ESE's works engine tuner

[lodgernz]

Top tip: run some oil in there too. It helps lubricate the piston and the various crank bearings.

Don't mention it. :msn-wink:

I think there's some oil in the gearbox. Does that count?

[F5 Dave]

If you nick the seal it might be like autolube. :confused:

[TZ350]

If you nick the seal it might be like autolube. :confused:

The crank flapping around in the seal acts like an oil pump and will pump oil from the gear box. Its a problem with our GP's. Not sure if its poor crank alignment, the GP crank flexing at 12,000 rpm or the C3 bearings allowing the crank to hop up and down. But it will shift most of the gear box oil in a days racing.

[jonny quest]

I'm pretty sure the Viton slipped seals are primarily used for lower friction benefits.

TZ350, didn't I see a post of yours years ago where you did some seal friction experiments?

RS125 bulletin even mentions removing one of the seal clips for less friction I seem to recall

[husaberg]

I'm pretty sure the Viton slipped seals are primarily used for lower friction benefits.

TZ350, didn't I see a post of yours years ago where you did some seal friction experiments?

RS125 bulletin even mentions removing one of the seal clips for less friction I seem to recall

AFAIK Vitron is used as its one of the more durable rubbers in contact with fuel and solvents and wear. Its used on fuel needle tips as well
Teflon is a low friction seal.

[lodgernz]

The crank flapping around in the seal acts like an oil pump and will pump oil from the gear box. Its a problem with our GP's. Not sure if its poor crank alignment, the GP crank flexing at 12,000 rpm or the C3 bearings allowing the crank to hop up and down. But it will shift most of the gear box oil in a days racing.

Wow. Never seen that on my Hondas. Must be a Suzuki thing...

[philou]

the material of the seal must be adapted to the linear speed of the shaft.

nbr is not suitable for high rotational speeds. the lips are burnt.

[Flettner]

Ready to start, at last. Just got to sort through this LINK, so different to what Im used to, way more complicated than the Atom.

[jbiplane]

Hello All

I have pistons with 15mm crank pin and Suzuki AX con rods with d=18mm 18mm wide upper hole
https://www.royalrods.com.tw/suzuki-connecting-rod/RS-3012.html

Engine revs up to 8500 and have 15hp

What is better
- just put in gap 34 of 1.5mm needles as on outboards (gap about 0.024 needle to needle)
- use 15x18x22 bearing cutting inside piston from 19 to 22.5 mm to fit it
- make custom separator

[WilDun]

Ready to start, at last. Just got to sort through this LINK, so different to what Im used to, way more complicated than the Atom.

Getting there! - You are going to overtake John Britten soon with your artistic exhaust efforts ! :niceone:

[wobbly]

Crowded needle roller small end bearings were discarded years ago, being only suitable for low reving boat and chainsaw use. They start to " skid " against each other and or the bearing surfaces causing heat related failure.
Proper , caged small ends , are the only way to go as we now have no issues at all with reliability in this area.
Modify the piston bosses to suit .

[jbiplane]

Modify the piston bosses to suit .
Thanks. Will think how use 14mm piston pins in 15mm holes or try use bearing with small 1.5mm diameter needles.
Exist 15x18x22mm.

[190mech]

That size is hard to find!
Here is a double roller one for a Stihl chainsaw;
https://www.huztl.net/Aftermarket-Stihl-070-090-Chainsaw-Drum-Needle-Cage-Bearing-15x18x22-OEM-9512-933-4050-p372598.html

Also INA bearing has one listed,but only 17mm wide;
https://medias.schaeffler.com/medias/en!hp.ec.br.pr/K*K15X18X17-TV

[jbiplane]

That size is hard to find!
Also INA bearing has one listed,but only 17mm wide;
https://medias.schaeffler.com/medias/en!hp.ec.br.pr/K*K15X18X17-TV
The second variant fit perfectly. Thanks for INA link.

I consider as well use conrods with 20mm upper hole. But 15x20 bearings even more difficult to find.

[Brett S]

The second variant fit perfectly. Thanks for INA link.

I consider as well use conrods with 20mm upper hole. But 15x20 bearings even more difficult to find.


From a pro-x catalogue YZ125 97/99 uses 15x20x18 LE bearing

[speedpro]

Ready to start, at last. Just got to sort through this LINK, so different to what Im used to, way more complicated than the Atom.
One wire at a time, one sensor at a time, one injector, and so on. As you have probably done before. Link's setup documents are pretty good I reckon. Same sort of thing as the Atom I would think, start at the top and work down. I'd be interested to come down and help but, you know. I bought a really good Weller soldering iron and a selection of tips. Small stack of wires and collection of heatshrink. I used some black braid to thread the wires through as I put the loom together on mine. I think it kept it reasonably tidy though it still turned into a birds nest at the main connector

[TZ350]

From a pro-x catalogue YZ125 97/99 uses 15x20x18 LE bearing

Wossner 15x20x17,8 Yamaha YZ125 LE bearing cage. About 8 Euro on Ebay. I use them in my 14,000 rpm NSR110cc beast.

[jbiplane]

Thanks for advice related YZ125 top end bearings! Will definitelly get some.

[Flettner]

One wire at a time, one sensor at a time, one injector, and so on. As you have probably done before. Link's setup documents are pretty good I reckon. Same sort of thing as the Atom I would think, start at the top and work down. I'd be interested to come down and help but, you know. I bought a really good Weller soldering iron and a selection of tips. Small stack of wires and collection of heatshrink. I used some black braid to thread the wires through as I put the loom together on mine. I think it kept it reasonably tidy though it still turned into a birds nest at the main connector

Yes slowly stepping through it. Its all comming back to me now. Usual problems, coolant leak all over the floor, fixed that, forgot to fit an oring. Gearbox full of oil, autolube full of oil, wait, where is the gearbox breather? You know silly little things. Now Im trying to kick it over, with this bastard left hand kick start, bad idea, its bloody awkward.
So sooner or later its going to end up on the engine dyno, so it might be sooner, dyno is getting an electric start fitted. Idea is to take the rear wheel out and make a small carrier, chain to the rear axel then a sub chain to a set of bearings connected to the dyno via a universal drive shaft.
It was going to happen anyway, just its bought forward now.

[ken seeber]

WHY DO 2 STROKES BLOW SMOKE? (or do they just want lung cancer?)

After seeing skywriting planes yesterday during the Australia Day celebrations, it got me thinking. They do it by injecting oil into the hot exhaust = incomplete combustion. I’m sure we have all chucked on an oil soaked rag or bit of paper onto a fire. If it is really soaked we see smoke. Less soaked = less smoke. Years ago at Orbital we ran a generous flow of oil into the intake of a 2 stroke 4 cyl engine carb at high load. No smoke.

Can think of a couple of reasons for smoking, but based on the above, I’ll make the statement that a typical 2 stroke premix fuel (eg 25:1), if completely combusted, does not smoke, and, in the inverse, we get smoke.

Some possible reasons being:

1. One being the short circuiting of some of the charge, escaping out the exhaust and acting exactly like a skywriting plane. One test for this might be to run an engine on straight petrol, not withstanding that the petrol that has short circuited might smoke (a bit). Anyone want to give this a try, in the interests of science of course.
2. Oil, possibly with some of the petrol lighter fractions evaporating off (due to the high engine internal temps), working its way up the bore around the piston skirt and ring and passing into the exhaust passages.
3. An accumulation in the crankcase after draining down after stopping, either escaping into the exhaust directly or around the piston as above. Can be fully or partially eliminated by a draining circuit.
4. Similar to the above, but an accumulation of oil after full or partially closed throttle on an overrun situation passing thru engine.
5. An excess of oil being delivered to the engine, eg a separate pump controlled by a properly programmed ECU. My 300 EXC TPI is an excellent smoker at startup and low loads, either as a result of shit mapping or as per reason #3 above.
6. Others?

Gotta say that I have seen many (but not all) fast race bikes down the main straight and not blowing any smoke at all. Presumably this is because the plugging pulse is so strong that all the mixture that might pass out the cylinder into the exhaust passage is fully returned and fully combusted.

It'd be nice to be able to stop it. Thoughts?

Jeez Ken, nice post and you’ve got me thinking.

On the basis of your points #2 & 3, I am going to try a drain circuit as in the sketch Essentially it is a gutter across the full width if the bottom of the exhaust port. To assist feeding into the gutter , the liner has been ground away to encourage any oil (or oil/fuel mix) to run into the gutter. From the bottom of the gutter, a small drilling will act as a drain. Perhaps a small valve in the drilling to be able to cut off any drain flow. The net positive exhaust system pressure should act as the propulsion force.

345163


What if it works and there is actually a flow? Well I reckon it’d be logical to just return it into the intake of the carb/throttle body. Keep the stuff active and not creeping into the hot exhaust the inevitable incomplete combustion = smoke.

Have no idea, even if it actually works, of what would happen in a horizontal cylinder with an exh. port on top.

So have put a gutter in the base of the exhaust of this Yamaha KT100J cylinder Used a Dremel #199 slot cutter, it’s around 3 mm deep * 2 mm wide. Bit shitty, as hard to get to. Still have to put in the actual drain hole, it will need some careful setting up to meet the gutter.

345164345165

Oh shit, I forgot to put in the transfers….shouldn’t haven’t listened to Fletto…

Further to this, I might also put in a crankcase drain. When we did the Orbital 3 cyl X engine, we did this, and manifolded the drained flow to enter the inlet above the reed valves of the “trailing” cylinder to enhance the pressure differential of the draining function.

Hopefully should have it running in a few weeks…..more to come…..

[F5 Dave]

Jeez Ken, nice post and you’ve got me thinking.

On the basis of your points #2 & 3, I am going to try a drain circuit as in the sketch Essentially it is a gutter across the full width if the bottom of the exhaust port. To assist feeding into the gutter , the liner has been ground away to encourage any oil (or oil/fuel mix) to run into the gutter. From the bottom of the gutter, a small drilling will act as a drain. Perhaps a small valve in the drilling to be able to cut off any drain flow. The net positive exhaust system pressure should act as the propulsion force.




What if it works and there is actually a flow? Well I reckon it’d be logical to just return it into the intake of the carb/throttle body. Keep the stuff active and not creeping into the hot exhaust the inevitable incomplete combustion = smoke.

Have no idea, even if it actually works, of what would happen in a horizontal cylinder with an exh. port on top.

So have put a gutter in the base of the exhaust of this Yamaha KT100J cylinder Used a Dremel #199 slot cutter, it’s around 3 mm deep * 2 mm wide. Bit shitty, as hard to get to. Still have to put in the actual drain hole, it will need some careful setting up to meet the gutter.



Oh shit, I forgot to put in the transfers….shouldn’t haven’t listened to Fletto…

Further to this, I might also put in a crankcase drain. When we did the Orbital 3 cyl X engine, we did this, and manifolded the drained flow to enter the inlet above the reed valves of the “trailing” cylinder to enhance the pressure differential of the draining function.

Hopefully should have it running in a few weeks…..more to come…..

Jezsus. I'd generally thought you were the cleverest person on here, but I have no idea what you are on about.

. . . Actually that doesn't change the original tenent.

[Vannik]

Further to this, I might also put in a crankcase drain. When we did the Orbital 3 cyl X engine, we did this, and manifolded the drained flow to enter the inlet above the reed valves of the “trailing” cylinder to enhance the pressure differential of the draining function.

You do know Suzuki used to do this on their triples in the early 70's?

[WilDun]

Sorry guys,
I'll stick my neck out (and no doubt get my head chopped off!)
Lets get out of the nasty habit of filling a large bulky exhaust chamber with fresh charge - in fact, why not get rid of the bloody chamber! - that's where all the smoke and oily shit comes from - we have to face facts that that is why the two stroke became unpopular in the first place and hasn't got a hope in hell of getting back again without acknowledgement of that fact - it needs a complete redesign.

Why can't we stop using the exhaust as a supercharger when we can do any supercharging from the inlet side? - I acknowledge that this thread is mainly based on improving "normal" two strokes of course - that is fine and a great obsession to have and a lot of fun, but these machines are fast disappearing and soon we will have no "normal" two stroke motorcycles to improve the performance of!

I don't normally contribute here but there have been plenty of weird and wonderful ideas coming from this thread and I'm sure there are plenty of enterprising guys contributing here who could come up with ideas to bring out the huge potential of this engine and so be able to discard all the offending things in the current models which quite frankly have almost made it a dead duck and which we have continually been making excuses for (is it now too late?)!

[Frits Overmars]

Idea is to take the rear wheel out and make a small carrier, chain to the rear axel then a sub chain to a set of bearings connected to the dyno via a universal drive shaft.Let's KISS that idea:
345172



Why can't we stop using the exhaust as a supercharger when we can do any supercharging from the inlet side?We can only effectively supercharge a cylinder via the last opening that closes before compression begins. In a four-stroke that is the inlet port, in a conventional two-stroke it is the exhaust port.

[WilDun]

We can only effectively supercharge a cylinder via the last opening that closes before compression begins. In a four-stroke that is the inlet port, in a conventional two-stroke it is the exhaust port.

Yes, you are correct and I do see what you mean, but I never think "conventional two stroke" - I think "next generation two stroke". I believe that it's got to change drastically in order to make a comeback, or even survive! - my knowledge of the finer details is limited of course, but even a dummy like me can see that!

[lohring]

We can only effectively supercharge a cylinder via the last opening that closes before compression begins. In a four-stroke that is the inlet port, in a conventional two-stroke it is the exhaust port.

However, you can seriously supercharge a conventional two stroke if you raise the exhaust back pressure along with the intake pressure. Turbochargers do this, but Ricardo tested his sleeve valve two strokes by simply restricting the exhaust. During one test he got a BMEP of 321 psi (22 bar) with 36 psi (2 1/2 bar) intake pressure and 12 (.8 bar) psi exhaust pressure. You could run a really effective catalytic muffler with that back pressure. The mechanical supercharger would take some power to run, so a turbo is probably a better and proven solution.

You knew all that, though.

Lohring Miller

[ceci]

We can only effectively supercharge a cylinder via the last opening that closes before compression begins. In a four-stroke that is the inlet port, in a conventional two-stroke it is the exhaust port.



Dear Lord, I hope that you are well, like everyone else.
Excuse me, but I can't help it, such is my admiration for what you say, that I can't hold back from letting you know.
His words to me are sacred and in them I always see the truth and maximum efficiency in engineering

[WilDun]

"His words to me are sacred and in them I always see the truth and maximum efficiency in engineering"

CECI Sorry, but not sure who you are discussing here - is it Lohring or Frits?

Then of course I may not be quite 'up there' in my ability to understand things ! :rolleyes:

[Flettner]

He who hoards the most stuff wins.
Certainly makes you think how to use the stuff you have, because you can't just go out and buy what you want. Lucky I have an extensive scrap heap and a spare one just down the road to wade through ( within my bubble ).

[ceci]

CECI Sorry, but not sure who you are discussing here - is it Lohring or Frits?

Then of course I may not be quite 'up there' in my ability to understand things ! :rolleyes:



With all my respects to everyone.
There are people here who do many great things and prove to be very talented.
But Mr. Frits, from my little knowledge, is the person with the most experience and wisdom.
I don't know where I'm wrong, but I enjoy reading everything he writes

[Grumph]

He who hoards the most stuff wins.
Certainly makes you think how to use the stuff you have, because you can't just go out and buy what you want. Lucky I have an extensive scrap heap and a spare one just down the road to wade through ( within my bubble ).

Very true. I'm a little envious of your scrap heap. Mine is smaller. By the end of the lockdown we'll all be MacGyvers - able to make something out of whatever's lying around.

[ken seeber]

Neels, yeah aware of the Suzuki and others, particularly the vertical shaft marine 2 strokes. I think it was Mercury who connected the lowest main bearing drain to the top of the uppermost main, allowing the oil to seep thru the intermediate labyrinth inter chamber seals.

Dave, just a product of being old, really old, and waking up in the middle of the nights and the brain going crazy. Probably C19 socially deprived, dementia or some other serious mental disorder. You'll get your turn in 100 years or so.

[wobbly]

Jesus Ken , did you use a wood lathe to machine that piston crown.
I have been practicing making semi flat top TM pistons , so I know it aint easy.

[ken seeber]

Jesus Ken , did you use a wood lathe to machine that piston crown.
I have been practicing making semi flat top TM pistons , so I know it aint easy.

Ha, ha....nope, it was just a rough as guts set-up piston to understand timings. Should be able to do a little better next time, there's a cool place pretty close that should be able to help.

PS, thanks for the tip though..:laugh:

Wood file....turns out there's two types of people in the world....woodies and metalies….I'm a metalie.

[lohring]

Snowmobiles have run turbochargers for a long time. Now there is a factory version. I think this is the future of small two strokes.
https://www.youtube.com/watch?v=UxZY2DegTzU&feature=youtu.be

Lohring Miller

[WilDun]

Snowmobiles have run turbochargers for a long time. Now there is a factory version. I think this is the future of small two strokes.
https://www.youtube.com/watch?v=UxZY2DegTzU&feature=youtu.be

Lohring Miller

Lohring, - Yes, I agree that at least, its a big step towards the future of small two strokes - I think they are now definite leaders in two stroke development, using turbos with electronics controlling things! Guess the prices of electronics does tend to decrease dramatically later on.
How are they doing with fuel injection etc? - are they using direct cylinder injection? and I assume that exhaust piping has changed dramatically - I need to check it all out .... somewhere?? - anyway I'll have a browse on the subject.

[Flettner]

Not so fast, dont need no turbos or direct injection, Uniflow, throw the exhaust down the other end of the cylinder.

Pictured here, piece of Champion grader tool bar, cast iron tool holder out of a old turret lathe and a welded up bearing housing I built years ago for some other un related project, waste not want not.

And thankyou Frits, your advice is as always very welcome, Im copying the above photo.

[190mech]

Sorry Will,Looks like Rotax is still using a stupid expansion chamber with their Turbo engine!!WTF??

[WilDun]

FW190,
Didn't even know that Rotax had a turbo (you're talking snowmobile engines?) - if so, I haven't studied them as yet - but will have a look soon no doubt! - why the hell would you need an expansion chamber AND a turbo?

Flettner,
Yes I reckon! - but the exhaust would still need to close a little earlier (preferably as the fresh charge just gets to it) either by asymmetric port timing or a shutoff valve of some sort! ( a rotating sleeve? ) - just a suggestion inspired by a hunch based on a dream I had a while ago :rolleyes:

[Vannik]

- why the hell would you need an expansion chamber AND a turbo?

The best way to look at a turbo is to consider it a device that increases atmospheric pressure. Then all the requirements at 1 atmosphere are still there at higher atmospheres.

It stays a 2T so you still need blowdown, and a plugging pulse. Because of the extra power you can go for a milder tune if power spread is required but the snowmobile drag sleds use very high levels of tune.

If you do not want to use a tuned pipe you have to go for a Uniflow engine.

[Tim Ey]

The best way to look at a turbo is to consider it a device that increases atmospheric pressure. Then all the requirements at 1 atmosphere are still there at higher atmospheres.

Thank you Neels :-)

A question I always had: Will supercharging a rotary inlet 2 stroke work? I was always sceptical in terms of rotary valve wear.
But since the turbocharger is shifting the median pressure everywhere inside the engine, the pressure difference crankhouse to intake manifold might remain the same?!
A friend tried it with a VW smoke pump roots on a 100cc kart engine - that did not work with a short manifold due the pulsation of the roots compressor. Has anyone tried this with a decent volume between supercharging device and rotary plate? Flettner by chance?

[TZ350]

.

Here you go. Original 26hp Sporty 125cc two stroke turbocharged complete with expansion chamber.

Basically they just doubled the hp by adding a Turbo. They got 53hp at 11,000 rpm with 1 bar boost.

<iframe width="560" height="315" src="https://www.youtube.com/embed/Oxj_OAb5bqk" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

Guess who at Team ESE wants to turbo his 2T ...... :yes: ... me me me.

[TZ350]

.
This is a good look at their 50cc version.

19.6 hp at 11,931 rpm, low boost. As 15,000 rpm is easily possible and higher boost there looks to be plenty of potential.

<iframe width="560" height="315" src="https://www.youtube.com/embed/gv377_f3cvU" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

The particular racing class that Team ESE are involved in allows for turbocharged 70cc water cooled two strokes.

[lohring]

And then there's a really serious turbo engine with maybe 800 hp on nitrous:

Lohring Miller

345235

[Vannik]

And then there's a really serious turbo engine with maybe 800 hp on nitrous:

Lohring Miller

345235

Lohring, I have a number of photos of that sled but no info on it running. Do you know more?

Neels

[Flettner]

And then there's a really serious turbo engine with maybe 800 hp on nitrous:

Lohring Miller

345235

How do they not melt the pistons?

[gamma500]

I think that might be Gus Bohne built sled, he has built some really powerfull 2 stroke turbos.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.dynotechresearch.com/file_upload/page_files/DTRDNEturbo.pdf&ved=2ahUKEwiK2J3Ay9ToAhVMxIsKHXPIDUwQFjABegQIBhAK&usg=AOvVaw17bKfQnk1qpvxwvxonIu6y

https://www.google.com/url?sa=t&source=web&rct=j&url=https://nlrsystems.com/files/pdf/newsdocs/DTRtrilogy.pdf&ved=2ahUKEwiK2J3Ay9ToAhVMxIsKHXPIDUwQFjAEegQIARAB&usg=AOvVaw0ZpO1qJKVg5M2JvPH198de

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.dynotechresearch.com/file_upload/page_files/dtrgusbohneturbotuning.pdf&ved=2ahUKEwiK2J3Ay9ToAhVMxIsKHXPIDUwQFjAAegQIBhAC&usg=AOvVaw0HYlsQ_ksfK9QdzlqyUc9a

[Muciek]

Here's 3 cyl

https://www.youtube.com/watch?v=T44ZVTQtLUk dyno


https://www.youtube.com/watch?v=K1JTriQmNg4 in action :blink:

[Flettner]

How do they side step physics, all that extra thermal load. Aluminium pistons would surely have long vaporized within seconds.

[190mech]

Perhaps lots of extra fuel and water injection like the Reno Air Racers have used forever?

[Flettner]

Methanol I guess and as you say lots of it. Hardly practical for an off road enduro bike. Or does this mean we need to use really small engines.
Never the less, impressive performance, I'd like that next time I come up a 450 in a drag race out of a corner. 😆

[Flettner]

now just to join the drive shaft.
Drive shaft sized to handle turbo charged twostrokes in the future.😆

[Flettner]

And not to forget the picture.
Looks like I might have to raid the backup scrap heap.

[wobbly]

Running on Nitrous simply increases the combustion pressure , as its effectively air and fuel mixed together.
The combustion temperature could essentially be exactly the same - thus no reason to melt anything.
And as we have talked about before the mechanical forces on the crank and piston increase as the square of rotational velocity and are several orders of magnitude greater than combustion forces
pushing down on the piston.
So as I have been saying for years , you could double the power of most any engine and if its not reved any harder its inherent reliability isnt affected ( apart from ring pressure on the bore ).

[Flettner]

Now we mean business.

[husaberg]

Now we mean business.

Landy or RL bedford

[Flettner]

I think Bedford.

[Flettner]

An old exercycle fly wheel, will become the A section drive pully sandwiched into the drive shaft assembly for starter purposes. Three phase motor as the starter on a hinge arrangement.

[Ocean1]

Now we mean business.

Might have to brace up that milk crate a bit...

[wobbly]

Hey Neil , been there done that with the " flip off the belt once its started thing ". A real PITA.
Use a small auto trans flex plate and a starter motor , way way better.

[Flettner]

Ahr, you havent seen the finished product yet.
I dont want a 12V system, I want 480V 😆. I want the ability to motor this engine for a time, might be a bit hard on a starter motor.

[Flettner]

Might have to brace up that milk crate a bit...

Yeah, they are not very strong, its barely strong enough to just hold this end of the drive shaft. All my wooden boxes are in use, ' storing stuff ' 😆.

[F5 Dave]

Ahh, the good old bottle ones were great. I managed to acquire one before they fell out of fashion. Well before. Every engine I have split and reassembled has been done on that and a million other uses. Super strong, lots of holes for shafts and won't scratch anything. Heck now I'm concerned that I should take better care of it.

[Flettner]

Dirty old exercycle flywheel is now a 400mm pully.

[Frits Overmars]

Hey Neil, been there done that with the "flip off the belt once its started thing". A real PITA. Use a small auto trans flex plate and a starter motor, way way better.

Ahr, you havent seen the finished product yet. I dont want a 12V system, I want 480V ��. I want the ability to motor this engine for a time, might be a bit hard on a starter motor.You're right about the longevity or lack thereof of a starter motor.
Of course Wobbly is right too: belts are a pain. But we don't need them. And since you are already planning a hinged start motor, take a look here:
345287 345288 345290 345289

The kart tyre was hydraulically driven and pressed against the flywheel, because hydraulic pressure happened to be available on that dyno, but of course you can use your 480V instead. Come to think of it: where do you get 480V? In the old world we are happy with 380V...

[Flettner]

The problem is, only being able to use whats available within my two scrap heaps.

[Larry Wiechman]

Frits,
What is under the red half-round guard shown in Koene-3 and Koene-4? Break away torque limiter or a clutch of some sort?

[wobbly]

You gotta have a one way clutch somewhere in a direct driven engine dyno setup.
Just imagine the chaos caused by the huge drum inertia , continuing to spin everything , if for some reason the engine siezed or the gearbox drive failed.
I have discovered that a cheap , small one way clutch used on tractor PTO shaft outputs works perfectly , and is easy to adapt.

[ken seeber]

One of the benefits of using a suitably sized 3 phase synchronous motor, is that in addition to providing motoring ability, can also be used as a steady speed state load absorber. Obviously up to the rating of the motor and the available electrical power supply. As an absorber it can turn the meter backwards. Imagine that, a 2 stroke engine powering NZ’s energy grid.<_<

Yeah, a sprag somewhere might be useful, certainly with an inertia flywheel, but how could you start or motor the engine as Fletto is suggesting? Maybe just rely on the belt shitting itself? Or keeping his hand on the clutch lever or motor pivoting position, relying on Neil’s ultra-sharp race tuned reflexes.:laugh:

[Larry Wiechman]

Possibly one sprag clutch to keep the flywheel from over-running the engine and another sprag clutch (before the one for the flywheel) in the driven sprocket of the starter drive?

[husaberg]

use a one way clutch off a tractor they are made for non live drive tractors using mowers so the mower doesn't put you through a fence.
anyon who has used a TEA feg with a mower will know why its a must have.
https://www.hoyetractor.com/overrun.htm
https://www.hoyetractor.com/PROD/or-660.htm

[Flettner]

All bloody good ideas, but I dont have any such things laying around and Im not waiting another two weeks. If the engine seizes, it will be a catastrophe for sure. Clutch is my saviour for now.

[husaberg]

All bloody good ideas, but I dont have any such things laying around and Im not waiting another two weeks. If the engine seizes, it will be a catastrophe for sure. Clutch is my saviour for now.

You have a tractor and Farms are still essential business, you live on a farm, order one it will arrive in the heart of dairy country to your old dairy shed the next day.

345306345307
bloody things are only $38 USD in USA

[Frits Overmars]

Frits, what is under the red half-round guard shown in Koene-3 and Koene-4? Break away torque limiter or a clutch of some sort?
You gotta have a one way clutch somewhere in a direct driven engine dyno setup. Just imagine the chaos caused by the huge drum inertia , continuing to spin everything , if for some reason the engine seized or the gearbox drive failed. I have discovered that a cheap , small one way clutch used on tractor PTO shaft outputs works perfectly , and is easy to adapt.Right. The drawback is: with a one-way clutch in the power line you cannot use the starter motor to start the combustion engine. That red half-round guard is shielding a one-way clutch, lockable for starting purposes.

[speedpro]

. . . . . Clutch is my saviour for now.

speaking from experience - by the time you get the clutch in all the bits will be rattling around your shed

[folke]

[QUOTE=WilDun;113115
te for years!

[Frits Overmars]

I have a poppet valve outside the port to try to create a pulse ore a bounce of the gases to help the plugging effect.Any chance of a picture or two?

[folke]

Any chance of a picture or two?

Yes i have some pictures, but i need to work out how to put the on.
Cant get the grandkids to help at the moment.

[lohring]

Our inertial dyno did not have a one way clutch. We used a square key into a centrifugal clutch at the flywheel. We had only one engine seizure in over a thousand tests. The piston seized at over 15000 rpm. The engine was completely destroyed. All that was left was a holed crankcase filled with metal chunks. The key twisted 180 degrees. The good news was this was only a 26 cc engine and was relatively easy to replace. I would seriously consider a one way clutch on a more exotic engine.

Lohring Miller

345304

[Flettner]

What I do need is a one way clutch with a dog clutch over ride for starting purposes.
Because I need to transmit torque both ways.

[Frits Overmars]

What I do need is a one way clutch with a dog clutch over ride for starting purposes. Because I need to transmit torque both ways.How about this Neil? Slide these two parts partly axially together and you'll have a one-way clutch. Slide them further together and you'll have a dog clutch.
I once built something like this from kickstarter parts and I guess you'll find some useful stuff in your scrap heaps.
345308

[WilDun]

I am with you and don't believe the expansionchambers size and bulk will not be acceptable much longer in any new two stroke design.I am from the pre expansionchamber aera, my first two stroke bike had a
straight pipe.In the early sixties we got to see and copy the first conical pipes with a blank end and a pipe welded into the end,60 years on and we are still cutting and modifying but now in an science way.
My love was always MX- Enduro so many pipes later I'm sic of them and have started experiating with a straight pipe again.I was always a tinkerer.I have a poppet valve outside the port to try to create a
pulse ore a bounce of the gases to help the plugging effect.Runns well and sounds good but still very raw in development.
Is it only Will and myself thinking along this lines ore anyonelse GAME ??

Being locked up might give me to much time on my hands and hence reach out to likeminded.

I have enjoyed this site for years!

Sorry FOLKE, just fired up the old computer (a bit late today)! - Unlike you, all my tinkering is just done in my mind now and I would be quite happy to see you contribute here or elswhere in this forum.

Firstly I'm not brave, but sometimes a bit rash with my statements, (and I'm getting too old to care about niceties) so, often what I say won't make much impression on the (real) experts we have here, I can live with that, but I just contributed that "proclamition" to provoke some movement amongst contributors - (the thread had almost stalled completely for the first time in years!).

All I'm really trying to do is point out the reality of the dire situation of the two stroke engine - sometimes it takes a dummy who who can actually see the "forest" and whose mind isn't totally focused on the minute details of fine tuning and trying to wring out the dregs from the present day two stroke - and only in the area of competition! - Dont get me wrong! - that's all great fun, but for the future of the two stroke, we need to be able to take a much wider view!
My belief is that the future lies in world wide sales - generally, competition machines have been a spinoff from bikes designed for transport only!

This ESE thread in the Kiwi Biker forum I think was started by TZ350 specifically for Bucket Racing, which was definitely a fun spinoff from road going motorcycles and I think it should remain so!

I do look in now and again. I'll probably disappear again just as quickly.
It would be unthinkable to see this thread go down - it's been a fantastic success!

Hope we all survive the Virus! - I think we will! :niceone:

[wobbly]

My hand is shaking as I write this , consumately aware of being stabbed in the eye with one of your intellectual forks by contradicting you Frits , but there is an easy way of incorporating a starter motor
into a dyno setup as well as a safety sprag overun clutch for the spinning inertia mass.
The left hand chain comes from the sprocket and direct drives the secondary shaft.This has the starter motor flex plate on the RH end , so when the starter sprag engages it drives the test motor for firing it up.
The PTO tractor sprag is internally connected to the jack shaft , and its outer is connected to the central sprocket/chain that drops down to direct drive the inertia wheel.
The inertia wheel shaft also has the disc brake.

When the output sprocket exceeds the secondary shaft speed , the sprag locks and the inertia drum is driven ie allowing acceleration dependant upon input Hp
Whenever the inertia drum rotational speed exceeds the output sprocket speed , the sprag overuns , in effect allowing the engine to stop instantly , and the disc brake can then be used to independantly halt the inertia wheel.
This also means the disc brake can be used as a secondary load to prevent the engine from accelerating at all , if needed.

My dyno run number exceeds 1000 , as the computer counter has recently reset itself to zero , and I have saved 3 engines from destruction without even having their clutch cables connected.

[folke]

Post no longer wanted

[WilDun]

(When posting a message and want to add photos,) - scroll down further, click on "Manage Attachments" - "Upload Manager" will appear.
Then click on "add files" then it will say "choose files" - find your file then "upload" - and I think it says insert online click that and I think (from memory) hopefully you're done! - any problems consult the experts! :niceone: (it won't do PDF files though.).

[husaberg]

https://www.kiwibiker.co.nz/forums/album.php?albumid=4916&attachmentid=309051
https://www.kiwibiker.co.nz/forums/album.php?albumid=4916&attachmentid=309050

you can also attach a image as a address of the net instead of off your files

[ceci]

This is the first version i tested, to get the valve as close to the port as possible i removed the power valve, to get it running on the dyno it needed a lot of clutch,we learn as we go.
The camshaft i made had a lot of dwell, valve fully open when piston opened the port, stayed open until BDC then fully closed when piston was half way up the port.That was my theoretical
plug, it was not a bad guess going by the sound of the engine running.Obviusly this is were
R&D time must be spent.By having a solid close of the exhaust valve will allow for additional
inlet pressure to be added and will also stop fresh fuel mixture escaping.
Now version two is nearly ready for a run.

Excuse my impatience.
From reading the description of your mechanism, I liken it to that of this other one.
They may be similar

[folke]

Post no longer wanted

[ceci]

the advantages of using a cam mechanism are that you model the times more appropriately, in the mechanism that I showed it has more limitations, in the BDC the exhaust port does not remain completely open

[Frits Overmars]

My hand is shaking as I write this , consumately aware of being stabbed in the eye with one of your intellectual forks by contradicting you Frits, but there is an easy way of incorporating a starter motor into a dyno setup as well as a safety sprag overun clutch for the spinning inertia mass.
The left hand chain comes from the sprocket and direct drives the secondary shaft.This has the starter motor flex plate on the RH end, so when the starter sprag engages it drives the test motor for firing it up. The PTO tractor sprag is internally connected to the jack shaft, and its outer is connected to the central sprocket/chain that drops down to direct drive the inertia wheel.
Whenever the inertia drum rotational speed exceeds the output sprocket speed, the sprag overuns, in effect allowing the engine to stop instantly.The starter motor flex plate might object to that sudden stop. It may have much less inertia than the flywheel, but it may still be enough to grind the engine to grit.

The Corona virus seems to affect us in curious ways. In your case, it apparently stimulates a literary vein that I never suspected in you, Wob.
Stabbing you in the eye with a fork, it could have been written by Shakespeare.
You do know, don't you, that I have the highest regard for you. I would never puncture your eye, at most a tire from your chair :devil2:.
See? That is what Corona does to me. The deprivation of social contacts seems to be turning me into a monster. Normally I am the gentlest guy out there. I would never intentionally hurt a tire.


The camshaft i made had a lot of dwell, valve fully open when piston opened the port, stayed open until BDC then fully closed when piston was half way up the port.That was my theoretical plug, it was not a bad guess going by the sound of the engine running.Obviously this is were R&D time must be spent.By having a solid close of the exhaust valve will allow for additional inlet pressure to be added and will also stop fresh fuel mixture escaping.This begs for some form of supercharging Folke. Something like this, maybe?
345335
Your asymmetric exhaust timing would enable real four-stroke-like supercharging, which could make Formula 1-two-strokes feasible, and we could substitute our bulky expansion chambers with a small after-the-turbo muffler. Or in the case of F-1 no muffler at all; they want noise. Well, two-strokes are your friends.

Come to think of it: if we use a mechanical compressor instead of a turbo, we no longer need crankcase pumping to start the engine.
That allows for another four-stroke benefit: pressurized lubrication for all crankshaft bearings. F-1 is coming nearer and nearer, even without opposed-piston technique, because I doubt (sorry Flettner) that an OP-engine would tolerate so much phase offset that the exhausts would close well before the transfers.

Instead of a camshaft plus valve, did you ever consider using a rotating drum parallel to the crankshaft? I think the drive could then become noticeably simpler.
Maybe a hollow drum (# 4) rotating around a stationary core (# 10 + # 11) like MZ was planning in 1960 (lack of funds prevented MZ from actually building it).
345337

[Pursang]

Technical Puzzles for the Socially Isolated. #1

I'm prepping a 1984 Maico 500TE for general off-road use.
A very rare beast , air cooled, reed valve, compliance plated for road legal.
Very little info available for this year anywhere on the net, and then only the SC(MX) model.
Hopefully someone here has knowledge & experience with these.

Pulled the barrel to check for wear. Oversized 88mm piston & bore, still in spec.:niceone:
(though looks and feels like the ports weren't chamfered/dressed at last rebore).
No holes in piston for reed valve use, but Boyesen style ports into the transfers.
Does this seem correct or does it have an earlier 490 non-reed piston?

My major problem is this: At BDC and with top of piston flush with floor of exhaust port, the piston lip is above the transfers bottoms by close to 3mm.
The step looks like a serious impediment to transfer flow. (This is very strange and I wonder if it was perhaps a dodgy way to de-tune the SC for enduro use)
If I pack the bottom of the cylinder, to lift the transfers flush with the piston, I will be increasing Ext duration from around 188 to 196!
One of the main benefits of the 500 is the amount of instant torque at low revs.
Is the increase of transfer flow likely to balance the earlier opening and extra duration of the raised exhaust? ie. no nett loss of lower RPM torque
I'm happy to leave the new 3mm step at the bottom of the exhaust port.

3mm seems a lot to remove from the top of the cylinder as it will be cutting away the lip at the top of the liner! (Or 2mm if I eliminate the original head gasket)
Does it sound reasonable/ sensible / practical to machine the alloy cylinder and leave the liner lip proud, to form a spigot? (Bultaco style, with a matching recessed groove in the head).
Or is it better to just shorten the cylinder and leave the head and gasket stock (+/- squish clearance adjustment)

Any advice will be appreciated,
cheers, Daryl.

[Frits Overmars]

What would raising the cylinder by 3 mm do to the transfer timing Daryl?

If you raise the cylinder, I'd prefer to modify the head so it intrudes into the bore. Finding a head tends to be simpler and cheaper than finding a cylinder. And welding additional material to the head, if done carefully, can be undone.

[F5 Dave]

Daryl, many engines are as you describe, which is not ideal but raising the exhaust port to crazy for a 500 is unlikely to make you happy, or increase your crank life. If it makes you feel better every engine spends most of the time with the piston in a worse position than that.

You could consider filling the floors but transfer floors are the devil to work on. 88mm bore is a luxury not encountered mind.

I'd sew it back together as is and spend my attention replacing that Bing with a nice new Keihin.

[Frits Overmars]

F-1 is coming nearer and nearer, even without opposed-piston technique, because I doubt (sorry Flettner) that an OP-engine would tolerate so much phase offset that the exhausts would close well before the transfers.Me and my big mouth. This will teach me not to express an opinion without first checking whether it is correct.
It dawned on me that I have an easy way of checking: the HCCI program that I wrote some time ago for you, Neil.
Here's what I did: 130° transfer timing , 140° exhaust timing, with the exhaust crank 30° advanced relative to the transfer crank, so the exhausts will open 100° before transfer-BDC, which gives a conventional 35° blowdown angle.
And the exhausts will close 40° after transfer-BDC; 25° before the transfers close, so there is 25° available for supercharging. And it could easily become even more, if need be.
345338

[Frits Overmars]

The 30° phase offset in the above example is much less than what I'd expected to be necessary. It made me think of a DKW opposed-piston bike of 1949,
the US 250 (nothing to do with the United States of Trump).
345341 345340 345339

[Larry Wiechman]

What became of the Beare Six-Stroke? Death by lawsuits? http://www.sixstroke.com/index.html

[yatasaki]

Napier deltic had 20° advance on exhaust piston. Opening exhaust before scavenging (transfer)ports ( it is a diesel) in adittion with 20° resulted in exhaust closing before...transfers. So transfers became supercharging ports.

[Flettner]

Me and my big mouth. This will teach me not to express an opinion without first checking whether it is correct.
It dawned on me that I have an easy way of checking: the HCCI program that I wrote some time ago for you Neil.
Here's what I did: 130° transfer timing , 140° exhaust timing, with the exhaust crank 30° advanced relative to the transfer crank, so the exhausts will open 100° before transfer-BDC, which gives a conventional 35° blowdown angle.
And the exhausts will close 40° after transfer-BDC; 25° before the transfers close, so there is 25° available for high-pressure supercharging. And it could even become more, if need be.
345338

Frits, I should never have forsaken the uniflow concept :msn-wink:. Im convinced its the way ahead, now, with revised transfer scavenge and the ability to HCCI relatively easily plus crank phasing.

Im committed to building this single cylinder uniflow engine for some experiment and off road use. BUT Im also now keen to get back to building an Autogyro twin cylinder uniflow using this new scavenge system but still the ''cross transfer'' , two crankcases into one cylinder. After all it work so well on my now 25 year old uniflow boat engine.

But first I have to get this 360 going.

[Pursang]

What would raising the cylinder by 3 mm do to the transfer timing Daryl?

If you raise the cylinder, I'd prefer to modify the head so it intrudes into the bore. Finding a head tends to be simpler and cheaper than finding a cylinder. And welding additional material to the head, if done carefully, can be undone.


Daryl, many engines are as you describe, which is not ideal but raising the exhaust port to crazy for a 500 is unlikely to make you happy, or increase your crank life. If it makes you feel better every engine spends most of the time with the piston in a worse position than that.

You could consider filling the floors but transfer floors are the devil to work on. 88mm bore is a luxury not encountered mind.

I'd sew it back together as is and spend my attention replacing that Bing with a nice new Keihin.

Ah Ha! Raising the cylinder flattens the transfer flow and increases the transfer port area by 17% (at the short end of the sta). But it also lifts the transfer timing from 130 to 140.:Oops:

An 88mm piston bouncing at the revs required to work with 196 ext and 140 transfers is probably not something that should be put between your legs! :eek5:
My Crank Life is precarious enough at the moment anyway!:facepalm:


I think I will follow Dave's advice, a new carb will improve the reliability and rideability and that's what this thing needs, most of all.

Thanks Frits & Dave for the reality check, ;) Hang in there everyone, during these most interesting times!

cheers, Daryl.

[ceci]

This is the first version i tested,
Now version two is nearly ready for a run.



the photos are from the 1st or 2nd version.
The truth that his approach has made me see details in other prototypes that had escaped me, Frits showed photos of one with a rotary valve on the exhaust, the details that I see are that an artificial negative pulse is created caused by the Zhukowski pulse.

[wobbly]

FRRRIOLI - what pipe wall temps are you using, this will be the issue.

[lodgernz]

I need some advice please.

My normal practice when making a new head insert is to make the squish band straight, i.e. not to match the arc of the piston dome, for the required width based on the usual percentage of squish area to bore area.
I then cut the outer part of the piston dome to match the insert squish angle.
Actually I do it the other way around, but the point is that I cut the squish band on the piston at the chosen angle until the lathe tool hits fresh air.
This leaves some of the original dome in the middle of the piston.
As a result of this method, the straight cut squish band on the piston is wider than the squish band in the head insert.

My question is: Is this bad?

345358

[Flettner]

Oil pump works, gears work, clutch works, throttle opens and more importantly shuts, belt clutch works. But one problem, water goes in, level goes down but no water external. Found it, in the gearbox, bugger it.

[Frits Overmars]

My normal practice when making a new head insert is to make the squish band straight, i.e. not to match the arc of the piston dome, for the required width based on the usual percentage of squish area to bore area. I then cut the outer part of the piston dome to match the insert squish angle.
Actually I do it the other way around, but the point is that I cut the squish band on the piston at the chosen angle until the lathe tool hits fresh air. This leaves some of the original dome in the middle of the piston. As a result of this method, the straight cut squish band on the piston is wider than the squish band in the head insert.
My question is: Is this bad?
345358No . . . . . .

[WilDun]

It looks that historically, externally (blower) charged engines using this layout did use the crank phasing idea and had it already worked out!
However, what effect does this crank phasing have on events at the other end of the stroke? ...... it seems to me that when the exhaust piston arrives at TDC then it must follow that the transfer piston arriving at TDC sees the exhaust piston already descending - right? - so, would this (in effect) mimic a dwell at TDC ? - Is that a good or bad thing? - ie does it help combustion or hinder it?

[yatasaki]

At some point theoretical TDC is prolonged by transfer piston hunting exhaust piston meaning combustion volume is moving with pistons. It works with diesel spining 2000-2200rews max. but with gasoline and 10-12k rew would say ignition should follow that volume-time.

[folke]

Post no longer wanted

[folke]

Post no longer wanted

[ceci]

Hi Ceci

Photos is from version 1.
On version 2 i have refitted the power valve so i can have a stable and accurate reference between std engine specs and experiments i am doing.I have also reversed the flow through the port to be more efficient and the bounce should be
stronger,in my head it says so! The cam gear have a fine spline so i can experiment with different closing positions of the valve.I could have some more pics soon if of interest.


Hi Folke
I thank you for having my mind active trying to find out how your prototype works and its architecture, because in these bad times it comes in handy.
There are many unknowns that I have as described by you of your prototype, if you were so kind as to publish more photos and thus help me solve them.
Thank you very much

[Frits Overmars]

Come to think of it i might contact Christian VKE.I am impressed with Christians four-stroke products; it would be nice if you could interest him in two-strokes as well. He might surprise us.
Not everybody here may know Christian VKE, 'the man who never has to shave'. Here's some background info:
https://www.koenigsegg.com/innovations/ (https://www.koenigsegg.com/innovations/)
https://www.freevalve.com/freevalve-technology/

[ceci]

This begs for some form of supercharging Folke.
Come to think of it: if we use a mechanical compressor instead of a turbo, we no longer need crankcase pumping to start the engine.



Hi Fritz
.Your advice of supercharger might be a bit bald,i was actually thinking of an electric turbo.



Both solutions are typical of 4S, from my modest opinion I do not find them appropriate, 2S requires specific solutions for it, solutions that in 4S are not valid, because they are express for 2S

[wobbly]

Lodger - I tested all manner of combinations of angled piston edge and insert squish ratios fot the TM R1 engine.
Best by some margin was a 50% area,angle on the piston , with the " normal " 35% insert angled width.
The piston then has a flat top.
This result is coloured of course by the narrow insert squish width - mandatory with the idiotic straight line ignition we are forced to use.
But having equal widths on both made less power.

[lodgernz]

Thank you Frits and Wobbly.
I would love to have made the piston flat top with the squish areas equal on both piston and insert, but that would mean a very thin crown, so not an option.
From what you have both said, it seems that the arrangement I have is not going to be too negative, if at all.

[speedpro]

Wobbly said it made more power having it like you suggested, and less having the areas matched

[lodgernz]

Wobbly said it made more power having it like you suggested, and less having the areas matched

Yes, but that was in a kart engine with straight line ignition, so I'm not sure what I can draw from that, given that I have variable ignition.
I have 50% squish area in the insert, but lots more on the piston, whereas Wobbly's insert had only 32% in the head.

[WilDun]

At some point theoretical TDC is prolonged by transfer piston hunting exhaust piston meaning combustion volume is moving with pistons. It works with diesel spining 2000-2200rews max. but with gasoline and 10-12k rew would say ignition should follow that volume-time.

Thanks, I suppose that (in theory) if the stroke of each of the pistons is the same and we were using very high compression, eg say an extreme 20:1 (in phase shift mode that is), if we reduced the phase shift to zero, the crowns might then overlap at TDC ? :eek: - then I guess we would have to increase the distance between the crankshaft axes to prevent this "piston clash"? ....... I think I've just coined a new phase (I mean phrase)! :laugh:

[Flettner]

Engine on its way back together, leak fixed.

[WilDun]

Engine on its way back together, leak fixed.

Will be great to hear it run! - long journey!

[ceci]

Hi Folke.
I am a faithful defender of the basis of its principles, but I disagree in the form.
I don't understand why it needs to be. "Having a solid seal on the exhaust valve will allow additional inlet pressure to be added and will also prevent the fresh fuel mixture from escaping."
I do not see the need for the "theoretical plug" to have to be SOLID (an example: neither is it necessary to have a deflator to direct the load upwards) you only have to orient the jets properly).
I may be wrong wrong about the ways, but the important thing is to show that the principles are appropriate and in that I see that you are fighting to achieve it

[Frits Overmars]

I suppose that (in theory) if the stroke of each of the pistons is the same and we were using very high compression, eg say an extreme 20:1 (in phase shift mode that is), if we reduced the phase shift to zero, the crowns might then overlap at TDC ? Then I guess we would have to increase the distance between the crankshaft axes to prevent this "piston clash".You're right about the overlap, Will. And yes, you could increase the distance between the crankshafts.
But don't you think it would be easier to fit shorter con rods? Or use the KISS approach and just fit shorter pistons?:msn-wink:

[Flettner]

or just put everything in the right place in the first place?

[husaberg]

or just put everything in the right place in the first place?

https://quotefancy.com/media/wallpaper/3840x2160/1610469-Keith-Duckworth-Quote-Development-is-only-necessary-to-rectify-the.jpg
https://www.azquotes.com/picture-quotes/quote-turbochargers-are-for-people-who-cant-build-engines-keith-duckworth-61-67-63.jpghttps://www.azquotes.com/picture-quotes/quote-rules-are-for-the-obidience-of-fools-and-interpretations-of-smart-men-colin-chapman-142-63-91.jpg

[WilDun]

You're right about the overlap, Will. And yes, you could increase the distance between the crankshafts.
But don't you think it would be easier to fit shorter con rods? Or use the KISS approach and just fit shorter pistons?:msn-wink:

Yes Frits/Neil - that was just my mind sort of "doodling" and thinking of possible (theoretical) scenarios, ie maybe possible but never likely to happen - basically "tounge in cheek" that's me I guess!.
But .... As I have always said, (and I have nearly always been correct) - every joke is inspired by a serious thought, so I never take a joke at face value! ..... and yes I've also thought about the possible remedies you describe, - didn't need to, but just in case! :facepalm:

Maybe I'm just trying to say that there are better ways of obtaining blow down / plugging etc than phase shift! ( not arguing, just suggesting!).

Can't think why a lot of people don't at least consider opposed piston - (BTW I realize this thread is really for Bucket Racers, but unfortunately ALL 2T stuff has defaulted back here again, it would seem)..... but the OP engine was successful in the past and apparently there are a lot of fishing boats in Brazil or somewhere still working daily with their original Commer three cylinder OP two stroke engines (well over 60 years later!!). - is that good or not?
Not so sure about using a turbo - definitely not a KISS solution if you have to spin it up in order to get the engine going!

[WilDun]

Husa,

I thought Duckworth was a far seeing man, but he didn't consider the two stroke or turbos - so he can't have been!

Colin Chapman obviously couldn't spell for shit! ( going by the quote you posted) - and he made a mistake in becoming mates with John DeLorean!

[Flettner]

Wiil D, there was once an OP bucket.

[husaberg]

Wiil D, there was once an OP bucket.

345401345402

[WilDun]

Wiil D, there was once an OP bucket.

Yes, I think I may have heard about that one - I'm sure it had its "debut" race down the country somewhere and the experimental ignition upset a few people... or something? - built by some obscure guy - maybe you can fill me in on all that and correct me if I'm wrong?

Is that bike still around? (maybe down in the old cowshed?) or did the engine end up powering the boat? - Neil?

[Flettner]

The down side of the out door dyno, had to wrap a tarp around the whole thing, and wait. Never mind back to project no. 483 😆.
Actually just drawing up a cross section of the 175 uniflow engine. All other projects on the side bar until enthusiasm strikes me.

[folke]

Post no longer wanted

[yatasaki]

Thanks, I suppose that (in theory) if the stroke of each of the pistons is the same and we were using very high compression, eg say an extreme 20:1 (in phase shift mode that is), if we reduced the phase shift to zero, the crowns might then overlap at TDC ? :eek: - then I guess we would have to increase the distance between the crankshaft axes to prevent this "piston clash"? ....... I think I've just coined a new phase (I mean phrase)! :laugh:
If pistons are flat, no need for overlap...but good thinking, if any other kind of dome,higher compression ratios are not achievable.

[WilDun]

If pistons are flat, no need for overlap...but good thinking, if any other kind of dome,higher compression ratios are not achievable.

I never think domes with opposed piston, Especially if it's HCCI. ..... It was just a mental exercise really, not to be taken as a new invention! nor for anyone to think that I was contemplating doing it! - I like thinking about and exploring all the different scenarios, (most of them possibly not viable!) - but with no real workshop or a place to have one anymore, none of the stuff I dream about will ever come to fruition - guess being a thinker only, is not enough! - gotta be a doer! :rolleyes:

BTW, hope you don't mind me asking - would you consider yourself Croatian? or Dalmation? - Many people in New Zealand have Dalmatian ancestors.

[Frits Overmars]

I thought Duckworth was a far seeing man, but he didn't consider the two stroke or turbos...Oh yes, he did. He proposed a Formula 1 two-stroke engine with a huge compound turbo and a huge exhaust timing, so the combustion engine would in practice serve as a combustion chamber for the turbine that would drive the wheels. The advantage over a conventional gas turbine would be that the combustion takes place intermittently at a higher pressure. The higher pressure would ensure a better thermal efficiency and the intermittent character would reduce the thermal load, keeping the engine parts from melting (no ceramics to speak of available back then).
At the same time Duckworth proposed a restricted fuel regime instead of the cylinder capacity regime. In other words: "Here is your 100 liters of fuel and you can do with it whatever you want".

[WilDun]

Oh yes, he did. He proposed a Formula 1 two-stroke engine with a huge compound turbo and a huge exhaust timing,................
At the same time Duckworth proposed a restricted fuel regime instead of the cylinder capacity regime. In other words: "here is your 100 liters of fuel and you can do with it what you want".

Frits,
Well, there you go! - that news restores my faith in him - I had always heard that he was a great man, but I guess I didn't dig deep enough!
On the other hand, I have heard a few things about Chapman which weren't terribly complimentary though!

Has anyone ever tried using the Wankel layout for a blower (possibly even without seals, as in the Roots type supercharger?).

[Pursang]

Hi Folke.
I am a faithful defender of the basis of its principles, but I disagree in the form.
I don't understand why it needs to be. "Having a solid seal on the exhaust valve will allow additional inlet pressure to be added and will also prevent the fresh fuel mixture from escaping."
I do not see the need for the "theoretical plug" to have to be SOLID (an example: neither is it necessary to have a deflator to direct the load upwards) you only have to orient the jets properly).
I may be wrong wrong about the ways, but the important thing is to show that the principles are appropriate and in that I see that you are fighting to achieve it

Perhaps a variation on the COMPREX supercharger principle could provide a valveless seal/plug in the exhaust duct, phased to rpm (and a pressurised charge).

https://upload.wikimedia.org/wikipedia/commons/d/da/US4563997_Fig1_Pressure_wave_supercharger.png


cheers, Daryl

[Frits Overmars]

Has anyone ever tried using the Wankel layout for a blower (possibly even without seals, as in the Roots type supercharger?).Yes, there are multiple examples of it. The first may have been NSU (who else?) , supercharging the piston engines in some of their land speed record machines.
Rolls Royce went one better: they used a Wankel blower to supercharge their Wankel diesel, and drove that same blower with the diesel's exhaust gases, much like a turbocharger.
345415 345414 345413 345412

[Philski]

Hi all. Thank you all so much for blowing my mind so often. Artificial intelligence variable valves. omg. um. I was just wondering if anyone has seen a tesla turbine on a bike? I was thinking of a tesla crank web to help pull fresh charge in.

[lohring]

The common screw type (Lysholm (http://www.lysholm.us/superchargers.php)) compressor has a lot of advantages for small engine superchargers. It can generate high pressure efficiently at engine rpm. You would still need to supply back pressure to keep the mixture in the cylinder. That's the reason turbos are a good idea. You can set up the whole system so most of the power comes from either the engine or the turbine. All this was known and tested a very long time ago. One of the most efficient engines developed with these principles was the Napier Nomad (https://en.wikipedia.org/wiki/Napier_Nomad). More successful was the Wright R-3350 (https://en.wikipedia.org/wiki/Wright_R-3350_Duplex-Cyclone) turbocompound engine. Both were stopgaps until efficient turbines were developed. Detroit Diesel (https://en.wikipedia.org/wiki/Detroit_Diesel_Series_71) built a series of successful both naturally aspirated and turbocharged two strokes from 1938 to 1997. Today snowmobiles are the main user of turbocharged two strokes. Modern turbos are available at low cost in very small sizes. They should work very well with two strokes as small as 50 cc.

Lohring Miller

[lohring]

Note that the Detroit Diesel engine could be configured as a constant power engine. That gave it the performance characteristics of steam engines and electric motors. Truckers especially appreciate this characteristic.

Lohring Miller

[ceci]

Can you tell me some 4S engine that uses piston pump supercharging.
At 2S we all know that they were serially produced by a certain brand and for a few decadeshttps://3.bp.blogspot.com/-L9_6s7imSVY/WOYzfx1C2aI/AAAAAAAAB8E/c1IzlmWnaoAwbkrtqbwjnU6So_94zvp_gCLcB/s640/5.png

[WilDun]

Can you tell me some 4S engine that uses piston pump supercharging.
At 2S we all know that they were serially produced by a certain brand and for a few decades

This probably doesn't really help in answering your question of course! .... but the piston type compressor was used on quite a few successful two stroke engines based on (relying on my memory here) Ricardo's "Dolphin" V2 layout ie Power cylinder/compressor cylinder arranged as a V twin) this engine appeared around 100 years ago, and I think was also used in fishing boats.

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=345424&d=1586821782


This layout was also used successfully in the Trojan light delivery truck in Britain - I think a V4 - it also used 'split single' layout) - however, basically the Dolphin layout).

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=345425&d=1586821791

Then of course there was the DKW racer which was raced in pre war, pre-expansion chamber days and which (reputedly) shattered windows all round the IOM TT circuit! - it used the 'split single' arrangement and a piston type supercharger.

345423 (DKW)

345426 (Montesa)

345427 (Motobecane)

Another interesting site :- https://www.elsberg-tuning.dk/supercharging.html

[Muciek]

Rg250 turbo from back in the day.
345422

[Flettner]

Is this turning into the odd ball engines thread? If so.

My uniflow engine has ended up 295mm crank center to crank center, 48 stroke on each, 100mm long rods. Not as bad as it could have been. Normally I build my uniflows with a split in the middle between the cylinders but this time Im having a go at casting the whole cylinder as one. With lugs cast in for sparkplugs, or whatever, or not at all. Three lugs at 120 degrees with water flow right over the lugs. Same size pistons this time so the bore can be bored, nikasil finished easily. Six transfers, three from each crankcase, four exhaust ports. In house manufactured pistons, or should that read round the back of the house. The plan is to still run tuned pipes and a kind of powervalve setup, blocking off two of the ports at low speed? Possibly some on the fly timing changes between the cranks? Many possibilities.

[WilDun]

Note that the Detroit Diesel engine could be configured as a constant power engine. That gave it the performance characteristics of steam engines and electric motors. Truckers especially appreciate this characteristic.

Lohring Miller

Yes, it's probably worth looking at these types of layout - but we took a wrong turn way back in the sixties and opted for high revving top end power instead - mistake! - we were all guilty!

[WilDun]

Is this turning into the odd ball engines thread? If so.

My uniflow engine has ended up 295mm crank center to crank center, 48 stroke on each, 100mm long rods. Not as bad as it could have been. Normally I build my uniflows with a split in the middle between the cylinders but this time Im having a go at casting the whole cylinder as one. With lugs cast in for sparkplugs, or whatever, or not at all. Three lugs at 120 degrees with water flow right over the lugs. Same size pistons this time so the bore can be bored, nikasil finished easily. Six transfers, three from each crankcase, four exhaust ports. In house manufactured pistons, or should that read round the back of the house. The plan is to still run tuned pipes and a kind of powervalve setup, blocking off two of the ports at low speed? Possibly some on the fly timing changes between the cranks? Many possibilities.


Just look on it as "helping ESE out" because of buckets not being allowed out to play these days! - I do hope TZ sees it that way! - reckon "Oddball" will get this sort of stuff back again one day! - that's why it started anyway - to relieve the congestion here at ESE!!

Your scheme sounds good so far - lots of future variations and possibilities available and above all, some concrete evidence ( as opposed to all the wild theories we have been chucking around!). .... I'm a little biased of course, but just do it I reckon! :niceone:

[Flettner]

Or perhaps three exhaust ports, block two off at low revs then one, and then none at high revs. Three small pipes of varying lengths with little flaps in them to make them the same short lenght at high speed, mmmm.

[ken seeber]

OK you blokes, I can see that ESE is getting lots of posts on things that are not exactly related to buckets, which it was then in 2008 when it was started by TeeZee. Since then it has matured / morphed into probably one of the most informative and instructive current threads in the world (that I am aware of anyway) on getting high specific power from 2 strokes.

In no small way this is due to the contribution of many: Wobbly, Neels, Frits, TeeZee, Husa, Jan, Fletto etc etc.

So, back to the latest round of contributions. Should they stay, despite some of the higher specific power aims (eg turbo) that fit in with the goals of ESE. Maybe the goals of ESE should be strictly crankcase scavenged, but remember we did have the fling with Ryger that fitted in with the general ESE philosophy.

So, just don’t know. Thoughts?

Anyways, all the above is just skirting around the fact that someone over here has been working on a fairly novel method of a crank scavenged 2 stroke operating principle. Nothing in terms of high power, more of a mundane application, with a goal of lower fuel consumption and unburnt HCs. As with everything though, it might have some high power potential, given certain add-ons. Could be a total flop as well. As it has a bit of history and potentially a fair few words and pics to go with it and it could go on and on, the question is where to put it? Just don't want to give anyone the shits.

I think I’ll be guided by your thoughts on the above round of questions. Or would you like a bit of a teaser ??

[WilDun]

OK you blokes, I can see that ESE is getting lots of posts on things that are not exactly related to buckets, which it was then in 2008 when it was started by TeeZee. Since then it has matured / morphed into probably one of the most informative and instructive current threads in the world (that I am aware of anyway) on getting high specific power from 2 strokes.

In no small way this is due to the contribution of many: Wobbly, Neels, Frits, TeeZee, Husa, Jan, Fletto etc etc.

So, back to the latest round of contributions. Should they stay, despite some of the higher specific power aims (eg turbo) that fit in with the goals of ESE. Maybe the goals of ESE should be strictly crankcase scavenged, but remember we did have the fling with Ryger that fitted in with the general ESE philosophy.

So, just don’t know. Thoughts?

Anyways, all the above is just skirting around the fact that someone over here has been working on a fairly novel method of a crank scavenged 2 stroke operating principle. Nothing in terms of high power, more of a mundane application, with a goal of lower fuel consumption and unburnt HCs. As with everything though, it might have some high power potential, given certain add-ons. Could be a total flop as well. As it has a bit of history and potentially a fair few words and pics to go with it and it could go on and on, the question is where to put it? Just don't want to give anyone the shits.

I think I’ll be guided by your thoughts on the above round of questions. Or would you like a bit of a teaser ??

Yes, I would have preferred that it all went to the "Oddball" thread of course and to be fair to the Bucket guys it's cluttering up their thread but seeing that both "Oddball"and "Foundry" threads have now ground to a halt, what can be done about it? - what does TZ think? he did indicate earlier (about a year ago) that it was ok - still not a perfect arrangement though! and the fact that Buckets are on lockdown for the moment doesn't help. ....... I'm sure that the stuff you want to post will be well accepted in any of these threads (but which one is best?)

[Flettner]

Turn it into a Ryger guessing game😁

[breezy]

Me and my big mouth. This will teach me not to express an opinion without first checking whether it is correct.
It dawned on me that I have an easy way of checking: the HCCI program that I wrote some time ago for you, Neil.
Here's what I did: 130° transfer timing , 140° exhaust timing, with the exhaust crank 30° advanced relative to the transfer crank, so the exhausts will open 100° before transfer-BDC, which gives a conventional 35° blowdown angle.
And the exhausts will close 40° after transfer-BDC; 25° before the transfers close, so there is 25° available for supercharging. And it could easily become even more, if need be.
345338

F1 considering switch to two-stroke eco-fuelled engines for 2025

Published on 13 Jan 2020 08:17 comments 8 By: Harry Mattocks

Formula 1 is considering a switch to two-stroke engines for 2025, according to the sport's chief technical officer, Pat Symonds.

Two-stroke engines are best known for powering much smaller vehicles, such as lawnmowers and small motorbikes. It is called a two-stroke as it completed a power cycle with two strokes of the piston (a stroke is an up and down movement) during a single rotation of the crankshaft.

They were previously known for using lots of fuel and having poor emissions, as the burning of oil, as well as fuel, means smoke was often seen coming from the exhaust.

However, Symonds believes that these issues are no longer present, and is currently working on what 'the future of our power units will look like.'

He is quoted by Motorsport Magazine: "At F1 this is what we are engaged in at the moment. I’m very keen on it being a two-stroke [engine].

"Much more efficient, great sound from the exhaust and a lot of the problems with the old two strokes are just not relevant any more.

"The opposed-piston engine is very much coming back and already in road car form at around 50 per cent efficiency.

"Direct injection, pressure charging, and new ignition systems have all allowed new forms of two-stroke engines to be very efficient and very emission-friendly. I think there’s a good future for them."

Eco-fuels are also being considered as a viable fuel option, as the sport continues to find ways of reducing their carbon footprint.

"I think there’s a very high chance that there might still be an internal combustion engine but maybe it’s running on hydrogen," Symonds said.

"I certainly think that the internal combustion engine has a long future and I think it has a future that’s longer than a lot of politicians realise because politicians are hanging everything on electric vehicles.

"There’s nothing wrong with electric vehicles but there are reasons why they are not the solution for everyone."
F1 News
<< Previous article
Next article >>
Trending news
small section from an f1 magazine.

[WilDun]

Turn it into a Ryger guessing game��

Ryger? - what's that? - ah yes that's what it nearly did become at one stage! - (The Ryger Guessing Game Thread) but it always does seem to recover! (I did worry about it a few weeks ago though, it just stopped!) - first time it's stopped!

[ceci]

Hi Ceci
Im not sure i follow your thinking correctly,my theoretical plug is not solid ,it is the back pressure against the exhaust port in the cylinder, and it is created by the exhaust valve.

Hi Folke.
Exactly as you describe it is how I have always thought it has to be.
I'm afraid I got confused trying to find out how your prototype works (I thought it has two cams and therefore two mechanisms: 1st closure to the outside, 2nd creation of the pulse).
For everyone else:
Sorry if I follow this topic here in this thread, (I suppose if it has to be changed to "Odball" it should be Folke who takes his posts there, I hope he keeps posting about his experiment)

[WilDun]

Hi Folke.
Exactly as you describe it is how I have always thought it has to be.
I'm afraid I got confused trying to find out how your prototype works (I thought it has two cams and therefore two mechanisms: 1st closure to the outside, 2nd creation of the pulse).
For everyone else:
Sorry if I follow this topic here in this thread, (I suppose if it has to be changed to "Oddball" it should be Folke who takes his posts there, I hope he keeps posting about his experiment)

Trouble is, it always seems to default back to here (because this is a very popular thread) so it ends up half here and half there - never just one thread or the other! - "The Bucket Foundry" is also involved in the same way! - a lot of overlap! - there is a solution, - go to Oddball or Foundry threads!! - I tried to remain there but it was like being isolated and in lockdown - I was the only one there! - perhaps I've got B.O.!

[yatasaki]

BTW, hope you don't mind me asking - would you consider yourself Croatian? or Dalmation? - Many people in New Zealand have Dalmatian ancestors.

Yep, Dalmatian at first place, but my relatives are from Australia and Alaska

Since corona, no buckets racing around here as well but I can tell you "never enough time" phrase is no longer valid.

Little or no money at all is second issue..perfect to finish bucket(s) project(s)

[jbiplane]

My idea of boxer mechanism with decreased friction losses
You can see how small is side force at right cylinder 3.5...7kgf for 66mm piston at 8300rpm. Left piston loaded harder - it responsible for engine torque, but side force as well less than in classical mechanism and could be just guide, not working piston.
This mechanism could be "rygerized" for 2-stroke use, at momeny it is only idea

https://www.youtube.com/watch?v=SZtqMpOF3Lc

16.04.2020 I added to my old post other video to dont overload this thread

https://www.youtube.com/watch?v=ZzTPbcNfUIU

[Frits Overmars]

Valery, I know that your above video only shows the principle, not the actual construction. But in the video I noticed that the connecting rod is not hinged on the left gudgeon pin, but on its own pivot point, closer to the crankshaft.

If you let the connecting rod hinge on the gudgeon pin, you can use a longer connecting rod without the construction getting bigger. And then the side force will become lower still.

[jbiplane]

I know that your above video only shows the principle, not the actual construction....

If you let the connecting rod hinge on the gudgeon pin, you can use a longer connecting rod without the construction getting bigger. And then the side force will become lower still.

Thank Frits. I tried variant like you proposed, but Ansys had converge error. It a bit lottery. Sometimes simple mechanisms dont solved, but more complicate solved easily. Will continue modify this mechanism to real life. Hope succeed. I have tenth of ideas to implement, but have to do first real simple engines and experimental stuff delayed. So I share some ideas without minor details which could be wrong, may be someone will implement better than me :)

[WilDun]

Valery, I know that your above video only shows the principle, not the actual construction. But in the video I noticed that the connecting rod is not hinged on the left gudgeon pin, but on its own pivot point, closer to the crankshaft.

If you let the connecting rod hinge on the gudgeon pin, you can use a longer connecting rod without the construction getting bigger. And then the side force will become lower still.

Or if you made the connecting "link"? (lets call it the piston carrier ) with bearing pads at each end top and bottom (and as close to each piston crown as is practical), these pads could bear on the casing/cylinder or whatever and you would have no side forces on the piston whatsoever! - any side thrust being taken by the pads and bearers! - pistons are really quite flimsy so far as sidethrust is concerned but bearing pads are sturdy! and you then wouldn't need a longer conrod (or even a gudgeon pin on the piston for that matter - but it's handy to have one though!)...... Then, there's balance to think about too!
Anyway, - something like that! :yes:

[Frits Overmars]

Thank Frits. I tried variant like you proposed, but Ansys had converge error. Maybe Ansys will behave it you give it some room to move - like 0,001 mm distance between the piston pin center and the con rod bearing center?

[folke]

Yes, I would have preferred that it all went to the "Oddball" thread of course and to be fair to the Bucket guys it's cluttering up their thread but seeing that both "Odball"and "Foundry" threads have now ground to a halt, what can be done about it? - what does TZ think? he did indicate earlier (about a year ago) that it was ok - still not a perfect arrangement though! and the fact that Buckets are on lockdown for the moment doesn't help. ....... I'm sure that the stuff you want to post will be well accepted in any of these threads (but which one is best?)

Ops im in the bad books,i was not sesitive enough to the law of the forum, sorry.I will still enjoy the forum but will not post again.Well back to my tinkering.....Bye

[Frits Overmars]

Ops im in the bad books,i was not sesitive enough to the law of the forum, sorry.I will still enjoy the forum but will not post again.Well back to my tinkering.....ByeYou're joking Folke.
I may well have posted half of my posts in the wrong threads, but I don't have the impression that many people have bothered about that. I would be sorry to miss your contributions, in any thread.

[Flettner]

Personaly I'll go back to the bucket foundry, probably where I should be I guess, there is a lot of pattern and foundry stuff comming up anyway.
Pity about the weather.

[WilDun]

Yes Folke,
I agree with Frits and can't see why you are in the bad books?? - I don't think there were any laws - it was just me talking about the other threads which were petering out and I have been trying to keep them going for a while now - nothing more than that - no laws or even any restrictions involved! - Kiwi biker is sort of self moderated with only the occasional input by moderators! - I'm not a moderator or anything else but just like to keep things going!
We have been enjoying your contributions so don't go away! This thread has done everything 'two stroke' for yonks, it has survived many ups and downs and will no doubt do so again! - At the moment this is THE two stroke thread so we're all here - the other two threads have ground to a halt - but who knows what will happen after the "virus" has settled down - just keep going! - don't need to be sensitive - look at me, I have managed to talk all sorts of crap, for years - (Frits, Flettner and Ken etc. think so) yet I still have the gall to stay here! ..... and you were doing so well - I thought! :niceone:

[WilDun]

Personaly I'll go back to the bucket foundry, probably where I should be I guess, there is a lot of pattern and foundry stuff comming up anyway.
Pity about the weather.

Who would have thought it! ..... but the future of the two stroke may be huddling under that tarp - can't wait for the unveiling!

[TZ350]

.
It is all Ok by me. I only get to play with 2T Bucket stuff because that is what we have.

But others are playing with other 2T stuff because that is what they have.

In the end its the playing with 2T stuff and showing it to all of us that I think is interesting ..... :niceone:.

And between us, by some miracle we may even resurrect 2T's.

[WilDun]

Yep, good to hear that - Oldies need to survive the virus to resurrect the Two Stroke! - otherwise it will be totally forgotten! (not that I think you're old Rob!).

[TZ350]

.
Well, with all this talk about turbo 2T's the other day, I got over exited and brought a small RHB31 turbo.

Then I discovered on Wikipedia talk about compound turbo engines where the exhaust turbine is directly connected to the crankshaft instead of a compressor impeller.

"" (From Wiki) A turbo-compound engine is a reciprocating engine (https://en.wikipedia.org/wiki/Reciprocating_engine) that employs a turbine (https://en.wikipedia.org/wiki/Turbine) to recover energy from the exhaust gases. Instead of using that energy to drive a turbocharger (https://en.wikipedia.org/wiki/Turbocharger) as found in many high-power aircraft engines (https://en.wikipedia.org/wiki/Aircraft_engine), the energy is instead sent to the output shaft to increase the total power delivered by the engine. The turbine is usually mechanically connected to the crankshaft (https://en.wikipedia.org/wiki/Crankshaft), ""

Now that has got me thinking. I have a spare turbo turbine. And with a one way clutch and reduction I could attach it to a 2T engine. It could be geared onto the clutches big primary gear. I wonder what our F4 race rules say about it. Not much by the looks.
Hmmmmm a grey area I might be able to exploit ....... :eek:

[TZ350]

.
All this has re ignited my interest in a turbo charged Crecy two stroke sleeve valve engine for Bucket racing.

https://ww2aircraft.net/forum/threads/rolls-royce-crecy.50534/

[Flettner]

here is one, open ended sleeve like Crecy
https://youtu.be/bwsu5td6nko
https://youtu.be/6keqpL3rmwk
https://youtu.be/TmXFkbD3s5g

[TZ350]

.
Some more work in progress photos of Flettners Crecy sleeve valve engine.

345455345456345459345460

I am not sure if these two casting pictures are Crecey but they show Flettners foundry handywork.

345458345457

[ceci]

Hi Folke
Your experiment is of great interest to me, since you published the photos I have not stopped analyzing them and trying to understand the mechanism (for now with more mistake than success).
The last conjecture on how it works and tried to capture it in these drawings:
In drawing 1 we have a cone that corresponds to the back pressure pulse focused towards the exhaust port.
In drawing 2 we have the cone and the exhaust nozzle.
In drawing 3 in this we see the part of the back pressure cone that is added to the exhaust outlet nozzle.

[ken seeber]

UHV 1

For some time I have had the idea that one could feed the cylinder in a supplementary or totally different manner than using the side transfer ports. So, without going thru the piston (Frits April 1st) the only other way is via the head.

No camshafts or any of that 4 stroke stuff. Gotta be passive. However, the old 100 year old sprung loaded poppet valves don’t seem appropriate. So, it is a reed valve. Where to put it or them? Seeing reeds wouldn’t like non flat surfaces, the only logical position would be is the in a flat squish area. Something like this:

345466

More to come

[yatasaki]

Ken, this would be backwards-uniflow scavenging?

[wobbly]

Anyone seen or plotted the ignition curve for a late model KTM125.

[ceci]

UHV 1

For some time I have had the idea that one could feed the cylinder in a supplementary or totally different manner than using the side transfer ports. So, without going thru the piston (Frits April 1st) the only other way is via the head.

No camshafts or any of that 4 stroke stuff. Gotta be passive. However, the old 100 year old sprung loaded poppet valves don’t seem appropriate. So, it is a reed valve. Where to put it or them? Seeing reeds wouldn’t like non flat surfaces, the only logical position would be is the in a flat squish area. Something like this:

345466

More to come

Hi Ken
Let me remind you that there are always two limitations in any project: 1º those of the prototype's architecture or geometry. 2º the appropriate materials.
In the project you are showing I believe that the limitations are of the 2nd, because what material supports temperatures and also maintains elasticity (I tried to look for it since, as you can see, I also thought this solution).
His approach is excellent

[Flettner]

I guess pulse jets bathe their reeds directly against the fire.

[husaberg]

I guess pulse jets bathe their reeds directly against the fire.

Pretty sure jet engines were the reason stainless and austenitic steels were invented like nimonic 80 as made famous for its nicker dropping properties on BSA Goldstar clubmans exhaust valves.
https://i.pinimg.com/originals/f7/7a/09/f77a0911f9054ac29a0f13b3273d1afc.jpg

[ceci]

I guess pulse jets bathe their reeds directly against the fire.

Hi Flettner
On the left, the sheet at rest, allows an exit of burned gases through the pipe and blocks the outlet of the supercharging gases.
On the right the sheet is flexed due to the pressure of the supercharging gases.
The two previous drawings correspond to how the sheet have to behave in the mechanism, in a FEM study they do not behave like this, because there are different lengths (shorter in the center than at the ends)

[ken seeber]

UHV 2

Can see a couple of questions / points re this, but maybe if you could hold off for a couple more posts, it might become more clear and self-explanatory.

How to feed the reeds? Down thru holes in the head, maybe with an initial design something like this.

345479345482345481


Cool, but how is the mixture going to get up there? Well, despite another alternative, I went for crankcase scavenging. So I blocked off the cylinder transfer ports and set in 2 aluminium tubes that were flush with the top deck of the cylinder


345478345480


More to come..

[lohring]

The expanded gas at the exhaust port should be at a lower temperature than in the head. The temperatures would be even lower in the pictured setup. I bet steel reeds could work. My question is; would that be better than a straight FOS cylinder with a tuned pipe? Maybe at part power and low rpm, but I bet it would reduce peak power. If you're thinking about a supercharged engine, it would help. However, tuned pipes work really well on small engines.

Lohring Miller

[Tim Ey]

Anyone seen or plotted the ignition curve for a late model KTM125.

I have strobed and reverse engineered a
125SX 2017

RPM \ Spark timing (°CA bTDC) \ ExhaustValve Opening (%)

5000 \ 15
5500 \ 17
6000 \ 18
6500 \ 19
6800 \ 19 \ 0
7000 \ 19
7500 \ 19
7600 \ 18,8
8000 \ 18
8500 \ 17 \ 50
9000 \ 16
9300 \ 16
9500 \ 16
10000 \ 15 \ 100
10500 \ 14
11000 \ 13
11500 \ 10
12000 \ 8,5
12500 \ 6
13000 \ 20


I ported a little, tested a few pipes and got to 40HP at the backwheel in combination with an ignitech. 1500rpm powerband were also on the menue.

Looking from today, an 3° offset key or rotating the pickup a few degrees might hav been the KISS Version of that Ignitech installation.

[wobbly]

Wow , a total surprise there with the ignition timing.No advance at all in the mid range compared to what we think is " normal".
Thank you so much.

[ken seeber]

UHV 3

One obvious question is what could it offer? Given the somewhat (the combined hole size area and escape curtain area) limited port area it might not be high performance thing. For me the thinking is that if one could arrange the total fuel/air charge to come down from the head as a compact, tangentially rotating, increasing in size, “pancake” type slug, then maybe it might not escape out the exhaust, as is the Achilles heel of current engines. A sort of uniflow. If successful, this could then offer an improved fuel consumption and significantly lowered unburnt HC emissions. So, lower power and clean might see its application in say generation sets and other stationary units.

Could be total bullshit as well, but for me it was worth a go.

In all this and other ideas, we are competing with the time proven Schnurle scavenging principle and also the proven Husqvarna X-Torq scavenging system (a neat approach to eliminate the short circuiting losses via the A ports).

Hope these pics help. The reed was wire cut from 0.2 mm stainless “spring steel”. To do this, multiple blanks were sandwiched between 2 * 3 mm alum plates. Look at the detail of one of the wasted centre pieces. A beautiful process, just so handy to have a friend that has access to one of these.
To create the head, I made a 3d printed pattern to sand cast the blanks. Then a touch (?) of time on the lathe and mill, manual. The barrel was dowelled to match the location holes in both the head and reed. All interfaces are metal to metal, no gaskets or O rings.

345503345504345505345506

More to come.

[dutchpower]

I have strobed and reverse engineered a
125SX 2017

RPM \ Spark timing (°CA bTDC) \ ExhaustValve Opening (%)

5000 \ 15
5500 \ 17
6000 \ 18
6500 \ 19
6800 \ 19 \ 0
7000 \ 19
7500 \ 19
7600 \ 18,8
8000 \ 18
8500 \ 17 \ 50
9000 \ 16
9300 \ 16
9500 \ 16
10000 \ 15 \ 100
10500 \ 14
11000 \ 13
11500 \ 10
12000 \ 8,5
12500 \ 6
13000 \ 20


I ported a little, tested a few pipes and got to 40HP at the backwheel in combination with an ignitech. 1500rpm powerband were also on the menue.

Looking from today, an 3° offset key or rotating the pickup a few degrees might hav been the KISS Version of that Ignitech installation.

Tim what a difference !!!!!!!!

[speedpro]

I can see the incoming streams circulating around the outer circumference of the cylinder and possibly not scavenging the centre so well. If the reeds are in the squish area they may not even get all that hot. Very interesting though, and wide open for a plain bearing bottom end and pressure feed to the reeds from a supercharger.

[speedpro]

Maybe even a Ryger style bottom end to separate the plain bearing bottom end from the cylinder

[Pursang]

I can see the incoming streams circulating around the outer circumference of the cylinder and possibly not scavenging the centre so well. If the reeds are in the squish area they may not even get all that hot. Very interesting though, and wide open for a plain bearing bottom end and pressure feed to the reeds from a supercharger.

Some of the Initial flow would be sideways, away from the wall and towards the centre.
One or more of the ports could be angled, to help scavenge the combustion chamber, but the curve of the reed might do that anyway..

Definitely cool, putting them in the in the squish, even more so in the Mk2, water-cooled head, big port version.:niceone:

cheers, Daryl.

[Tim Ey]

Wow , a total surprise there with the ignition timing.No advance at all in the mid range compared to what we think is " normal".
Thank you so much.

Oh yes! That bugger totaly woke up with an ignitech. My guess was, that KTM wanted to ensure that this bike may also be used with russian potatoe booze...
Just short: Droppin' in "usual" advance of odd 29° in the low end, did not gain much.
That was, what I ended with a slightly modified ignition curve 8R of my Overrev CDI.
3 000 23
4 000 26
7 000 26
8 500 24
11 700 16
12 500 10
13 000 5
14 800 3
15 400 2
Here is a excelsheet to play with Here is the excelsheet of the different curves to play with (https://1537118469.jimdofree.com/app/download/11640945597/Overrev2018_Interaktiv_English.xlsx?t=1567615828)


Tim what a difference !!!!!!!!
Indeed! Did you got an SXS CDI by chance? Or did I one of us mess it up badly?

[dutchpower]

What HP you start whit Tim (std .bike )


SXS till 2008

[wobbly]

The particular race KTM I am modelling made peak power at 11500 , so simply adding 5* of static advance would give the " usuall " 15* at this rpm.

[jonny quest]

What did you guys do with porting on the SX125?

[ken seeber]

UHV 4

Couple more things:

1. The back of the head obviously needed to be covered in. So printed a cover plate.

345694

2. What does UHV stand for? Well, my oldest brother had a Morris 8/40 and it was a side valve = SV. Then my old man got a Holden and it was an overhead valve = OHV. Then this thing comes along and, as the valve is under the head = UHV.

So far all you have seen is words and pics, no generous graphs or proof that it works. So, the moment you have all been waiting for…

https://www.youtube.com/watch?v=8RX9iAhscSI

As you can see, this was some time ago, so with some more running, playing, changes etc after this, there is more to come…

[F5 Dave]

Well neither of you are fatties. That's some attractive shins right there.;)

[ken seeber]

Well neither of you are fatties. That's some attractive shins right there.;)

Ha, ha..an absolutely superb observation Dave...:laugh:

Actually it was cold that day, around 39 deg, so we hade to wear our longies....you would have seen more if it got to be well over 40 though....

[Tim Ey]

What HP you start whit Tim (std .bike )

Black curve: Standard '17 125SX, measured in Gear4
345698
Blue curve: Standart airfilter, OEM Exhaustpipe, Standart jets, OEM ignition, cylinder raised by 0.45mm, same squish, Gear5
Pink curve: Modified airbox cover, HGS Factory pipe, Standart jets, Ignitech with OEM curve, cylinder+0.45mm and slightly ported, same squish, Gear5
Red curve: Same setup as pink curve, but with the Ignitech setup to Overrev #8R curve (see page before)
Magenta: Same as Red curve but with slighly leaner jets

Fun story: The bloke that has ridden it in the european mastership (am not allowed to tell his name) went from his training bike (Bog standard '16 125SX) to the red-curve setup. He thought, breaking at the same point as with his training bike would do the job. In his first lap he flew out of a corner :-D

I would have loved to do more on the bike. I am confident that I would have been able to gain even more power and powerband (other head insert, propper jetting, leaving the ignitech on the bike and adjusting it with a TPS carb with electrical PJ, own pipe...).

[dutchpower]

Oke Tim

Here only different pipe's

Green is HGS factory pipe

Looking out for Wobb his Pipe design in the sim

[F5 Dave]

Ahh, chance for question: only run ignitech on road race push start bikes with a capacitor or roadbike with battery. Always wondered if you could kickstart a bike with capacitor driven Ignitech setup? Answering my own question I seen CR250 kits so just be ok. Do they start harder? Or pretty much the same?

[wobbly]

When I first used Ignitech you had to have a battery , or no start.
I asked them to change the firmware so that the gradual rise in available voltage from a capacitor storage system would allow it to be push started.I think 6V is the threashold.
All DC DC CDI Ignitechs now have this built in.

Anyway thanks guys for the ignition info - are the two dyno printouts showing Rear Wheel Hp.
Looks like 40 Hp is the bench mark for fairly minor mods with a reasonable pipe.
I am working now on getting the sim to be close to replicating reality , and will then go to town on the ports/pipe/ignition.

[F5 Dave]

Thanks Wob. Gives me options if GasGas CDI gives out.

Ha! And for the ignition Rain setting which apparently is only like a 3* retardation, the rain switch could ground the knocksensor port to do the same thing.

If I had the spare I should put one on the shelf.

[Frits Overmars]

So far all you have seen is words and pics, no generous graphs or proof that it works. So, the moment you have all been waiting for…
https://www.youtube.com/watch?v=8RX9iAhscSICongratulations, Ken and Brett :clap:

[Tim Ey]

Anyway thanks guys for the ignition info - are the two dyno printouts showing Rear Wheel Hp.
Looks like 40 Hp is the bench mark for fairly minor mods with a reasonable pipe.
I am working now on getting the sim to be close to replicating reality , and will then go to town on the ports/pipe/ignition.

My curve is backwheel hp.
But I think with increased CR, a nicer head design and a propper jettet carb the 44hp are in plain sight.

[dutchpower]

To get a sim for the ktm is a Hell of a job

There are so many things in the engine that are so wrong

Got it now

Al the pipe's ( not the red / green one ) in the dyno grafiek are made in the sim and tested on the dyno ( backwheel HP )

[Tim Ey]

There are so many things in the engine that are so wrong


Like what?

[TZ350]

So far all you have seen is words and pics, no generous graphs or proof that it works. So, the moment you have all been waiting for… https://www.youtube.com/watch?v=8RX9iAhscSI
Congratulations, Ken and Brett :clap:

<iframe width="560" height="315" src="https://www.youtube.com/embed/8RX9iAhscSI" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Yes. Totally congratulations........ :banana:

[archie-no2]

Ahh, ok it's a racebike. That wasn't clear


I replaced my older zeel with ignitech just easy. (Old zeel on shelf if keen)

Mine as it came had TZR reedblocks and PWK28s. Massive improvement over std setup.

You'll need to rebuild the crank with decent stuff if you want to rev higher. You can buy stroked cranks of various quality (research) . It isnt a bad idea as it gets you closer to square which brings benefits beyond just the cc increase.

I sold my Toomey pipes to Sam down in chch, I don't think he ever got around to putting them on. There will be much better pipes but depends upon the budget. Managed 70hp so they aren't total dross.

Any chance you have a rz350 zeel cdi still?

[F5 Dave]

Every chance. I'll send you a PM

[ken seeber]

UHV 5

In some respects I wasn’t completely excited with the engine performance, so wanted to do 2 things before I progressed any further.

The first thing was the cylinder. It was something left over that was junked for one reason being a hole through the bore to the outside world. I did fill this with Devcon, but as you can see that this wasn’t lasting and was externally seeping. So, created a new liner (we fortunately had some spare blanks kicking around) with exh and inlet ports only.

345716

The other thing was the nature of the flow coming from the 3 petals. Are we getting a nice pancake mixture descending slug or is it some high velocity swirl motion around the outside of the bore, perhaps not displacing the centre exhaust gases?

So, with a bit of 3D printing made up the rig in the vid so one could see the valve movement and also maybe get an idea of the gas motion.

https://www.youtube.com/watch?v=iceFOIRa6Fw&t=8s

The problem with bloody 2 strokes is that, when “off the pipe”, there is always exhaust gas remaining in the cylinder. The scavenging streams are intended to both displace this as much as possible out the exhaust, and not itself escape out the exhaust and also, remain stratified enough to ensure there is a combustible mixture at the plug. Each and every cycle = a 2 stroke that 2 strokes.

So, the plan is to observe the 3 petal flow plus try some other alternatives that I have ready to go.

In some respect it could be treated like a Jante rig, but I don’t think that this is a great system. Interestingly the Jante rigs I have seen used a fixed piston and air being blown thru the crankcase, whereas in this case, the flow will be derived from a motored engine.

More to come.

[TZ350]

hey tz . What did the port timing of your stort stroke bucket engine end up been .just building my one

Shortened Suzuki crank to 48mm stroke and NSR250 54mm bore cylinder. Packed up the barrel to get transfers opening 116 deg ATDC and that positioned the exhaust opening at 80 deg ATDC without any additional porting required.

The shorter 48mm stroke has the effect of increasing the blow down time area on the NSR cylinder that originally had a 54mm stroke. As the short stroke crank needs to turn a lot more degrees to get between Ex opening and Trans opening.

We did this conversion with a basically stock Suzuki GP100. A little later closing on the Rotary valve (80 deg ATDC). Used the original Suzuki GP carb and inlet tract. Honda RS125 NF4 pipe. Made a strong 25 RWHP. With another engine (my EFI bike) and a lot more work (and much more crankcase volume) we have managed a good 30 RWHP.

[jfn2]

Hello everyone:
This question is not necessarily related to two stroke or four stroke but to dyno building. If this is not the right place please move it. I was looking at the post that Frits put up with the picture of the bike on a dyno and I noticed in the background was a second roller and shaft up against the wall and it looked different then the one on the dyno. I thought it looked a little smaller in width. And I thought, how does a person know what MOI to design into a roller for a certain size bike like a 125cc MX or a 250 roadracer or a 50cc moped or a 1100cc road bike? I have a inertia dyno with a 355mm dia and 406mm length. How can I figure out what size bike this was designed for and how much weight to add for a bigger size bike or different application.

[Frits Overmars]

how does a person know what MOI to design into a roller for a certain size bike like a 125cc MX or a 250 roadracer or a 50cc moped or a 1100cc road bike? I have a inertia dyno with a 355mm dia and 406mm length. How can I figure out what size bike this was designed for and how much weight to add for a bigger size bike or different application.You do not need to change the inertia; adjust the gearing so that the bike on the dyno goes through its power band in the same time as it would do on the track.
That is the nice thing about inertia dynos; they allow you to develop an engine for the exact circumstances that it has to perform in.

[jfn2]

Frits
Thank you very much for the response.

[Haufen]

Hello everyone:
This question is not necessarily related to two stroke or four stroke but to dyno building. If this is not the right place please move it. I was looking at the post that Frits put up with the picture of the bike on a dyno and I noticed in the background was a second roller and shaft up against the wall and it looked different then the one on the dyno. I thought it looked a little smaller in width. And I thought, how does a person know what MOI to design into a roller for a certain size bike like a 125cc MX or a 250 roadracer or a 50cc moped or a 1100cc road bike? I have a inertia dyno with a 355mm dia and 406mm length. How can I figure out what size bike this was designed for and how much weight to add for a bigger size bike or different application.

If I remember correctly, when the roller weight is double that of the bike+rider, then the acceleration time will be like on the road for every gear.

You can find further info and a nice excel spreadsheet on roller design on the sportdevices homepage (https://www.sportdevices.com/download.php)

[TZ350]

Thanks for that . Mines even shorter stroke again but good to see ratio difference From standard Nsr to yours . Just need to find that now

Suzuki GP125 Bore 56mm stroke 50mm ratio 1.12: 1

NSR MC21 Bore 54 stroke 54 ratio 1:1

De stroked Suzuki GP with NSR cylinder Bore 54mm stroke 48mm ratio 1.12:1

So these 110cc hybrid engines have the same bore/stroke ratio as the original Suzuki GP's. Which was not ideal but worked well enough.

[mr bucketracer]

Suzuki GP125 Bore 56mm stroke 50mm ratio 1.12: 1

NSR MC21 Bore 54 stroke 54 ratio 1:1

De stroked Suzuki GP with NSR cylinder Bore 54mm stroke 48mm ratio 1.12:1

So these 110cc hybrid engines have the same bore/stroke ratio as the original Suzuki GP's. Which was not ideal but worked well enough.mines 44.8 stroke and 56mm bore . Cr80 is 45mm stroke . As a starting point I will set the exhaust at the same hight as a cr80 and go from there . Just will keep machining the head to drop in the barrel as I lift the barrel

[TZ350]

mines 44.8 stroke and 56mm bore . Cr80 is 45mm stroke. Just will keep machining the head to drop in the barrel as I lift the barrel

My guess is you are going to use a RGV250 twin cylinder or better yet a 30hp std Aprilia RS125 road bike cylinder with reed valves. That would be my choice. I could not de stroke far enough for 44.8mm. I would have had to sleeve the pin boss and re bore it. That was beyond me so I take my hat of to you.

[Myron]

Sorry Will,Looks like Rotax is still using a stupid expansion chamber with their Turbo engine!!WTF??

Stupid expansion chamber? Could you explain?

[mr bucketracer]

Thanks tz . It has a rgv barrel on it but have a tzr to try and also a hole aprilia engine which I may short stroke and build a frame for as the drive is on the other side. Not really my thing as a true bucket engine but is within the rules . Guess I need all the help I can get lol

[F5 Dave]

What we really need is an early Mito. Only because it has 7 gears which seems impossibly exotic (but in reality is just another gear).

[TZ350]

Aprilia engine which I may short stroke and build a frame for as the drive is on the other side. Not really my thing as a true bucket engine but is within the rules .

Yes. we took a good look at an Aprilia engine but back then we could not de stroke the crank. Otherwise we would have used it for sure.

[JanBros]

Stupid expansion chamber? Could you explain?

I agree with your question mark.

I don't think I'd be still interested in a 2-stroke without an expansion chamber, even if a turbo would make it a better engine.

The moment the pipe begins to sing is THE haleluya-moment of riding bikes. and I hate flat torque-curves, they make bike-riding boring.

[WilDun]

I agree with your question mark.

I don't think I'd be still interested in a 2-stroke without an expansion chamber, even if a turbo would make it a better engine.

The moment the pipe begins to sing is THE haleluya-moment of riding bikes. and I hate flat torque-curves, they make bike-riding boring.

But you haven't heard one with a turbo, when you do, then you can decide which is better!

[Vannik]

Quote Originally Posted by 190mech:
Sorry Will,Looks like Rotax is still using a stupid expansion chamber with their Turbo engine!!WTF??


Quote Originally Posted by Myron:
Stupid expansion chamber? Could you explain?


I agree with your question mark.

I don't think I'd be still interested in a 2-stroke without an expansion chamber, even if a turbo would make it a better engine.

The moment the pipe begins to sing is THE hallelujah-moment of riding bikes. and I hate flat torque-curves, they make bike-riding boring.

I would also like the comment explained. A high performance conventional 2T with or without a turbo must still follow the general "rules" of having enough blowdown and strong suction and plugging pulses, otherwise you just blow all the boost out during exhaust port closure.

[190mech]

Sorry guys,I was kidding with Wil as he has commented several times about getting rid of the expansion chamber!I love the expansion chamber and have been building them since the 70's..I remember Mr. Jan Thiel did a test with an RSA trying it without a pipe and I think it went from 54hp to 17hp even after rejetting..

[lohring]

Two strokes in the model engine world followed the developments in the full size world. My first racing engines had open exhausts with cross flow scavenging and high compression crankcases. We used exotic fuels that smelled like shoe polish and probably weren't healthy. A 10 cc engine developed around 1 hp at 10,000 rpm When tuned pipes were added the power jumped. Today's 11 cc tuned pipe engines develop over 4 hp at over 20,000 rpm. We still run a lot of nitro, but the porting is a long way from motorcycle state of the art. In small sizes friction probably is more important than perfect scavenging design, but tuned pipes were a huge improvement.

Exotic add on superchargers (https://www.youtube.com/watch?time_continue=184&v=5jTKPKpeH0E&feature=emb_logo) have been useless in model engines except for advertising. A turbo for a really small engine (under 50 cc) would be very difficult. It would be an interesting project but would need to turn rpms in the hundreds of thousands. Tuned pipes are a lot easier.

Lohring Miller

[Frits Overmars]

Today's 11 cc tuned pipe engines develop over 4 hp at over 20,000 rpm. We still run a lot of nitro....Aha, that must be where it goes wrong Lohring. We extract about 5 hp out of a 6,5 cc engine, but we do not use nitro :msn-wink:.
Joking apart, we are not allowed to use nitro; instead we are compelled to use a mixture of 80% methanol and 20% oil.
No, it's not a typo, the obligatory oil/fuel ratio is not 1:20 but 1:5. And I suppose it's that way because it has always been that way. I would have been happy with 1:20 but no one asked me.
Oh well, it keeps the mosquitoes away. hhttp://www.youtube.com/watch?v=5aBCQGq5Al4

[WilDun]

Yes, I know there is a lot of kidding goes on here - all great fun too!

But ..... we still need to change to save the two stroke ..................The expansion chamber (which does increase the power a lot), only does it well within a certain rev range ..............

We need to redesign the whole thing (the two stroke engine) to make any progress in restoring it to it's rightful place! - racing is a spinoff from transport, (that's where the money is made)!
The people most needing motorcycles are in emerging countries - they are buying bikes by the million .... in the form of four strokes!

........This is a fact - it has happened - it's just we are just too blind to see!

[Pursang]

Perhaps a variation on the COMPREX supercharger principle could provide a valveless seal/plug in the exhaust duct, phased to rpm (and a pressurised charge).


I posted this a while ago, but nobody bit.

The Comprex supercharger uses 2 Stroke technology. It's just ports and volumes and lengths and timings.:yes:

Properly configured (beyond my headspace, at the moment) it would provide exhaust extraction, reverse and blocking effects,
PLUS generate pressure and timing control at the intake side.

These would be phased to engine RPM and, I expect, generate a pretty even power curve.

Sorry, no 2 stroke Hit, because everything could be in maximum harmony for the entire working range.:violin:

Here is a pic without those pesky poppets confusing the process.

345778

Cheers, Daryl.

[Vannik]

Yes, I know there is a lot of kidding goes on here - all great fun too!

But ..... we still need to change to save the two stroke.

This is a fact - it has happened - it's just we are just too blind to see!

We need to redesign the whole thing (the two stroke engine) to make any progress in restoring it to it's rightful place! - racing is a spinoff from transport, (that's where the money is made)!
The people most needing motorcycles are in emerging countries - they are buying bikes by the million .... in the form of four strokes!

https://deltahawk.com/content/deltahawk-dh180a4

WilDun, I disagree that we are too blind. We just do not post about it here. The engine in the attached link was originally developed with my software that can simulate it quite well. The last phase of development they are using GT/Power because it includes the mechanical design portion.

The work Neil is doing is also moving away from tuned pipes, and in his line of opposed piston engines with or without uniflow scavenging there are a lot of research and development happening, once again, just not posted here.

[husaberg]

I posted this a while ago, but nobody bit.

The Comprex supercharger uses 2 Stroke technology. It's just ports and volumes and lengths and timings.:yes:

Properly configured (beyond my headspace, at the moment) it would provide exhaust extraction, reverse and blocking effects,
PLUS generate pressure and timing control at the intake side.

These would be phased to engine RPM and, I expect, generate a pretty even power curve.

Sorry, no 2 stroke Hit, because everything could be in maximum harmony for the entire working range.:violin:

Here is a pic without those pesky poppets confusing the process.



345778

Cheers, Daryl.
Page 4 oddballs Daza......
https://www.kiwibiker.co.nz/forums/showthread.php/171300-Oddball-engines-and-prototypes?p=1130798205&highlight=Comprex+supercharger#post1130798205
or 8 years ago here
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130420185&highlight=Comprex+supercharger#post1130420185
Frits and Flett here
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131016317&highlight=Comprex+supercharger#post1131016317

[WilDun]

https://deltahawk.com/content/deltahawk-dh180a4

WilDun, I disagree that we are too blind. We just do not post about it here. The engine in the attached link was originally developed with my software that can simulate it quite well. The last phase of development they are using GT/Power because it includes the mechanical design portion.

The work Neil is doing is also moving away from tuned pipes, and in his line of opposed piston engines with or without uniflow scavenging there are a lot of research and development happening, once again, just not posted here.

I was talking about road going two stroke powered motorcycles.
That link looks and sounds promising! - have to check it out a little more - not sure how the lubrication system actually works as yet - it still has expensive add-ons, (the supercharger and a turbo) but it's all a step in the right direction though.

[Pursang]

Page 4 oddballs Daza......
https://www.kiwibiker.co.nz/forums/showthread.php/171300-Oddball-engines-and-prototypes?p=1130798205&highlight=Comprex+supercharger#post1130798205
or 8 years ago here
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130420185&highlight=Comprex+supercharger#post1130420185
Frits and Flett here
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131016317&highlight=Comprex+supercharger#post1131016317

Husa, your ability as a Source of Reference is beyond amazing.

Comprex reference repeated (again) aligned to current discussion of finding some means to provide the advantages of an expansion chamber, without the negative elements.
Not the actual Comprex itself, but to consider a system using similar principles to achieve the 2 Stroke goals.

And obviously not for Bucket Racing, but might be a clever solution for a future F1.

Cheers, Daryl.

[lohring]

Aha, that must be where it goes wrong Lohring. We extract about 5 hp out of a 6,5 cc engine, but we do not use nitro :msn-wink:.
Joking apart, we are not allowed to use nitro; instead we are compelled to use a mixture of 80% methanol and 20% oil.
No, it's not a typo, the obligatory oil/fuel ratio is not 1:20 but 1:5. And I suppose it's that way because it has always been that way. I would have been happy with 1:20 but no one asked me.
Oh well, it keeps the mosquitoes away. hhttp://www.youtube.com/watch?v=5aBCQGq5Al4

You run real rpm compared to the engines I mentioned. That's the benefit of modern scavenging coupled with great mechanical design and manufacturing. That's probably more important than some magic fuel. When I was young back in the dark ages, model engines cost as little as $5 (1950s $), well within the budgets of middle income families. We flew model airplanes on playgrounds and the navy sponsored national contests. It was hoped these modelers would be tomorrow's scientists and engineers. A few like Burt Rutan did. Today it's become the realm of a few.

Lohring Miller

PS The oil is probably more important for sealing than lubrication. We double the recommended oil in the ringed 26 cc engines and get a measurable power increase.

[WilDun]

.............. It was hoped these modelers would be tomorrow's scientists and engineers. A few like Burt Rutan did. Today it's become the realm of a few.

I wouldn't think that many of today's scientists and engineers missed out on the joys of being modellers in their earlier years - most of them would have had a lot to do with the little two strokes!


PS The oil is probably more important for sealing than lubrication. We double the recommended oil in the ringed 26 cc engines and get a measurable power increase.

Yes with ringless (and tapered) pistons and bores - all that oil (ridiculous amount to me) is actually necessary for sealing - lubrication requirement is way,way, less! than that! - and the requirement for oil in the cylinder could be cut right down with the right design, ie where there is no sidethrust on the piston and no distortion of the piston caused by uneven heating (as in the case of the present two stroke design)....... however, that's another story!

[ken seeber]

Don't be scared of using high oil content fuel, as the calorific value are very similar. As long as the plug doesn't oil up, the thing detonates crazily, it doesn't combust or anything else
I can't think of, it might be quite ok.

345782

[F5 Dave]

So that's crude oil, but what about Amsoil Super Dominatrix Fairy oil (at 204:1)?

And where can I get some of this Yourainyum stuff? That seems good.

[WilDun]

So that's crude oil, but what about Amsoil Super Dominatrix Fairy oil (at 204:1)?

That is crude! - but maybe reduce to 200:1?


And where can I get some of this Yourainyum stuff? That seems good

They've got heaps of that in Niue!

[jbiplane]

Hello guys

Could you recommend 70...125cc very light cylinders capable produce 13...17 hp for a long time permanently.
Says for 30 minutes+
I want to make 2-cylinder 25hp + engine which should weight no more than 7,5 kg complete with radiator end exhaust

[koenich]

Did you check the Airsal range for Derbi Euro 2 or 3 engines? Plenty of options reg bore/stroke and everything above 70cc should be able to produce the power you are looking for...plus they are cheap and readily available.

[41juergen]

Can someone help me with that problem: I'm preparing RZ cylinders to get aux ex ports in to increase the blow down. The currently mounted Woessner piston has cutouts to reduce the weight. So how far shall I go with the aux ex port? Going to approx. the middle of the bore I would gain more blow down than going only until were the cutout starts… So will the higher blow down eaten up by the short circuting with the Transfers?

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[Frits Overmars]

Can someone help me with that problem: I'm preparing RZ cylinders to get aux ex ports in to increase the blow down. The currently mounted Woessner piston has cutouts to reduce the weight. So how far shall I go with the aux ex port? Going to approx. the middle of the bore I would gain more blow down than going only until were the cutout starts… So will the higher blow down eaten up by the short circuting with the Transfers?The blowdown will be fine Jürgen. But before the exhaust ports even start to open, there will be a massive short-circuit between the transfers and the auxiliary exhaust ports. So forget about using those pistons in combination with aux ex ports.

[F5 Dave]

Interested to know how you were going to get around the cotton reel powervalve? Also the aux port looks as high as the main which for much of the time will be lowered by the pv. On a steel bore you will need a thicker bridge than you would get away with with plated.

[wobbly]

What they said before me - except to add that having the Aux at the same height as the main is never a good plan.

[41juergen]

The cylinder in the left picture with the wide aux port was a trail on an damaged one to see how to do the porting. The cylinder in the middle pic is the one I work on currently. I'm aware to have the aux ports lower, I have them approx. 2mm lower than the main.
So Frits would you think the samller aux ports (which do not go into the cutout) would be a problem? Of course depending on the budget of my finacial minister I will get some new pistons somewhen…
@Dave: I have attached some pics how the porting looks like currently incl. the modified / (rough) cutted bushing of the inner side. This is not the final version, I will modify the bushing (with the "nose" as the mounting point) to get the "channel" done. The bridge between the aux and the main port is approx. 5mm thick.

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[jbiplane]

Did you check the Airsal range for Derbi Euro 2 or 3 engines? Plenty of options reg bore/stroke and everything above 70cc should be able to produce the power you are looking for...plus they are cheap and readily available.

Thanks. Still estimating. One friend suggest me
to use a 50cc cylinder "bigbored" to 95cc or 100cc (52mm) with 44mm stroke

Are there are racing scooter engine called Malossi C-One / RC-One, it use "flange" style cylinders like racing motorbikes.
the 95cc cylinders are 24-26hp peak power, the lightest seems the Stage6:

it seems very small cylinder to be a 95cc
https://www.motoscoot.net/cilindro-minarelli-horizontal-lc-95cc-stage6-r-t-bigbore-c-44-biela-90mm-bulon-14mm.html

I want as well try Vespa 125 cylinders cutting of some metal to make it light

Are there another brands like 2fast
https://www.scootfast.net/2fast-cylinder-kit-100-cc-100-mm-conrod-passion-c-one-rc-one-pre-crankcase.html

[Frits Overmars]

Frits would you think the samller aux ports (which do not go into the cutout) would be a problem?I can't see a problem with that, except that you will be very limited in the width of those ports. Maybe you can enlarge them afterwards, when your financial minister approves the purchase of decent pistons.

[41juergen]

I can't see a problem with that, except that you will be very limited in the width of those ports. Maybe you can enlarge them afterwards, when your financial minister approves the purchase of decent pistons.

That's the plan... :niceone:
Would you go up to approx. the middle of the bore even with that "large" 66 mm bore? Of Course that will increase the blow down dramatically on the engine, I need also to check and balance the transfer TA's as also a bit limited in the width… Neels software will help.

[peewee]

if your just wanting a common 64mm yami banshee style piston then you could use wossner 8075da. theres no pin cutouts at all. but its a bit heavy so you might want to machine off some material from the underside.

[F5 Dave]

I'm surprised there was room there. Might be a little soggy in the middle but so what. Be interesting what effect it has. I've added auxiliary to my MB100 race bikes on a few cylinders.

[Frits Overmars]

That's the plan... :niceone:
Would you go up to approx. the middle of the bore even with that "large" 66 mm bore? Of Course that will increase the blow down dramatically on the engine, I need also to check and balance the transfer TA's as also a bit limited in the width… Neels software will help.Is a 66 mm bore large? Wärtsilä mechanics will disagree, and I would say large is a rather undefined term. If you have sufficient material in the right places, and good quality piston rings, extending the auxiliary exhaust ports to the middle of the bore shouldn't be a problem.
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if your just wanting a common 64mm yami banshee style piston then you could use wossner 8075da. theres no pin cutouts at all. but its a bit heavy so you might want to machine off some material from the underside.Most of a piston's mass is concentrated between crown and piston pin holes, so if you want light pistons, try to find pistons with their pin holes close to the crown.
Maybe Yamaha TZ750-pistons could be an option. They have a 66,4 mm bore, so if you have a big enough hammer, they should fit https://www.kiwibiker.co.nz/forums/images/smilies/whistling.gif

[41juergen]

Jeep, you are right that are really big engines, our company will supply the catalysts in future, that will be a nice business. Maybe we will sell only for 2 or 3 ships per year, but the volume…. :clap:
I will talk with Woesser what they have, I need the piston for the 115 mm rod either, so let's see. And material for the wide aux ports is there, so let's see.

[tdc211]

Been a while since I been on here.
I still fiddle around with 2 strokes time to time.
This last time I really wanted up my power on the newer ktm 85. No small feet. I was already at 29ish hp. Up from 23. So I flowed the cylinder on my flowbench and redid the exhaust tunnel with clay to find the optimum shape.then welded it and it is pretty much right on size to eng mods rules in sim and I found the cfm as well on the bench. But yet no more power with close to my usual port timings. Of course I tried many things. Had adj ign box as well . Of course next time I will probably do the tunnel 1st. Before grinding to my usual timings. And I am guessing results will be different. What do u think wob?