I am looking a buying a bayliner 2859, 2003 it has a mercrusier mag 350 with bravo II, fresh water cooled with ~1150 hours. I had a mechanic test the compression in the cylinders they all ranged from 210 to 215. I am curious if this seems high?"
Yes....... cylinder pressures in that range (for this engine) would indicate an incorrect piston profile and/or an incorrect cylinder head combustion chamber combination!
Is there a spec range for compression for this engine?
I don't know what the exact cylinder pressures should be.
I do know that 210/215 psi is excessive knowing what piston profile and cylinder head combustion chamber volume would be typical for a 2003 5.7L Mag.
The 5.7L Vortec cylinder head chamber volume is in the range of 64cc to 65cc.
With the GM style Full Dished piston (of the correct dish volume), pressures are more typically 165 to 170 psi.
With these being that high, I would suggest that something has been changed.
We know that the Vortec chambers are 64/65cc.
We don't know if someone changed piston profile...... such as reducing the dish volume.... which may explain the excessive pressure readings.
In any event....... 210/215 psi is very likely going to cause detonation problems.
.
