Frebius

So if that is the case, what is the PSI threshold to tell if you have problems within your engine or not?

Frebius

What is the difference of Compression Ratio and the reading of compression you get from a tester?

myshifter

you guys seem to be talking on 2 different planes. The guy wants to know compression ratio ie; 9:1-10.5:1 NOT cyclinder compression 150psi-160psi. To accurately calculate his compression ratio he needs to know a bunch of things. chamber volume,head gasket compressed thickness, gasket bore size, cc's of relief valve on piston, how far piston is below the deck. Give me those and I can tell you CR

ikeybmg

were seeing I 2 I myshifter. i figured it close to around 11.3.1. i have 60cc combustion chamber, .040 head gaskets, flat top pistons, 4.030 bore, 3.40 stroke, which is as, yall know, a 347. only thing im not sure about is the deck height.

myshifter

ok give me a second, it will be lower than what you think since the gasket bore is larger than 4.030 and there is a relief in the piston which is good for a few cc's and I will guesstimate the piston is 10-20 in the hole, brb

myshifter

10.9 ASSUMING a few things, piston is 10 thou below deck, maybe-maybe not. Gasket bore is 4.040(probably) 1-2 cc relief on piston ( they have a valve relief right?)

ikeybmg

yesser they do. id say youre pretty accurate. so its bound to fall somewhere in between mine and your calculation then, though prolly closer to yours thanks man.

myshifter

you knwo where to find me

ikeybmg

you think i could get away with small boost or a little nos? ill have around 400 motor without it on a stock block.

myshifter

i would go with the NOS, compression is a non factor with that, boost, nah