Yeah, I already have a 90mm plate and box full of jets.
Hoping to get my son's car (98 in sig) to high tens on motor (and the juice is for me).
Just interested in some more cathedral port combo's for the low compression LQ4.....

 

Pop some 59cc 5.3 heads on to bump the LQ4 up to 10.5 and pair with a TSP 228/232 .600" camshaft for a really snappy street combo

 

Pocket blended 862



Surfaced



New springs/seals

 

I have some 317's....how far can you mill (to what cc) and still run a bigger cam in the .620 range? Probably just send them to AI and let them tell me...
Again, OP and I are both interested in a max effort for track only.
Thanks,

 

Lsxrt fast 102. Let AI work the 317. Hardened pushrods. Ls7 lifters ,or full roller, the lightest valves you can afford maybe even step up to ls9 valves if they work them in the 317 . Get them milled as far as you can. Gonna need a cam specd to your heads.

 

AI can weld up the chambers on the 317 heads to up the compression without milling. Then they port them so they are very close to the 243's ported.

 

i have purchased a set of 823s from a member here. Now looking for what piston to go with. Engine shop say lets make the bore 4.030, since ill be buying pistons is there a shelf piston that can bring me up to around 11:1 compression or should i just mill the heads with a flattop piston?