Anyone with experience using 95 or 100 octane gas on the track in an untuned car? I'm wondering if it'll do any good since my GR is bone stock engine wise. Going Laguna tomrw!

 

Higher Octane is good for reducing knock and detonation.

 

You will not get any power gains. It will do what Strider said, reduce knock and detonation. If I was going to the track I would mix in a little 100 octane for peace of mind but not a full tank as that would be a waste.

 

I really would not say that there is no power gains. Look at the difference cars running 93 or 94 Octane make vs cars running on 91 Octane. The ECU's are capable of adapting, but only to a point (somewhere between 94-96 Octane but nobody seems to have posted the exact data showing where the Max Limit truly is for ECU Compensation).

You are right though and I fully agree that it is a waste to run a full tank for a car that is not tuned for it. I have run a mix before and would essentially recommend the same to the OP. Mix about 3-4 Gallons of 100 Octane and then top off the rest with 91 Octane. That should provide a mixture that would get somewhere around 93-94 Octane.

 

Or run a couple gallons of E85. I run 1:3 ratio for my 93 tune.

 

Be careful not to put leaded high octane in the tank.

 

Actually with only 100oct in the tank you may loose some power but it will be safe. Car needs to be tuned for 100oct. Beware of Laguna Seca gas prices - they are terrible (unlike Sonoma or Thunderhill).