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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.”
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.
Holley and QFT both offer tools for testing ethanol content in E85 blends. Part #26-147 (shown above) will ensure that you know exactly what's going in your tank or fuel cell.
As more and more racers have started singing the praises of E85 in recent years, the fear factor once associated with making the switch is quickly fading. First and foremost, there’s nothing to fear, as converting to E85 involves very few changes to the fuel system. Recalibrating any 4150- or 4500-style carburetor for E85 duty is as easy as swapping out the metering blocks and boosters, and replacing standard floats with corrosion-resistant sealed Nitrophyl units. Quick Fuel Technology offers convenient E85 conversion kits to take all the guesswork out of the process.
QFT offers turnkey options for racers interested in making the change to E85. The FX-4710-E85 is a 3-circuit 4500 carburetor intended for race-oriented large cubic-inch engines.
For an even easier solution, QFT has also developed turnkey E85 carburetors. Although the richer stoichiometric air/fuel mixture of E85 does require moving a greater volume of fuel than gasoline, unless your current fuel pump is already near the limit, it can probably handle the extra fuel flow. “Methanol requires two and a half times the fuel volume as gasoline, but E85 required just 30-percent more flow,” Benoit explains.
Think of E85 as an industrial cleaner, it's important to verify your pump, lines, and regulator are all rated for ethanol blends. Holley has a complete lineup of bolt-in E85 fuel pumps for fuel cells (Part #: 12-146 shown here).
Perhaps one of the biggest myths that scares people away from E85 are horror stories of rotting fuel lines and clogged up filters. In truth, these tall tales have been largely exaggerated by a combination of inexperience and hearsay. When adapting a fuel system for E85, a little bit of common sense goes a long way. “E85 is like an industrial cleaner,” says Benoit. “If you have an old fuel system that isn’t in good shape, E85 can wash out all the gas residue and dirt in the system and push it into the carburetor.
That’s why it’s very important to clean out your fuel system well, before switching to E85. E-85 rated, rubber fuel lines work well, but E85 shouldn’t be used with aluminum fuel lines. We also recommend using a high-grade fuel filter and making sure that any anti-slosh foam in the fuel tank is compatible with E85. Taking these few simple precautions makes it very easy to adapt a fuel system to run reliably on E85.” In addition to the intake charge density and octane advantages of E85, it also offers bracket racers greater predictability as track conditions change throughout the day.
It's important to clean your fuel system well, using high-grade fuel filters, and E85 compatible anti-slosh foam will aid in prolonging your fuel system's life.
“Due to the cooling effect of E85, changes in density altitude don’t affect engine performance nearly as much,” Benoit explains. “With gasoline, you’ll typically lose a hundredth of a second for each 150-ft increase in density altitude. With E85, that figure is more like 200- to 225 feet. That means fewer jet changes, and better round-to-round consistency.” For dual-purpose hot rods that will also see time on the street, E85 pays dividends on the open road as well. “On average, the coolant temperature on an engine running E85 will be 10-15 degrees cooler than a gasoline engine,” Benoit adds. “With the cooling effect and octane advantage, you could even run a race motor on the street.”