Specialty File
Our affection for the BMW 3-series is no secret. We've awarded the sporty Bavarian cars enough 10Best trophies to bow a 10-inch-thick oak mantel and likely enough comparison-test victories to swell the engineers' heads to the size of beach balls. That is, after all, why we call them "benchmarks."
Messing with perfection is always a risky proposition. But that's exactly what Active Autowerke in Miami has done with the very nearly perfect 3-series—in this case, a 2002 330i model with a five-speed automatic (the kit is available for any E36 or E46 3-series with a manual or automatic transmission). To the AA guys, the best way to spice up the 330iA was, naturally, to give it more power—albeit in an unnatural way.
They bolted on a Rotrex SP30-94 centrifugal supercharger that forces a maximum of 7.5 psi of boost into the Bimmer's 3.0-liter inline six-cylinder engine. AA went with the Rotrex unit because of its compact design and relative ease of installation—no moving or modifying the throttle body as with a Roots- or screw-type supercharger. This particular Rotrex features a self-contained oiling system.
AA estimates installation to be a 12-hour job, and it charges $1000 to install the $6500 supercharger kit. There's no charge for voiding BMW's factory warranty. The kit includes an installation guide on a CD, technical support, a front-mounted intercooler, higher-flow fuel injectors, a bypass valve, mandrel bent tubing, high-temperature hoses, and a K&N air filter.
According to AA, the kit bumps horsepower from 225 at 5900 rpm to 310 at 6500, and torque goes from 214 pound-feet at 3500 all the way up to 280 pound-feet at 4750. An M3 makes more horsepower (333) but at a stratospherically high rpm number (7900) and can't match the AA's torque, mustering just 262 pound-feet at 4900. AA further says you can add a nominal nudge of eight ponies if you purchase a $679 high-flow stainless-steel exhaust system that was fitted on our tester.
With AA's claim of 318 horsepower onboard, its car ripped from 0 to 60 mph in 5.5 seconds and clipped the quarter-mile in 13.9 at 102 mph. The numbers are quicker than those posted by the hottest 330i currently available—the 235-hp, six-speed-manual 330i with Performance package, which hit 60 in 5.6 seconds and turned the quarter in 14.3 at 97 mph [ C/D, September 2003]—but still slower than the last M3 we tested ["Compact Adrenaline-Delivery Systems," May 2003], which met those marks in 4.8 and 13.6 at 105, respectively. That M3, like the 330i with Performance, was equipped with a shift-it-yourself six-speed, and since we've never tested a current-gen 3-series with an automatic transmission, a direct comparison is impossible to make. Had AA been able to supply us with a manual example, we believe the car would chop about a half-second off 60-mph and quarter-mile times and be a lot closer to the M3's. As they were, they came right on the heels of another supercharged über-sedan, the 349-hp Mercedes C32 AMG, which recorded 0 to 60 in 5.2 and the quarter-mile in 13.6 [C/D, May 2003].
Nonetheless, the AA's times are quick, and reflective of how the supercharger transforms the 330iA from a stellar stock sedan into the closest thing to a four-door M3—not to mention one with a silky slushbox that makes it gridlock friendly. Furthermore, the Rotrex unit delivers its oomph with no unwanted surges or hiccups, but rather with the smoothness and refinement of the factory-installed unit of, say, a C32. Throttle response was excellent, and the Steptronic automatic always seemed to be in the desired gear. And whereas many centrifugal blowers tend to whistle like upset teakettles, the Rotrex kept a lid on the dissonance, emitting just enough sound to remind you where your money went.
Besides the supercharger kit and fancy exhaust system, the AA 330iA was left mostly stock. The only other modifications were harder-compound front brake pads and Michelin Pilot Sport PS2 rubber. The tire upgrade netted a sticky skidpad number of 0.91 g—better than the M3's 0.87 and the 330i Performance's 0.86—and together with the higher-performance pads achieved a fade-free 70-to-0-mph braking distance of 164 feet, an unexpected three and six feet longer, respectively, than the other BMWs' lengths.
Our friends at Active Autowerke are already planning to bring a supercharged M3 to our upcoming supertuner shootout. If that car ups the ante over an M3 like the blown 330i did to its naturally aspirated counterpart, then AA might have a chance to bow its mantel with one of our trophies.
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Active Autowerke, 9940 S.W. 168 Terrace, Miami, Florida 33157; 305-233-9300; www.aatuning.com.
