ESE's works engine tuner

[motogpdriver]

I thought it a good idea to investigate the size of the piston side thrust force (N) in a normal 125cc engine with different conrod lengths. The attached picture shows those forces for a conventional 125cc engine and in each case the power and combustion pressure was the same. I cannot do this for the Ryger as I do not know the pressure history in the combustion chamber:

Attachment 331856

btw does the ryger use variable compression ratio?
read this somewhere: The engine (1) also includes features for varying the compression ratio so as to increase the engine efficiency
I dont know if this was mentioned before

[lucf]

I thought it a good idea to investigate the size of the piston side thrust force (N) in a normal 125cc engine with different conrod lengths. The attached picture shows those forces for a conventional 125cc engine and in each case the power and combustion pressure was the same. I cannot do this for the Ryger as I do not know the pressure history in the combustion chamber:

Attachment 331856

Thanks Neels, for your investigation. I wrote that I also used the same burnig pressure.
In comparing only the conrod, the same pressure is the only good starting point.

[OopsClunkThud]

I was thinking about the " too short" rod needed to fit inside the lower piston dia ( too short in most peoples eyes) - does that piston need to be round? why couldn't it be a narrow rectangle shape or maybe a similar shape to the pistons used in the V4 four stroke Honda racer (of the eighties)?
This acting as a crosshead and leaving plenty of room for a longer rod to be accommodated?
Sealing of the "gland" could still be achieved - after all, if they could seal Wankel rotors against the combustion forces there, then surely in this case it would be a piece of cake!
- Or is my line of thought too far outside the "square" ?

a rectangular lower piston shape would give a flat surface to spread the side thrust over.

[WilDun]

a rectangular lower piston shape would give a flat surface to spread the side thrust over.

That's what I figured, and at the same time the possibility of being able to fit a longer rod deeper into this piston/crosshead (or whatever it might be called).
This of course would essentially divide the "pumping chamber" - or is it "crankcase" ?? into two parts and I have no idea how that would affect gas flow etc or how it would tie in with blocking off the exhaust port! - (with all this resonance talk, do they need to block it off ).

It wouldn't necessarily need to be a flat ended rectangle, It could be a round piston with the sides cut away as much as is necessary to accommodate small end bearing/s ( in the web formed by the flat sides of the "rectangle"). I'm sure the sealing around this shape would be quite achievable.

To me, the length of the present rod just isn't sensible! - why is it short anyway? - even a 25mm taller engine wouldn't have hurt anything, just look at present day four strokes, the head is as tall (and heavy) as the rest of the engine! Guess it has something to do with making it a conversion based on other engines.

I haven't sat down to try and work it out however - just a passing suggestion which might be crap and can be ignored. (but perhaps someone might consider it worthwhile to have a look and tell me if and where I'm wrong).

[wobbly]

The square piston idea isnt necessary as with the guide bush/seal/pushrod within the spacing plate there, is no side thrust on the piston.
But Luc seems to hint that the short rod makes more power - now from a pure physics standpoint,the short rod dwells at BDC longer then the opposite at TDC.
So with whatever internal trickery is at work,in this case the 90mm rod must overcome the its natural horrendous angular side forces on the guide bush/rod with a better Delivery Ratio
for the overall system to make more power.

[OopsClunkThud]

from a packaging perspective the one thing I like about the concept is the prospect a 90° V with shared crank journals (even retrofit to 4T). now just add a bit of turbo to bring back the primary pumping efficiency...

[F5 Dave]

. . . . now just add a bit of turbo to bring back the primary pumping efficiency...

Oops. There goes your packaging, erm. . , package.

[Flettner]

Ok Luc, seeing as you are here, let's discuss something you can talk about. The FOS type cylinder concept, can you point out to us why your setup didn't work? You certainly did give this concept a good go by building a working prototype but what happened? Why did you give up on it?

[WilDun]

The square piston idea isnt necessary as with the guide bush/seal/pushrod within the spacing plate there, is no side thrust on the piston.
But Luc seems to hint that the short rod makes more power - now from a pure physics standpoint,the short rod dwells at BDC longer then the opposite at TDC.
So with whatever internal trickery is at work,in this case the 90mm rod must overcome the its natural horrendous angular side forces on the guide bush/rod with a better Delivery Ratio
for the overall system to make more power.

Thanks Wobbly, I do realize I'm not up with the play and maybe not quite grasping the theory of the thing - be patient with me, you'll get there ...... I am talking about the lower part of the piston (ie small dia part of the piston / piston rod / crosshead or something) - an integral crosshead really, being roughly rectangular - and not necessarily flat ended, basically the whole piston would be roughly the shape ( possibly longer and slimmer across the flats in the skirt) of the old slipper type pistons used in Manx Nortons etc. This odd shaped "rod"/ piston skirt being sealed by an equally odd shaped seal in the plate of course.

However, the apparent theory behind the short rod blows all that out of the water! but I must say that those horrendous side forces still have to be taken up by something, which means friction (and equally horrendous wear) - I need to wind myself up slowly and get to understand all this stuff which I have not paid a lot of attention to previously!

[husaberg]

That's what I figured, and at the same time the possibility of being able to fit a longer rod deeper into this piston/crosshead (or whatever it might be called).
This of course would essentially divide the "pumping chamber" - or is it "crankcase" ?? into two parts and I have no idea how that would affect gas flow etc or how it would tie in with blocking off the exhaust port! - (with all this resonance talk, do they need to block it off ).

It wouldn't necessarily need to be a flat ended rectangle, It could be a round piston with the sides cut away as much as is necessary to accommodate small end bearing/s ( in the web formed by the flat sides of the "rectangle"). I'm sure the sealing around this shape would be quite achievable.

To me, the length of the present rod just isn't sensible! - why is it short anyway? - even a 25mm taller engine wouldn't have hurt anything, just look at present day four strokes, the head is as tall (and heavy) as the rest of the engine! Guess it has something to do with making it a conversion based on other engines.

I haven't sat down to try and work it out however - just a passing suggestion which might be crap and can be ignored. (but perhaps someone might consider it worthwhile to have a look and tell me if and where I'm wrong).

The square piston is so 1970's

[lucf]

Ok Luc, seeing as you are here, let's discuss something you can talk about. The FOS type cylinder concept, can you point out to us why your setup didn't work? You certainly did give this concept a good go by building a working prototype but what happened? Why did you give up on it?

All information about FST-twostroke-design https://www.facebook.com/notes/luc-f.../4080202582494

[breezy]

I thought it a good idea to investigate the size of the piston side thrust force (N) in a normal 125cc engine with different conrod lengths. The attached picture shows those forces for a conventional 125cc engine and in each case the power and combustion pressure was the same. I cannot do this for the Ryger as I do not know the pressure history in the combustion chamber:

Attachment 331856

how about an engine with a 38mm piston and 54mm stroke and 90mm conrod length.? isnt the lower part of this rygers piston where the most piston thrust would occur? could the high pressure oil supply to the oil hole in between the piston rings help centralies the upper piston within the cylinder reducing any piston thrust force?

[Lightbulb]

LucF, did you ever try a liner with the exhaust ports coming out of the liner being inclined 20 to 25 deg, and the transfer passages also inclined at the 15 to 20deg ? The Paw engine company made some small changes to their cutters making the liner back in 08, and gave a 5k performance improvement. So from 15 k to 21,500 rpm from a small geometry change to their radial port engine that was designed and made since the late 1960's.
Neil

[lucf]

LucF, did you ever try a liner with the exhaust ports coming out of the liner being inclined 20 to 25 deg, and the transfer passages also inclined at the 15 to 20deg ? The Paw engine company made some small changes to their cutters making the liner back in 08, and gave a 5k performance improvement. So from 15 k to 21,500 rpm from a small geometry change to their radial port engine that was designed and made since the late 1960's.
Neil

Yes Neil, we tried several portangles.
We still can change to the old concept of 70hp at 17.500rpm and max rpm of 30k.
But we don't want to sell an engine which runs to easy to 30k.
That we will leave that to anyone who want it.
This is the current Ryger https://www.youtube.com/watch?v=RJbxxdzhESA

[jellert]

Yes Neil, we tried several portangles.
We still can change to the old concept of 70hp at 17.500rpm and max rpm of 30k.
But we don't want to sell an engine which runs to easy to 30k.
That we will leave that to anyone who want it.
This is the current Ryger https://www.youtube.com/watch?v=RJbxxdzhESA

The way you put it makes it sound like the max RPM can't be limited with the ignition. Am I right? Very interesting if that's true.