On the tuning side, Dez fired up the SCT software and changed the stoichometric number from gasoline's 14.7:1 to the E85 rating of 9.76:1. There is a pull down menu to adjust this ratio. Another change was to increase base fuel pressure (a total of 28 percent) from 40 psi with gasoline to 55 psi with the E85. An easy check-out pass on the dyno showed the fuel injectors were already near 100-percent duty cycle with the fuel pressure at 40 psi, so the combo really needed larger injectors. Since we didn't have them, we increased pressure for the purpose of the test. Leaving timing the same we saw the baseline of 616 rwhp increase to 635 rwhp—a gain of 19 rwhp with no other changes except the extra fuel. "The reason for the increase in power is the greater oxygen content of the E85 compared to pump gasoline," says Dezotell.
One of the reasons for running your car on E85 is the benefit of the increased octane rating, thus allowing more boost, more compression, and more timing over pump-gas applications. Increasing the compression ratio was out of the question since the engine was in the car already. Dezotell shied away from adding more boost because the P1SC-2 was at maximum impeller speed (60,000 rpm) thanks to a 3.20-inch blower pulley and a 6.60-inch crank pulley (impeller speed = crank pulley size/blower pulley size x step-up ratio x max engine rpm).
The boost gauge on the DynoJet chassis dyno shows a peak of 16 psi at the 7,100-rpm redline. It left Dezotell with only one option and that was increasing the ignition timing, and he did so conservatively with an extra 3 degrees throughout the entire curve. That put total timing at 22 degrees at the peak of 7,100 rpm.
The Two-Valve screamed with the extra 3 degrees as it worked its way up to redline, and when the pull was complete, the results were outstanding—669 rwhp and 519 lb-ft of torque. The E85 fuel allowed timing to be increased by 3 degrees, which resulted in gains of 53 rwhp and 34 lb-ft of torque. "I think there is more power in there," Dezotell comments, "but for now we're happy."
E85 is a power enabler allowing more cylinder pressure and/or more timing as if the engine was running on race fuel, but it cost us $3.69 per galloon as compared to $12-$17 per gallon for a quality high-octane race fuel. Make the switch to more power for less money—being greener is an added bonus.