'66 Slant Six Turbo Build
Do you have forged pistons? How much total spark advance are you running, what octane gas, and what was your A?F ratio when you began to experience detonation.
Our engine is pretty similar to yours but with us running only 8 pounds of boost and using 110 octane gas (and 18 degrees of total spark advance) we haven't seen any detonation, yet.
Thanks a lot for all the good info!!!
Hi Bill,
Yes, the engine has forged pistons.
Total timing is at 38, under boost the msd box is pulling a a degree per pound up to a bar and 1.5 degree past a bar, based on the reading from the MAP sensor.
Essentially, under 16.5 psi we should end up pulling about 18.5 degrees for timing of 19.5.
Now we also have a out of boost map that gives us a smooth ramp to 4.5K rpms to total timing of 38, we're pulling a lot before 1.5K. No problems out of boost though of course :-)
At this boost we were only at 4,000 rpms and the AF/r was 12.7 - getting too lean. I need to figure out how to keep the boost down, at full rpms we would probably see 18psi+
Until I can get to the dyno again I'll probably set the total timing to 36 to dial everything back 2 degrees, that would give me 17.5 degrees at 16.5psi. Meanwhile I'm getting a little miss between 3.5-4K rpms that wasn't there yesterday, I may have fouled a plug already - we used a NGK 8 heat range because I didn't have any 6 or 7s available.
We'll see... Tons to play around with now :-D
