Deel 1:
The package would be unique. While others have drifted BMW 3 Series models, the new GSR Autosport "BMW 350R" (acknowledging the 5.0-liter V10) would be the first all-BMW model in the field–a pure German drift car. The team set a target weight of 2,700 pounds (the stock "E92" 335i weighs 3,571 pounds) and 550 horsepower (a stock "S85" V10 puts out 500 horsepower). The transmission would be a custom sequential gearbox and the custom rear end would be fitted with a quick-change clutch-type rear differential to offer adjustability for different tracks. Wheels, suspension and all of the other go-fast parts would come later. The hunt for a donor 335i and V10 engine began...
Deel 2:
Deel 3:Starting with more than 100 feet of DOM (drawn over mandrel) steel tubing (1.75 x .095), Michael Essa measures, cuts, bends and welds a custom roll cage complete with race gussets. Once complete, the stunning metalwork is primed gray. The stock 335i battery cable (made of aluminum, not heavy stranded copper) is shortened and relocated from the underbelly to within the cabin. The rear crossmember in the chassis is redesigned and reinforced to accept the new rear differential. The stock subframe bushings are replaced with solid units. Custom motor mounts are fabricated, and the transmission tunnel altered to accept the new engine (the stock inline-six is long by design, so fitting a rather-compact V10 in the same space wasn't too much of a chore). Formula Drift rules dictate that the engine cannot be moved further rearward than the stock firewall.
The engine, a stock 5.0-liter V10 (S85B50) yanked from the donor M5, is moved into place complete with its factory cooling system (the engine weighs 50 pounds more than the N54). The stock air intake is removed and an AEM DryFlow dual-cone intake is fitted. Internally, the engine is left stock and GSR Autosport runs OEM BMW factory synthetic oil. (The factory oil sump has two oil pumps-one on each side of the engine. Under high cornering loads the pumps automatically pull from the side with more oil, thus preventing oil starvation.) The radiator is filled with water and a wetting agent. While the stock M5 exhaust headers are used, the catalytic converters are removed and a custom 2.5-inch dual exhaust with an X-pipe is aimed right out the back. There are no mufflers, so the blare of the rev-happy V10 should drown out the sound of spinning rear wheels.
Nearly all of the engine electronics are custom. Apex supplies a hand-made wiring harness and a unique engine map run through a custom Pectel ECU. The digital dashboard display is a Pi Omega. Thanks to the custom engine management software, redline is increased from a stock 8,250 to 8,400 rpm.
The car, still missing its front bumper, hood, roof and windows, isn't exactly done... but it needs to put some time in at the track to be honed. The team loads the 350R into a closed trailer and heads for Willow Springs International Motorsports Park in Rosamond, California.
Willow Springs Speedway, a quarter-mile paved oval, is the smallest track at the desert complex (not counting kart tracks). It's a lousy road course, but the open figure-eight is the perfect grounds for testing a drifter. Unloaded from the rig, fully fueled and running an engine map borrowed from a performance-tuned street M5, Michael takes a few hot laps to get a feel for the car. Then he takes many, many more.
Over the next several hours, shock settings are tweaked, springs are adjusted and tire pressures are both bled and increased. The final settings are as guarded as the recipe for Coca-Cola.