depends on a lot more than the info given.

I have about 11 to 1 and 230+ PSI in my daily driver 6.4 hemi ram and no knocking on 87 octane (well it does just a little when driven stone cold but that is a tuning problem), it does have a plastic intake and much better chambers that help. My dads 97 geo metro would crank 210 PSI and ran fine on 87 octane. A BB mopar could easily be built with the right components to run safely up to 11 to 1 in a street motor. If your just going to slap a bunch of random parts laying around and try to make it work you would probably not want to go over about 10 to 1.

For the other side of the equation e-85 acts like a higher octane than it actually measures because of the cooling effect of the evaporating alcohol, I have seen as high as 16 to 1 but 13 or 14 to one is pretty normal.


I am not causing global warming, I am just trying to hold off a impending Ice Age!