siggyfreud

Yeap, thats the method I was talkin about. Just good practice and insurance to avoid the money shift hehe.

jahudso2

Actually it does matter on the compression ratio because the amount of cylinder pressure is directly related to the compression ratio using the following equation:

P2 = P1 * (rc)^k

P2 is cylinder pressure after the compression stroke
P1 is the intake pressure
rc is the compression ratio
k is assumed to be between 1.35 and 1.4 for the polytropic process

siggyfreud

While this is true, the original compression ration of the given engine will not be indicative of the damage potentially done. By the time one figures out the new compression ration, you've already taken readings on the cylinder pressure, thus the information the OP was after, would have already been figured out.

Shadow7874

Yep, just test each cylinder pressure with a gauge and make sure the numbers are close together. 170 sounds like a nice average number but i too dont know what it should be. Normally as long as they are +/- 5 psi or so your fine. On my 14 year old jet ski the numbers were within 3 psi of each cylinder just for reference.

TorchRed04GT

Thanks for all of the replies everyone. I am having a compression test done this Friday. So if I have benst valves, this will not effect the compression of the motor?