ShevrolayZ28

iTrader: (4)

Are the thick Cometic HGs a viable solution for lowering compression on a ~10psi SC car?

Available thicknesses up to 0.120", but I'd probably want to use a 0.074", which would lower my compression to around 10.4:1.

DeltaT

iTrader: (5)

You need to do it right and change either the pistons or head chamber size. Just sticking a thick gasket in there ruins your quench, which needs to be around .040" and if it isn't, can lead to bad detonation problems.

Sounds like your compression must be in the 11:1 range? Switching from NA to FI?

You might be able to boost it now with a good intercooler and alky injection, and the right cam.

Jim

ShevrolayZ28

iTrader: (4)

Yep, I'm around 11:1. I never thought I'd go FI, but here I am.

I really hope I'm able to do this with these heads (62cc AFR 205s). If methanol and a FMIC will allow me to run them and still make good power and run safely, I'd be willing to spring for them.

I guess the cam will probably have to be changed. It's a Comp XER 224/228 114+1. (Virtually no overlap and pretty high DCR.)

DeltaT

iTrader: (5)

I'd keep the cam and heads, and do a piston swap. Get down to the 9.5 to 10 range and you'll be good to go.

If you went FMIC and meth, I suspect you will be limited to <10# boost with that setup, and you would still probably have to change the cam to something bigger to get the DCR down.

Jim

helicoil

iTrader: (104)

That is actually a pretty decent blower grind for mild. I have been thinking about slapping a D1 on my 11.2:1 (62cc AFR's) stock 346" with maybe 5 or so lbs of boost. I figured a rich tune and very conservative timing would net 525-550RWHP or so and maybe live for a while.