calculating octane

[sil80phobia]

Anyone know how octane calculations work?

In california, we get this 91 octane crap. Instead of dumping $10 octane booster in every fillup (which I doubt works), i'm considering buying a 5 gallon drum of 114 octane racing unleaded, and adding a gallon or two to each fillup.

Do I just average it out? Let's say

13 gallons of 91 + 1 gallon of 114 = ~92/93 octane equivalent

or
12 gallons of 91 + 2 gallons of 114 = ~94/95 octane equivalent?

or I can just dump in a tank of 100 octane all the time, which turns out to over 70 bucks a tank. Ouch.

I'm looking either into that or a suitable water injection setup.

[AKADriver]

Yep, that's pretty much how it works.

How much is that 5 gallon drum of race gas? Try finding some toluene (which also has octane of about 114 and no lead) at a paint supply store and using that for your mix instead.

[R.W.240]

Ive heard Mothballs dissolved in the fuel work too from someone that worked at Exxon... im not sold on it though.