ASK THE MXPERTS: WHAT IS THE BENEFIT OF COLD GAS VERSUS HOT GAS?

Keeping your gas can in an ice chest would be a big hassle for very little reward for a local racer

Dear MXA,
I’ve always heard that cold gasoline makes more power than hot gasoline. Should I be putting my gas can in an ice chest?

You could, but motocross is not Formula 1. The gain in horsepower, which is very small in any case, is caused by the cold gas being denser; however, on a warm 85-degree day, by the time you put 50-degree cold gas in your tank, ride to the starting line and sit there for 10 minutes waiting for your race to start, the 35-degree difference in fuel temperature will be greatly reduced, especially since the fuel tank sits directly over the Bunson Burner heat of a very hot four-stroke engine and exhaust pipe. MXA ran a dyno test comparing 85-degree fuel and 50-degree fuel and found that peak horsepower was identical with both hot and cold gasoline. We did find a very small improvement at high rpm (after peak) with the colder fuel, but it was a very small percentage gain, in a very narrow rpm range, and disappeared in mere minutes as the fuel heated up.

 

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