Thread: Toluene as an Octain Booster

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Funny (to me) story: Years ago when I started out as a lowly Asst. Prof. they gave me all night classes and a night lab course so one night I went out to find my 1500 cc VW dune buggy was out of gas. I went back to the lab stockroom and found a big can of heptane which is a C7 hydrocarbon and which will knock really bad but nearby I also found a smaller jug of toluene so I remembered that toluene has an octane rating of about 110 while heptane must be down around 80 or so. So I mixed a quart of each into a jug and took it out to the parking lot. This mixture should have had an octane number of about (80 + 110)/2 = 95 and I used the cap of the jug to pour a capfull down the carb throat and put the rest in the tank and it started right up and ran great for the two blocks over to an all-night gas station. I know toluene is a great fuel but I do not know how to compare it to racing fuel although it should have an octane number close to 110.

Don Shillady
Retired Scientist/teen rodder

Actually the octane rating is 114