Roadster Renaissance - Three versions of tuned, topless fun

By E.K. Cozzene -- Turbo Magazine September 1997

The BMW Z3 roadster made quite a splash when it hit the market in late 1996. Fueled by an appearance in James Bond action/adventure movie "Golden Eye" and rave reviews in the media, the Bavarian drop top punched the buttons of many enthusiasts. Availability of a six-cylinder engine added more fuel to the fire. The enthusiasm meter should jump a few notches when the M-Roadster hits the streets in the Spring of '98 and a Z3 coupe in late '98. Why wait? Who needs M-Power when there's "the forced-induction solution."

The Turbo is nestled out of view, but the front mounted intercooler is a dead giveaway that this is no factory Bimmer. The 2.8 liter six cylinder has been boosted with an Aerodyne variable-vane turbocharger.

This particular light bulb flashed above the head of MechTech Motorsport's Jim McFarland. He soon acquired a Hunter Green 2.8-liter in-line six-powered Z3 and a battle plan was formulated that would bring turbocharged tenacity to the muscle-bound BMW. The plan included more criteria than raw power. The system had to feature bolt-on installation and 50-state legality was paramount. With these parameters in place, wrenches started turning.

The interior is outstanding and we really felt comfortable behind the wheel. While we did'nt put a lot of miles of the Z3, we ran nearly 1000 miles on the stock Z3 (in another article).

The Z3's engine, which is factory rated at 190 horsepower, runs a 10.2:1 compression ratio so intercooling was a definite necessity. Jim determined the best position for an intercooler was behind the front grille. This position ensured the air-to-air unit would get ample flow with as little piping as possible. The turbo system is transparent which will thrill those who like sleepers.

The turbo and most all of the ducting are located beneath the engine. The turbo used for the Z3 package is a MechTech/Aerodyne variable vane unit with custom housings. The variable vane concept speeds exhaust gases to the turbine wheel in low-rpm situations by closing off part of the housing via radially-placed vanes within the unit. When the unit's hinged vanes are closed, or lying on one another, the velocity of the exhaust gases increases providing usable boost at low engine speeds. As more exhaust gases are generated, the vanes open allowing for high-rpm boost. This "two-faced" personality is designed to give the turbo the responsiveness of a small turbo and the top-end performance of a large turbo. For the Z3 project, the Aerodyne is dialed in to provide five psi of manifold pressure. With only five psi of boost, the stock injectors were deemed up to the task. A Vortech boost-dependent fuel pressure regulator increases line pressure in accordance to boost. The ignition is factory BMW.

After the air/fuel mixture is fired off, exhaust gases are evacuated by a MechTech fabricated 2.5-inch exhaust that uses a stainless-steel Ultraflow muffler to deaden the 2.8's throaty howl. On the road, the turbo feels linear. Boost is produced so early in the rpm range that it is hard to detect. The 2.8-liter doesn't feel like a turbocharged engine, but like a bigger displacement engine. Driveability is unaffected which should be a pleasing attribute to the BMW owner.

The increased power output of the Mechtech Z3 is smooth through he entire RPM range. The results can be very eye opening for the unsuspecting red light victim.

At the strip the car lived up to its billing. During shakedown testing at Carlsbad Raceway, the Z3 clicked off 14.0-second e.t.s at 101 mph. This was running traction-limited 2.65-second 60-foot times in Carlsbad's slushy launch pad. Afterward, Jim took the BMW to a nearby open stretch of road. He ran 2.30-second 60 foot enroute to 13.58 and 13.60-second quarter miles at 103 mph.

With those numbers, the turbocharged Z3 makes a dramatic statement even without the Stinger missiles that 007's Bavarian bomber had. The MechTech package is a best of both worlds proposition with enhanced performance, unchanged driveability and the all-important 50-state legality. James, this is the car you should have used.

Contact us today to get your Z3/M3 Turbo kit.

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