Thread: Figuring octane when mixing fuel.

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Originally Posted by R Pope

You might get into some legality issues running avgas, you do in Canada. No road tax on av, they can bust you.

yep that is right how or if you do this is up to you but if you mix it or going to race it at the track and some is in the tank and your on the street and who going to wast there time busting you ? your going to tell evey one your going to get busted ? i do not think so. there just not going to sell to you not like your going to pull up to the pump with a fleet of cars ? your talking 5 or 10 gallons ? in you gas cans . i used it at the race track.but i did drive the car there. i did have to fill it with low grade pump gas driving it home so most all of the 100LL was burt at the track . i just use race gas now i can pull up and pump it in

I don't think you will be very successful mixing fuel. You have no idea what proportions of what are in the fuels. It will be a pure guess. Even with something like a hydrometer it will be hard. What value will you be looking for??

Just ask any old top fuel racer how hard it is to bring too low of percentage back up. Usually it means starting with fresh 'good stuff' and adding a very small amount of low stuff then carefully measuring with the hydrometer and taking temp into consideration.

You might try some octane booster.

My suggestion is to get an air fuel gage and start tuning. I have a blown SBC at 6 psi boost and run 89 octane with no ping or problems at all. I have over 1000 miles on this hotrod in the last 2 months including a bunch at less than 32 degrees F. Gas is purchased at the closest station at the time required.

By the way don't use octane booster with an air fuel gage. The O2 sensor won't last long.

Thank you Pat, R Pope & Bentwings. One of the reasons I was asking about mixing is because it will be impossible to not mix unless I always run the aviation fuel. And I don't want to do that cuz the airport is to far away from my house plus they won't pump it straight into my car so I'll have to use 5 gallon cans. I tried octane booster & it didn't make any difference. Don't know how true this is but the guy at the auto parts store told me that octane boost actually raised the octane level so little that it wouldn't make any difference.... Is this true? Thanks again to all!!! Bill