Would Race Fuel Make a Difference?

[Naz24]

I was at a sunoco the other day, and saw a pump for race fuel. first of all, can our engines take that fuel? and secondly, would it make any performance or gas mileage differences?

just curious

[FSETH]

Not sure if our ECU's will adapt to that.

I came across a Shell that had 100 octane "race" fuel the other day as well. I stuck with regular old premium, but took note that the cost was $9 and some change per gallon for the race stuff. I asked the attendant if they sold a lot of it and she said the moved a good amount to the motorcycle crowd and the rich folks with Ferraris, etc.

Before this, the last place I saw it at the pump was near the Tail of the Dragon. Once again, an area notorious for tons of bikers and high performance cars.

[Hit Redline]

Sure it can take it and would run better and make a little more power, but not worth the added cost.

The higher octane would allow you to make more power if it was tuned for the higher octane. Biggest difference is going to be for folks with forced induction, higher boost without detonation.

[motordavid]

My guess is the engine electronics won't make much of anything over 93 octane rating...
and, interestingly, Sunoco's website has 4 paragraphs of marketing bs, but really says nothing
technical about its "Race Fuel", as in what it is.
Maybe JCL, ard, or another tech knowledgeable can chime in.

I think I would toss in a tank of 89 in our '01 3.0 and put the remainder toward a good wine buy. ;>)
GL, mD

PS...Edit: a couple of interesting links:
"Should I put Race Fuel in my regular car?":

So You Want to Put Sunoco Racing Fuel in Your Street Car

And, Sunoco Race Fuel 101:

A lesson in Racing Fuels 101 - Racing - ESPN

[amacman]

well , the higher octane fuel will benefit a very hot engine because there will be no heat induced detonation . the fuel will only ignite when the plug sparks to ignite it .
I use high octane fuel more often than standard fuel because the car just runs smoother especially in hot conditions .
I drove an old van which had a Rover K-series engine running on 100LL avgas whilst on DZ duties and I can tell you that old engine developed a lot of power using avgas .

[JCL]

On a factory tuned X5, ie no change in compression ratio and naturally aspirated, nothing over about 91 AKI has any benefit. Remember that the anti-knock index (AKI) is the average of the motor octane number (MON) and research octane number (RON) methods, ie (M+R)/2. You can't directly compare it to the 98 RON in Europe. With anything over about 91 AKI, there is no more power for an X5, it doesn't run cooler, it is just throwing money away.

The qualifier to that is that in some regions of North America, higher octane fuels contain less (or no) ethanol. That doesn't make any difference to AKI or detonation, and thus power, but it does make a difference to your fuel mileage, since ethanol, in addition to making engines run like crap, has less energy content for a given volume (so you burn more). I sometimes buy 94 not for the AKI but because I want to avoid ethanol entirely, and we have a distributor that gives me that option. It depends on the price spread, and if the increased mileage is cheaper than the price premium for 94. Not all states/provinces permit gasolines with no ethanol, but mine does.

[JCL]

Originally Posted by amacman

I drove an old van which had a Rover K-series engine running on 100LL avgas whilst on DZ duties and I can tell you that old engine developed a lot of power using avgas .

No chance of running any fuel with that much lead in it on any modern vehicle.

DZ? Doctor Zhivago?

[GSXRliterbikz]

Not a BMW, but I was drag racing a 96 Impala ss one time. When I was getting low on fuel at the strip I filled up on Shells 100 octane as that was the lowest one they had there. I added a full second to my 1/4 mile times. I had made 3 runs before putting it in and then made 2 more runs after. That car did not like the higher octane stuff.

[J.Belknap]

The fuel doesn't make the power, it allows a tune with leaner A/F ratio and advanced timing to be used (unless peak power is already seen at the current timing advance, which makes the race fuel unneeded IMHO, although it can be added as a knock suppressant for the "peace of mind" factor.) But with nothing else changed, the car will be down on power until the tables have been tweaked.

Also makes for a great air freshener. Mmmmm... C16.... yummy

edit: JCL nailed it already.

[admranger]

It will make a difference in your wallet thickness and/or the thickness of your credit card bill.