so im having upcoming track day. and was wondering since our cars are high in compression would it be necessary to run 100 octane or at least half a tank of 100 octane to prevent detonation? or will 91 octane be fine.

also when you go turbo (like greddy kit for example) is it then better to run 100 octane for track days even though its tuned for 91? or will 91 be fine?

thanks guys.

 

It's always best to run what the car was tuned for. If you're stock, then up to 93. The ecu will "learn" what's going on and adjust accordingly. This is not the case with stand alones. Running anything higher than what the car is tuned for and you'll be running richer. Running too rich for too long of a period and you run the risk of washing the cylinder wall and promoting increased wear.

An example of a time you might consider running a higher octane might be when using a pre-programmed tune at a significantly lower air temp than when the tune was performed.

 

I've run on both 93 and 100 octane(forced to at the 2007 Runoffs). I have the Hondata reflash and found the car actually runs better on 93. I will soon have dyno results on the 100 octane(I doubt there will be a hp difference, but I am interested in the a/f ratio), but I believe I will see better results on the 93. I have never had a problem so I advise you to run 93 and enjoy the day!
This is for a NA car. I have no knowledge on FI, but i would think if it was tuned for 91 then run on 91.

 

school me plz:

I have a van with factory SC running about 6.5 lbs boost. I usually run 91 (recommended, but any unleaded will work) in the hot weather months and 89 in the cooler months. Is this backwards in theory of what I should be doing? Or doesn't it matter like it might on a turbo setup?

thx

 

Octane is burnt rate, so isn't the only thing that matters here ignition timing? Compression on our car is not high enough to call for 100 octane. I've seen 12.5:1 Integras run fine on pump gas (93)