High Compression/ Boost on the street...

[Flash68]

Is E85 available in your area? That's what I am doing with my 13:1 engine. Under $3 a gallon round here.

[Ben@SpeedTech]

Thanks for the insight!

We're in a bit of a secluded area and I haven't seen any E 85 pumps locally. :/

I put maybe 100+/- street miles on this motor in the Nova when I rebuilt it. I did plenty of hard first and second gear pulls and one really hard full 1/4 mile pull on 91 octane at 16 deg initial timing, no pinging at all. That was at 4500 ft altitude, so I'm assuming the high altitude's thin air and clean pistons helped. I'm more worried about what happens when carbon starts to build up on the pistons that could contribute to detonation issues.

Although I will be driving it to work and back most every day, I will only be hard on it on occasion, and that will only maybe for first and second gear and then slow down. Whenever I race it I will use race gas, so it's not a huge concern, I'm just trying to play it safe. I'd hate to waste a brand new motor because of pinging.

[Twoblackmarks...]

Maybe check your cranking compression to get an idea where the low RPM pressure will be around?

As cold plugs as possible and a real lazy ignition curve. Try no hotter than 8s if NGKs, and ensure a real good spark.

And the air temperature the engine sucks in has a big impact on knock and performance anyway, try to get it from outside of the engine compartment and keep heat down under the hood.

I would guess the worst "knock" situation would probably be at low to mid RPM under a bit load. like under 3000RPM.

A SMALL amount of knock most engines can handle, but it is the pre ignition that kills. Maybe get an oxygen sensor to look at lean spots, to insure engine gets what it needs.