Best comp ratio for a b18a

what would be the best comp ratio for all motor b18a? 11:1? 11.5:1? 10.5:1?

well, since you live in cali it’d probably be best not to go above 11:1 or so. I’ve heard you can go as high as 11.4:1 on 91 octane, but personally i think thats pushing it a little.

I plan on running 11:1 in my b17a here in cali. Elmer is running that in his b17a and it runs good. he gets a little bit of pinging, but it should be fixable with a little bit of timing retard, and permanently when he gets some fuel upgrades.

here are some options:
pr3 pistons: 10.8:1
p30 pistons: 11:1
jdm itr pistons: 10.8:1 (will require that you modify the rods)
usdm itr pistons: 10.3:1 (will require that you modify the rods)
jdm gsr pistons: 10.1:1 (will require that you modify the rods)
ctr pistons: 11.4:1 (will require that you modify the rods)

If i were you i’d get either the pr3’s or p30’s depending on how high you want to go. This way you can cut costs as well (by not having to pay to have a shop machine the rods down to size).