Was wondering if anyone knows what the MAX compression ratio is for a '99 SSE (L36 - non supercharged).

I'm putting on a turbo eventually and I need to know the max PSI my engine can handle.

I guess I don't understand the question your are asking here.

The compression ratio on the stock L36 bottom end is 9.4:1. Without touching the bottom end obviously you can mill the heads/block and/or use thinner head gaskets.

But, if you're going turbo, I think I'd leave the compression alone because 9.4:1 is actually a pretty nice compression ratio for something with boost.

I think he'* asking what the max PSI he can run is, which if I understand correctly, is a lot different than the compression ratio...

Until we get clarification, pretty high boost levels have been achieved on stock heads. I've hit 15psi myself, but my compression ratio is only 8.5:1. My effective compression ratio is FAR higher however, when the boost pressure is taken into consideration.

How does that effect stock internals? or have you upgraded those too?

the bottom end of the L36 will be fine....but an upgraded valvetrain will let him maximize the mods

My bad! I thought that compression and PSI were one and the same. So I guess what I really wanted to know was what the MAX PSI my engine can handle.

Stock L36

Max PSI as in max boost pressure or max PSI as in max cylinder pressure????

If you're talking about max PSI as in boost level, then it depends completely on what type of power adder, intercooler, and cam profile and whatnot. Just an M90 on a basically stock L36, you'd probably only want to run like 5-6psi. Do some valvetrain mods and exhaust mods and unintercooled you could probably pull off like 9-10psi on pump gas. Throw an intercooler on and 13-14psi shouldn't be that hard to do. My setup is making around 13psi right now with an intercooled M90 setup.

However, for your turbo setup, it all depends on what the turbo is, what you are doing for an intercooler, and your cam profile and the rest of your exhaust and whatnot. The bottom end will not give you any problems until you are making A LOT of power. So that shouldn't be the issue as long as you get everything else done right. Head gaskets will start to give you issues somewhere around 18-22psi. If you go with like MLS gaskets and head studs though, you shouldn't have any problems unless you get VERY serious.

Is this some type of a turbo kit you are getting or are you doing it yourself or what?

Yeah, I'm curious as to what size turbo you planned? Any ideas on the BOV yet? Where can you get the exhaust manifolds for this?