Active Autowerke exploded onto the BMW scene more than a decade ago with a turbocharger system for the E36 BMW. The cars coming out of its Miami-based facility were hands down the quickest BMWs in the country. I drove a few of them and walked away weak-kneed and whiter than usual. You don't forget thrust like that...ever.
Ten years is a long time, and while I still remain a big fan of AA's turbo systems, I could easily give it all up for its new take on forced induction (yes, AA still does turbos and yes, they remain terribly fast, so relax). AA has developed a supercharger system for the current generation of BMW 3 Series that is quite possibly the best tuner program this writer has experienced. Powerful, smooth, quiet, AA's supercharger system has the refinement BMW owners expect and deserve.
The AA supercharger system is a fairly straightforward piece of work, basically just an air pump driven off the crank pulley. What makes AA's system special is the brilliant attention to detail. This is a genuine turn-key kit that can be installed in less than a day. It fits as though placed there by the factory, and its bits and pieces are wrought largely from O.E. stock. The Rotrex supercharger, made in Denmark, has jewel-like internals and is virtually silent on idle. The Rotrex blower is programmed to run 6 psi of boost and features its own proprietary lubrication system, filled with a viscous-like fluid supplemented with the firm's own front-mounted cooler.
Under hard boost there is a distinct whoooosh as though a booster rocket had fired. It's quiet in the cabin, but the noises coming from the exhaust are like feral music. And while the hardware of the AA supercharger system is beyond reproach, it would be wasted without the proper software. I must say this system is a tremendous victory for computer geeks everywhere. Barry Elton, a former software engineer, is responsible for a large part of the kit's design and fabrication and, ultimately, getting everything to work with the factory ECU.
"Making the hard parts is relatively easy" said Barry. "I'd say 85% of the work is in the programming. We spent months on this system, testing and re-testing on our Mustang dyno. It's tedious and time consuming, but that's what it takes with modern cars."
Given the fact Barry was working within OBD II parameters, it is a worthy feat of engineering. OBD II is so sensitive it can detect a pinhole leak anywhere within the engine. That the AA supercharger system runs flawlessly with nary a fault code or engine light to be seen speaks volumes of his work.
"You cannot trick OBD II," added Barry. "You need to work within its parameters...we don't try and fool it into thinking something else."
AA brought three incarnations of BMW's vaunted 3-Series: a pristine 325Ci owned by Yohancef Chin, a 330Ci belonging to Martin Elmore, and AA's shop M3. Karl Hughes of AA thought it would be a good idea to progress from a base car to its most powerful supercharged iteration.
The cars gathered at AA were devoid of "bling." These guys are only interested in performance and the cars, to the untrained eye, look largely stock. Yohancef actually borrowed a set of 18-in. Mille Miglia wheels for the occasion in the same way someone would rent a tuxedo-you know, make a good impression. Yohancef's BMW was running the Rotrex supercharger in SP30/94 trim, producing 8 psi. On AA's dyno, the car made 250 whp and about as much torque. It ran like every other 325Ci I'd driven; the only difference was this one was much faster. At 1:30 p.m., Yohancef's BMW was my favorite car.
Next in the line-up was the 330Ci of Martin Elmore. Martin is a software engineer for Motorola (I told you, the geeks are taking over) and helped Barry work out some the 330's software coding. On the Mustang dyno, the 330 was producing 277 whp, nearly 80 whp more than in stock trim. Martin has put some 30,000 miles on his car, every one of them with the supercharger. "I drive about 100 miles each day" said Martin. "Florida is pretty damn flat, with lots of long, straight roads. Let's just say the AA supercharger is definitely put to good use. While the distance I drive has not been reduced, the time it takes to get there sure has."
Martin's car was augmented with BBS RC wheels (borrowed) and Intrax coilovers. Boost comes on so smooth and so fast I found myself hitting the rev limter with each shift. At 2:00 p.m., Martin's BMW was my favorite car.
Last on the list was the Imola Red M3 that served as AA's test mule. Hardware-wise, the M3 was significantly different than the other two, as its engine was never intended to see increased boost. The intake manifold and velocity runners were eliminated and replaced with AA's proprietary system. "We tried using the stock intake manifold, but it was in danger of bursting," said Karl Hughes. "The whole thing was literally bulging at its plastic seams. We fabricated a new manifold from aluminum...it's much stronger."
The M3 also required more work be done on the software, as Barry needed to program two systems, the double VANOS and the engine itself. At my insistence, Barry showed me a few pages of the M3's hexamidecimal coding-I thought my head would explode. How AA managed to crack this seemingly random series of numbers is, to my feeble intellect, nothing short of a miracle. Not only did they crack it, they improved its efficiency. The M3 produced 265 whp in stock trim. After the supercharger, it was making 360 whp, almost an extra 100 ponies. As a safety precaution, the rev limiter was reduced to 7600 rpm; it was no longer necessary with 7 psi of boost.
The M3 sat over Ground Control coilovers and camber plates, which came in handy over the reptilian Florida pavement. At the insistence of Prestige, an AA crew member, I found several miles of open pavement and let it fly. At 150 mph, the M3 was still pulling, and I would have continued if not for the irregular surface. Like the other AA BMWs, this M3 was perfect, just like a stock car, only much, much faster.
Perhaps the most asked question today's performance enthusiast asks is, "Do I go turbo or do I go supercharger?" I just answered it myself in Project Corrado SLC with the VF-Engineering supercharger. In the case of AA's offering of two approaches to boosted performance, I think it all comes down to how you use your car. If it's a daily driver, I'd say go with the supercharger. Its reliability is on a par with a hammer, and its power delivery is virtually the same as the stock curve, only much higher. That means the transmission and associated bits are not subjected to the stressful torque of a turbo. And the car's demeanor and driveability remain basically unchanged. You walk away from AA BMWs thinking you just drove a very powerful factory car.
AA still does turbos, and the system just keeps getting better thanks to the geeks down south. If I wanted a second car just to play with, I might consider an AA turbo. Until then, make mine supercharged.