Compression is the best way to take advantage of higher octane fuel but advancing the timing will also provide some extra power when using higher octane fuel. This is true for street engines that are running normal pump grade fuels. At this point it is not important to me why this is true and I don't want to research it to find out all the details.
I do know it is true because I have personally experienced it. I have a tuner that is programmed for two grades of fuels (87 and 91 octane) at different performance conditions. I have used an acceleration test that uses only 3rd gear at the same location to determine if this tuner works or not. I use an accurate stop watch to time acceleration from one speed to another about 40mph higher. The test has repeatedly shown the 91 octane program gives higher performance than the 87 octane program.
I did not program the tuner but I do know that it is using timing to obtain more power out of the higher octane fuel. Obviously it is not changing compression.
As an added benefit the higher octane program (with high octane fuel of course) also provides slightly better gas mileage when driven under comparable conditions but not enough to offset the higher cost.
This is in no way intended to disagree or support any of the other posts. It is provided as additional information.
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