Originally Posted by
Ender.
A compression test is by no means a way to figure out what compression ratio you have. It is a very basic tool to give you some insight on the condition of the motor. Different gauges will read different readings on the same motor. Albeit if the compression reading is fairly high it might have a higher compression motor, but don't count on a compression gauge alone to tell you this.
True but it IS a good start if he doesnt want to turn a wrench on it. I compression tested a COLD engine over the weekend that came back 280 - 290
Warm it broke the compression tester
Compression tester only went up to 300. Here is a very general guide
8:1 - 8.5:1 compression: 150-170 psi per cylinder
8.5:1 - 9.5:1 compression: 170-210 psi per cylinder
9.5:1 - 11:1 compression: 210-275 psi per cylinder
11:1+ compression: 250+ per cylinder (highly depends on cams being used)