mikemskater

I am getting my gsr block sleeved with 84.5mm sleeves and I am wondering if I should get my combustion chambers matched with the size of the sleeves or not and if I do match the bore and run say an 8.5:1 Piston will my compression be 8.5:1 or lower. Is 8.5:1 a decent compression for this type of build or should I go 9:1?? This is on a boosted application aiming for upwards of 700 whp. If someone can help me out here I would appreciate it.

TheThiefTheKnife'NTheGun

are you going to drive this on the street or is a race car. I wouldnt suggest reworking the combustion chamber or it will be a slug on the street. The bigger the chamber the lower to compression will be.
Just my two cents

0morgan@synapse motorsport

ive got an 84mm block with matched 84mm combustion chambers. they measured the volume to 44cc each vs the stock gsr 41.60 which dropped my compression from 9:1 to 8.7:1 so its not too big of a deal.

if you already have the 8.5:1 pistons thats fairly low so its up to you.

mikemskater

I don't have the pistons yet and yes I will be driving it on the street . So 9:1 on the pistons?? and matching the chambers wouldn't be good for street driving?

0morgan@synapse motorsport

its really up to you, i would go with 9:1 as with the reshaped chambers you would be looking at around ~8.1:1 with the 8.5: pistons.

drivability is fine on the street, with the increased displacement u will make way more tq off boost than most boosted setups with stock chambers.

mikemskater

thanks for the advice, much appreciated