Racing fuel in a Z

Originally Posted by RCZ

Anytime you are running at the track your engine experiences more stress than usual. More stress and higher revs over an extended period of time lead to higher cylinder temps. Sometimes hotspots are created within the cylinders which can ignite the fuel mix pre-tdc. , aka detonation, pinging, knock, whatever you want to call it.

I have intakes and a full exhaust, which can lean the car out a little bit. I am tuned so I know where my AFR is so that's not that big of an issue. Either way its always safer to run higher octane when your are putting your engine under that much load. This engine normally runs really hot, I would even think about running some meth or WI later on for extended sessions. Specially if I am going to eventually run a supercharger.

Its funny, but I think you were expecting me to not know what Im talking about. Knocking isnt only caused by higher compression and boost like you said. If you are near the knock threshold because of your AF mix, simply filling a bad batch of gas can cause knocking. Bad batch of gas being something with lower octanage than what is advertised. It happens...

Did I mention I live in Florida and sometimes I track the car in 100+ degree weather.