The moment of truth came late in the evening when the '01 Mustang GT was strapped to the DynoJet chassis dyno. The testing procedure was simple-Dezotell would warm up the engine to be consistent with the baseline pulls and he would make three consecutive runs to ensure the numbers were accurate. A short break is taken between pulls to let the engine cool off, and we didn't ice the intake.
The car utilizes a Big Stuff 3 standalone EFI and it was kept in closed-loop mode so timing and air/fuel would remain identical in both tests. Closed loop is when the ECU operates in the user-defined values for fuel and timing-meaning the engine would use the same amount of fuel and the timing would be locked in. Dezotell had the timing set at 10 degrees total due to the pump gas and big boost. Open loop in a Big Stuff 3 system is when the ECU will alter the air/fuel ratio using the 02 sensors. A target value is inputted and the computer will constantly adjust to achieve the target value. The pulley on the ProCharger blower and crankshaft were left the same, changing them would negate our goal of an equal comparison.
Dezotell ran the car up to its redline of 6,600 rpm, and the final results was an impressive 695 rwhp and 566 lb-ft of torque. The calculator shows a gain of 18 rwhp and 2 lb-ft of torque-yes, the engine picked up torque despite the belief that short-runner intakes produce less torque than long-runner manifolds. Boost increased, despite the pulleys remaining the same, to 19.3 psi from the baseline of 18.8 psi. McCarthy attributed that to the Victor Jr. 4.6L being less restrictive.
Dezotell made a few back-up runs and tried turning the engine higher, but the peak power came at the same 6,600 rpm with both style manifolds. Both Dezotell and McCarthy feel there is another limitation, possibly cylinder head flow or the camshafts restricting the engine from going even higher. But the output increased in both horsepower and torque when we switched over to the Edelbrock Victor Jr. 4.6L intake.