douwannarace

iTrader: (4)

I am trying to figure out what compression I should fun in my street car. I want close to the most compression I can get out of it and still run on pump gas. I was thinking about getting my heads reworked. They are a set of 243's. I was thinking of running the MS4 cam. I have a ls1 with -4cc mahle pistons. I want to get as high of compression as I can get on pump gas thats safe. I am also having a decent shot of N2O but I will be using a race fuel mix when I spray so I should be ok there. Im trying to figure out how much to mill my heads is the goal when I get them freshened up. Let me know what other info I need to let you know about. Thanks!

Isolde

iTrader: (4)

well-tuned, 11.5:1 should be possible. But I don't know as I'd have my heads milled more than 0.030", which won't get you there on a stock LS1.

douwannarace

iTrader: (4)

ok I forgot to say one thing which is kinda important. I will have to find my build sheet but I am a little out of the top of the hole so that should help some too on compression. What do I need to measure how much I am out of the top? I think thats kinda important to figure it out. But 11.5:1 is good to know. I will try and find a way to get close to that number. How close would I be with milling the heads .030? Im almost sure the were .026 out of the top of the hole. My builder said dont go below a .046 gasket in thickness. Does that sound right? I might be remembering wrong but Im pretty sure thats what he said. Im looking for my build sheet but Its going to be hard to find.

Isolde

iTrader: (4)

Even stock, all the LS-family engines have the pistons at least 0.008" out of the hole, AFAIK. I've seen damage from piston-to-head clearances in the 0.031" range, even with good parts running just 6500 rpm, so I'd add 0.035" to your out-of-hole measurement, then buy the next thickest gasket.
Others may disagree, but I remember seeing the carnage, and I'm cautious about this aspect.