Increase CR

positive

Is it safe to increase CR to 10.5 or 11.0 on a standard engine (bottom end, cams, map) with head skimming? Has anyone use such a configuration?

vocky

Obviously it puts greater pressure on the rings, so if the bottom end is in good order it should be fine.

I have used the z22yh pistons OR skimmed the head by 1mm to get 11:1 CR on a few engines.

I found increasing the CR gave good power results. I now run 12:1 CR on my tweaked 2.5 engine.

positive

The only thing I am worrying about is detonation.
I have found some formulas to determine the dynamic CR, but knowing the cam timing is essential for it and I don't know that. 🙁
Do those engines have standard cams and map? Since larger cams reduce the dynamic CR, increasing static CR with performance cams (as on your engine) is a different story.
Anyway, I have read about your engine. Really like it. 😉

vocky

standard cams are 244 degree, so very mild.
Certainly longer duration cams help increase power, GM restricted the z22se engine because it made too much power :censored:

Kb1974

Is there any other standard cams by vx that give a power Increase like the xev cams on the 2.0 @[deleted]?

vocky

not that I am aware of, the saab cams are milder than the z22se.

Which means someone could probably use two inlet cams in a z20net and get a little more power, not a lot though :LOL: