92GreyGT

I have 10.8:1 and run 93 with out any problems. Put as much compression in it as you can, it is worth it. It makes for better throttle response and helps with low speed drivability with a big cam.

67mustang302

Yeah, camshaft, quench height, rod ratio....there's a bunch of variables that affect what compression you can run with what gas. The new LS7 Vettes are like 11.0:1 engines on pump fuel, and they're using hyper pistons, so obviously GM isn't too concerned about detonation with premium pump fuel.

w8less

is there a regualr gas station that sells 97-98 octane gas? or is it more like a race gas?

92GreyGT

Near where I live, about 20 miles, there is a World Wide Racing Fuels warehouse that has pumps outside just a normal gas station. You can pull up and put unleaded race gas right in your ride. The leaded style race fuels have to be put into a container, barrel, or in your car on the trailer. The unleaded come in 98, 103, 110as best I can remember.

anthros

new gas station near my house just opened and they sell ALOT of diff gas. E85, unleaded 85, 87, 89, 91, 93, 97,103, Diesel fuel, they also sell non road gas in 106,110,114 octane ratings. So i was just getting really curious at to what comp ratios are ok with what gases because iam looking to rebuild my recently lost 427 short stoke as a 445 short stroke. and if i can get fuel to make it able for me to run gobs of boost on a 10-10.5 comp engine then why not use it to get more power?

92GreyGT

You can run to high an octane of fuel I have been told. The higher the octane the slower it burns, so if you have 9:1 compression and you are trying to run 114 octane it will hurt power. I am not sure whototell you to even ask. My dad's carhas over 14:1 compression and he runs blue Sunoco fuel. I think it's 114 octane.I'm sure there is somemath formula to figure what cylinder pressure you havewith a specific compression and boost level that should help you figure out which octane to run.

grnsleeper

thats true. youcan lose power with too much octane. your suppose to run just enough octane to make maximum power

my77stang

^ yup, my car liked the 100 octane Low lead av/gas better than the sonoco 110 or the 117.

greenstreak9205

o yea you, had that bada$$ motor runnin all that boost + a 250 for "spool" and popped the motor on the cold day or whatever didn't you? well whatever you end up doin, i hope its as awesome as the last motor sounded. but one thing to remember when building this, is that gas station may be the only place you can get the gas anywhere around you. not sure where you live but im sure that there isn't many places that carry gas like that for ya