I am trying to figure out what kind of boost level I will be able to run per a certain octane level. I know there are lots of variables in regards to this topic. Does anyone have any charts, experience or technical info on this? Octane level required per boost, boosted compression ratio, cylinder pressure, etc?

This has come about since I have started research for the upcoming turbo build. I found a few charts and table relating octane to CR and then found a few boosted CR calculators and for boost numbers over 10-15psi, depending on CR, yields boosted CR in the 15-20:1 range. Even for high octane fuel (116-120) that are good to 17-18:1 CRs, you could get out of that range pretty quick with a high boost setup, for example at 9:1 CR with 16 psi boost yields a boosted CR of 18.8:1. I guess my question is how does one cope with the high boosted CRs in terms of octane? I know retarding timing, intercooling, etc helps here but...? Any advice, wisdom, or knowledge is certainly appreciated.

_________________
Stephan Nelle

I've run a 50/50 mix of 110 and 93 with boost levels over 20psi with no issues. I did however have an intercooler, methanol injection and total timing around 18 degrees.

_________________
11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

_________________
We are thankful and live each day as if we had no tomorrow.

Rough rule-of-thumb would be 1 octane increase for each pound of boost .

_________________
V8?? We don't need no stink'n V8!!