mobius

hey guys... what kind of compression can i get down to from 12:1 WITH AFR 225 heads.... currently have afr 205 heads unported... btw this is for a friend of mine looking to go turbo and is n/a right now.....

mobius

bump bump bump

jrp

iTrader: (16)

with a stock shortblock 9.4 to 9.9 depending on gasket thickness and deck height with the 72cc's.

mobius

well how bout this is there a way to go from 12:1 to under 10:1 to run a turbo without changing pistons... what is on the car now is a forged 346 and afr 205 heads compression is 12:1 as stated... dont know what gasket etc...

jrp

iTrader: (16)

is he running domed pistons or did he just mill the **** out of the 205's?

mobius

must be running domes as the 205 are untouched

jrp

iTrader: (16)

is he running the lunati rotating assembly? at any rate, he's SOL w/o a piston change unless he has the chambers opened up on the heads a large amount.

mobius

ill find out more and let you know... i think he has new rods and pistons not crank... must be domes, ill check. although builder said it was possible to switch to the 225 heads and run 12 psi... just trying to verify that... what would compression have to be for 12psi on 93 octane???

jrp

iTrader: (16)

lunati's got a +12cc dome off the shelf piston which using stock deck height and gasket will give you ~12.1 CR. based off that using the 72cc 225 and a .060 gasket the lowest i get is 10.8 CR. i'd run a sub 9.5 CR for 12psi and pump gas myself.

mobius

it didnt sound right to me either, thanks for the info... ill verify the pistons he is running

mobius

ok i believe they are flat top pistons and the heads are milled... not quite 12:1 but 11.7 or something like that...

jrp

iTrader: (16)

9.1 - 9.7 SCR w/ 72cc 225's and assuming a 2cc valve relief and stock deck hieght and a gasket range from .040 to .060.