b00stedOne

iTrader: (1)

ok, I have a b18b block with 9.8:1 (81.5mm) srp pistons, and I have a stock gsr head. I wanted to know what putting the gsr head on that block would do to my compression.
in the end I would like my compression to be around 9:1 or close to it. I know I can just use a thick head gasket to lower the compression but, how thick would it need to be to get it down to around 9:1? And does anyone know anywhere I could order one already modified for an ls-vtec?

oh yeah, the car will be turboed running around 450whp.

b00stedOne

iTrader: (1)

bump, anyone?

GhostAccord

How did you figure out that you have 9.8:1 CR pistons? How many cc's is the dish in the top of the piston?

If you are running a 5cc dish top piston in a B18B with a (GSR) 42.7cc combustion chamber (approx. 9.77:1 CR). You would require a head gasket thickness of approx. 0.060" (1.52mm) crush height to bring you down to 9:1.

I'm not a boost guru but isn't 0.060" a bit thick for a HG for a 1.8L if your looking to put 450hp to the wheels?

Note* I did the math very quickly and I am not a B series guy so someone should probably double check my measurements

b00stedOne

iTrader: (1)

I dont have the pistons here because there at the machine shop with my engine. I bought them from a guy that told me they were 9.8:1. I imagine that would be if they were in the b18 block and head.

GhostAccord

Assuming then that they are a 9.8:1 81.5mm B18A/B piston. They would have approx 2.5cc - 3cc dish (flat top). If that is the case then you are looking at approx. 0.07 - 0.08" HG thickness to drop your now 10.1:1 CR (w/GSR head) down to 9:1.

I have seen 0.080" SCE Pro Copper head gaskets for sale. From what I have read you would need an o-ring of some sort for them. They have a advertised tensile strength of 32,000 psi to handle high-horsepower applications.

b00stedOne

iTrader: (1)

thanks for the info. I will double check the pistons when I get the block back to make sure they are infact what they guy told me.