compression ratio question

[MustangGlx]

at what point do you need high octane?

 

[mustang70]

Generally 10:1 is considered the highest for a street compression. Some people get away with higher because of cam specs and aluminum heads.

Oh, I'm guessing by high octane you mean more than 92.

 

[MustangGlx]

yea, im not sure what compression ratio my car has, but i have to put 93 octane in it, i was just trying to figure out rougly what it might be around
thakns

 

[6Stang7]

Like mustang70 said, usually around 10:1, but this isn't always the case. I have seen cars with 11.5:1 that run 87 and cars with 9:1 that needed 91. If you have a set of heads that have quencher chambers, then you will be able to run a lower octane then a motor whose heads don't have quencher chambers. Timing will also be a factor along with air/fuel will also play a minor roll.