With the Forced Air Performance kit installed, we took the car to Gillett Diesel to test the horsepower and torque output on the MD-250 dyno. All dyno testing was performed at 5,000 feet above sea level, so the horsepower numbers are about 20 percent lower than what we would've seen if this testing were done at sea level. All the horsepower and torque numbers are actual and not corrected for altitude. For the sake of comparison, we also brought along a stock '08 Mustang GT and an '07 Foose Stallion Mustang that has a competitor's 12-psi centrifugal supercharger kit.
On the dyno, the Forced Air Performance Mustang produced 401 hp at 5,750 rpm and 377 lb-ft at 4,800 rpm. We made four back-to-back runs to prove the kit's consistency and immunity to heat soak. The first run was 399.5 hp and the fourth run was 401 hp. While the stock Mustang was nearly this repeatable, the other supercharger kit lost almost 10 hp per run for a combined decrease of 35 hp between the first and fourth runs.
Road TestEven being a mile high, we couldn't knock the wind out of this Pony. With 400 rwhp, the Mustang was fast on the road with incredible lo-end pull. compared to the other centrifugal blowers on the market, the Rotrex blower is smaller and spins much quicker (around 90,0000 rpm), therefore it makes the car responsive but still gives good top-end pull. In comparative terms, the Rotrex produces a Roots-style/twin-screw bottom end while still yielding turbo/conventional centrifugal charger top end.