How to choose the right fuel for a race engine?

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Update by Tim Suddard to the Ford Mustang Fastback project car
May 19, 2023 | Ford, Sunoco, Mustang, Vintage Racing, fuel, gasoline, Ford Mustang, Vintage Race Car, Race Fuel, Sunoco Race Fuels

Our Mustang is so close to starting that we can taste it. But before we could fire it up, we needed something: fuel.

We turned to the Sunoco Racing Fuels catalog and found a wide range of offerings.

So, how to decide? Throw a dart?

Fortunately, these aren’t unchartered waters for us as we have discussed the topic several times. Some related reading:

We also discussed our situation with Zachary J. Santner, senior specialist of quality at Sunoco.

First, our situation: The small-block Ford V8 in our Mustang vintage racer runs about 12:1 compression along with heads that flow a bit better than stock. The car will see both sprint and endurance events.

Several fuels from the Sunoco catalog will work in this application, but thanks to our carburetor, Santner recommends staying away from blends that have ethanol. High-octane, high-ethanol fuels–meaning more than 10% by volume–like 260 GT Plus, Evo 10, E85-R and Green E15 can deliver more horsepower on the dyno but, he notes, require more precise fuel systems and more attention to fuel storage.

He recommends that we keep things simple and run Sunoco Standard, a leaded 110-octane fuel. Standard will work with our compression ratio while providing extra protection against detonation from heat–likely to be encountered during an endurance race situation, he notes. The 110-octane fuel would also provide more headroom for increased spark advance.

Sunoco Standard is designed for compression ratios up to about 13:1 in conventional V8 engines with iron cylinder heads,” Sunoco’s site states. “It can tolerate higher compression ratios in aluminum cylinder head applications or engines with smaller or more efficient combustion chambers. While most racers use Sunoco Standard in naturally aspirated applications, it is also a good choice for mild nitrous, turbocharged, and supercharged applications.”

Sunoco sells this fuel in five-gallon pails as well as in 55-gallon drums. And of course, it is available at a myriad of race tracks and specialized gas stations around the country.

A quick search on Sunoco’s Fuel Finder revealed about 50 retail outlets within a hundred miles of our Central Florida base. Plus the fuel can be mail ordered.

We had a 55-gallon drum shipped to our shop so we have enough for our initial dyno session plus those first tests and events. We like to arrive prepared.

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SkyNoLimits8 New Reader
5/22/23 7:44 p.m.

Leaded fuels were removed from production cars almost 50 years ago. Lead is a KNOWN health hazard to humans. Literally ZERO parts per million or billion is an acceptable level in blood. Children whose brains are still growing are more susceptible to stunted brain development, but adults are also at risk, who wants to say they got more senile just from car exhaust?  Truly no one should be using leaded fuel any more. The remaining aviation industry is trying to lurch toward unleaded also. Drivers in leaded fuel cars, their families, and spectators, are putting themselves at risk to be breathing in leaded fuel fumes. It's time for all motor sports organizations to allow some rule changes to allow whatever technology is needed to keep performance, but change to use unleaded fuels. In fact for people born after 1980 or so, they have likely never even thought or heard of the dangers of lead (maybe the news about Flint water) and might not even know of how many race cars could be using it, and they are exposed to it but aren't even aware. For the health of drivers, families, corner workers, and everyone involved, we need to discontinue leaded fuel ASAP.

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