Toluene has a very high octane number - about 110 MON. Not sure about it's heating value relative to commercial gasoline, but kerosene and diesel are a bit higher.

Your mix certainly had a high octane rating, so it would have allowed you to advance the timing on a very high compression engine to the peak power value without detonation, and the mix might have had a slightly higher heating value, but the higher octane is probably why it performed better, especially if it let you advance the timing.

Many high compression vintage engines require better than currently available pump octane to operate without detonation. Mixing up to 25 percent 100LL avgas or race gas to commercial pump premium will usually keep them out of detonation, but on a road trip when race gas or avgas may not be readily available, adding a gallon or two of toluene or xylene, commonly available at hardware stores, and mixing it with 10-20 gallons of pump premium when you refuel will usually provide a high enough octane to keep an 11:1 compression ratio Special High Performance Corvette V-8 out of detonation.

Duke