I am scheduled to run a track day on the 17th.

The track has 98 octane unleaded fuel.

I have the Vortech V3 S/C with injectors, fuel pump, Greddy EMU.

Will running the higher octane not work well because of the tune or cause problems after the fact?

Is it even worth trying? Will it result in a substantial gain in performance that would make it worth
The extra expense ($8.00 a gallon!) and possible side effects on the tune and the motor itself?

 

Its always ok to use a higher octane from your tune, the danger would be using a lower octane from what you were tuned for. Although you wont see and power increase, you will have an extra blanked against knock if its really hot out. I would personally never use any fuel lower than 91 or what your tuner has tuned your car for.

 

I do have problems towards the end of track days when the car is hotter, it starts to bog at partial throttle but not so much at WOT

could this be the knock you referred to?

And you're saying the 98 octane won't help the performance at all?

 

^That would probably be heat soak you are experiencing. The higher octane will help run more timing if tuned but other than that as stated about just gives a bigger safety net for detonation.

 

^ Exactly, heat soak is a constant battle for many of us. There are afew measures you can take to help here and there but that little devil always seems to show its ugly face again.

Larger heat exchanger and stronger pump for the aftercooler, Vented hood with louvers properly positioned are the biggest two cooling ideas off the top of my head.

I did some experiments last summer with insulating the aftercooler to protect it from engine bay heat soak, it seemed to slow down the temps, but in both directions so it would heat up slower and cool off slower.

As for the extra timing from a higher octane, personally, I wouldnt do it. I like to run on the safe side and have that extra blanked of safety incase temps get outta hand or whatever mishap that could arise.