The 5R55S automatic transmission-equipped...
The 5R55S automatic transmission-equipped S197 Mustang is a potent little beast. With minor bolt-ons and a torque converter from TCI, we've begun our quest of putting one of these things in the 10-second zone.
Welcome to the second installment of our project automatic '05 Mustang-dubbed "Project Automatic Weapon." Thanks to longtime Mustang racer Kenny Moss, we've obtained unfettered access to his brand-new car. Last time, we reviewed why the 5R55S-equipped automatic S197 Mustang is such an amazing performance car in stock trim (May '06, p. 147). With a few upgrades from C&L, DiabloSport, and Nitto, we put the car solidly and convincingly into the mid-13s. One of the keys to its success is the amazing new five-speed 5R55S transmission.
We also identified a problem with the car. In stock form, you can't power-brake the car much past idle without pushing it through the beams. The cure for what ails the 5R55S is to install a looser torque converter that allows you to launch the car hard. The trans was first used in the Ford Explorer and Lincoln LS. With a lightning-quick first three gears, it launches fast, shifts hard, and quickly makes you rethink your decision to buy a five-speed manual-transmission Mustang GT.
Our buddy Tony Akins at TCI Automotive was happy to offer his company's latest product-a10-inch converter especially designed for use in the new automatic Mustang GT. Designed as a nice street/strip converter, the TCI Streetfighter consists of a high-stall stator, needle bearings, a furnace-brazed impeller, and turbine blades. The base stall speed for the TCI converter is 3,000 rpm, but that can vary by how much power your 4.6 Three-Valve puts out. Of course, TCI Automotive can also provide a custom-built converter for racing applications or other special needs.
According to Tony, "The internals of the TCI Streetfighter work in conjunction with each other to provide the most durable and efficient converter of its kind while still doing a tremendous job of dissipating heat." The list price for the Streefighter converter is $611. You can buy it direct from TCI or any of its vendors.
"The converter is a direct bolt-in," Tony adds. "Just double-check your clearance between the flexplate and torque converter. That measurement needs to be between 11/48 and 31/416 inch. Always install one quart of transmission fluid in the converter before installation."
Paul's Automotive Engineering in Cincinnati adopted our test '05 Mustang. The company's professional staff, super-clean facility, and years of Mustang experience have served us well in the past, and owner Paul Faessler was intrigued with the potential of the newest Mustang. So we wanted Paul's to handle the installation of the TCI Streetfighter converter. With our friend Big Mike Wilson handling the wrenches and the shop manager lending a hand when needed, our TCI converter was in Kenny Moss' Mustang in less than eight hours. The following photographs of the swap will help you install your converter with minimal drama.
We never had a chance to test this converter swap at the track. Our Midwest tracks were closed by the time the installation was complete, and we had no way to evaluate the converter on this car. But while messing around on the street, we could power-brake the car to 2,800 rpm, launch it like it meant business, and completely transform its nature. Reports of four to six tenths of a second dropped off the quarter-mile time seem realistic. That would put this car right in the 12.80 to 13.20 range, and that's how fast it feels. That's a 12-second car with simply a converter, tires, cold-air, and tune. Amazing!
Perhaps Big Mike had the best description of this car's transmission: "You've got to do something to let people know this isn't the automatic transmission of old."
Hot on the heels of the Streetfighter converter's success, TCI is in the experimental stages of building a Super Street Fighter converter for the '05 Mustang. According to Tony Akins, this converter will have similar components, with a 3,500-rpm stall speed. If your car sees more track time, this would be the perfect converter for you. As it is, the TCI 3,000-stall Streetfighter converter is a mandatory upgrade your automatic S197 Mustang GT deserves for increased efficiency, better performance, and more fun.