Originally Posted by preludeSI94
Thanks for the reply andrew
i know on the gude head package they shave the head quite a bit, enough to raise compression about a full point so around what compression piston do you think would be good? im guessing like 10:1 or so...I know with a mildly ported and shaved head the type-s piston fits in the h23 but im a little worried about it with the gude head
Well if it helps any our motors stock have about 9.5:1 compression (9.6:1 Im pretty sure), so if the head raises the compression a full point which is a fairly big jump your looking at 10.5-10.6:1 which is around the H22's I believe. So nothing higher than 10-10.5:1 or else you will be going pretty high and need a good tune (a good idea regardless) We already are supposed to run 93 octane on our H23's same with H22's so I think 10:1 pistons (which would then be increased to 11:1) would be great...but remember not all gas is created equal if you live in an area that has poor gas (California comes to mind) you may not wanna do it as their production cars have a hard time running optimally on their gas (The 350Z with cams and other bolt on parts from Nismo nets nearly no horsepower gains in CA as the computer cannot send any more fuel as detonation will occur with that crap gas. Just check out the magazines complaining about their test cars using CA gas if they are based there.)
Sorry that was so long but thought it might help you out. As GA where I live has pretty good gas, but the past few months a few random tanks have been awful and my car has sputtered, stalled, popped, and wheezed because of it. If that happened with 11:1 compression it may result in more serious problems unless the computer can put it in a "limp home" mose or something.
Sorry for the long wind :-)
Andrew