The company's '08 Mustang GT, which some of you may recognize as the flagship ride in the ProCharger booth at the '07 SEMA show, is outfitted with the result of Paul's research: a P-1SC H.O. supercharger system that features the new Quiet Blower option. Note the trick pulley on the head unit. Company President Ken Jones tells us the holes were added as part of a weight-reduction experiment, in addition to the ongoing effort to make the blower as quiet as possible. While it's not quite ready for public use yet, Ken says the lightweight pulleys may be offered at some point in the future-as an option, of course.
This is a close-up look at the guts and glory of ProCharger's standard P-1SC head unit. Internally, the blower features straight-cut gearing in its transmission. Gearing engagement, or mesh, is a major contributor to its distinct sound. Another reason we hear so much from standard blowers is that, unlike other centrifugal blowers, ProChargers are totally comprised of billet material (case, impeller shaft and impeller, bearing housings, and so on). "Billet 'sings' and doesn't have the same sound-softening ability that cast iron has, so it's a lot tougher to quiet our blowers," says Paul.
"We looked at all of these criteria as we developed our quiet option, but the data we gathered was mostly used to help us make changes to the driving frequency (vibration) of the gearbox and the bearing frequency. The vibrations are audibly represented as sounds that come from the blower's driving gear, driven pinion, and slinger. On the bearing side, the speed of the inner race, bearings, and outer race is calculated, and changes are made accordingly in an effort to make the supercharger as quiet as possible. None of the changes affect the quantity of air that is delivered into the engine at the pressure we're delivering it."
If you're looking for a visible difference between a P-1SC's standard gearset and an optional Quiet blower, this is it. A lot of the reduced sound comes from these helical-cut gears. The gears' angle-cut profile spreads the transmission load over more surface, which makes their engagement much smoother and quieter than straight-cut hardware. Quiet blowers' gearsets feature matched-pitched sizes (driving and pinion gears) and optimized alignment and bearing bores, as well as impellers that are balanced to tighter specs than those included in the standard units. Ken stresses that none of the changes have any ill effect on airflow, power, or the overall durability of the superchargers in any way. When equipped with the Quiet Blower option, the '08 makes the same 456 rwhp and 408 lb-ft of torque that it does with a standard P-1SC
Some 'Stang fans firmly believe that something must be wrong if a blower doesn't make a loud, mechanical racket. We saw-well, heard-for ourselves that this sentiment is far from true. We performed our own nonscientific sound test outside the shop and were blown away by the difference. The blower on the red 'Stang sounds "normal," if you will, but the custom-painted '08 GT on the right is whisper-quiet. Video of our test is available on our Web site at www.50mustangandsuperfords.com. Understand that ambient sound plays into the audio in our crude test, but the difference is discernable nonetheless.
Since we had only seen the mocked-up demonstration system (displayed on a SEMA "New Products" table) prior to our trip, the crew at ProCharger was kind enough to set up two employee-owned Foxes on hoists and provide us with an up-close look at how the system lays out on a fully dressed, street GT 'Stang and a street/strip LX.