Castrol Syntec Top Car Challenge Buildup Part 3 - Topped Off

Here's a look at the difference in pulley size. The Lysholm 3.3 is set up with a 4.0-inch wheel from the factory (left). The new 3.25-inch pulley spins faster and increases max-boost by 5.6 psi (from 16 psi to 21.6 psi).

With the boost tasks handled, installing Centerforce's new Dyad dual-disc clutch system is the next upgrade for our Top Car Challenge entry. Removing the passenger-side long-tube header makes extracting the transmission a bit easier, as does slightly raising the engine.

Ford installed this 8-inch, twin-disc clutch in Shelby GT500s. The discs are ceramic; they have a tendency to hiss when the clutch is released and shudder/grab a bit, typically at startup.

Centerforce's Dyad clutch system measures 10.5 inches; it features a pair of discs that are made with high-temperature organic material on one side and a metallic-ceramic alloy on the opposite face. Using the two materials facilitates increased holding power and maintains smoothness, which is critical for street-driven cars with big power.

This look at the disassembled Dyad details its hub-and-pin drive setup, which links the two disc plates. This innovative design eliminates the need to add springs on disc #2 (on the left in this photo), which keeps the unit fairly lightweight, as well as noise/chatter free. Drilled holes around the perimeter of the steel flywheel is another cool feature of this system. Lightening the outer region of the flywheel helps improve acceleration, which will be a big benefit to our heavy 'Stang.

The Dyad dual-disc clutch is designed to fit snugly on the transmission input shaft for positive clutch engagement, and to reduce wear and potential damage to the shaft. Centerforce makes its Dyad clutches with hubs that actually are softer than a tranny's input shaft to ensure the hub will wear before the shaft does. Notice the thick drive lugs, which connect the primary clutch disc with the secondary disc.

Fasteners receive an upgrade, too. Centerforce uses ARP fasteners (flywheel bolt shown on the left) throughout the Dyad clutch system.

Prior to actually installing the new clutch, there was some talk concerning "tricks" or special tools required for putting the Centerforce twin-disc in a Shelby GT500. The reality is that the swap is no different than bolting one in any other S197 (the drive lugs actually make it a bit easier). Removing and replacing the tranny is the only heavy lifting required with this job.

Returning the Shelby's transmission and headers to their proper places closes the clutch-swap deal.

However, before everything was buttoned up, Mason exchanged the stock shifter with a short-throw unit from Ford Racing Performance Parts.

While we believe replacing the factory two-piece driveshaft is a "must-do" upgrade for all S197s, we definitely encourage the mod for Shelby GT500s that put more than 500 hp on the ground. This lightweight piece comes from Coast Driveline and Gear of Ventura, California (www.coastdriveline.com).

Lysholm created an SCT race-gas/small-pulley PCM calibration for its Shelby GT500 3.3 twin-screw supercharger system, when Carlos's car served as the guinea pig for the blower's development. Making the plug-and-play file transfer via an XCalibrator 3 unit the last task in this upgrade effort. A full set of Nitto's ultra-sticky NT01 road-race boots were added just as this story deadlined. Details and pictures of the new tire-and-wheel package are included in Tom Wilson's report on the Castrol Syntec Top Car Challenge, which you'll find on page 90 of this issue.