ESE's works engine tuner

[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 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 .
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.

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.

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



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.

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.

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





Cheers, Daryl.

Page 4 oddballs Daza......
https://www.kiwibiker.co.nz/forums/s...post1130798205
or 8 years ago here
https://www.kiwibiker.co.nz/forums/s...post1130420185
Frits and Flett here
https://www.kiwibiker.co.nz/forums/s...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/s...post1130798205
or 8 years ago here
https://www.kiwibiker.co.nz/forums/s...post1130420185
Frits and Flett here
https://www.kiwibiker.co.nz/forums/s...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 .
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.

[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!