350 exc-f compression?

[patrik16]

Compression being 12.3:1 and with all of the variables that go into converting that to psi. What is the psi that this engine should produce in a test?

[patrik16]

hmm?

[Bullmoose C]

• it can not be calculated in that manner. CR is a theoretical ratio of cylinder volume compressed into the remaining head volume. Actual cylinder pressure (measured ) depends on Valve overlap and cam timing as well How long do the valves stay open on the upstroke of the piston and is there overlap and how much between intake and exhaust cycles to bleed off the pressure on your upstroke. So with out cam specs it is not possible to calculate with math. You can effectively soften a CR with diff cams.

 

[patrik16]

Thanks for your response, but I know that part. The question is what should be the psi? Factories give us compression ratio. But to know what state the cylinder, and rings are in you would need to know the psi. Because as far as I can tell they haven't invented the compression ratio tester. Only a compression tester that reads in psi. I probably should have phrased the question differently. After break in what should the compression be in PSI? sorry