Saw a couple of newer efi cars adding some race fuel (mixing). Safe? how much? to 1/2 tank in my camaro. Looking to spray 100-125 shot.

 

A tank of 91/93 is all you need with a 125-shot on a stock engine. That assumes you are pulling a couple degrees of timing, with an external "box". You could possibly avoid pulling timing by mixing in a bit of 100-octane unleaded. You can approximate the new octane by using a 50/50 mix and averaging the pump gas and racing fuel octane..... (93 + 100) / 2 = 96.5

Do not use leaded racing fuel. It will cause the O2 sensors to gradually deteriorate.

 

good enough for me. I run 93 at all times. damn gas prices.