ESE's works engine tuner

[Haufen]

Nothing about this setup is ideal, it just gets me started on the 2-Stroke EFI learning curve, things will get better.

They tell me nothing worthwhile gets done without making a few mistakes and if you want to get some where faster, then make more mistakes quicker.

I hope they are right.

I understand, and I totally agree. But wouldn't it be better to avoid things which might be not so ideal in the first place? Dealing with EFI alone will be challenging enough, I guess. On the other hand, I understand that you are looking forward to trying it out, finally.

[FastFred]

... wouldn't it be better to avoid things which might be not so ideal in the first place?

I am sure TZ would if he could see a better practical way of doing it.

[TZ350]

The issue you are up against TeeZee is that EngMod has no way of knowing how bad your transfer duct ans scavenging pattern really are.

The ducts you have and the port geometry ( mains too big ) means the transfers as modeled are not, and cant, perform anything like the simple one dimensional numbers suggest.

Thus you have to use the blow down to shoot for the actual power you need, and the transfers MUST be way bigger in STA than the calculations suggest.

And in doing this, the Ex port STA number is basically irrelevant.

But in any case of trying to extract any worthwhile power out of a race engine worthy of being called one, it is near on impossible to generate sufficient REAL transfer STA, then add the correct Blow STA on top of this - with a limiting total height at 188*, It just cant be done.

The ONLY thing 188 has going for it is strong port/pipe resonance over a wider band, but no matter what you do the power achieved (with 188 Ex duration) will always be severely limited. Just pointing out hard learned basics of the physics,gained from fucking it up myself.

Wob had a look at my original 188 ex duration file and made a few changes for me. Starting by getting the blow down STA in the right area for the power we want, and that meant the exhaust now has 194 degrees duration, a bit up from my original 188.



Wobes notes he sent me with the updated EngMode file.

TZ
Here is the new pack with a little work.
Biggest issue I found was 15.5 com with 17.5* spark would be instant death to an air cooled piston.
So way more power now with much less com and timing - adding com and timing would bump up sim a heap, but isn't reality.
A - transfer angle is corrected to 25* as well as heights. Ex is 194 with nozzle, and rear cone is way shallower.
Original power band would be say 8200 to 12200 = 4000, new setup would be 9000 to 1300 = 4000 with a ton more area under the curve.

cheers
wob

ps - the pipe wall temp i changed to 50 - from 450, not on the money at all for accurate pipe length behavior, Neels recommends 50 to 150



And an EngMod graph comparison.



The exhaust and transfer port details.

Thanks Wob, it looks good, I will use your new layout when I make the next triple port cylinder.

[F5 Dave]

Well had a good talk to Neil at the epic ride today. Good to see the Bighorn in the flesh and the YZ. Bit sodding wet though.

[TZ350]

That fuel injected Kawasaki Big Horn is impressive.

[2T Institute]

With a decent pipe would be about 50HP as well.

[Flettner]

Good to see you there F5 Dave, I didn't fire the Kawasaki up in the end, we just concentrated on testing the two YZ's. Then went home cold and wet! The EFI YZ goes real nice, smooth power output. I think I might like mine EFI as well now.

[TZ350]

Ok, making a bit of progress with setting up the EFI systems throttle body.



The original idea was to run the 32mm Ball Valve inside a plenum feed by a 24mm carb equivalent, but things change and now I am going to try it with a 24mm insert first.



The 24mm venture insert is going hard up behind the Ball Valve. I am not sure exactly where reversion will accour but it looks like it will be a reasonably short inlet tract.

The insert has an aerofoil shaped leading edge and the trailing edge is a 14 degree (included angle) divergent cone, in fact it diverges at 14 deg more or less all the way out to the rotary valve face.



32mm Ball Valve with 24mm carburetor equivalent throttle body venture behind it.

[Rick 52]

I am please to say I am now riding for the ESE team with a satellite ride, this has already produced 1.5 extra HP and much better curve through some fantastic advice and set up on the Dyno from Teezee.
Improved pipe design, new carb and a little porting and we now have 22.8 HP from the TF
Teezee has started to design a new engine for me to build with the intentions of getting the very most we can get from a TS 125 engine, this will take some time but would be aiming for the middle of the NI rounds or GP .

Thanks Teezee, the bike was a missile today, had a little trouble learning to ride it again, qualified 2nd behind the currant lap record holder Garry Cunningham in the dry but cold track conditions, hole shot both points races but locked the front in the rain in the first race and went very wide, finishing 4th and finished 3rd in the second race struggling with the extra power in the pouring rain, the dyno curve showed the biggest increase in power on the overrun, over 4hp extra! Looking forward to a dry race to show what we can do .

[F5 Dave]

Good to see you there F5 Dave, I didn't fire the Kawasaki up in the end, we just concentrated on testing the two YZ's. Then went home cold and wet! The EFI YZ goes real nice, smooth power output. I think I might like mine EFI as well now.

Today the track was unbelievably well drained. Even got the sun out.

[G Jones]

I also make the skull face around the spark plug 0.1mm low, so that the top of the dome is pushed down by the head cover, and then the studs also pull the cover down over the inserts
outer flange as above.

Hi - I know the amount is not much - but could that 0.1mm cause any problems with the outer O ring leaking ? (I'm thinking of this on a TZ350 head)
Thanks...

[TZ350]

Thanks Teezee, the bike was a missile today, qualified 2nd behind the currant lap record holder Garry Cunningham.

I am glad to hear you enjoyed it.

[wobbly]

The head studs are outside the diameter of the skull flange, and usually they pull the cover down hard enough to keep the crush on the insert as well as " bend " the
cover enough to keep the outer O ring seal intact.
A 2mm head O ring should have around 0.3mm crush, so the 0.1 would not cause any issue.The outer water O ring has virtually no pressure
on it - well it shouldnt , anyway.
I have done many TZ350 heads with the 0.1mm protrusion with no issues.

[G Jones]

I have done many TZ350 heads with the 0.1mm protrusion with no issues.

Thanks - very much appreciate you taking the time to explain...
I've been machining some new inserts earlier today - and was basing the measurements on those taken from a head I had "inserted" by someone else a couple of years ago - I'm guessing those inserts / head have probably "settled" a bit in use - so wasn't sure how valid those measurements would be - your figures seemed to make sense - I was just a bit unsure how the outer o ring would cope...
Thanks again - just got to machine the chambers & squish now...

[Flettner]

F5 Dave, just knew we should have gone on Sunday! Had a good time anyway. Proved our point, 2T EFI works in the real world. Out of the four bikes we took only two had carburetors.