Compression Ratio

[boosted88]

Hi guys has anybody got any figures for the acceptable comp ratio range on a Starion block with EVO III head I'm seeing close to 200PSI which seems a bit high to me???

Having issues with crankcase getting pressure on anything about 2000RPM

Cheers
Paul

[docile]

200Psi is above average, sounds like you are running 9:1CR pistons with stock cams, and possibly out of alignment, or at the very least a shaved cyl head?

The only way the crankcase should be seeing too much pressure is if your piston to wall clearance is too much?

If you want to lower static comp pressure fit larger cams, but thats possibly only a bandaid solution because combustion pressures go above 1000psi.

I think you probably need to provide as much info as possible for one of us to pick out the real issue.

[TOMSUN]

Ring gaps could be too big? If you are getting a lot of blow by or piston to cylinder clearance?

[Xentro]

Also check the check valve on the valve cover.. those are notorious for leaking, and if it does leak it'll use the turbo to pressurize the crankcase.