ondatrack

iTrader: (15)

I was originally going to build my LSA block with a 4" stroke for my twin turbo 2006 GTO but have decided to use the stock forged crank for a number of reasons. I already purchased new Diamond pistons for the 4" stroke with a 1.12 ch and I plan to use these now with 6.30 Lunati rods I just purchased. I was planning on running LS9 head gaskets with the .051 thickness but have not purchased them yet. My question is since the pistons will be .009 in the hole is there any reason to deck the block to zero or .005 and run the LS9 gaskets verses leaving the deck alone and using .041 Cometics? This is assuming cost is not the primary factor. Any advice would be appreciated.

KCS

iTrader: (20)

I'd leave it alone. Boosted engines don't really seem to be as critical to quench as an NA engine.

Exidous

iTrader: (11)

The quench will only really come into play out of boost. It's purpose it to induce turbulance in hte air/fuel mix at tdc. Under boost it's done for you already.

If possible run a .030" gasket. The LS9's will leave you at .060" quench which is pretty huge for a motor not running aluminum rods. The .041" wouldn't be too bad and certainly easier than decking the block.

bugy

what's the stock deck distance when piston tdc in a ls9?

ondatrack

iTrader: (15)

Thanks for the responses. I was leaning toward leaving the pistons in the hole and running the thinner gaskets unless there was something that I was overlooking. I didn't actually realize that they made a shelf .030 gasket for the 4.085 bore, the next size up is actually .045 not .041 as I originally stated. It looks like the .030 gasket would be a good compromise. Any other opinions?

Steve - Race Eng

iTrader: (1)

The aluminum GM blocks are rarely square from the factory. I have seen them off five or more thou bank to bank and front to rear.

So first check the block to see what the actual deck height is in all four corners. Then decide the best course of action.

Steve