Racing gas in Roush motors

[Excaliber]

First thing, stop using the Octane booster, 98% of the time their a sham product to begin with. Many actually DECREASE performance. The can/bottle may say it will raise the octane number by one. From 92 to 93 octane? NOT! From 92 to 92.1, big freakin' deal.

Many engines respond well to more octane, many don't. The KEY factor is typically when the engine has computer controlled timing. Lower the octane, the computer retards the timing. Engine may run fine but isn't making the power it could/should. Raising the octane increases the timing, result is more horse power. Some engines may be doing a fine job with ignition timing set point all ready. In that case higher octane offers no benefit at all. The computer will not advance the timing any further anyway.

IF your timing is all ready advanced a bit to far for 92 octane all ready, THEN additional octane would make a noticeable difference in power and drivability. Adding more timing is almost always a good thing (up to the max reasonable curve). I suspect your distributor timing curve is bringing in max advance at a lower rpm than is optimum for 92 octane. Therefore, higher octane is more compatible with the timing curve.

If it were me I'd retune for lower octane and the street. I DID have a 12.5 to 1 compression side oiler that ran GREAT with race gas! But it's not reasonable for a primarily driven street car. I retarded the timing, lost a bunch of horse power, ran 92 octane and it was acceptable, barely. Going to the track? I'd bump up the timing, run race gas and say, "WOW, what a difference!" But no way I'm going to fill up all the time at $6.00 a gallon and have to drive to the only dam station in town that sold the stuff!