Re-doing my big block stroker motor. Strictly street. I know that camshaft selection makes a big difference, but as a rule of thumb, what static compression ratio should I be shooting for to use 89 octane mid-grade fuel with aluminum closed chamber heads? 4 speed 3.23 car. I guess that another way to ask the question is how much cranking compression is max on 89 octain pump gas with aluminum heads?

Around 10-1, it depends on what kind of combustion chamber design is, if it requires quench, you maybe able to go higher. I went 9.5-1 with my hemi. Never have a problem with any gas. Tim

I went with 10.9 on a alum head SB 416.. I had it on
the dyno and had no problems with 93 octane at 38*
EDIT
on the street I plan on using 89 octane but we ran it
with 93 on the dyno for max power... I will pull 2*
of timing just to be safe

You run one more point cr with aluminium heads than iron heads, so 11:1 is non problem...the more quench you have, the less problems you will get

Dan