ESE's works engine tuner

[tjbw]

Neil,

... over a crank cycle, the engine will not run at a constant speed, but it will speed up and slow down thru the cycle. This being the case, the port durations, whilst maintaining a constant number of degrees, will in fact vary in time, due to the cyclic speed variation.
A couple of numbers: At 39,000 rpm, the crank rotates 650 times per sec, ie a rotation takes 0.0015 sec.
If, as I suggested earlier, one had a 360 T encoder wheel and this signal was logged against time, one could have three (or more really) basic scenarios. (Note the 360T is a bit arbitrary, but something I am familiar with, and could be less (less accuracy) or more (more accuracy). I guess it somewhat depends on the capacity of your acquisition system.) See the attached sketch.

Attachment 317067

One can see, exaggerated, the different scenarios, and the effect on port durations. Could turn out to be ¾ of 5/8 of stuff all, but would be interesting to know. The key variable I think, being crank inertia.

That would also be useful, for comparing the effect of converting an engine to HCCI.

If instantaneous combustion results in an acceleration after TDC, can that be damped by anything in the drivetrain other than a larger flywheel?

[Frits Overmars]

If instantaneous combustion results in an acceleration after TDC, can that be damped by anything in the drivetrain other than a larger flywheel?

Sure, a transmission shock absorber in the primary gear, in the clutch or in the rear wheel hub.

[m4r]

this came up on facebook today, looks like a stepped piston

[Ocean1]

this came up on facebook today, looks like a stepped piston

Stepped or not the displayed face looks conical. Assume it's the combustion face... have you ruled out a fully floating piston yet?

[ief]

Long shot but anyone went to the trouble to model a puch maxi and/ or tomos a35 in engmod and want to share the pack file?

[MotleyCrue]

Yesterday Jan Thiel wrote

"I have absolutely nothing to do with it.
And I would have to see a powercurve before I believe any 125cc engine gives
70HP and revs to 30.000!"

Thats a bit unexpected I think.

[ken seeber]

Thank's for the feedback Frits.

So Ken would you sell us your idea?

Our situation on the plugs is this. The one in the pic did work, but was a prick to install and was destroyed on removal. As with any such plug, as Frits said, its dimensioning is strongly dependent on the position of the piston circlip groove relative to the piston skirt face plus piston pin offset plus the geometry of the bore beyond the circlip (different manufacturers had slight variations in this area ranging from an enlarged diameter to a stepped bore, to suit their processes.

Since that time, we have come up with a snazzy locating arrangement, but this is still subject to the circlip/bore details as above. For us, we are holding back on this until the Ryger thing comes out as there might be a relevance there and/or it might very quickly kill existing style engines and we all have to think again about a new direction and/or things might just revert back to the status quo.

56 days to go.

[2T Institute]

theyre not athenas but i believe theyre loosely based on that casting. the timings are low. around 182/122 i think but i havent checked yet. these are also sitting at 65mm bore right now but ill probly have to go to 65.5 so theyll straighten up. athena bores start at 68mm i believe. i believe theres a few other differences also. now if i could get them around 100hp with methanol i would feel all the effort was worth it. totall cc will be around 391-397 depending how the bore cleans up

They look identical except for the athena logo. Where did you get them from?

[breezy]

Wobbly, by removing oil from the fuel used in the 2 t engine, what impact would that have on transfer flow/ scavenging patterns?

[husaberg]

Wobbly, by removing oil from the fuel used in the 2 t engine, what impact would that have on transfer flow/ scavenging patterns?

Less carbon deposits ...................

[F5 Dave]

An upset sheik?

[polinizei]

this came up on facebook today, looks like a stepped piston

I don't belive its a typical stept piston.
You wouldn't grap a round body outside the 12 and 6 o'clock position. Also Frits gave the hint, we wouldn't see any thing special through the exhaust port.

[m4r]

I don't belive its a typical stept piston.
You wouldn't grap a round body outside the 12 and 6 o'clock position. Also Frits gave the hint, we wouldn't see any thing special through the exhaust port.

guess why you wouldn't see anything special through the exhaust port

Edit: He is probably holding it at what is left of the piston skirt to cover the exhaust

[breezy]

An upset sheik?

ahhhh of course..

[d2t]

we are holding back on this until the Ryger thing comes out as there might be a relevance there and/or it might very quickly kill existing style engines and we all have to think again about a new direction and/or things might just revert back to the status quo.

This!

With details just beyond the horizon, makes me wonder if there's any reason to try new things in regards to existing configurations as any positive steps may be trumped by the Ryger design. The answer is nothing is certain. Aside from karting, there's no garuntee other racing organizations will even allow the Ryger-style engines to compete if they make 100% of the current field obsolete. So, yes, there's still reason to try new designs but with 2016 rapidly approaching, it may be worth delaying such efforts as they usually involve considerable development time/cost.