The freeway south of here has limited access, is lightly traveled at night and has gentle curves. It's my route home from work most nights, and a few weeks ago I was tooling down the road around midnight in Turbo Performance Center's newest project car. Well, maybe "tooling around" is a bit of an understatement, considering I was in a supercharged Porsche 996 with full-house GT3-spec suspension and brakes. It was red, too, the quickest of all colors.
I was trying to maintain a sense of decorum, but then a set of unwavering xenon lights filled my rearview mirror. Being a well-mannered driver, I tucked over to the right and let the silver 996 Twin Turbo zoom on by. "It's a Turbo," my passenger noted. I responded in the only way a car guy must respond: I dropped two gears to fourth and pressed down on the accelerator.
The driver in the Turbo, perhaps wanting to show off, picked up the pace. No doubt he was planning to leave us in his wake. What he didn't figure on was the TPC blower tucked under the GT3 wing of the Guards Red 996. Before he could react, I was shifting from fifth gear to sixth at an indicated 150 mph, some 5 miles further down the road. Delivering a proven 338 hp through the rear wheels has its advantages. The gentle curves in the road didn't seem all that gentle at 2.38 times the speed limit, but the suspension worked flawlessly, the Michelins gripped endlessly, and the engine pulled as effortlessly as a tractor. A very fast tractor.
Soon-very soon-my exit came up. I lit up the 14-in. rotors of the GT3 brakes, and shaved 120 mph off my velocity-just enough to make the exit. Everything slowed down except my heart rate and my admiration for the TPC 996.
And that Turbo? The driver had, very admirably, maintained the space between his car and ours the entire 6 miles or so-but he should have expected stunning performance from the extra 40 or 50 grand he spent on his Porsche compared to the investment in this TPC wunderkar
Which is also a wonder of packaging-fitting a number of components into a limited space. It's one of the biggest challenges faced by today's automotive engineers. A quick glance into the engine compartment of a 996 shows this was no different for Michael Levitas and the crew at TPC. In fact, it's simply amazing that all of the components fit, nothing rubs and the rear deck closes. They do, nothing does, and it will.
There doesn't seem to be room to fit your hand into the compartment, let alone room to fit a supercharger with drive system and manifold; large, free-flowing ducting; an intercooler; and of course, all the stock emissions, electronics and fuel-injection systems. But Michael did fit it all, and rather elegantly, in that tight space.
An Eaton Model 90 supercharger is mounted on the passenger side of the engine compartment, driven by the factory serpentine belt system. Air is drawn through the factory throttle body and mass airflow sensor, into the supercharger, and sent out through 3-in. aluminum ducting to be cooled in a water-to-air intercooler, and then sent into the stock intake manifold. A digital controller matches fuel and other engine parameters to keep the system happy. And it is happy-maximum torque bumps 299 lb-ft, while the horsepower jumps to 338. All without a fuss or even a tiny ping. It just works, seamlessly.
One of the secrets to reliable and efficient power production in a boosted engine is an intercooler to keep the charge-air temperature at a reasonable level. To achieve that on the 996 Turbo, Porsche built complex intercooler ducting and plumbing at the rear of the engine, a tricky, expensive solution, difficult to duplicate in the aftermarket
TPC chose water-to-air intercooling, a simple, efficient method well suited to the constricted space of the engine compartment. Rather than passing cool air through the core to lower intake air temperatures, cool water is used. This is the solution used by Jaguar, Aston Martin and Lotus for their high-output boosted automobiles, and it is an effective one.
TPC's 996 intercooler is positioned at the intake to the throttle body. A small reservoir of coolant is in the engine compartment, and a high-quality electric pump circulates water through the intercooler and up to the front of the car. At the front, a factory Porsche GT3 upgrade radiator, in the factory location complete with all ducting, does an efficient job of dropping the temperature of the coolant before returning it to the intercooler to do its job once again. The entire cooling system installs without drilling a single hole, and the intake for the front radiator is conveniently stamped for a cut-out in the back of the stock bumper. This is a very tidy solution. Note that this is a completely separate system from the 996 engine cooling system. TPC's intercooler system works extremely well; our instrumented tests showed that even during hard runs at full boost on an 80F day, the intake air was at ambient.
In stock form, the suspension and brakes of the 996 are stunning. So, naturally, Michael upgraded them. The results are incredible and put some stress on the writer. Sometimes even a Thesaurus can run short of superlatives. TPC essentially pushed the 996 in the direction of the Porsche GT3 Cup cars, like the two TPC race cars in the Grand-Am series.
Modifications to the suspension began with help from H&R's GT3 Sport coilover springs and shocks-a natural choice, since that's what the factory uses for the GT3 and its race cars. TPC chose relatively stock rates for this street version of a race suspension. Cup car uprights are used to allow mounting the larger brakes, and correct the bumpsteer inherent in lowering the car, while Cup car lower control arms allow camber adjustment with camber shims. Stock rubber bushings are retained
At the rear, the stock lower control arms are used with TPC spherical bearings to remove unwanted deflection and allow better control while keeping an excellent ride. Modified GT3 tie rods replace the factory toe arms, allowing more flexibility in wheel alignment. GT3 anti-roll bars are used front and rear. The result is a seemingly bionic connection between the driver's central nervous system and the car's response-think left, and there you are.
Brakes go from simply awesome (or some superlative of your choice) to a few steps beyond with the addition of the GT3 Cup car brakes-a tidy package using factory ABS with a modified bias adjustment and bright-red four-piston Brembo/Porsche calipers, gripping massive 13-in. rotors. Stock pads are used; they work well.
Ground contact is handled by what simply has to be the ultimate street tire: Michelin's Pilot Sport Cup. Sized at 225/40-18 up front and a whopping 285/30-18 at the rear, this soft-compound version of Michelin's extreme performance tire sticks like a race tire. Mounted on the newest BBS wheels, forged three-piece "Cup" wheels, the interface to the road is unbeatable
The Porsche tuner faces a two-edged sword in trying to make a great car better. The good news is that the 911 has always had "headroom"-a structure that allows for a greater performance envelope. The bad news? Porsche 911s are always so terrific to begin with that modifying them successfully is a tricky enterprise. TPC took that two-edged sword and swung it with abandon: With 338 bhp at the rear wheels, and almost 300 lb-ft of torque virtually everywhere, this is one 911 that melds commanding performance with Porsche's vaunted friendliness to the daily driver.