Please consider this advise for what it is.
Long ago in my limited stock oval racing days we mixed toluene, a paint thinner, with the highest grade pump gas we could find, Chevron 94 octane.
As I am much older and a bit wiser I know now that toluene has an octane rating of 114. So a 30% by volume mix with 94 octane gasoline would make a 100 Octane mix.
I found that this mix ran about 15 degrees (F) cooler than the 100/130 Avgas that we had to beg to buy.
The stuff was cheap too.
The engine was a 410 cuin Chevy with 12.75:1 CR. No probs