I have been mixing c12 and 93 octane. I have people telling me I need to use C12 fuel. I have others telling me I don't. If I need it, I don't mind using it. If I don't, I would rather save the $400 per tank full. My engines are 8.5 to 1 and I am running about 7 lbs of boost. i have just over 1,100 HP. Is there an accurate way of figuring out if you need the extra octane?

Who built the engines call them.

Yes.

My engines will run on 93 if they need to but I go ahead and run 110 for piece of mind.

at 8.5 to 1 and 7lb's of boost with a innercooler, I will post a chart.

http://www.blowerdriveservice.com/techcharts.php

I think the chart is with no innercooler. Talked to BDS and they said, as long as you are at your max rpm, you are not going over 7lb's of boost of innercooled air, 93oct is what you should run. Thats with alum. heads and a 12 to 14:71 blower.

I am at 9lbs on 93 only no boom yet We Dynoed it at Precision Marine past 9 lbs and it picked up some detination so we put it on some race gas and went up to 11.5lbs of boost with no detination

The motor in My old Scarab was at 11.5psi on 93 with no probs.Tuned it on Oddys Dyno

Rob

Other factors to consider along with simple boost/compression are inner coolers, aluminum heads, and blower size.

I have 14-71's, Aluminum heads, intercooler, mechanical and electric fuel pumps. I figure the last thing I need is to ber kicking Rio Roses Ass and having a problem because I used 93 octane!

sounds like all that and 18lb's of boost, real good gas and you will be ready......no excuses.