No Juice

iTrader: (11)

How come I get 10.4:1 using stock LS1 specs? Bore=3.905, stroke=3.622, deck=-.007, gasket=.052, cc=66.5

Haans249

iTrader: (24)

Thats because you have your bore wrong...


Bore = 3.898, the 3.905 is a honed bore size.

Oh, and your deck height should be a positive .007, not negative. The negative is with the piston coming out the hole, but most LS1's are in the hole about .005-.008.

No Juice

iTrader: (11)

good point, but that still only changes it from 10.43 to 10.4?

Haans249

iTrader: (24)

no it doesn't, it changes it from 10.43 to 10.07....

No Juice

iTrader: (11)

Oh, I thought they were out of the hole?

Haans249

iTrader: (24)

Nope, LS1 pistons are in the hole. That's why a lot of people run 40thou gaskets, as its a safe and easy way to up the compression on a stock LS1 motor without having to deck the heads or block.

Adrian

WhiteRhino

iTrader: (6)

Almost every lsx i've seen or read about is out of the hole. With very few in the hole. Not sure why you say ls1's are in the hole. If you search "piston out of the hole" or "quench", tons of threads come up with piston out of the hole talks. Most people run thinner gaskets to get proper quench that i've read about. Added compression is a bonus as well.

I thought ls1's were around .007 out of the whole from the factory. That's why it's best to measure before swapping gaskets. So the piston doesn't smack the head.

Haans249

iTrader: (24)

Well, I must be mistaken then! Its been a while since I worked on a LS1 motor haha. Maybe the difference in the compression is the top-ring-down volume that isn't accounted for in that calculator.

My bad fellas.