hockeyguy

I need to visit my parents more often!
They live about an hour away... but about 10 minutes from their place is one of those gas stations (in Livonia, Mich) that sells Sunoco 260 GT-100 racing fuel (100 octane, lead-free, ethanol-free). Wow what a difference! (2009 C2S pdk). The performance gain with ethanol-free gas feels amazing....
Now, every time I visit them, I will plan on arriving with an empty tank and filling up with this gas! I want to use it too for winter storage if I can, get rid of the ethanol sitting in there...
It's expensive though, at 6$/gallon.

beentherebaby

Placebo effect... <LOL>

hockeyguy

well, I'll take that placebo effect and "rush" once in a while at 6$/gallon-- it's a lot less expensive than the itch to trade up to the turbo for its "rush".
--LOL

kosmo

race fuel burn hotter so does it hurt the engine?

Skibum

I've spent the entire summer playing with GT-100 and diluting it with various concentrations of pump 93.
What I have come to believe is that the only time that the 100 octane seems to make a big difference is when I am coming off of a bad load of hi-test. Otherwise I'd challenge anyone to be able to tell what gas is being used in a double blind test.

What my procedure is now is to fill with hi-test and see how the car feels and sounds. Usually I can tell bad gas by the little "tip-in" ping or ping on "blipping" the throttle. If I hear that; I add a few gallons of 100 octane and the problem goes away and the car is a rocket again. I've been buying the GT-100 in 15 gallon drums and keeping it handy in my garage.

hockeyguy

Unless it's a turbo, the 100 octane won't make much of a difference. The difference, I believe, is the absence of 10% ethanol.

Also, with DFI engines, there are other advantages to ethanol-free fuel. Less deposits (lower engine temperature required vs. ethanol-gas to burn off), less possible fuel pump issues (ask BMW 335i and 535i owners).

RollingArt

Race fuels will typically burn cooler than street gas. Especially if the race gas contains ethanol. More ethanol = more cool fuel entering combustion chambers.

hockeyguy, are you sure the 260 GT-100 contains no ethanol? I checked the Sunoco website and it didn't say one way or the other about ethanol for this fuel.

We use Sunoco 260 GT-plus in our race cars. It's rated at 104 octane. Their website also didn't list the ethanol content of this fuel either, but I know it's in the 10-20% range.



Phil

hockeyguy

you're right...
Sunoco doesn't specify ethanol content, so yes, I think the GT-100 does contain ethanol...
I know that The GT plus absolutely has ethanol, that's how they get the octane to 104.

Nugget

Any difference you felt was purely imaginary, and that would be true in a Turbo as well.

Down here at MSR Houston the on-track gas pumps routinely run dry of the normal octane fuels and from time to time I end up having to fill up with 101 octane to finish out a day of lapping. The extra octane doesn't affect my lap times one bit. No additional power at all.

alexb76

I guess we're pretty lucky up here in BC! Almost ALL Chevron gas stations have 94 Octane, ethanol free gas that is just a few cents more than 92 Octane!

I really don't understand how in the world it's so difficult to find 91+ octane gas and ethanol free in US?! I always had difficulty going south in my Audi which had a custom program requiring 93+ Octane!

kosmo

and Porsche and AUdi owners...

CarGuy21

A truer statement couldn't be made.

Octane rating is a measure of a fuel's resistance to pre-ignition i.e. knock, pinging. If an engine's configuration or tuning is not set up to take advantage of the higher octane rated fuel then there will be no measurable difference in the power produced by the engine. Anyone who runs a higher octane fuel than what the engine will run on without pre-ignition is wasting their money.

Additionally, racing fuel being higher octane would burn cooler as higher combustion temperatures contribute to pre-ignition.

wiggy

Because Ethanol brings down the price of gasoline when mixed in with conventional RBOB fuel. Since most people don't drive around in Porsches, they want the cheapest gas possible - up until recently, 87 octane fuel could be reduced by about 5 cents a gallon when mixed with ethanol.

Interesting that ethanol fuel is trading near gas prices, so combined with the decrease in MPG - there is currently no real economic advantage.

But the farm lobby has a tremendous amount of leverage - so, we will have gas with ethanol in it and pay more for everything that consumes corn.

Macster

May not be a placebo effect. EVO (UK car mag) did a gasoline test a while back and found measureable and noticable differences between various brands of gasolines of the same octane rating. Additionally EVO tested one or two higher octane gasolines (99 vs. 95) and even tested a Sunco racing fuel and found the car (VW GTI turbo-charged) performed best of all on this Sunco fuel.

Of course, the Sunco fuel's cost meant it only made sense to use on the track.

For a car equipped with a high compression engine and active knock control a racing gas can deliver noticable benefit by allowing the engine controller to use as much advance as its timing maps allow. Also, an engine's octane requirements change over time, from age (chamber deposits), wear/tear, and a higher octane gas may deliver better results in this case.

IAC, while the engine may not develop much more HP the torque curve can be improved and even max torque production can be improved, from in the case of the VW from a low of 238ftlbs to 252ftlbs.

Additionally the test driver on the track noted the behavior of the engine running with the various different gasolines was quite different.

In some cases the engine had more get up and go in mid-range and top end was brighter, the engine more willing to run to redline.

Lastly, IIRC one of the better performing gasolines had 10% ethanol.

Sincerely,

Macster.

ADias

Ethanol may bring down the pump price, but not the overall cost of fuel. The gas mileage of cars running E10 is 10-15% lower.