What is the highest CR you can get away with on 93 octane?

I'm guessing 11:1 with careful tuning(fuel curve, advance).

 

12:1 with careful tuning...

11.5:1 would be safer depending on mods.

 

Depends on the tuning and where you set your ignition timing. I am guessing 13.1 or more is possible.

 

i disagree.... but then again i guess it would really depend on the engine, the mods, and the beating that you will be giving the car.... i really don't think over 12:1 would be safe... and i'd only suggest 12:1 if you had it tuned by a pro

 

If you have big cams that have a lot of over lap, you can running higher CR. So 12:1 is totally possible with 93 octane and a good ECU.