458 Highest Octane Fuel for Track?

As long as it's unleaded I don't think there's a "highest" that the car can take. Octane is just a rating measuring the stability of the fuel and its ability to resist auto-ignition.

Cars tuned to run on higher octane can make use of this increased stability and use more aggressive spark timing -- waiting for maximum compression in the cylinder.

Some modern cars I believe can slowly try to be more and more aggressive and "tune" themselves. Though I imagine with "normal" compression ratios there is a point where higher octane does nothing.

I can't imagine you're getting much more power by using incredibly high octane. And in a non-competitive track day there isn't really a point, anyway. Save your money and go with the 91/93 stuff.

 

I agree, unless you have an aggressive tune to exploit earlier timing, or it's a really hot day where the stock tune has to take out timing to avoid detonation, you normally wouldn't see any benefit from more than 93.
I think what will give a benefit is having no ethanol in the gas, since ethanol has less energy density than gasoline. Race track gas tends to be ethanol free since
You definitely don't want leaded. It will foul the cats and could be an expensive day.

 

93… those other octanes will not benefit you and the higher the octane the less volatile, meaning harder to ignite and you can lose power.

 

Your car has Ion sensing technology and adjust you injection and timing every time it fires or injects. If you add 100 octane it will "see" the Ion result is not as close to optimum as it was before and make adjustments. This how it was explained to me in tech school when 458s came out.
I have had a car at the track and did a back to back with an instructor that had no idea what I as doing and he reported back that whatever I did made a huge difference and he was easily 6 mph faster on the straight (Road Atlanta) and the car pulled harder.

 

I have to correct you here. The volatility is the exact same and so is the BTU. It is all a matter of resistence to detonation from compression. The flashpoint is what determines the ability to ignite from the spark, not the octane.

I've done tests on both engine dynos and chassis dynos playing with octane. I've run VP C16 in engines tuned for AKI 89 and no difference in power. A 458 will not make less power with the higher octane options, at some point it is just pointless. Now if the 93 AKI found trackside at Sebring, is the same dogwater garbage fuel California is famous for, which can hardly keep up with a good 90 AKI due to an extremely low MON, the 98 and 100 is a good choice. But if the 93 is a quality fuel with a proper MON of 87.5 or better, then the 93 will be sufficient. If the MON of the 93 is unknown, then I would not hesitate to run the 98 to make sure the engine performed at its best in a stressed situation. I know Sebring is in FL, just using the quality of the Cali fuel as,an example.

If the pumps are next to each other, mix the fuel to keep costs down. Half 93 and half 98. Mixing fuels is not an issue.

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This is correct
Octane has nothing to do with horsepower

 

I have looked into this a lot and tests on my own and tests in various articles through out the years one in particular noted that using the 89-octane fuel showed a similar number as the 87-octane fuel. The more pulls we did on the dyno, however, the more the power dropped off as the engine ran hot. The 87-octane fuel maintained more power than the 89-octane fuel.

The dyno sheet for the 91-octane fuel showed horsepower and torque figures within one point of those measured on the 89-octane fuel. However, it showed a much higher decrease when the engine returned to its normal operating temperature, and as it got hotter on the dyno, showed an even greater a loss of power.

Run the car on the octane it was designed for. Running a higher octane will not provide more power and can hurt power at engine temps as they get hotter.

Octane is simply a measure of the fuel makeup, and its tendency or resistance to cause engine knock or ping when used under duress (higher RPM). The octane index rating is not based on a quantity of a chemical in the fuel mixture, but is a measure of the efficiency of the fuel blend, expressed as a ratio, relative to the efficiency of a pure hydrocarbon, which would have an octane index rating of 100 (or 100 percent). Higher octane fuel is harder to ignite/less volatile.Because higher octane gas burns slower, it is more resistant to knock when subjected to higher RPM and cylinder pressures. Compression ratios also factor into cylinder pressures. Higher ratios cause higher cylinder pressures and therefore cause the engine to be more susceptible to pre-detonation or knock.