The valuable benefits of running a race fuel

You don’t need to read the label on the container. You can sense the presence of race fuel as its sweetness wafts through the paddock. 

While most race fuel talk is aimed at those in the pits, Nomex undies aren’t required to understand the part it plays in our sport. A big reason for running race fuel? More octane. Where street fuels usually top out at 93 octane, race products often range from 96 to 118. 

That extra octane doesn’t provide more power, however, as octane is simply the fuel’s resistance to knock and preignition. One common cause of that engine-damaging preignition? The elevated combustion chamber pressures often associated with forced induction, increased compression ratios, and aggressive cam and ignition timing settings–things often found at the track. 

Excessive heat can also cause preignition, and Zachary J. Santner, senior specialist of quality at Sunoco, offers a real-world possibility: A car on track has an issue with its cooling system–maybe not bad enough to send it to the pits but enough to push the gauge deeper than usual. “Using a higher-octane fuel would be like insurance,” he notes, as it could simply provide a safety net of sorts to protect the engine from knock and preignition. 

Race fuel also provides consistency. At least in the case of Sunoco’s race fuels, they’re always blended to consistent recipes and all come from the same refinery in Marcus Hook, Pennsylvania. Street fuels, he notes, can change considerably depending on season and geography, introducing a tuning variable that can be hard to tame. 

Santner notes another big advantage of race fuels: They’re simply cleaner and more stable, which can mean longer shelf lives. Street fuels, he explains, are designed to be purchased and burned, so they contain acceptable amounts of gum and varnish. Race fuels start with compounds that are simply cleaner and inherently more stable, he explains. 

So, back to the beginning: Why that distinctive smell of race fuel? To combat knock, higher-octane fuels will often contain a lot of isooctane, he explains, which can have a sweet aroma, especially when coming from an engine that’s idling a bit rich.

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