Silenced S197 Superchargers - Sound Decision

ATI ProCharger's engineering manager, Paul Ebner, holds a microphone in front of the standard P-1SC Stage 2 blower, installed on an otherwise stock '07 GT. In addition to the manually held mic, the supercharger on this test 'Stang is outfitted with sound-measuring equipment that allows Paul to determine where sound is amplified in various areas of the head unit.

Horse Sense: Although a pair of V-8-powered S197s were the highlights of our recent trip to ProCharger's headquarters, we once again had the opportunity to ride in the blown '05 V-6 Mustang featured in our first-look report in 2005 ("Blowing the Budget," Dec. '05, p. 143). The low-mile 'Stang is currently for sale and now packs one of the optional Quiet Blowers you'll learn more about in this report. From a stealth-power standpoint, we still believe a blown V-6 S197 is a great alternative for those who don't have the coin for a GT. Imagine how much stealthier it is when the blower is there, but nobody can hear it.

As power adders go, the sound of a centrifugal supercharger-at idle or warp speed-is recognized by most 'Stang enthusiasts as a mark of serious performance, especially when it's coming from under the hood of a street-bred Pony.

However, while some 'Stangbangers view the circular-saw-like zing of a blower as the ultimate statement-maker and confirmation of credibility, we're finding there are others-especially S197 owners-who prefer to drive softly, if you will. That said, even the quiet types still want to have enough boost on tap to lay the smack down on the Chevy, WRX, or Evo in the other lane.

Each sensor measures internal vibration on the top and side of the supercharger. The top-mounted sensor evaluates up-and-down vibration; lateral vibration is recorded with the side-mounted probe.

If you own, plan to own, or would like to own a new ('05-to-present) Mustang, what's your preference? Which centrifugal supercharger (audible or quiet) would you add to your ride? Some of you probably see this as a difficult choice, but ATI ProCharger has come up with something that might make deciding a lot easier.

The ching-zing sound generated by ProCharger's straight-cut gearsets has always been a trademark characteristic of its two popular supercharger systems for street Mustangs (P-1SC and D-1SC). The gears are the most notable contributors to each blower's audible signature, but there are other variables that play roles in the type and level of sound the superchargers emit while operating.

Based on feedback from current and potential customers, engineers at ProCharger have developed new gearing for these units and have improved various areas of the superchargers' casings, impellers, pulleys, and bearings, resulting in dramatically quieter blowers.

Paul uses this graph and evaluates where vibrations and sound spike inside and around the perimeter of the blower. The top graph represents vibration that the case-mounted transducers record coming from inside the gearbox. The graph below is external sound, which Paul captures by holding the microphone at different points around the supercharger's case.

As we said earlier, a supercharger's sound is often considered an indicator of its performance. While this myth is a cool way of thinking about blowers, facts are a much more important concern.

Intent on learning all we could about ProCharger's newest technology, offered as the $100 Quiet Blower option for complete P-1SC Stage 1 (PN PC050A-045) and D-1SC (PC051A-045) supercharger systems, not just head units (for Fox through S197 Mustangs), your tech editor ventured from Los Angeles to the company's Lenexa, Kansas, headquarters for a firsthand comparative look-and listen-at P-1SCs in standard and quiet trim on two S197s in the company's test fleet.

Our interest in ProCharger's new Twin High-Flow intercooler system for '86-'93 Mustangs has been high since we first laid eyes on it at the SEMA show last year.