If you use race gas like a 50/50 mix of 93 & 100 octain with a 100-125 shot (wet kit)do you still need to retard timing on a 93 Z28. Stock fuel system. Also i have a MSD 6al. What timing adjuster can i get that goes with it. A part # would be great. Thanks.

 

I still add 2-3 gallons of 100 octane when my tank is about 1/4 full of 93-95 octane. I think of it as insurance. I also run 32 degrees of total timing at WOT. Better to let the engine live and race another day is my motto.

 

I run 110 in my car mixed 50/50 with 93 and don't pull any timing. I've never had a problem. Maybe I'm lucky...who knows.

 

I don't get any knock on a 100-125 shot on straight 93 octane with no timing pulled. So, yes, you should be able to get away with race gas/93 with no timing pulled.

 

Yes, you should still retard timing. The nitrous mixture will burn faster than just gas. If you don't pull timing, peak cylinder pressure will occur too early and you will lose hp. You may also damage the engine, not from detonation per se but from excessive cylinder pressures.

If you are running a small shot, the difference is small and the chance of damage slight. So in that case, it's not critical. But if you have a convenient way to reatard the timing, it's not a bad idea.

Rich Krause