I'm with Bro. Terry about starting low on the timing and working your way up. Again, I'd rather be safe than have Big Balls - which equates to sore, Sorry, balls!
Lots depends on the octane of the fuel you use. From the beginning of my build I knew the fuel would NOT be pump gas. At first the plan was for propane, kept liquid until leaving some specialty injectors. Propane has an
research octane rating 110, and a pump rating of 104. https://www.google.com/search?q=oct...j0i22i30l6.7943j0j15&sourceid=chrome&ie=UTF-8
I had run liquid propane through a converted mechanical fuel injection throttle body that was laying around. It was neat to make a hard pull with heavy boost, then find frost on the intake - with no signs of detonation.
Anyway, plans changed to E85 with it octane rating dependant on where you live. Here it is only
70% ethanol. That lower blend gives
approximately 102 octane while E85 would be about 109.
E85 and Ethanol - Octane Rating of E-70? Winter Blend? - I have been thinking about switching to E-85 and wondering if it would be best to tune to E-70, the winter blend to be safe. Because if you have a E-70 tune your never going to have to worry about a lesser blend of ethanol...but then I was...
www.evolutionm.net
Bro. P.J., you are correct that when boost goes up, timing comes down. But even that depends on the octane of the fuel you are running, as well as the camshaft timing and static compression. There are no simple answers. That is why you have to factor in all of the above variables -- and THEN decide if and at what point the timing should be backed down.
Again, my engine was built with heavy boost in mind and that is why studs, both head and main, were in the plans. Mine were some specialities grade nines that Marty got from -- I think it was Milodon.
Even with all of my preplanning, including a high octane fuel, timing with start low and work its way up to meet what the engine likes - and will live with.
bro. "fingers crossed," d