RWC

iTrader: (5)

Does anyone know what GM did different to raise compression from 10.5 on the L92 to 10.7 on the LS3? Different head gasket, pistons or chamber volume? Head gasket would be the easiest and cheapest. I've read it has a different head casting #, so maybe that's it.

Greg Fell

iTrader: (9)

didn't notch the pistons? seems contrary to logic but...?

drain89

iTrader: (13)

I'm wondering also. Hopefully it's a thinner mls head gasket, but I bet it's the pistons.

ringram

The valves are different too, perhaps they take up more volume in the chamber!?

RWC

iTrader: (5)

I hadn't thought about the valves, but the difference is small. I get 1.7 cc's or about .008 thinner gasket. Do the L92 pistons have valve reliefs or are they flat tops? Maybe someone from SDPC can check to see if the LS3 has the same part no. gasket as the L92 and the piston differences. Using a thinner mls gasket would be good.

drain89

iTrader: (13)

from the pic I have of the ls3, it doesn't have valve reliefs. the l92 has them. I still would like to know the thickness of the head gaskets.

RWC

iTrader: (5)

No valve reliefs (flat tops) would be enough (usually about 2cc) to raise it to 10.7 CR. That would be all they would have to do to get there if everything else is the same. Thanks for the info.