It was a very challenging task to take one of Audi's most accomplished cars, the S4, and improve its performance without compromising the essential "rightness" of the car. We consider our efforts a success.
In the first three parts of this project, Project S4 received a set of very light wheels and tires, much greater stopping power and a sportier suspension. In Part 4, we put all of these upgrades to the test. For a street car, the Audi performed remarkably well on the track. And in terms of outright power, this car also made dyno pulls that could threaten the egos of E46 M3 and Porsche Carrera owners.
However, before returning Project S4 to its owner, we wanted to add some final touches to the already beautiful performance sedan.
Though the S4 is equipped with a nice shifter from the factory, we shortened the throws with a shifter from UUC Motorwerks, a company well known for its excellent shifters for BMWs. We were pleased to find the firm had one for the S4. UUC's shifters are made from 100% stainless steel and aluminum and are machined to exact tolerances for a slop-free lever. UUC does not achieve short throws by cutting down the top portion of the shift lever. Instead, UUC keeps the upper portion unchanged, leaving the shift knob at the height the factory meant it to be. UUC changes its motion ratio by addressing the shifting mechanism from below the pivot area, which requires engineering a lever not only to duplicate all of the factory features but also incorporate its geometric calculations for the short shifter. As a result, you can expect smooth shifting with up to a 40% throw reduction.
Since we've had no problems with the APR performance parts installation (featured in Part 3), Project S4 returned to Hartmann Motorsports. In addition to the short shifter, owner Scott Hartmann installed a UUC transmission brace to limit unwanted movement. The installation of both parts took less than an hour and a half, but the car felt like a different machine. With smooth, short throws of the shifter, you can carve through the gears much more quickly and improve acceleration. In conjunction with last month's installation of Forge bypass valves, this shifter helps make the car feel much quicker during full-throttle acceleration in first through third gears. Though the throws are slightly heavier, they are also more exact, making a costly miss-shift much less likely.
After tackling all of the major performance categories, our project car still wouldn't be complete without some aesthetic touches. The choice to replace the front bumper cover was an easy one--not because we don't like the stock S4 bumper, but because the one used on the European Audi RS4 is simply so "bad" looking we wanted it on Project S4. It also serves a functional purpose, its side gills aid heat dissipation from the intercoolers. However, the RS4 has flared fenders and the much wider bumper cover won't fit U.S.-spec S4s, a problem for Audi owners desiring this bumper design. Reiger Tuning provides a solution. The North American distributor of Reiger Tuning products for Audi cars is LL Tek Motorsports in Canada, so we made a call and placed our order for the pseudo-RS4 bumper cover. LL Tek offers the RS4-style bumper with several upgrade options, including factory built-in foglights, built-in xenon foglights and factory headlight washers.
Within a week, a box the size of a large coffin showed up at the office. The bumper was already pre-painted, an option I highly recommend. I brought it home and, with the able assistance of my father, put it on Project S4. The factory bumper cover came off with no problem, and the new Reiger piece seemed to fit perfectly as well. The only problem was figuring out the installation of the factory foglights, which took us several hours. The RS4 bumper cover had to be slightly modified to accommodate the foglights--the holes provided weren't big enough. Other than that, the bumper cover is a straightforward installation and makes Project S4 look much more aggressive.
Heat-soak problems were discussed in Part 4 of this project, including the suggestion of larger intercoolers. This bumper cover has more room to accommodate them, and LL Tek stated it may offer a high-capacity, high-performance intercooler upgrade by the time you read this. If released, it will be critical for S4s running increased boost pressure, especially for track use. For the rear, the car's owner didn't want a wing. Instead, he ordered a factory rear lip spoiler meant for the new E46 BMW M3. Surprisingly, this BMW piece was a perfect fit on the rear decklid of Project S4. It had to be painted, however, so we took the car to custom fabricator Jeff Toberg of DJ Exotic Imports in Huntington Beach, the same gentleman who did most of the custom work on Project M3 (see european car 05/02 and 06/02). Jeff quickly painted the spoiler and installed it with strong 3M(TM) double-stick tape. The spoiler stays on with no problem.
When Andy flew out from Texas to drive his car home, I drove Project S4 to greet him at the airport. Of course, he spotted the car driving up well before I spotted him waiting for me at the baggage claim. His walking pace toward the car turned into a quick jog--and then almost a full-blown sprint. After this 100-yard dash, he arrived at the car and circled it a couple of times, definitely not minding the presence of a police officer trying to shoo us away from the no parking zone. He had a grin from ear to ear. "This car looks so awesome! Get out; I'm driving!" Once we got out of the airport, the next several minutes involved license-threatening activities--Andy was getting a little too excited with all of these new performance enhancements. Nevertheless, we survived. In the end, Project S4 made use just of bolt-on upgrades, taking each of the performance categories to another level while maintaining the car's street driveability and maintaining a realistic budget. If you wish to get even wilder upgrades for your Audi S4, APR has an RS4 turbo conversion kit and a high-performance clutch kit. LL Tek should have larger intercoolers available, and Eibach has heavier duty shocks and springs available. For the brakes, these rotors and calipers will more than suffice; just change the pads and fluid to higher temp stuff if you wish to go all-out.
At european car, we tried to keep in mind this question: "If Audi offered an even sportier version of the S4 in the U.S., what would it be like?" I think we've answered that question with Project S4.
Special thanks are given to the Advantage Audi dealership in Loma Linda, Calif., for its prompt and excellent 45k--mile service on Project Audi S4.