Folks shouldn't introduce odd hydrocarbons into their gasoline without CAREFUL RESEARCH. People prize good high OCTANE precisely because THERE REALLY IS NO SUBSTITUTE FOR THIS ALKANE! Alkanes have a specific enthalpy to each one, and consist of SINGLE C-C bonds surrounding the rest of the carbons with simple hydrogen. The ONLY substitute for octane in my book would be a methyl heptane (7 carbon with 1 extra carbon attached to one of the 5 middle Cs, thus the methyl-designation) or an ETHYL hexane which would have 2 carbons strung to one of the four middle ones. Any other isomers than these will deviate too far from the simple 8 carbon, single bonded chain and its energy properties.
Suffice to say, damned TOLUENE, like NAPTHALENE* DISSOLVED IN METHANOL ("hillbilly octane"), BENZENE, CAMPHOR and other sundry aromatics might temporarily get an engine to run hot and hard, but they mostly will wreck one, leaving EXTREMELY CARCINOGENIC RESIDUES to remove.
I say stick with aviation gasoline as an octane rich source. One can blend to whatever level desired below the highest octane source purity. The one great obstacle to this approach lies in the fact that premium crude mineral oil, the "light" or "sweet" crude once pumped from Pennsylvania, Texas and Libya, no longer abounds so in those places as it did in the days of the C body. I think it should be relatively easy to synthesize octane from methane, but this may become politically impossible for environmental reasons....
