ESE's works engine tuner

[Muhr]

The only other way is to use a truth table in the ecu to switch the flow depending upon TPS and rpm , but this is problematic to tune , causing jerking response on part throttle

Thanks for the tip Wobbly!

Ahh I see, it is a lot lower than I thought it would be with quite a lot of slide cutout showing.

So if you could control 2, a short one in from the side real low down that only works high revs closed throttle and another as Wob described.

Yes definitely could be a way forward !!
the goal so far has been to achieve a good piston cooling with the help of PJ, which it looks like we have succeeded with.
The reason for this is that we have a fuel with limitations (98/90). the idea is to now start pushing the boundaries and see if we can go further with this approach than if we had a traditional carburetor setup

[wobbly]

My first reaction was that if you want flow at high rpm , closed throttle , the put the PJ tube on the other side of the slide.
Plenty of vacuum on closed throttle to pull fuel thru.
But why then did KTM feel the need to use an injector for the same thing ?

[F5 Dave]

Trick factor? Additional control options like adding fuel if knock sensor goes off? Would love to know.


But yes pj on other side of slide sounds better idea than mine (as usual) . Would have been useful on an old air-cooled bike of mine that was fine on kart tracks but would nip on hairpin at Ruapuna unless jetted so rich on pilot that it stumbled on reapplication. Think I'd cured the float feed as well.

[Muhr]

My first reaction was that if you want flow at high rpm , closed throttle , the put the PJ tube on the other side of the slide.
Plenty of vacuum on closed throttle to pull fuel thru.

Yes it might be a better solution.
My theory was that I wanted a pressure difference between the air bleed hole and the spray hole. for increased function at lower airflow?




bit of topic but cool slow motion pictures of a "carburetor" at work
https://m.youtube.com/watch?v=toVfvRhWbj8

[Pursang]

Matt Hudson from The Workshop YouTube channel is doing some development work on a multi-cylinder 2 stroke based on the Hossack engine.

https://www.youtube.com/watch?v=VRzSpSYQ2EU

Good description of prototype design and analysis of components using Solidworks.
5 videos so far in the series.

Cheers, Daryl.

[Tim Ey]

Yes it might be a better solution.
My theory was that I wanted a pressure difference between the air bleed hole and the spray hole. for increased function at lower airflow?




bit of topic but cool slow motion pictures of a "carburetor" at work
https://m.youtube.com/watch?v=toVfvRhWbj8

Huh? I never saw that air bleed hole before on a powerjet?!
How does it change its behaviour?

KTMs injector: Probably their bike turned out too light for the class? :-D

[Muhr]

Huh? I never saw that air bleed hole before on a powerjet?!
How does it change its behaviour?

KTMs injector: Probably their bike turned out too light for the class? :-D

Emulsion of the fuel before it leaves the tube was my thought
which should also widen the RPM range as the air hole (s) are static while the fuel feed will be dynamic to a greater extent. There are many who call a power needle a power jet.
As I see it a power jet has jets and emulsion tubes while the power needle is a needle and a tube. But I could be wrong

Do not know what the rules looked like in gp racing but if it was ok to have an injection / overpressure system you would probably have it, as the possibilities are endless

[lohring]

Matt Hudson from The Workshop YouTube channel is doing some development work on a multi-cylinder 2 stroke based on the Hossack engine.

https://www.youtube.com/watch?v=VRzSpSYQ2EU

Good description of prototype design and analysis of components using Solidworks.
5 videos so far in the series.

Cheers, Daryl.

I'm not sure why people keep trying to redesign the old round piston design. The issue in IC engines is the seal. Steam engine builders settled on the standard round piston because it could be produced accurately enough with simple machines to get a good seal. A century or so of experimenting hasn't improved on it. The Wankel engine was the latest attempt at sealing a different shape. Lots of alternate designs have been successful in hydraulic pumps, but the round piston still dominates. Lots of oil at lower temperatures make the problem easier.

Lohring Miller

[JanBros]

Matt Hudson from The Workshop YouTube channel is doing some development work on a multi-cylinder 2 stroke based on the Hossack engine.

https://www.youtube.com/watch?v=VRzSpSYQ2EU

Good description of prototype design and analysis of components using Solidworks.
5 videos so far in the series.

Cheers, Daryl.

I wonder why he thinks that the transfer port still open after the exhaust has closed is "gold" ? the piston is already going back up so not much suction, plus the exhaust is closed so you can not benefit from presurising the cylinder with mixture drawn in the expansion pipe.

[Pursang]

I'm not sure why people keep trying to redesign the old round piston design. The issue in IC engines is the seal. Steam engine builders settled on the standard round piston because it could be produced accurately enough with simple machines to get a good seal. A century or so of experimenting hasn't improved on it. The Wankel engine was the latest attempt at sealing a different shape. Lots of alternate designs have been successful in hydraulic pumps, but the round piston still dominates. Lots of oil at lower temperatures make the problem easier.

The earliest steam engines relied on cannon manufacturers for their technology. (The earliest cannon manufacturers relied on tree trunks!)
The square bore provides an extremely compact package for a multi cylinder engine.
The "square" piston eliminates the gudgeon assy. (Weight, parts, precision machining, lubrication requirements & a potential failure point)
Thanks to years of Wankel development the technology & materials to provide durable and efficient lip sealing are now available.

I wonder why he thinks that the transfer port still open after the exhaust has closed is "gold" ? the piston is already going back up so not much suction, plus the exhaust is closed so you can not benefit from presurising the cylinder with mixture drawn in the expansion pipe.

The 'design exercise' is not for a racing engine.
Having an extended time period available for direct F.I. (Or Air/fuel injection) is useful.
For a low(er) performance application, loss of mixture back to the transfer is way better than out the exhaust.

IMHO, the ability to provide pressurised transfer via an externally pressurised common multi-cylinder cranckcase will allow efficiency within the smallest possible dimensions and simplest construction. (Not sure if Matt is considering that option, the individual reed blocks suggest not... yet).

Cheers, Daryl.

[Frits Overmars]

The "square" piston eliminates the gudgeon assy. (Weight, parts, precision machining, lubrication requirements & a potential failure point)
Thanks to years of Wankel development the technology & materials to provide durable and efficient lip sealing are now available.

Eliminating the gudgeon assy can just as well be achieved in a round cylinder bore; in fact it has been done in several air compressors.
It would also make sealing a whole lot simpler; all you'd need is one spherical piston ring.
One drawback: it's not suitable for piston-controlled exhaust ports.

[JanBros]

The 'design exercise' is not for a racing engine.

then why would he be talking about getting the weight of the P-rod down to 100grams to rev it's nuts off ?

[wobbly]

The hole in the PJ tube is exactly the same as a normal idle or main air corrector . Air mass passing thru the venturi continues to increase past the
peak of BSFC @ max torque , thus the fuel curve goes progressively richer.
An air corrector may help atomization as a by product , but its designed function is to bleed in increasing amounts of air to change the fuel
curve closer to ideal as the power drops over the top of the pipe.
A Lectron has no air bleed system , and it atomizes the fuel droplets way better than any emulsion tubed carb.

[Vannik]

A Lectron has no air bleed system , and it atomizes the fuel droplets way better than any emulsion tubed carb.

After watching the see through carb video something struck me - the unemulsified fuel traveled quite deep into the venturi and the emulsified and evaporated very good. A Lectron must do something similar but even better, the fuel also shoots up into the venturi and is aided by the adhesion to the rear of the needle and is partially protected by the same needle. So it penetrates quite far before being carried away by the air stream. This should give superior atomization and vaporization combined with a more homogeneous mixture distribution early on in the air stream. Should be especially superior in very short intakes.

[Pursang]

then why would he be talking about getting the weight of the P-rod down to 100grams to rev it's nuts off ?

He says an awful lot of things! I often disagree with some of his pronouncements.

I think some of the weight thing was just demonstrating the ability of the engineering software to design and test for a particular operating condition.
The other part was explaining the concept of "margin of safety".

I'm not here to defend or apologise for him. I do think the exercise is interesting.
Putting it all up online, showing the process and the progress or otherwise is brave, same for Neil, Ken & Alex's projects)

Then again...perhaps he is considering taking Alex's challenge to build the WMPTSE ??

Cheers Daryl