whats this mean exactly.

[Mogobs30th]

Originally posted by stuffy236:
</font><blockquote>quote:</font><hr />Originally posted by Mogobs30th:
</font><blockquote>quote:</font><hr />Originally posted by '94firebirdv6:
if you want to stay NA you would want to up your compression. however if you wanna go forced induction, you actually need to drop your C/R because a lower CR allows you to run a higher psi of boost without detonation. most boosted applications run a CR of about 8:1 or 8.5: most NA CR are around 9.4 upt to 12:1

I didn't want to say this because this is a VERY common misconception. By dropping the compression, it HELPS with detonation when applying boost. BUT, you can raise compression and add boost, seen it done many times on a few V8 engines, just never been done on a 3.8l to my knowledge. If you have the right equipment, resources, and knowledge, then applying boost to an engine with a raised compression is possible, without the detonation. Now if you factor in driveability, street legallity, light to moderate internal work, on pump gas, then no, I wouldn't raise compression on a boosted car.

If you plan on keeping your car NA, then I think 11:1 is possible, you will have to do a helluva tune on that PCM, or order one that will suit your needs. Running on pump gas will be iffy at best, might have to go with a higher octane than what can be provided at a neighborhood pump. I am also not sure about how you will get 11:1 compression. I can't see thinner head gaskets and milled heads being enough, you might have to get a custom set of pistons made for that compression, but I could be a little off with that. </font>[/QUOTE]i hate to keep posting with links to the grandprix site, but this is also a good read about FI with higher compression: http://www.clubgp.com/newforum/tm.as...mode=1&smode=1 </font>[/QUOTE]I never said anything about upping compression on a high CR engine being a SMART move. Best thing that can be done is one of two things.

One, find a PSI you are comforable with, stay with that PSI, and change the compression around it till you reach optimum HP, thru calculating the volume of air within the chamber to the HP attained within the volume variable...

Or two, (and FAR easier), adjust the boost to the compression ratio that you are using, and using similar calculations, find the optimum HP for that CR by adjusting that boost.

I had personally planned my own project car to have a CR of 8.2:1 or 8.3:1, probably 8.2:1. Seems to be the best for the application that I have.