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1973 Dodge Charger - The E85 Mule

A Story Of Alcohol Abuse, Centrifugal Superchargers, Big Horsepower, And Low-11-Second Times From A '73 Dodge Charger.

Photography by , Bob Woods

With the conversion complete, they took the Charger to Xact Dyno in Tempe, Arizona, to do a straight-up comparison using Xact's hydraulically loaded Dynapack, which bolts to the rear axles, eliminating tire slippage as a variable. The test consisted of running the Charger on both pump gasoline and E85 at the same boost level to compare the power output. The accompanying graph illustrates the difference in power especially along the torque curve, where differentials of 30 lb-ft of torque or more between 3,400 and 4,800 were the norm. Studying the air/fuel ratio curves later revealed that both the gasoline and E85 mixture levels were on the rich side, but the power differential was still clearly evident. Terry and Bob are confident that this amount of torque along with a conservative 25hp improvement at the top of the curve is due mainly to E85's ability to cool the incoming charge.

Terry believes that if the engine were optimized by bumping the static compression from 8.8:1 to 10.0:1 or more, the power curve would clearly benefit. Part of the reason for this is that in addition to the use of E85, the brothers also equipped this 440 with a complete water-injection system that includes a 5-gallon reservoir, a high-quality, high-pressure pump, and The Supercharger Store's own spray nozzle designed to inject the water as a fine mist directly into the inlet side of the supercharger. Doing so introduces the water as far upstream as possible to produce the most reduction of inlet-air temperature. This takes advantage of something called the latent heat of vaporization of water. When vaporized, water can remove roughly four to six times the amount of heat from the inlet-air temperature compared to gasoline, and when combined with E85, this inlet-air cooling improves even more. As an example, during the chassis dyno testing, the gasoline-fed and water-injected combination saw an inlet-air temperature of 173 degrees F at 15.8 psi of boost in the intake manifold, while the E85 combo registered a mere 109 degrees F at 15.5 psi. That's a huge difference, especially when you consider that there is a 1 percent potential power increase with every 10-degree decrease in temperature. This is probably where the power increase originated.

The reason that water injection works so well is because not only does it reduce the inlet air temperature, but the proper amount of water also reduces the peak cylinder pressures to prevent detonation. Terry feels that the combination of E85's strong octane rating along with a properly designed water-injection system could potentially sustain boost levels as high as 20 psi in their Mopar motor without having to compromise total ignition timing.

The final evaluation was a full dragstrip blast at Southwest International Raceway in Tucson, where the 4,300-plus-pound Charger ran a solid 11.20 pass. But because the Charger doesn't have a rollbar, the track wasn't thrilled with allowing more than one run. Think about that: Here's a massively heavy Mopar running low 11s at a track located in the high desert on pump gas ethanol with a little squirt of water mixed in. It puts a whole new perspective on the term "alcohol abuse," doesn't it?

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