ESE's works engine tuner

[MotleyCrue]

Did Frits ever say if the normal looking transfer ports in the cylinder also have normal directions of flow for A and B and C transfers?

[karter444]

Is there any advantage in running a dome top piston over a flat top piston or visa versa ,most pistons do seem to be dome top

[Lightbulb]

On testing I did with model engines, there was no gain with a domed piston and matching head over a flat top piston and matching head. But this was 6.5 cc engines. I still don't know why the MB 6.5 engines use a domed piston, I guess it looks like it makes more power as a result.
Frits may be able to comment better. To me a flat piston is the least area from the center to the edge to dissipate the heat. There may be other reason in bigger engines like trying to keep the flow adhering to the piston crown to try and cool it, just not sure. All I know is, with the limited testing I did, the domed piston was slower and made less power. CNC does not care what a shape is, it is just all just a tool path.
Neil

[tjbw]

Is there any advantage in running a dome top piston over a flat top piston or visa versa ,most pistons do seem to be dome top

There was some discussion about this here, also on pitlane and elsewhere.

IIRC domed piston can give more power, but you need a matching profile on the head. Jan Thiel found best results with 0.7mm squish clearance (on a 125cc RSA engine with domed piston).

The combustion chamber shape and compression ratio are important too.

google searches for more info:

wobbly domed piston
frits domed piston
jan thiel domed piston
ricardo domed piston

[MotleyCrue]

Did Frits ever say if the normal looking transfer ports in the cylinder also have normal directions of flow for A and B and C transfers?

Was it ever mentioned if the bore was stock, if not stock that might help with the speculating.

Every once in awhile one poster generosly puts up a Ryger summary of the main things we know, but there have been some fine points that maybe should make it to the summary list like things Frits said he wasnt at liberty to answer and some ideas that Frits avoided responding to altogether.

[seattle smitty]

The speculating a few pages back about how the Ryger might handle extra F/A and extra heat . . . does this square with Frits' hints (incl. a small radiator) about less heat being absorbed? I don't understand all the ramifications of a relatively "instant" combustion of the F/A mixture (as compared to a usual burn), but doesn't that include an ignition point much closer to TDC, with less "negative-work-effect" and less time for the engine parts to absorb that heat (and therefore more of the heat turned into useful power)? Also, does the decreased (eliminated?) use of pre-mixed oil in the F/A enable or at least assist in getting the "instant burn" to work, to light off at a precise timing? Is there a reason that HCCI would produce fewer nitrogen oxides? And wouldn't that (relatively) "instant" burn require better-than-usual F/A mixing? as well as more precise than usual spark timing? Could a conventional racing 2-stroke like Jan Theil's last Aprilia be set up to use an HCCI fuel burn (without turning it into a Ryger)? So far, in looking at internet articles on HCCI, I have only a sketchy understanding of it (about like my understanding of anything else, alas).

[m4r]

The speculating a few pages back about how the Ryger might handle extra F/A and extra heat . . . does this square with Frits' hints (incl. a small radiator) about less heat being absorbed? I don't understand all the ramifications of a relatively "instant" combustion of the F/A mixture (as compared to a usual burn), but doesn't that include an ignition point much closer to TDC, with less "negative-work-effect" and less time for the engine parts to absorb that heat (and therefore more of the heat turned into useful power)? Also, does the decreased (eliminated?) use of pre-mixed oil in the F/A enable or at least assist in getting the "instant burn" to work, to light off at a precise timing? Is there a reason that HCCI would produce fewer nitrogen oxides? And wouldn't that (relatively) "instant" burn require better-than-usual F/A mixing? as well as more precise than usual spark timing? Could a conventional racing 2-stroke like Jan Theil's last Aprilia be set up to use an HCCI fuel burn (without turning it into a Ryger)? So far, in looking at internet articles on HCCI, I have only a sketchy understanding of it (about like my understanding of anything else, alas).

there is quite a bit explained here

https://idea.library.drexel.edu/isla...ect/idea%3A901

[MotleyCrue]

If exhaust gas is purposely mixed with the fuel and air mixture, for HCCI which it seems like it is, why bother then with the usual A, B, C porting arrangement to get good cylinder exhaust scavenging which would defeat the purpose.

Why not just aim A, B, C at the exhaust port and blow as much fuel air mixture as possible right out the exhaust port forgetting the whole loop thing then stuff it ALL back into the cylinder so none of the fuel air mixture is left in the port when the port closes. On a regular engine this would go against the grain but the Ryger engine has HCCI, needs no power valve and a regular length pipe seems to work to unheard of rpm levels so somehow stuffing all the mixed up fuel, air and exhaust back into the cylinder before port closing might be realistic.

[Norman]

If exhaust gas is purposely mixed with the fuel and air mixture, for HCCI which it seems like it is, why bother then with the usual A, B, C porting arrangement to get good cylinder exhaust scavenging which would defeat the purpose.

Why not just aim A, B, C at the exhaust port and blow as much fuel air mixture as possible right out the exhaust port forgetting the whole loop thing then stuff it ALL back into the cylinder so none of the fuel air mixture is left in the port when the port closes. On a regular engine this would go against the grain but the Ryger engine has HCCI, needs no power valve and a regular length pipe seems to work to unheard of rpm levels so somehow stuffing all the mixed up fuel, air and exhaust back into the cylinder before port closing might be realistic.

A relatively sharper "cut" between the fuel/air mix and the exhaust makes it easier to control what ends up where? My guess is that blowing everything straight out and letting it all mix, and then force it back into the cylinder, will give a too high exhaust content and too little fuel/air mix ratio for high rpm operation, and misfire at lower rpm?

I still think that aome key aspects points towards ATAC/HCCI combustion, but still spark induced flame front combustion at certain rpms and loads? The believed relatively high pre compression, valve arrangement, lubrication principle and other parts of the Ryger concept are not very unlikely the last things needed to take the earlier 1980's-90's low emission ATAC/HCCI assisted like combustion intentions all the way.

[Frits Overmars]

Is there a reason that HCCI would produce fewer nitrogen oxides?

Yes, the burn temperature does not rise quite so high with HCCI.

Could a conventional racing 2-stroke like Jan Thiel's last Aprilia be set up to use an HCCI fuel burn?

Jan had practically reached that state. The Aprilias had to be jetted too rich, otherwise they wouldn't listen to the quickshifter's ignition cut-out and keep on running without a spark.

[MotleyCrue]

My guess is that blowing everything straight out and letting it all mix, and then force it back into the cylinder, will give a too high exhaust content and too little fuel/air mix ratio for high rpm operation, and misfire at lower rpm?

I do believe there is a way to make that work. A spark plug might not light off a charge with a high exhaust content but HCCI is not a spark event, not at all.

[jonny quest]

Yes, the burn temperature does not rise quite so high with HCCI.

Jan had practically reached that state. The Aprilias had to be jetted too rich, otherwise they wouldn't listen to the quickshifter's ignition cut-out and keep on running without a spark.

So the 54hp dyno run isn't really the numbers the bike ran with on the track? Meaning, it was jetted max effort on dyno. But track configuration was 1 to 2 hp less to make everything work for the rider?

[Lightbulb]

It will be a good day when Frits can respond to my comments.
Neil

[steamroller]

Hi people,

I have a KR150 motor that runs a balance shaft that I would assume would run smoothly. We have put a CNC barrel on it based off a Honda RS125, and now run a 125 piston in it. The motor however now vibrates really badly.

Any suggestions? Is there a ratio to how much weight we should take off the balance shaft to compensate for the 125 piston?

[husaberg]

Hi people,

I have a KR150 motor that runs a balance shaft that I would assume would run smoothly. We have put a CNC barrel on it based off a Honda RS125, and now run a 125 piston in it. The motor however now vibrates really badly.

Any suggestions? Is there a ratio to how much weight we should take off the balance shaft to compensate for the 125 piston?

I will post a link but are you 190% sure it is timed correctly?

attached is a file that explains how the maths work std.

post the weight of the new piston and bearing and the old piston and bearing.
Neil has designed them so I am sure he will give you a simple rule of thumb as will Frits.