what is the most you would run on pump gas?
stop the internetQuiks asking a ?
Isn’t it dynamic compression ratio that really matters more then static? I’ve heard AROUND 9:1, but the whole setup really affects it, like how much cooling, tuning, etc.
I ran 185 psi to 195 psi in a 468 BBC…in my opinion that was over the threshold for 94 octane. It ran well, but if you wanted it to run at peak when the motor was hot…it needed toulene or racegas.
I lost a head gasket once too…a little detonation.
On a related subject, when I was into Pontiacs that was how we degreed the cam. Put a bushing in the cam gear, crank the motor, record the static. Whatever bushing yielded the highest static got installed. An old timer circle track guy taught me that.
I ran 11.8:1 compression with 270psi in my 1.8 motor. Ran tits on 94 pump
u kiddin?
my camaro has 12.5:1 compression, and runs like crap on 94 
nope no problems. thing pulled hard all the way to 9krpm. no knock or detonation
type of heads, compression, chammber size, etc… they all make a difference in how it will run on a given octane.
my pos FE runs like crap with 9:1 compression and 93 octane now. Once I rebuild it and fix the quench area and fix the heads, I should be able to run 10.5:1 with no problems on 93. Aluminum heads should get you another full point of compression with the same octane.
:dunno:
I don’t know shit about chevy motors, but good heads and a good tuned up motor should have no problem with 10:1 on pump gas.
Interesting method for cam timing, but on the whole, I think you guys have dynamic compression off a bit. What the hell is the base line for the test? It might mean a thing if you could make the starter crank the exact same speed every time, on every different engine. Thats compression checking. Doesn’t Dynamic compression refer to cylinder pressures when the engine is running?
Static is just the ratio between compressed & uncompressed based on dimensions. Dynamic takes into account when the intake valve closes, because you aren’t actually building compression if the intake valve is still open.