[X-TECH MAN]

My street rod with a bone stock ZZ4 crate engine with a GM rated 10 to one comp. (probably a true 9.5 to one unblueprinted) and alum. heads runs fine on todays 87 octane horse pizz.....oops. I mean todays junk pump gas. Car only weighs around 2700 lbs. Engine temp. plays a role also. Mine usually stays around 170 degrees and I run a 160 thermostat. Timing is set at 10 degrees and totals out at 36 degrees at 2500 RPM. I use a vacume advance on an HEI dist. and 3.55 gears with an over drive trans. Turns 2005 RPM at 65 MPH in overdrive. Not a lot of load on the drive train. Lots of things to consider when running pump gas and a med comp. ratio.
If its a race car around 3000 or under to 3400 lbs I would stay at no more than 10 to one with at least 4:11 gears unless its a late model with a computer, knock sensors, etc. then use 91 to 93 octain.