ESE's works engine tuner

[richban]

The STA says 100 Hp crank = 88 rear wheel at 11500.
The limiting factor is keeping the powervalve/port geometry correct, so it cant be ground up much.
Sorry I should have said the one here is going into an RS250 chassis.
And now that we have gone long rod the cylinder does not need cutting and we dont need a plate, so plug/wheel clearance will be helped.

Nice one. Mine is 73 at the moment with stock barrels dyno jet 73 that is. 60hp at 8k so quite fat. It will be interesting to see what happens after chopping the piston skirt.

I am going to weld up an grind the power valves to try get a better fit / flow. They also have that hole in the middle. The F3 250 version does not. And I noticed the RS250 nx5 power valve is a seamless fit in the barrel. And the exhaust port roof is dead flat when they are fully open. Unlike the NSR.

[TZ350]

Whatt 1130 ....

Edgecumbe Bucket NI 2015 Round 3



http://www.kiwibiker.co.nz/forums/sh...post1130840522



Team GPR Edgecumbe Videos:- http://www.kiwibiker.co.nz/forums/sh...am-GPR/page125

... one remarkable issue, at least to me.... it seems that Jan realized just from the Beginning that the rotary inlet is the best for power. there are not many pictures showing Jan with piston port or reed valve engine. maybe a stupid question but is that the only reason (power) that he so to speak started straight off with the rotary inlet system or are there other reasons that makes him preferring it?

Jan should be answering this really, but I'll give it a try. I assume he started with a rotary because everybody in GPs was using that when Jan built his first engine.

For his own constructions he always stuck to rotaries, with one exception: the reed valve Rumi. It produced 46 hp on the test bench in a season where the world title was won with 42 hp, so our prospects were bright. Sadly this could not be said of management...

Jan made a direct comparison at Derbi where he developed the RSA while Lorenzo's GP-winning reed valve Derbi was still around. Jan worked on both engines, extracting 49 hp from the reed valver before dropping it in favour of the rotary RSA that produced 10% more power with the same cylinder.

The rotary engine has other advantages over the reed valver: setting the carburation is much less fussy. But the power difference is the main attraction.

Smitty,
Have been reading the latest round on cooling discussion, but with the mind focussing on more pressing matters, haven’t had the opportunity to comment of late.
My take on cooling a 2 stroke is that, as Frits says, you can never over cool a 2 stroke. This is a very general statement, generally applying to the overall engine. Cold air passing thru equals:
• Higher charge density – more power
• Cooler temps mean better lubrication control and durability(less oil breakdown/carburizing)
• Cooler temps mean less opportunity for detonation
You are fortunate with boats in that you have the world’s biggest radiator at your disposal, with typically a 15 – 20 deg C inlet flow temp, compared to bikes/karts where the ambient temp can vary from whatever in the northern hemisphere to over 40 in Oz. From this potentially high ambient temp we need to cool the coolant down to as low as possible maybe as a guess, even with a huge radiator, that this might have delta T of 10 deg over ambient. Passing through the engine, I seem to remember that a fairly normal increase was around 5 deg, this being obviously dependent on the flow rate. The higher the flow rate the better the actual heat transfer rate, giving a smaller overall temp differential across the engine. If the 5 deg is in fact the case in current racing 2 strokes (will bow to Frits and Wob on these matters), then the need for a separate circuit is hard to justify, but who knows…I don’t. The downside to higher flow rates is the power required to drive the pump and its heat input into the cooling system (previously discussed).
However what Wob is saying, I am sure, that overall cooling is good for all the obvious reasons, HOWEVER in certain areas there are specific needs for power and engine durability. Specifically:
• We want the spark plug to remain as cool as possible
• We want the two surfaces (head outer circumference and piston crown edge) that form the squish zone to be as cool as possible to avoid detonation
• We want the combustion zone to be as warm as possible tor maximum Carnot cycle efficiency, consistent of course with detonation and even pre-ignition control.
There have been some attempts at detonation control (other than the more subtle methods that are being currently employed), one of these being Warren Willing’s Yamaha sprung loaded cyl head combustion chamber that after a certain cylinder pressure was attained, the whole insert would shift outwards, allowing the pressure to drop. Dunno if it was ever successfully used though.
Back to combustion chambers. I think the ideal shape for a combustion shape is a sphere, which offers a minimum surface area to volume ratio, thereby minimizing heat transfer, allowing maximum combustion temps and efficiency. By employing squish zones, this allows a more compact combustion chamber shape. Not perfect, but clearly the way to go. And as Wob has been saying, the toroidal shape within the head is desirable as (I think) it places the spark plug gap towards the centre of the zone (obviously more so in the case of the flat top piston) so the flame kernel can radially progress. My understanding anyway.
If you want to see a shit combustion chamber, have a look at this: https://www.youtube.com/watch?v=0SiRqmo5Onc It can be clearly seen at the 3 minute stage.
In recognition of this, a direct fuel injection system was developed that, under the generic terminology of the day, DISC (direct injection stratified charge) which allowed the fuel (and a small quantity of injection air) to be injected late in) the compression cycle such that no fuel entered the acres of squish area. In that case, we were chasing fuel consumption and low unburnt HC emissions.
As a digression, this fuel injection system was very successful, particularly so when applied to a 2 stroke engine. (both crankcase or externally scavenged). The system is still being commercially manufactured today with applications such as marine (Mercury Optimax) to small drone engines (spark ignited running on jet fuel).
Personally I wish that some of the dumb arse controlling bodies, particularly in karting (which in my understanding is the largest (numerical) arena for competition 2 strokes) where they stick to archaic/ill considered rules (possibly for pecuniary reasons) and don’t allow any significant technical advancement opportunities, would use their imagination.
That’s what is great about this bucket thing. Lots of regulation freedom and cultural freedom, allowing guys like Neil and TZ350 and many others experiment, hopefully leading to the advancement of 2 strokes and their rightful and justifiable place in the future.
My thoughts anyway.

Seems that we've been pumping the coolant the wrong direction, all these years. Wouldn't it be better to have the biggest temperature delta in the head instead of the cylinder?

There are two issues in the cylinder that need the most attention from the coolest water available.

Over the transfer duct outer walls, and the Ex duct outer walls.

The first as this keeps the inducted charge as cool as possible, the second is to keep the trapped slug of fresh ( ish ) fuel air in the Ex duct also as cool as possible.

The slug gets stuffed back past the closing piston ,thus this contributes to the combustion process - and if overheated it creates deto very quickly.

Wrap your header with glass insulation tape - and quickly find out what not to be doing.
We have a trade off situation in the cylinder/head interface.

As Frits alludes to we don't want a "hot " head contributing heat to the cool charge being compressed prior to ignition, but on the other side of this coin we dont want
cold alloy pulling heat out of the ignited mixture.

As DEA etal have found the tradeoff currently works in the favour of the carpet bombing approach of cooling the hell out of everything in the head.

But as I have found dozens of times if you ceramic coat the chamber only, power goes up.
When you ceramic coat, two things happen.The coolant temp drops, always a good thing, and this cooler water in the head then possibly has a chance to do more good by dropping the end gas temps, thus helping to keep deto at bay.

Jan found a very simple way of keeping the plug cool, you guys wanting to tune to the edge of available power need to think of your own solution to effectively cooling the squishband, in a better way than the current carpet bomb approach.

The Aprilia setup with 0.7 squish I believe would just clip at the absolute overev margin of 14500

Now I have the squish cooling organised in KZ2 I can run down at 0.9 ( from 1.3 min ) and it just clips at 15200.
The 66 bore Banshee/RZ based race engine with 58 stroke set at 1mm will clip at 12200.

A TM125 MX engine for open karts would clip at 13200 with 0.6mm A CR250 road racer set at 0.9 will clip at 11400.
That gives you some idea of the state of play from real experience.

The big open class Jetski World Champ engines I used to build needed an absolute minimum of .15mm = 0.006" clearance
on 78 to 92 bore when running 40*C out of the case and 60*C out of the head.

On the dyno the power would fade at the end of a 30 second pull if the case went over 40* - much under that and we would certainly squeek a piston. We used restrictor jets on the individual 6 outlet points to regulate the local temps.

Wobbly did you make an error and put the decimil place in the wrong spot there
is this supposed to read 1.5 mm

Was this a 951 seadoo with a huge piston

Nope - 6 thou is the correct number and yes a 951 out to near 1200.

wow thats tight squish. Am i reading it wrong is that measured at a certain rpm or a static measurement

Yeah I have been around the big bore 951 a little as well not at the same level as you i never took one to the world titles. They make good power until they don't and then you throw it all in the bin

I think he's talking piston to bore clearance .... were those forged pistons, did you have a shrinkage problem ? Or set them up tightish and run through several heat cycles ?

Yes, I was referring to bore clearance needed when using the cold water from the tap - or Lake Havasu in this case.

Smitty was talking about the loose clearances they have to run when going WOT with cold water in boat racing.
The only issue was simply that the low inlet temp along with an iron sleeve meant the piston would always be growing far faster than the bore size.

In the smaller bores there were cast pistons available and after long run in cycles these would survive at 0.004".
But the big bores were forged by Mahle, and nothing I did regarding slow run in, and sanding off the high spots etc would stop them locking up if under 0.006".

Of course this let the piston rock all over the shop, and the rings had a real hard time sealing effectively for long, but was the only way to get over 220 Hp from the big twin for open class racing against 1200 triples that had more power but were way heavier than the SeaDoo with titanium/magnesium everything, and a carbon hull.

I'm elderly and on slow dialup, i doubt I'd live long enough to print out the entire thread....And just picking Wob's posts, it doesn't as far as i can see anyway, give the full reply/post just the first couple of lines. Context is important too, someone should spend a week or so sorting the questions and answers...You've created a monster.

you don't print it you save it, (took less than 30 seconds for me on a set up worse than 50 per cent of nz has)then you put it in word use an advanced find, to search the key words for which ever topic you wish to separate out.
Then you sift through. Sort the wheat from the chaff.
If it was to be done it would need some sort of frame work to start from.
Say a previous book.

... some "average" minarelli am6 kit's come with good porting from stock (kit's with 70, 75, 80cc), but have a exit diameter of 28mm (and the initial header of the pipe should enter this 28 diameter), calculating a pipe says it should have 30 ou 31 header. Then I did the same for some pipes, after the piece that fits in the cylinder I put a first cone of 20 or 25 length putting the diameter where it belongs. Same goes for even bigger kits with 32 round.

All the kits I have looked at for 50cc have way too big Ex ducts.
Take AM6 Hebo 192 Ex for example.
The port effective area is 24.2 dia, the Ex exit is 25, it should be 22.2 dia, and the best scenario is the exit should be oval at 24 wide and the header match that.
The step top and bottom does "work", but an oval to round transition is much better.
You can do this as the first cone of the header, but is way better if its done as part of the slip joint spigot.
Stage 6 and the Athena 50cc kits are no better in this regard.
All you have to do is work out the T port or 3 port effective area diameter, and that is the header entry size.
The duct exit should be around 75% area - all this is done for you in EngMod code - easy.
Counterboring the Ex duct exit as far as you can and then pressing in a sleeve to make the correct oval shape is also easy enough if you cant or dont want to get a tig torch in there.

A question. I thought of the other day is a Main port with Aux Ports has effectively 2 bridges.
Yet it is said to produce more power than a bridged Tee port.
I always thought (irespective of any main bridge bulging issues) it was down to a interupting effect of the bridge.
But.............

More blowdown area in a 3 port.More of the exhaust area is concentrated higher in it despite the shape of the T port.

Several reasons for the 3 port being superior.
To gain the maximum blowdown the T port needs two things.
A straight top timing edge, and the outer corner rads ro be as big as possible above the A port.
These two requirements both have big downsides.

The first is that the flat top edge has a very big duct length delta between the corner at the T and the corner at the outer edge.
This smears the outgoing pressure front, reducing its peak amplitude, thus scavenging energy.
I tried helping this in a test where the outer, longer length corner was higher than that at the T - sorry no free lunch, no more power.

The second means that the T port side edge is wrapped around very close to the A ports front and top edges, thus dramatically increasing the possible short circuiting of the
flow out of the A port.

And yes the 3 ports stepped opening does create a stronger more coherent exit pulse, and at 98% width and even with big angled pockets at the outer corner exits into the duct, the Cd value
of the T is always compromised in relation to a 68 to 70% width 3 port setup, with lower Aux around to bore centre.

[husaberg]

Nice one. Mine is 73 at the moment with stock barrels dyno jet 73 that is. 60hp at 8k so quite fat. It will be interesting to see what happens after chopping the piston skirt.

I am going to weld up an grind the power valves to try get a better fit / flow. They also have that hole in the middle. The F3 250 version does not. And I noticed the RS250 nx5 power valve is a seamless fit in the barrel. And the exhaust port roof is dead flat when they are fully open. Unlike the NSR.

I could be wrong, but i think the RS has a longer valve from its pivot point so actually has better geometry.

[richban]

I could be wrong, but i think the RS has a longer valve from its pivot point so actually has better geometry.

Yep thats right. I think with some careful welding and shaping the NSR one can be improved.

[rodg]

Had an interesting few evenings this week playing with a small bike on the dyno. The interesting bit was watching the exhaust pipe extending 10-15mm against the retaining springs as the rpm approached peak torque and the internal pipe pressure was at its maximum. Then as the internal pipe pressure dropped the springs would pull the pipe back in for a bit of over rev.

With two springs this effect could be made to happen in two stages. I even figured out a very easy way to adjust the spring tension on the fly to tailor when and how far the pipe would slid out and back.

After peak torque the pipe would pull back in as the rpm approached peak power. I can't help thinking this trombone effect could be made to be useful in some way.

With a fixed pipe the useable power spread looked to be about 4,500 rpm with a power curve that was flat for maybe 2,000rpm. I am not sure how much the sliding pipe could be made to extend that but when I get time it sure looks worth investigating it a bit more.

Thanks to the efforts of these chaps we doubled the horsepower on my TZ80! We ended up running no spacer in the pipe but the trombone movement in the pipe TZ350 refers to is still doing whatever it does!. Before tuning and after tuning graph attached. Biggest problem initially was a badly mis-matched pipe. TZ350 has kindly lent me an RG50 pipe based on a 10 year old wobbly design. After too many runs and optimising ignition and jetting for each run the bike now pulls from 9000 - 15000RPM on the dyno and consistently makes 20HP. Funnily enough it doesn't feel this broad on the track - it doesn't bog but lift off happens around 11000 and carries through to 14500. By drilling the air correction jet from 0.8mm to 1.25mm and jetting up accordingly (Keihin 138 to 150) we were able to improve the over-rev significantly

Raced the bike on the weekend and it lasted the weekend and I had my best ever result in the last and longest race of the weekend. First two stroke (thanks to mechanicals on some of the other two strokes). Only change from dyno tune was raising the needle. Water-temp got to 87 degrees C so sorting cooling is the next trick. Bugger all room for a bigger radiator so may install a second smaller one out of the way.

Also not sure my PVL analog kart ignition is the best tool for the job. Doesn't retard until really high RPM leaving ignition too advanced in low and medium RPM.

Thanks again to the generosity of skills, time and gear to the chaps at the House of Speed

[wobbly]

The PVL kart ignitions come in all manner of flavours but the most common are the ones used on the 125 shifters.
If the stator winding resistance is around 50 ohms ( 1850 turns ) then the "curve " is basically a straight line ie no retard.
As the stator winding resistance increases, the line is still pretty much straight, but drops at a set rate /1000 rpm.
The 200 ohm stator ( 4000 turns ) retards about 8* from 2000 to 12,000, the retard characteristic is set by the inductive reactance of the stator winding coil number
that is directly related to the static measured resistance.
There is a stator winding that has cotton/epoxy covering the wire, this has the max number of turns that will fit on the bobin ( so the plastic moulded cover wont fit.
It has 5000 turns and it retards about 11* from 2000 to 12,000.
This was developed for the Banshee that has limited kick start travel, so needed the extra coil turns to get it to start.
I got PVL to make these and it puts out just enough spark at kickover to start the quad, and as a side benefit, gave the max retard available from an analogue.
They could do more turns, but the spark voltage at high rpm would kill the 458 ignition coil.

[TZ350]

Thanks for your explanation Wob.



At first I had trouble getting my head around their graphs, they did not make sense until I realized that the "0" line represents the static timing point which could be any number of degrees one chooses BTDC and their curve moves + and - relative to that point.


As I now understand it, in this graph, if the initial timing was set at 15 deg BTDC then "0" on the graph means 15 deg BTDC and at 2000 rpm the real ignition point is 15 + 3 = 18 deg BTDC, at 8,750 rpm it is 15 + 0 = 15 deg BTDC and at 12,000 rpm it means 15 - 3.5 = 11.5 deg BTDC.

Also things can get confused when using a timing light because the trigger circuit in the timing light has some capacitance and therefor some delay in flashing the light after the triggering event. This has the effect of the timing appearing to be more retarded than it really is. At low rpm when there is plenty of time this error is very small and not much of a problem but at 9 - 10,000 it can get very noticeable and at 12 -14,000 significant.

Exaggerated retard due to the timing light flashing late, is just another thing to watch out for.

[husaberg]

The PVL kart ignitions come in all manner of flavours but the most common are the ones used on the 125 shifters.
If the stator winding resistance is around 50 ohms ( 1850 turns ) then the "curve " is basically a straight line ie no retard.
As the stator winding resistance increases, the line is still pretty much straight, but drops at a set rate /1000 rpm.
The 200 ohm stator ( 4000 turns ) retards about 8* from 2000 to 12,000, the retard characteristic is set by the inductive reactance of the stator winding coil number
that is directly related to the static measured resistance.
There is a stator winding that has cotton/epoxy covering the wire, this has the max number of turns that will fit on the bobin ( so the plastic moulded cover wont fit.
It has 5000 turns and it retards about 11* from 2000 to 12,000.
This was developed for the Banshee that has limited kick start travel, so needed the extra coil turns to get it to start.
I got PVL to make these and it puts out just enough spark at kickover to start the quad, and as a side benefit, gave the max retard available from an analogue.
They could do more turns, but the spark voltage at high rpm would kill the 458 ignition coil.

thanks Wob too for that explanation.
So why could did they not try to achieve that same result with a simple delay/resistance circuit in the ignition module? isn't that how the Japanese tended to do it? pre digital.
What am I missing.........likely something obvious....
http://www.kiwibiker.co.nz/forums/sh...post1130181478
last and first attachment.

[TZ350]

So why could did they not try to achieve that same result with a simple delay/resistance circuit in the ignition module?
What am I missing.........likely something obvious....

My pick is simplicity, inductance of the stater does not change with age or heat like a separate RC circuit with discrete components could.

[RAW]

A couple of pictures for you all

[seattle smitty]

Does every bike racer in New Zealand have his own dyno??? Honestly, going by the posts on this thread it would seem you Kiwis have at least five times as many dynos per capita as anyplace other than possibly Holland!!

Which company's dynos are favored here, or do y'all build your own?

[richban]

Does every bike racer in New Zealand have his own dyno??? Honestly, going by the posts on this thread it would seem you Kiwis have at least five times as many dynos per capita as anyplace other than possibly Holland!!

Which company's dynos are favored here, or do y'all build your own?

From what I can tell. The old Dyno Jet inertia dyno's seem to put out a number that is globally comparable. But yes I have had my bike on 2 different home built versions, different numbers but repeatable in there own right. If I wanted to get more power I could put the bike on a Dyno Dynamics setup. Usually 10 to 12% up on the dyno jet. One day I will have my own in a shed. One day!

[rodg]

The PVL kart ignitions come in all manner of flavours but the most common are the ones used on the 125 shifters.
If the stator winding resistance is around 50 ohms ( 1850 turns ) then the "curve " is basically a straight line ie no retard.
As the stator winding resistance increases, the line is still pretty much straight, but drops at a set rate /1000 rpm.
The 200 ohm stator ( 4000 turns ) retards about 8* from 2000 to 12,000, the retard characteristic is set by the inductive reactance of the stator winding coil number
that is directly related to the static measured resistance.
There is a stator winding that has cotton/epoxy covering the wire, this has the max number of turns that will fit on the bobin ( so the plastic moulded cover wont fit.
It has 5000 turns and it retards about 11* from 2000 to 12,000.
This was developed for the Banshee that has limited kick start travel, so needed the extra coil turns to get it to start.
I got PVL to make these and it puts out just enough spark at kickover to start the quad, and as a side benefit, gave the max retard available from an analogue.
They could do more turns, but the spark voltage at high rpm would kill the 458 ignition coil.

Thanks Wobbly. I have the 200 ohm stator

See attached photos of the result of the weekend's racing. Am thinking last 30 lap race finished in the nick-of-time! Pooh about crack in skirt of barrel.

[chrisc]

See attached photos of the result of the weekend's racing. Am thinking last 30 lap race finished in the nick-of-time! Pooh about crack in skirt of barrel.

Oh shit! That could have ended really poorly Rod. I take it you'll just buy a new barrel there?

[rodg]

Oh shit! That could have ended really poorly Rod. I take it you'll just buy a new barrel there?

you bet! Lucky I didn't enter development class at the Nationals