Okay, what would be a way to check my compression ratio when my head is milled around 35-40 thousandths?
My headgasket is .067" thick... yea. big. lol.
LS/VTEC B16a head with JE 5.7 dome pistons...

I did a compression test and they were around 225, which would be correct compression for say... 10.3:1 but I'm not sure if that would be a good way to see what my compression ratio is.

Thanks.

Harry

 

I got 11.25:1. Interestingly your thick head gasket is canceling out any gains from your milling almost perfectly. Cylinder pressure w/ a gauge will lie, due to the effect of the compression lost through valves opening and closing.

 

Cool.. Thanks. I've been looking around FOREVER for the mathematics to accurately account for head milling... can u post the equations for that?

Thanks.

Harry

 

Didn't do any math...too lazy. I used C-speed's compression calculatricia, subtracted your head milling from your gasket thicknes, and used your dome displacement spec. Probably not precise, but it'll be close.

 

Oh ok... I actually think I found a formula... it's some long thing that takes your bore, your milling, and pi divided by 4 and I dunno. lol. It came up to 11.1 so you were definitely close enough for government work. lol.

Harry

 

The only way to be precise is to cc the combustion chambers and plug that into the formula. Even using equations w/o measuring exactly what space there is will be +/- a few tenths. Close enough for most purposes.