A guy I know has 240-241 all on 4 cylinders of his 98 GSR. He had teh head shaved some and did some chamber work. He claims he has like 12.5:1 compression now??!! Is this possible from just a regular compression test? Let me know! Thanks!

 

240psi per cylinder is probably around 10-10.5:1 compression. just a rough estimate.

 

Those testers vary fairly wildly. I have 2 and one is always 20psi higher than the other. The purpose of the compression test is merely to look for variance from one cylinder to another. Unless you get a reading below 100ish on a new B18C1 I'd not worry too much about the actual #s unless they vary wildly across the engine.

 

The compression on my B18C is 10.8:1 and my numbers were roughly 260 accross the baord.