Green Is Mean - E85 Isn't Just For Tree-Huggers
Uncle Sam wants you to drag race. Why else would he help pay for your race fuel? As a renewable energy source championed by environmentalists, some racers think of E85 as a wimpy fuel that has no place in a drag car. However, many bracket racers have shattered that perception by taking advantage of E85’s incredible 110-plus octane rating and dirt cheap pricing. E85 represents one of those rare occasions where racers come out on top when it comes to governmental decisions. As an alcohol-based fuel, the cooling effect of E85 on the air/fuel mixture offers significant increases in performance.
E85 has a greater latent heat of vaporization than gasoline, allowing more heat to be pulled from the intake charge during phase change (liquid to a gas).
Thanks to E85’s greater latent heat of vaporization compared to gasoline, it pulls more heat out of the intake charge as it changes state from a liquid to a gas. In other words, it requires more heat to vaporize than gasoline, resulting in reduced intake air temperature. This cooler, denser intake charge increases volumetric efficiency, which in turn boosts horsepower and torque. “E85 is like a cross between alcohol and gasoline,” said Marvin Benoit of Quick Fuel Technology. “It has the same cooling effect as alcohol, but it’s not nearly as corrosive. It’s also much easier to fire up an engine that runs E85 because it lights off at a much lower temperature than methanol.” With the aforementioned octane rating of 110-116, E85’s superior knock resistance allows running a much higher compression ratio, further increasing performance. “If you have a nine-second bracket car, the enhanced cooling effect of E85 can knock off a half a tenth to a full tenth of a second in comparison to gasoline,” said Benoit. “Switching to E85 in and of itself doesn’t always increase horsepower, but it will increase torque. Even bigger gains are possible by increasing the compression ratio to take advantage of E85’s higher octane rating. You can safely run as high as 14.0:1 compression with E85.”
E85 and Forced Induction
Considering how well E85 performs in naturally aspirated engines, then it’s not surprising that forced induction applications can benefit even more. Even with relatively low static compression ratios of 8.5 to 9.5:1, supercharged and turbocharged engines are typically limited to 12-15 psi of boost on pump gas. In contrast, the combination of lower inlet air temperature and greater knock resistance allows racers to routinely push twice as much boost on E85 than on gasoline. And twice the boost equals twice the power. Understandably, figures this big may seem too good to be true, but the proof is in the dyno results. The boost experts at Steve Morris Engines know outrageously forced induction big-blocks better than anyone, and the performance they’ve managed to extract out of E85 is stunning to say the least.
E85's cooling effect equals lower inlet temperatures, this added with its greater knock resistance allows racers to creep up boost levels higher than traditional gasoline blends.
An SME built 540ci block-Chevy strapped with an F3-139 ProCharger cranked out 2,500 horsepower at 30 psi on E85. Let that sink in for a minute. The same fuel capable of powering a 2,500hp door slammer into the 6s can be had at your local gas pump for significantly less than a gallon of gas, which compares quite favorably to the $10+ going rate for methanol, and the $15 or so per gallon price of admission for race fuel. “For a local bracket racer that wants an inexpensive race fuel, E85 is tough to beat,” said Benoit.