Here's a calculation i found of how to figure out how much toluene you need to get a certain octane:
(gallons of gasoline X that gases octane) + (How many gallons of toluene you're using X 114 {the octane of toluene?}) / size of your gas tank = Octane of mixture.
Here's an Example on the site I found:
"For example, the tank of an Audi A4 1.8TQ is 15.6 gallons. Filling it with 14.6 gallons of 92 octane and 1 gallon of toluene (114 octane) will yield a fuel mix of:
(14.6 * 92) + (1 * 114) / 15.6 = 93.4"
Here's the site, it has a lot more info on it:
http://www.gnttype.org/techarea/misc...explained.html