Fuel, From 91 to 104 (octane)

[Pisicaru]

Hello,

My name is Mike and I have a Celica GTS 2000 (27000miles). There is a gas station 5 min from my house that sells 104 octane gas.
1 gallon = $4.25 104 octane
1 gallon = $1.60 93 octane
What are the advantages/disadvantages for using 104 octanes?
Now I am in Des Plaines, IL but back in my country, Romania, we have from 93 to 102 octane at all gas station. Are cars in USA not designed for higher octane?

[loudceli]

I live in Colorado and I put 101 octane in my 00 gtsm and my car actually felt slower. But that was before my mods and I didn't have an AFC to tune it so I could have been running really rich. I'm not sure though so don't quote me.

[oldster]

Please do a search, there have been multiple threads that will answer your questions. The short of it is there is no advantage to running a higher octane than specified for the car. It would be good if you upped the compression, used NOS, turbo'd or s/c, or advanced the timing.

Loudceli, in CO you can actually get away with a lower octane rating as the actual compression ratio is less at altitude.

[GTS LAID]

and again as oldy has mentioned in the past; Its not that its good to run higher octane rating with all those mods, but that its required to keep from knocking.

I believe the conclusions of the threads were that if you were not knocking then you shouldn't bother.