Check this page out:
http://www.honda-tech.com/zerothread?id=201794 They discuss using pure tolulene from the paint store to increase octane.
Most over-the-counter octane boosters don't work very well. When they say they increase octane by five points, they mean .5. Thus 93 octane becomes 93.5 octane.
A rough equation to equate compression ratio with octane needed is to roll the decimal place over one. For example, a 11.0:1 engine needs roughly a 110 octane fuel. 9.5:1 engine needs about 95 octane fuel.
Retarding ignition timing by 2 degree increments, richening the fuel mix, and using cooler sparkplugs can help prevent pinging/detonation to some extent.
Good luck
chip
