Pelican Parts Forums - My new piston 3.0+

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Quote:

Originally Posted by PeteKz (Post 12551203)

What full-throttle, full-advance timing did you find for max torque?

Pete,

Benefits of full ignition control is to pinpoint the best timing for the full RPM range. That number is dynamic and unique to the fuel choice, ignition control vs actual spark event when ignition control latency isn't calibrated, RPM, and the engine package as a whole. The peak timing number is in the mid 20's in this case.

Michael

Mike, thank you for your reply.

I know that the timing is dynamic and depends on multiple factors, but I was looking for a comparison of the timing at a defined condition to compare to the timing typical of a conventional twin plug piston and chamber at the same condition. If your engine is in the mid-20’s with the Apgar piston, then that puts it in the range of the timing of the twin-plug ignition with a conventional twin-plug piston dome. Is that about right? Or does it require several degrees less advance?

Maybe I am not asking the question in the best way, but I am looking for some method of comparison, without having the same engine, but with conventional twin plug pistons, to run on the dyno for a direct comparison. I think that comparing timing is the next best method.

Quote:

Originally Posted by PeteKz (Post 12551686)

Pete,

When the hardware allows I do individual cylinder trims as needed so that is why I was ambiguous and mentioned that its dynamic, both this motor I posted about and the comparison motor were timed this way. Also I consider the tune information proprietary to the paying customer.

To give some numeric info though, it has a mean delta of 3-4 degrees less than a full dome piston in a pretty aggressive build on the same regional E10 pump gas.

Mile, thanks. That is what I was looking for.

Quote:

Originally Posted by PeteKz (Post 12548432)

What size pistons are in stock?

http://forums.pelicanparts.com/uploa...1762209190.jpg

We currently have 8 sets of the x97 design ready to go,
Sorry for the delay it’s field hockey state championships right now and my twins both play so I’m wrapped up with that

Cheers
James

Quote:

Originally Posted by Jpapgar (Post 12558190)

Looking at the spec sheet, this piston looks to be designed to be used in 3.2 Carrera engines with the 74.4mm stroke crankshaft and 98mm barrels.

With a nominal combustion chamber of 90cc and deck height of 1mm, the compression ratio would be 10.26:1.

Assume this is recommened for engines with twin plugged heads also.