Running 100 octane Blend in S54

[Mr. M Doggy]

Hey all, semi new to tracking my car and have heard some folks saying they do a blend of 100 octane and 91. Some running half and half to get about 95 octane achieved or some variation. They say temps are down and engine just feels happier.

Just seeing if this will have any issues on an N/A car, I'm running an ESS tune.

Any input would be appreciated, and if not damaging but actually beneficial, could I simply pump the race fuel directly into the car or would mixing prior be best. I was considering just having 3/4 tank on 91 and the pumping 100 on top of that, assumed it'd mix itself.

Cheers for any input.

[Slideways]

If the ESS tune is calibrated to run on 91, then that is all that is needed. Best bet is to stick to top tier gas stations.

[S54B32]

Better fuel means happier engine.
Even when timing in DME is only „calibrated“ to 91 or something, better fuel helps to compensate other negative influences.

As an example, when I had the car complete stock and with 95 octane I had 1-2° knock adoption. But with 102 octane (common in germany) i had zero knock adaption.

[EthanolTurbo]

I'd just drop 1-2 gallons of E85 in the tank and that should provide more safety, power, and knock protection.

[S14]

I experienced less overheating on track when I put half a tank of 100 octane in the car.

[Obioban]

It's not going to provide meaningfully more power (as in, <10 hp), it's hugely expensive over time, and if your car is healthy, there's no reason for a NA e46 M3 to be overheating on track.

If you're having overheating issues, save the money on race fuel and put it into a new stock cooling system.

... and if you're ignoring all of that, make sure you use unleaded race fuel if you have cats.

[sc_tr0jan_m3]

I run 93 oct pump gas and have 329 whp and that’s plenty for me to stay cool and turn reliable fast laps session after session. I’ve never needed or been tempted to run 100 oct


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[Sharocks]

If I'm really really low on track, yea I'll toss a gallon in of 100 or 110 to get me to the gas station so I can get 93.