS125 lose power when the steps are cut out? Is this a function of the duct entry to exit ratio changing?
Step or no Step in the exhaust duct.
For anyone still wondering about steps ( or not ) in the Ex or if a race plug is worth buying then this dyno sheet should give you the idea.
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Green is a straight round spigot with steps, brown is a CNC oval/round transition,red is the same transition but replacing the R7376-10
plug with what is commonly used alot in USA, a BR9EIX.
The transition needed 2 jets leaner to hit the same 650*C egt in the tests. It might cost 4X the price but the race plug is the cheapest 1Hp gain in a box stock engine you can buy.
Fancy Plugs.
The plug result just confirms that having a rare earth fine wire center AND a fine wire platinum ground electrode makes the ignition power required to initiate ionization under heavy compressive loads is way less with the race plug , when compared to the simple iridium plugs cast iron plank hanging off the side of the body. The dyno doesn't lie - check the overlay at the bottom of the curves, near as damn it identical in the range where the plugs efficiency makes no difference.
This 125 engine only just cracks 40Hp so isnt really stressing the conventional ignition that much, but as soon as things get tough the good plugs configuration makes a difference.
A low bmep engine with rezo spark would as you say make bugger all difference, as it simply doesnt need the extra grunt. When you really stress the hell out of the system, as in the Aprilia where simply changing to a bigger coil made more power, or when running big com on rich methanol engines the power difference can be really worthwhile. Ages ago my best TM125MX kart engine went up 2Hp to around 50 when changing from a BR10EGV.
So here it is as simple as can it be made - NO STEP IS BEST - but this does NOT mean grind the duct to make it round OR bigger in any way.
If its a 3 port or a T port, then the duct exit should be around 75% of the total effective Ex area, then the spigot should transition to 100% round diameter.
If its a single port, the duct should be around 90% exit area, with no step and the header the same diameter if its round. If you have a really dumb 3 port or T port with a round exit, THEN CHANGE IT.
Re the angle area of the RSA. The answer is all to do with finely balancing all the variables to optimize the end result. Do you REALLY think that if going to 204* was actually better then why the hell wouldnt Jan do exactly that. We have had the same question on here about the pipe dimensions,why not simply make it shorter and fatter, well if that was better do you really think that it would not have been done.
I have been running thru pipe designs for a 250 KTM for a road racing kart, and discovered in the sim that going over 132mm belly diameter makes
NO MORE power.
The cylinder pressure at exhaust opening can be as high as 7 bar,
Maybe Jan was under the thumb somewhat with the pipes, but still they were up to Tubo 120 or something so plenty of experimental ideas were a failure.
But something he did say was that they didnt pay enough attention to the changes in fueling when trying out the new pipe ideas. In that many pipes with changes to dimensions made little difference, but may have been better/worse if the carb tuning was strictly optimized to suit.
I have taken this onboard and find now that I need to change jets for nearly every single small change in any part of the engine, just to get back
to my baseline peak power egt on the dyno.
Re the KTM road racing pipe. My best pipe so far has a diffuser end ( belly front ) of 135 diameter and a rear cone diameter of 132.
Going up to 138 with either steeper diffuser angles, or a shorter or longer rear cone to suit, was always within no more than 1.5Hp everywhere across the powerband. Sometimes a bit more down low and less on top or visa versa.
The 135/132 has the best average everywhere, and as these things have a wide spaced MX gear ratio split with something like a 1500 rpm drop when running to 10800 and selecting 5th, the front side power slope is just as important as the overev.
As I have stated before I believe that we have finite energy available from the advancing wave front, and in this case the best result I could get from the engine involved a slightly steeper diffuser, but as soon as I shortened/lengthened ( reangled ) the rear cone I lost power - thus I ended up with a slightly tapered mid section just as the Aprilia had.
Hello guys Frits has already explained about port directions and axial angles.
Aprilia A-ports had about 28* axial angle and B ports had 7*.What about the opposite?
I was watching old Yamaha cylinders (B ports directed upwards and A ports are perpendicular) I was wondering what effect will these axial angles have with A ports having more duration (no exhaust power valve). Cheers!
All latest generations of engines with normal stagger ( A port first ) have the same axial relationships as the Aprilia.
Flat A ports are long dead.
Welding the roof corner is needed in the Yamaha B port to flatten it out as it goes into water, the A port simply needs epoxy
to fill in the top radius and increase the upward tilt.
The C port is always in the 50 to 60* range, depending upon the end use, the bore/stroke, and the port width in relation to the B width.
Crank pins and Mallory metal plugs.
The alloy plugs cant be weld retained ( but several pressed in dimples on the circumference helps ) so i press them in with around 0.03 to 0.05mm interference. The Mallory inserts can be retained by simply melting the crank material into the plug in a couple of opposite arcs on each side, so the press fit can be reduced to 0.01 - 0.02 . You have to be careful with this as I have had a crank web split out from the Mallory hole, to the wheel circumference ,as the press fit was too tight due to the plug being slightly oversize.
Welding of the center axle on twins is often needed - " advised " when there are two press fits on top of each other as we see in rebuildable RD/RZ/Banshee cranks. The inner press fit simply expands outward into the hole for the big end pin. This prevents the two inner wheels from turning in relation to each other and wreaking the phase, but usually this only occurs with a seize on one side.
Cranks like RGV and Aprilia etc have integral pins on the inner wheels so should not need welding of the axle if the press is sufficient.
If the big end press fits are not correct then welding is sometimes the only way to keep them true - but is really butchery of the first order.
Interesting thing to do! I once fitted a tungsten insert that started moving in the crank, by deforming the edge of it with a center punch.
Sorry for my curiousity but I really do not like to weld on cranks: Has anyone a hint how high I must go with the press fit without using any special tricks? :innocent:
For some Numbers: I just got my calculater working:
The Force of my tungsten insert will be 16,2KN @ 15000RPM (WOW!)
Incredibly high - perhaps I calculated it wrong...
Radius of the Center: 32mm
Diameter of the Tungsten: 22mm
Space to the edge of the crank: 3mm (is this enough?)
Space to the neighbouring Tungsten: 2,5mm (same question here)
Cheers!Tim
Having any sort of working press fit in a flywheel that has ANY hole only 3mm from the circumference is simply asking for failure to occur. Simple rule of thumb for this is that TWICE that is needed.
All that occurs with insufficient material is that if the core of the wheel is still under say RC40 hardness the hole will elongate outward to the wheels circumference and the press fit goes away - if the core is any harder the material will split outward from the hole.
Several USA tuning firms have done stroker cranks for Jetskis with only 4mm and they explode continually, even with only intermittent use as in Freestyling. They botched the problem by welding them initially, but later they got a bit cleverer and made eccentric pins,and welded those - still a dumb solution.
It is FAR better to have a light fit in your Mallory and tig melt a couple of small arcs of weld for retaining it, than having to use any excessive press that automatically creates a stress concentration.
chrisc
11th July 2015, 22:12
This has been playing on my mind from a comment that you made to me via pm Wobbly:
Also the [Honda RS125] A kit Ex manifold was the same as the later 250 with an oval to round transition in the flange, no step at the cylinder face.
I couldn't reconcile this with what I had read about not removing the step in the exhaust duct. Why would the A kit not have the step if it's supposed to reduce power. Clearly I don't properly understand the function of the step.
313615313616
So I went back and tried to connect the dots from the bits I remembered from the ESE thread:
Peewee, you are of course going to be tig welding the inside of the steel spigot to grind and match it to the duct exit shape,
by making an oval to round transition - yes.
is the roof and floor of the manifold supposed to flat like the cylinder exit ? i was just going by how the rsa looked.
Yes, you need to shape the manifold floor/roof as per the exit, and this shape as well as the side port ducts need to taper
down smoothly all the way to nothing at the face where the header starts. I have tested this numerous times and a proper oval to round transition always makes more power than having the steps.
ok so the manifold floor and roof should match the exh exit, no steps. then transition to round at the exit of the manifold. got it :niceone:. i hate to even ask but why was the rsa125 not that same way ?
The RSA indeed had steps at top and bottom of the cylinder/manifold junction; something to do with evolution I'd say, like why men have nipples. But I am with Wobbly on this one. Moreover, the RSA's exhaust port shape as it has become known through the numerous pictures, is not the latest version; the final version had the port floor raised even higher.
So no steps at the flange is better, so why does the NX4 RS125 lose power when the steps are cut out? Is this a function of the duct entry to exit ratio changing?
Frits Overmars
11th July 2015, 22:14
I mentioned that rod length because you gave up angle area. If a 2 stroke is angle area limited, why give any of it up? around 10% for rings, around 15% for crank bearings. Will you gain 50% more power with ultimate ports?"Why give any of it up?" is the mentality that wins races, so I had to look into your point of view, Jonny.
As I wrote earlier, shortening a 120 mm con rod to 100 mm gives 2% more blowdown angle.area and 2,9% more transfer angle.area.
The shorter rod gives about 26% more friction. That seems like a lot until you realize that at 90° before & after TDC a 54,6 mm rod would stand almost perpendicular to the bore in an engine with a 54,5 mm stroke, and give almost infinitely more friction.
Ring friction and bearing friction won't be heavily influenced by the con rod angle, and I can go along with a piston skirt friction in the area of 20%.
If this 20% is augmented by 26%, the piston skirt friction will become 25,2%, so the total friction loss in the short-rod engine will be 5,2% more.
That engine can rev 2% higher because of the increased angle.areas, which is not enough to compensate for the increased loss. Dammit Jonny, you are right.
Moreover, the short rod decreases the crankcase volume (OK, that can be compensated somehow) and the increased piston friction will mean an increased engine temperature, which will cause a secondary power loss. How much? Hard to say :rolleyes:.
Frits Overmars
11th July 2015, 22:26
I couldn't reconcile this with what I had read about not removing the step in the exhaust duct. Why would the A kit not have the step if it's supposed to reduce power. Clearly I don't properly understand the function of the step.
313615313616That A-kit paper is from 1992. You can tell by the picture and the drawing that show the coolant hose nipple still attached to the cylinder.
So no steps at the flange is better, so why does the NX4 RS125 lose power when the steps are cut out? Is this a function of the duct entry to exit ratio changing?Cutting the steps out increases the duct volume, which is bad. You may remember my bicycle-pump metaphor.
Filling in the steps until there is a smooth transition to the header is good.
Frits Overmars
11th July 2015, 22:52
husaberg, have you come across any 2 stroke engine designs that in corporate reed controlled transfer ports, with the transfer ports high in the cylinder above the exhaust port/s. transfer ports connected directly to the inlet and not through a crankcase?The cylinder pressure at exhaust opening can be as high as 7 bar, so if you put your transfer reeds even higher up, they must be able to cope with more than 7 bar.
This means strong, heavy reeds that will be very reluctant to open at the very limited scavenging pressure differential that the exhaust suction can generate.
And how would you start the beast? No running = no pipe suction = no starting...
Wobbly, would you think that if transfer ports could be controlled at the cylinder/face/ wall( reed type valve) that having the transfer ports high in the cylinder would enable the filling of the cylinder to be more efficient, using the the opening of the exhaust port to both expell combusted fuel and pull a fresh charge in behind it, with the transfers being open to atmospheric pressure while open? could this lessen the amount of fresh charge being pulled straight out the exhaust port as in the way transfers are positioned in the cylinders we have now? with this in mind if the piston was used only to compress the fresh charge and was not using the return to bcd to influence the goings on below wouldnt this enable the piston to move more freely?We'll have to wait for Flettners sleeve valve uniflow engine to give us a partly answer. Flowing top-down or bottom-up won't make much difference in itself.
It will still breathe through the crankcase though. It would be easy enough for Flettner to open the transfers direct to the atmosphere, but then he would have to fit a fistful of carburettors (like I once did with a Rotax-124 cylinder) and make a provision for crankshaft and piston lubrication. And again: how would you start it?
chrisc
11th July 2015, 22:54
That A-kit paper is from 1992. You can tell by the drawing that shows the coolant hose nipple still attached to the cylinder.
Cutting the steps out increases the duct volume, which is bad. You may remember my bicycle-pump metaphor.
Filling in the steps until there is a smooth transition to the header is good.
I was wondering if someone would notice that it was a NF4 example, good eye Frits. It was the only one I had on hand but have read the same thing regarding the NX4 steps.
Great, so it is the change in the duct which is causing the loss in power, rather than the step itself. Noted.
husaberg
11th July 2015, 23:36
Frits are you able to access your records at the moment?
I have a few questions in regards to the Reed Valve Derbi that Jan tweaked.
Frits Overmars
12th July 2015, 00:01
Frits are you able to access your records at the moment? I have a few questions in regards to the Reed Valve Derbi that Jan tweaked.I'm abroad but I carry some historical paperwork with me. What can I do you for?
husaberg
12th July 2015, 00:18
I'm abroad but I carry some historical paperwork with me. What can I do you for?
I was wondering what the specs were on the Derbi
What the crankshaft and the reed valve and tracks looked like. I assume the cylinder and pipe was the same or very similar to the original RSA prototype
ken seeber
12th July 2015, 01:10
Frits,
All this current angle area stuff got me thinking. A question on the exhaust vs transfer mixture in-cylinder interface. In the classic and generic current Schnurle scavenging layout, one could imagine that there is a vertical plane, in line with the crankshaft axis, in the centre of the cylinder. One on side of the plane is the downward exhaust flow, the other side seeing the upward scavenging mixture. Yep, I’ll concede this is pretty simplistic.
Disregarding the length of this interface, its width is the bore diameter. Now in a FOS, or other similar concepts, the rising gas flow might consist of a column that is, say, 50% of the bore diameter. This being the case, the perimeter length would equal pi*bore diameter/2, which is over 1.5 times the length of the Schnurle perimeter.
Do you think that this increased perimeter length might result in increased intermixing, hence more fresh mixture lost and more exhaust gas retention, neither good? Not a criticism or trying to give you the shits or anything though.
jasonu
12th July 2015, 03:47
I was wondering if someone would notice that it was a NF4 example, good eye Frits. It was the only one I had on hand but have read the same thing regarding the NX4 steps.
Great, so it is the change in the duct which is causing the loss in power, rather than the step itself. Noted.
My mate Owen Wilson ground out the step to match the exhaust spigot in his 1989 NX4 RS125 and made it go slower.
peewee
12th July 2015, 05:24
The short rod decreases the crankcase volume (OK, that can be compensated somehow).
then wouldnt you end up with something like the yamaha twins ? large voids in the crank cheeks. what good would it do to have your volume down there ?
adegnes
12th July 2015, 05:31
then wouldnt you end up with something like the yamaha twins ? large voids in the crank cheeks. what good would it do to have your volume down there ?
Or you could do like in the Peugeot speedfight 3 scooter - very wide and short transfer passages. It has a short rod, may be why they designed the cylinder and crankcase that way.
Haufen
12th July 2015, 06:40
Increased piston velocity would have been no issue at all in the RSA; the crankshaft was bulletproof.
There have been experiments with a smaller bore for the RSA, but only with 52,8 mm instead of 54 mm, because the special small-bore piston had to be made out of a standard forging. Making a special piston forging was considered too expensive (in a period where millions of euros were wasted on development of the three-cylinder foul-stroke MotoGP engine).
Changing something in a highly-developed engine will almost invariably lead to a power loss and it will take quite some development to establish whether the change was worthwhile, but Jan Thiel did not get the opportunity to carry out this small-bore development because it was aborted by the Great Leader when there was no immediate improvement.
I expect that at the very least the axial scavenging angles would have to be adapted to the altered bore/stroke-ratio.
So the scavenging angles were the same as with the square engine? And the crankcase volume, too?
I experienced the same when scaling engines. Once you've done it right, the theoretically expected results will show up. But it takes some time to find the correct parameters to modify, as not all of these are obvious.
Cutting the steps out increases the duct volume, which is bad. You may remember my bicycle-pump metaphor.
Filling in the steps until there is a smooth transition to the header is good.
If I remember correctly, the RSA was just like that, with a step in the header. Was the step better on that engine? What was the theory behind the reason for this?
Frits Overmars
12th July 2015, 08:07
If I remember correctly, the RSA was just like that, with a step in the header. Was the step better on that engine? What was the theory behind the reason for this?You may have some re-reading to do, Haufen: http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1211?p=1130876164#post1130876164
Frits, does the Ryger use Meyer's "Knickpleuel"? or even Mederer's "Doppel-Pleuel"?
Frits Overmars
12th July 2015, 08:25
Frits, All this current angle area stuff got me thinking. A question on the exhaust vs transfer mixture in-cylinder interface. In the classic and generic current Schnurle scavenging layout, one could imagine that there is a vertical plane, in line with the crankshaft axis, in the centre of the cylinder. One on side of the plane is the downward exhaust flow, the other side seeing the upward scavenging mixture. Yep, I’ll concede this is pretty simplistic.
Disregarding the length of this interface, its width is the bore diameter. Now in a FOS, or other similar concepts, the rising gas flow might consist of a column that is, say, 50% of the bore diameter. This being the case, the perimeter length would equal pi*bore diameter/2, which is over 1.5 times the length of the Schnurle perimeter.
Do you think that this increased perimeter length might result in increased intermixing, hence more fresh mixture lost and more exhaust gas retention, neither good? Not a criticism or trying to give you the shits or anything though.Obviously, the smaller the contact zone between spent and fresh gases, the better, Ken. But you can't really compare the classic Schnürle-scavenging with either the current 5-transfer systems or with the FOS system, if only because the two Schnürle-transfers would never yield sufficient angle.area for the current rpm-values.
Of course mixing should be avoided which means that the scavenging streams should form a non-turbulent column. In the Schnürle-scavenging this column gets its stability through leaning against the cylinder wall across the exhaust; in current systems much depends on the scavenging balance, which was painstakingly explored by Jan Thiel: every dimension of every port was varied in 0,25 mm steps; it were a lot of combinations...
Frits Overmars
12th July 2015, 08:26
Frits, does the Ryger use the Meyer's "Knickpleuel"? or even the Mederer's "Doppel-Pleuel"?Could you let us know what those are, before I answer that I'm not at liberty to answer?
Could you let us know what those are, before I answer that I'm not at liberty to answer?
something like this
http://www.evert.de/eft774a.jpg
Frits Overmars
12th July 2015, 08:43
I was wondering what the specs were on the Derbi. What the crankshaft and the reed valve and tracks looked like. I assume the cylinder and pipe was the same or very similar to the original RSA prototypeI managed to find the comment accompanying the concerning dyno run:
17-12-2004; albero VHM 4034 V4C21;biella Yamaha C21; cuccinetti Rulli Apr C120+viggiu'; pistone Vertex n*149 965 C04; testa DB15 tr. 0.65-0.65 C34; Mappatura G44; candela R7282A-110 gap 0,60mm; accensione microtec M127V2CAN; carb. HRC mod VHM ovale max222; miscela Agip +Elf 3,5%; alimentazione Lam. DaytonaCylinder, reed valve and pipe were still basically Honda stuff, copied for Derbi by Harald Bartol. I also managed to find a couple of pictures:
313621 313622 313623
Of course there are more pictures, but I haven't got them here.
wobbly
12th July 2015, 11:08
Removing the step in the old Honda engine makes its duct a bit like the IAME shown a few pages back.
The duct looses all its velocity well before it approaches the header - exactly the opposite to what is needed, so of course it looses power.
Fill in the spigot shape on any 3 port or T port Honda and power goes up - proven time and time again.
The trend has been to progressively reduce the duct volume, and at Aprilia this was started up at the port by lifting the floor and then filling
in the bottom corner radi, both reducing A port short circuiting as well as increasing blowdown velocity.
Later as Frits has said the exit area was progressively reduced as the floor and roof were machined closer to the center line thus reducing total volume again in the duct.
But we have never seen an Aprilia picture with this late version duct, so also cant tell if the flange entry was modified as well to eliminate the steps.
IF it was done that way then I can guarantee that it made better power.
Honda did this for years on the A Kit and RS250 factory bikes with a nice cast piece that transitioned from the very flattened oval to the round header diameter.
As I have said before, I developed a new T port cylinder that started with a 40 by 35 oval, with steps, and this evolved into a 41 by 32 oval with no steps and the power
increased with both the smaller exit area and the new CNC transition piece.
Then look at a new design like the TM KZ10B, this has a quite small exit area with small steps, modify this by welding the spigot to match the cylinder, then grind the Aux
ducts all the way from big 1/2 moons at the flange face ,tapering smoothly down to nothing at the header and it pics up a couple of Hp at peak,but revs on with something like 6Hp more at 14,000.
lodgernz
12th July 2015, 12:11
Attached is the pathetic dyno result for my Honda 50 that I used to think ran really well..
I'd appreciate any ideas as to why the curve is such a strange shape.
The engine is stock except for small Boyesen ports and 2-stage Boyesen reeds.
I wondered if this could be reed flutter. The exhaust is the standard muffler with the guts ripped out.
Apologies for the quality of the screenshot.
313625
husaberg
12th July 2015, 14:03
Attached is the pathetic dyno result for my Honda 50 that I used to think ran really well..can anyone suggest what it is.
It looks like Casper.
313625
313627
jasonu
12th July 2015, 14:17
It looks like Casper.
313625
313627
Miserable git!
Yow Ling
12th July 2015, 15:24
So this Ryger engine , which took a few years to develop, has about 40% MORE HORSEPOWER than the best ever 125cc engine ever produced, the RSA125 by Jan Thiel. It is difficult to belive. Is there going to be a technology transfer sometime soon or a share float. I guess when real evidence is produced we will be stunned, until then I still have faith in Jan Thiel.
F5 Dave
12th July 2015, 16:33
I think i
f it were reed flutter Roger you'd hear it going g.g,g,g,g,ghh and it would plateaux from that point on. My H had a similar curve when running an RG250 pipe. Next pipe changed the curve significantly.
wobbly
12th July 2015, 17:12
To have 3 peaks there has to be serious interaction of a couple of elements that are not even remotely matched to make power
in the same bandwidth.
The Boyesens are rubbish anyway so dump them to start with, but i would suspect the pipe is out of sync with the port as well as the ignition curve.
breezy
12th July 2015, 18:41
The villiers as well but to be fair the poms needed such long rods because the piston skirts were so long and the piston pins so low.
The cooking MZ's had very long rods as well.
I may have yes, but I am not at liberty to divulge where.
:weep::weep::weep::brick::brick::bye::bye:
husaberg
12th July 2015, 18:58
:weep::weep::weep::brick::brick::bye::bye:
Sorry it works for Frits.
The cylinder pressure at exhaust opening can be as high as 7 bar, so if you put your transfer reeds even higher up, they must be able to cope with more than 7 bar.
This means strong, heavy reeds that will be very reluctant to open at the very limited scavenging pressure differential that the exhaust suction can generate.
And how would you start the beast? No running = no pipe suction = no starting...
it?
I can't get my head around the very heavy reeds opening bit.
Surely reeds work best as a one way valve.
Maybe its time for Piano hinge reeds.
The trick would be getting them to open when needed. and when the required cylinder pressure differential was reached 4 strokes achieve this all the time with those cams wizwots.
breezy
12th July 2015, 19:36
The cylinder pressure at exhaust opening can be as high as 7 bar, so if you put your transfer reeds even higher up, they must be able to cope with more than 7 bar.
This means strong, heavy reeds that will be very reluctant to open at the very limited scavenging pressure differential that the exhaust suction can generate.
And how would you start the beast? No running = no pipe suction = no starting...
We'll have to wait for Flettners sleeve valve uniflow engine to give us a partly answer. Flowing top-down or bottom-up won't make much difference in itself.
It will still breathe through the crankcase though. It would be easy enough for Flettner to open the transfers direct to the atmosphere, but then he would have to fit a fistful of carburettors (like I once did with a Rotax-124 cylinder) and make a provision for crankshaft and piston lubrication. And again: how would you start it?
wow" 7 bar."... if that environment could be controlled ..."
And how would you start the beast? No running = no pipe suction = no starting." a removable / suction device attached to the end of the exhaust for stimulating the reeds to open when starting up,
but perhaps reeds are not the answer maybe a more mechanically/electrically operating shutter would be more appropriate sat between the sleeve and transfer port in the cylinder casting for better control. do you know the pressure values which occur in the transfer ducts prior to opening on a typical 2 stroke? i can see now how the blow down period is essential to bring down the "7 bar" to stop all the the transfer flow screaming out the exhaust port on a typical 2 stroke. would you think being able to control both transfer port openings and exhaust port openings through the 2 stroke cycle would enable more power to be produced, over and above what is produced now, with the transfer ports set high or even in the cylinder head?:sherlock:
lodgernz
12th July 2015, 21:13
Thanks Dave and Wobbly. On to the next engine...
Frits Overmars
12th July 2015, 23:07
So this Ryger engine , which took a few years to develop, has about 40% MORE HORSEPOWER than the best ever 125cc engine ever produced, the RSA125 by Jan Thiel. It is difficult to belive. Is there going to be a technology transfer sometime soon or a share float. I guess when real evidence is produced we will be stunned, until then I still have faith in Jan Thiel.I know what you mean Yow Ling. I felt exactly the same until I got some hands-on experience with the Ryger.
husaberg
12th July 2015, 23:14
I know what you mean Yow Ling. I felt exactly the same until I got some hands-on experience with the Ryger.
How long is it before there is liberty to discuss the details.
Frits Overmars
13th July 2015, 00:54
How long is it before there is liberty to discuss the details.This is the current state of affairs: http://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130876195#post1130876195
dark art
13th July 2015, 00:54
Too long anyway...
jonny quest
13th July 2015, 04:09
Dimensionaly, how do we keep a 190 exhaust. .. but have a very tall cylinder above exhaust port?
Lef16
13th July 2015, 04:40
Hello guys,I have (again :whistle: ) some questions.
First of all because i didn't get it and google translate does not help a lot...with one word what is better?Step between exhaust duct and exhaust pipe or not?And if the exhaust duct exit is round like a lot of production motorcycles should be a step also there?
And one more,i'm sure mr Jan Thiel have already try this but I have to ask :whistle: .You said that Aprilia couldn't make max power with more than 13000rpm because of the insufficient blowdown angle-area.What would be the results if the ehxuast port was raised into 204* or the B&C tranfer ports were lowered into 130*?Loss of power maybe?
Cheers!!
peewee
13th July 2015, 05:38
lef16 im not sure any of us have seen the final version of the rsa regarding the manifold/exh duct exit. atleast i havent anyways. last photo i seen still has a step. wobbly says that no step is best so we can probly assume he is correct. this would require welding inside the manifold so it goes from oval to round
i think somebody already asked ftrits what would happen if the rsa exh was raised beyond 202*. i dont remember his exact answer but it seemed like it had something to do with unfavorable torq conditions ?
peewee
13th July 2015, 05:45
Dimensionaly, how do we keep a 190 exhaust. .. but have a very tall cylinder above exhaust port?
simple. make a FOS :cool:
F5 Dave
13th July 2015, 07:59
What if they skimmed the head and really polished the ports?
Hey I bet that's the Ryger secret. We weren't super polishing.
wobbly
13th July 2015, 12:10
So here it is as simple as can it be made - NO STEP IS BEST - but this does NOT mean grind the duct to make it round OR bigger in any way.
If its a 3 port or a T port, then the duct exit should be around 75% of the total effective Ex area, then the spigot should transition to 100% round diameter.
If its a single port, the duct should be around 90% exit area, with no step and the header the same diameter if its round.
If you have a really dumb 3 port or T port with a round exit, THEN CHANGE IT.
Re the angle area of the RSA.
The answer is all to do with finely balancing all the variables to optimize the end result.
Do you REALLY think that if going to 204* was actually better then why the hell wouldnt Jan do exactly that.
We have had the same question on here about the pipe dimensions,why not simply make it shorter and fatter, well if that was better
do you really think that it would not have been done.
I have been running thru pipe designs for a 250 KTM for a road racing kart, and discovered in the sim that going over 132mm belly diameter makes
NO MORE power.
Aprilia under Jan would have actually thought about this and built the pipe - I dont need to waste my time, its called diminishing returns, proven easily now
by a major step forward in computing ability.
husaberg
13th July 2015, 12:10
wow" 7 bar."... if that environment could be controlled ..."
And how would you start the beast? No running = no pipe suction = no starting." a removable / suction device attached to the end of the exhaust for stimulating the reeds to open when starting up,
but perhaps reeds are not the answer maybe a more mechanically/electrically operating shutter would be more appropriate sat between the sleeve and transfer port in the cylinder casting for better control. do you know the pressure values which occur in the transfer ducts prior to opening on a typical 2 stroke? i can see now how the blow down period is essential to bring down the "7 bar" to stop all the the transfer flow screaming out the exhaust port on a typical 2 stroke. would you think being able to control both transfer port openings and exhaust port openings through the 2 stroke cycle would enable more power to be produced, over and above what is produced now, with the transfer ports set high or even in the cylinder head?:sherlock:
A reed if it was to be mounted against the cylinder wall (screws at the bottom) opening up of a high mounted transfer passage (likey easiest a c port) would open with flow pushing out into the cylinder(once the cylinder had been vented by the exhaust port lowering the pressure) yet be able to be shut quite gently by a rising piston. The skirt of the piston would then not allow it to open until the top of the piston again descending down towards BDC.
This would direct flow away from the exhaust as it would flow upwards it would allow airflow direct towards the cylinder head and should allow greater cylinder filling.
Neil whip one up this arvo.
Flettner
13th July 2015, 15:46
We'll have to wait for Flettners sleeve valve uniflow engine to give us a partly answer. Flowing top-down or bottom-up won't make much difference in itself.
It will still breathe through the crankcase though. It would be easy enough for Flettner to open the transfers direct to the atmosphere, but then he would have to fit a fistful of carburettors (like I once did with a Rotax-124 cylinder) and make a provision for crankshaft and piston lubrication. And again: how would you start it?
I've kind of run out of puff, (not a drug) 70HP has kind of run me up against the wall. Not that I ever thought I might even get close to 54HP but this Ryger thing has knocked the wind out of my sails, as it were.
I still have some ideas cooking in the back ground but 70HP, wow.
Frits Overmars
13th July 2015, 18:00
70HP has kind of run me up against the wall. Not that I ever thought I might even get close to 54HP but this Ryger thing has knocked the wind out of my sails, as it were.I know the feeling Neil. I'm very glad to be involved with the Ryger engine, but it has also made me very reluctant about everything I thought I knew about two-strokes.
Dutch Fisher
13th July 2015, 19:58
If its a 3 port or a T port, then the duct exit should be around 75% of the total effective Ex area, then the spigot should transition to 100% round diameter.
Wob have you got a formula or fixed length for the transition to the 75% choke point from the port and again from the choke point to 100%
jonny quest
13th July 2015, 20:16
Here's a Ryger question you may be able to answer Frits. Does the Ryger make more than 54hp at 13,000 RPM? Or less?
Frits Overmars
13th July 2015, 20:29
Here's a Ryger question you may be able to answer Frits. Does the Ryger make more than 54hp at 13,000 RPM? Or less?You're right Jonny. I'm able to answer that. But I'm not allowed to.
husaberg
13th July 2015, 21:35
A reed if it was to be mounted against the cylinder wall (screws at the bottom) opening up of a high mounted transfer passage (likey easiest a c port) would open with flow pushing out into the cylinder(once the cylinder had been vented by the exhaust port lowering the pressure) yet be able to be shut quite gently by a rising piston. The skirt of the piston would then not allow it to open until the top of the piston again descending down towards BDC.
This would direct flow away from the exhaust as it would flow upwards it would allow airflow direct towards the cylinder head and should allow greater cylinder filling.
Neil whip one up this arvo.
You're right Jonny. I'm able to answer that. But I'm not allowed to.
No love for the high reed controlled transfers?
Bert
13th July 2015, 22:17
And now for a sideline question
Hi Rob, how's the fuel injection project going?
It's been a little quite from the ESE boys for a while now and I suspect that means great things are happening.
Give us a little progress snippet while we wait for the patient office & FIA.
North island series is just around the corner and I'm looking forward to seeing the beast in full flight.
Frits Overmars
14th July 2015, 01:00
A reed if it was to be mounted against the cylinder wall (screws at the bottom) opening up of a high mounted transfer passage (likey easiest a c port) would open with flow pushing out into the cylinder(once the cylinder had been vented by the exhaust port lowering the pressure) yet be able to be shut quite gently by a rising piston. So you want the piston to close the reeds that close the ports? The piston can do that on his own, no reeds required. Think of an opposed piston. Or a sleeve valve...
The skirt of the piston would then not allow it to open until the top of the piston again descending down towards BDC.I see; the reeds would be leaning against the piston skirt. As oil scrapers, so to speak :devil2:.
This would direct flow away from the exhaust as it would flow upwards it would allow airflow direct towards the cylinder head and should allow greater cylinder filling.And how do you propose to scavenge the bottom part of the cylinder (the part were there used to be scavenging ports)?
No love for the high reed controlled transfers?Lots of love, if you can make them work.
husaberg
14th July 2015, 01:29
So you want the piston to close the reeds that close the ports? The piston can do that on his own, no reeds required..
I only want it to be open when the piston is descending and after the cylinder pressure is lower so it has to have a reed, I see it like a super high C port in a cylinder reed engine.only two of them feed from the rear there is space not utilised currently if the cylinder studs are moved out. the space is on either side of the C port entry to feed them.
I see; the reeds would be leaning against the piston skirt. As oil scrapers, so to speak :devil2:..
Yes they would be flat against both the cylinder wall and skirt unless open where it would pivot from the bottom out into the port at much the same angle as a C port in a cylinder reed engine it should be able to be gently shut by an ascending piston. Yet not be open when the cylinder pressure is high so no exhaust gases down the ports.
And how do you propose to scavenge the bottom part of the cylinder (the part were there used to be scavenging ports)?.
In the same manner as a normal one. I just see some more real estate available higher in the wall, plus maybe it should keep the incoming inertia higher with less stop start of flow as it should continue to flow for longer maybe just long enough to switch over to crankcase induction without a inertia robbing stop of flow.This might only work if it was breathing direct to the inlet rather than the transfers
Lots of love, if you can make them work.
Unlikely given my general malaise and proclivity for procrastination, but Neil could.
The question is would it make any useful contribution to increasing the output.
Maybe the greater transfer area of incorporating a high transfer would allow a wider ex port in a single 2 AUX ex Port set up as the AUX ports would be able to be less compromised by making the a ports smaller as the a ports show a compromise on the RSA to fit in the 2 wide AUX EX ports currently.
Maybe the high transfer might be also cleaner as it is directed well away from the EX port.
313681
Frits Overmars
14th July 2015, 02:32
313681
Initially I understood that you wanted to put those additional transfer ports above the exhaust, but your drawings made me see the light. I must say it's not as silly as I first thought, although I still shiver at inward-hinging reeds that are to be 'gently' closed by a piston that at 13000 rpm encounters the reeds at about 37 m/s :brick:.
breezy
14th July 2015, 05:52
The cylinder pressure at exhaust opening can be as high as 7 bar, so if you put your transfer reeds even higher up, they must be able to cope with more than 7 bar.
This means strong, heavy reeds that will be very reluctant to open at the very limited scavenging pressure differential that the exhaust suction can generate.
And how would you start the beast? No running = no pipe suction = no starting...
................. and make a provision for crankshaft and piston lubrication. And again: how would you start it?
http://www.google.co.uk/patents/US5816211.... maybe this would eliminate some lubrication for the piston/sleeve :ride:
wobbly
14th July 2015, 08:23
If I had a R&D dept with 100 people all looking for things to do i would be testing the relationship of the duct length,its exit area and
the optimum transition length.
There will be a direct relationship to how long the well cooled duct wall is, to the length of the A/F slug sitting outside the port waiting to be shoved in by the returning wave front.
All I can say is that in any normally dimensioned cylinder we usually end up with a duct and spigot around 2X bore length, and that a slip joint
spigot is usually around 1/2 bore - and that works.
Technically correct as Frits has pointed out, would be to derive a relationship between duct exit area and the blowdown needed to develop the target bmep.
But in any scenario keeping the duct volume down by lifting the floor and filling in the bottom corners, then restricting the exit and connecting that to a transition WITH NO STEPS
will make better power than any other solution that has actually been tested to date.
Flettner
14th July 2015, 08:36
http://www.google.co.uk/patents/US5816211.... maybe this would eliminate some lubrication for the piston/sleeve :ride:
So - if you had a super ceramic fit, no piston rings. Piston sides are spherical with no gudgin pin (fixed) so that the piston is forced to rock forward and aft through the cranshaft rotation (like these silly little chinese compressors). On the way down there would be more blowdown time because the piston would be rocked forward as the crank turns around BDC the piston would rock the other way giving more transfer time. Substantial asymmetric timing. How the underside of the piston would shut the exhaust off at TDC I can't say, so this is clearly not how it's done but just another thought.
Perhaps an articulated piston so just the head could rock? 30000K, I don't think so!
F5 Dave
14th July 2015, 09:06
If I had a R&D dept with 100 people all looking for things to do i would be testing the relationship of the duct length,its exit area and
the optimum transition length.
There will be a direct relationship to how long the well cooled duct wall is, to the length of the A/F slug sitting outside the port waiting to be shoved in by the returning wave front.
All I can say is that in any normally dimensioned cylinder we usually end up with a duct and spigot around 2X bore length, and that a slip joint
spigot is usually around 1/2 bore - and that works.
Technically correct as Frits has pointed out, would be to derive a relationship between duct exit area and the blowdown needed to develop the target bmep.
But in any scenario keeping the duct volume down by lifting the floor and filling in the bottom corners, then restricting the exit and connecting that to a transition WITH NO STEPS
will make better power than any other solution that has actually been tested to date.
I'd have them all changing tyres cause I hate changing tyres and it turns out I'd be a vindictive power tripping control freak of a boss.
Ohh the things you find out about yourself in a moment of fantasy.
Haufen
14th July 2015, 10:14
I know the feeling Neil. I'm very glad to be involved with the Ryger engine, but it has also made me very reluctant about everything I thought I knew about two-strokes.
When you first saw / heard of the numbers, what was your reaction? And how many times did you double-check that everything is just as it seems and that there is no miscalibrated dyno, rpm gauge etc?
husaberg
14th July 2015, 11:13
Initially I understood that you wanted to put those additional transfer ports above the exhaust, but your drawings made me see the light. I must say it's not as silly as I first thought, although I still shiver at inward-hinging reeds that are to be 'gently' closed by a piston that at 13000 rpm encounters the reeds at about 37 m/s :brick:.
Yeah but remember Trademarked (HUSA HIGH REED TRANSFERS) do exit higher as they are directed near straight up.
I would not expect the reeds to last forever.
I bet if you told a designer that did piston rings that had only ever seen four strokes that you want to cut these huge holes in a liner some up to a 70 Degree unsupported arc he would say the rings will not last.
But that's R&D's problem to solve I work in the silly ideas design department.
Maybe Mr Frits would prefer a loose ball valve arrangement in the port as a means of preventing reverse flow
lodgernz
14th July 2015, 14:03
Wobbly and Frits:
I've read and re-read and re-read the stuff about exhaust flange being 75% of effective ex port area for 3-port and T-port engines, and 90% for single port engines.
I've been unable to determine whether the flange DIAMETER should be that percentage of the ex port effective DIAMETER, or the flange AREA should be that percentage of the ex port AREA. I'm guessing it's area, but I'd like confirmation (or otherwise) please. Obviously 90% of diameter would mean 81% of area, so need to be sure before I start hacking.
Thanks to both of you for all your help.
karter444
14th July 2015, 15:09
So here it is as simple as can it be made - NO STEP IS BEST - but this does NOT mean grind the duct to make it round OR bigger in any way.
If its a 3 port or a T port, then the duct exit should be around 75% of the total effective Ex area, then the spigot should transition to 100% round diameter.
If its a single port, the duct should be around 90% exit area, with no step and the header the same diameter if its round.
If you have a really dumb 3 port or T port with a round exit, THEN CHANGE IT.
Re the angle area of the RSA.
The answer is all to do with finely balancing all the variables to optimize the end result.
Do you REALLY think that if going to 204* was actually better then why the hell wouldnt Jan do exactly that.
We have had the same question on here about the pipe dimensions,why not simply make it shorter and fatter, well if that was better
do you really think that it would not have been done.
I have been running thru pipe designs for a 250 KTM for a road racing kart, and discovered in the sim that going over 132mm belly diameter makes
NO MORE power.
Aprilia under Jan would have actually thought about this and built the pipe - I dont need to waste my time, its called diminishing returns, proven easily now
by a major step forward in computing ability.
Wobbly you say that the pipe didn't make any more power with a dia over 132 mm but did it make less power , we are running a pipe that is 147 mm dia ???
jonny quest
14th July 2015, 15:34
I'm not Wobbly, but when I built pipes that were too big, yes they lost power. And more noticeable the motor revved slow and was just lethargic and flat.
husaberg
14th July 2015, 15:50
Aprilia under Jan would have actually thought about this and built the pipe - I dont need to waste my time, its called diminishing returns, proven easily now
by a major step forward in computing ability.
Yes but I remember Frits saying a few times that Jan Thiel had to develop the cylinders to suit the Great leaders pipes, This may have changed later of course.
My thoughts is that you are jumping to conclusions, Dutch. But you are forgiven because I will admit that it is logical to assume that Jan developed that pipe.
In reality he didn't; technical director Witteveen (or The Great Leader as he was called) did; pipes were his hobbyhorse. And each time Jan Thiel had to adapt the cylinder to get it running with Witteveens pipe designs; not a great way to commit development.....
... never needed anybody looking for things to do, Wob; there were always more things to do than time, equipment and the Great Leader:argh: permitted.
Changing something in a highly-developed engine will almost invariably lead to a power loss and it will take quite some development to establish whether the change was worthwhile, but Jan Thiel did not get the opportunity to carry out this small-bore development because it was aborted by the Great Leader when there was no immediate improvement.
I expect that at the very least the axial scavenging angles would have to be adapted to the altered bore/stroke-ratio.
wobbly
14th July 2015, 16:13
Maybe Jan was under the thumb somewhat with the pipes, but still they were up to Tubo 120 or something so plenty of
experimental ideas were a failure.
But something he did say was that they didnt pay enough attention to the changes in fueling when trying out the new pipe ideas.
In that many pipes with changes to dimensions made little difference, but may have been better/worse if the carb tuning was strictly optimized to suit.
I have taken this onboard and find now that I need to change jets for nearly every single small change in any part of the engine, just to get back
to my baseline peak power egt on the dyno.
Re the KTM road racing pipe.
My best pipe so far has a diffuser end ( belly front ) of 135 diameter and a rear cone diameter of 132.
Going up to 138 with either steeper diffuser angles, or a shorter or longer rear cone to suit, was always within no more than 1.5Hp everywhere across the powerband.
Sometimes a bit more down low and less on top or visa versa.
The 135/132 has the best average everywhere, and as these things have a wide spaced MX gear ratio split with something like a 1500 rpm drop when running to 10800
and selecting 5th, the front side power slope is just as important as the overev.
As I have stated before I believe that we have finite energy available from the advancing wave front, and in this case the best result I could get from the engine
involved a slightly steeper diffuser, but as soon as I shortened/lengthened ( reangled ) the rear cone I lost power - thus I ended up with a slightly tapered mid section
just as the Aprilia had.
TZ350
14th July 2015, 16:28
And now for a sideline question. It's been a little quite from the ESE boys for a while now and I suspect that means great things are happening.
Give us a little progress snippet while we wait for the patient office & FIA.
No not much happening, work (the real work) has been keeping us pretty busy so not much being done on the bikes at the moment.
I am looking forward to learning more about the Ryger engine and hope that combined with the other clean technology's like direct fuel injection that it will herald a new era for 2T's.
Hi Rob, how's the fuel injection project going? North island series is just around the corner and I'm looking forward to seeing the beast in full flight.
The old Beast has been stripped and the rolling chassis is destined for a new venture as Flettners F4 supercharged 100 or maybe a test bed for his 700cc twin or maybe the 1000cc triple two stroke track bike project he is thinking about.
That is right, 1000cc's of triple cylinder, highly tuned, insane two stroke power, soon you might be able to buy an engine from Auto Flight, fit it to whatever you like and go full on all out Track Day Kamikaze with more power than the legendary Yamaha TZ750.
313695
I am confident about 2T's and EFI and expect to use EFI and a Plenum on the new Beast, but as much as I am looking forward to riding it, the new Beast is probably not going to be ready for the start of the season because the team is trying to get a brace of 14+rwhp 50's ready for F5 this year.
If the Ryger engine concept is easy enough to adapt to an existing 2T engine then I will definitely be trying that too.
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