Originally Posted by badtmpdgoat
Anybody try running a tank of 100 Octane?,,,station near me has it ,,,buddy says to try or mix it up with 94,,,what say the crowd?
Waste of money...
I run 100 or 104 unleaded race fuel in my stock Z06 in SCCA T1, but... my PCM has been reprogrammed with advanced timing and modified A/F mixtures.
I've read that a higher octane fuel has no more energy than a low octane fuel, it just has a different burn rate that makes it less susceptable to early detonation (e.g. knock or pinging). Early detonation is very bad for a motor and the LSx motors have knock sensors in the valley under the intake. As these sensors detect the inception of knock, they send a signal to the PCM to pull timing which reduces power in a big way.
So, unless your PCM is modified to run more advanced timing to take advantage of the fuels resistance to early detonation, you won't see any appreciable difference from 100 octane fuel. But... if the conditions are such that the car is on the verge of knock, a higher octane fuel will help prevent knock and thus the PCM won't pull timing. So, using a higher octane fuel on a stock PCM may prevent loss of HP, but won't gain you HP.
As a related note, be very careful about most Octane Boosters (including AMSOILs). Almost all of them have lead in them which is very very bad for the 02 sensors. If you are thinking about using an Octane Booster for the track (to prevent knock and pulling timing), read the bottle very closely.