Running 100 octane Blend in NA S54

[Mr.MikeE46]

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.

[slides]

I've been running 93/91 no problems for years.

[mmark.]

If the octane # is to high for the ecu to adapt to it will cost you 2-3 secs on a 2 mile track.
The engine will actually feel somewhat flat. Itried this years ago after running too low on fuel and buying 100 oct unleaded at the track.You could do the 75/25 mix for anti-knock insurance.
since you're a recent track attendee, I 'd forgo playing with octane and spend the money on better brake pad material.

[Feffman]

I've been running 93/91 no problems for years.

Ditto, we are fortunate we have 93 pretty much across the board. Considering 12.5:1 compression with race motor next year which means 98-100+ octane and significant increase in fuel cost at $9-$10 per gallon versus $2ish (for now) for 93.

Feff