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BMW Art Car 35th Anniversary

BMW M3 GT2: The Legend Is Back on the Track

Already in its fourth generation, the BMW M3, the high-performance sports car developed by BMW M GmbH based on the BMW 3 Series Coupé, demonstrates impressive sportiness – whether it’s the BMW M3 Coupé for road traffic, the BMW M3 GTS for club racing events, or the BMW M3 GT2 at endurance races and GT classics.

BMW Motorsport Director Mario Theissen says: “The series model of the BMW M3 has sportiness in its genes. For this reason it was a natural progression for us to develop a racing version of this car. The fact that the BMW M3 production model is driven by a powerful V8 engine gave us the ideal foundation.” When starting the development of the BMW M3 GT2 in the mid-2007, the BMW Motorsport engineers were faced with the ambitious task of taking a car already designed for sportiness to an even more sporty level. They could hardly have imagined a better starting point for this mission than the BMW M3, as the production model itself boasts powerful dynamics.

The series version’s eight-cylinder engine with 4.0-liter capacity produces an impressive 420 bhp. It’s a close relative to the V8 powerplant that had been developed for BMW’s Formula One project. The BMW P65 engine, derived from this unit powers the BMW M3 GT2, and has been further enhanced within the GT2 regulations. The eight individual throttle butterflies receive their intake air via a system made of carbon fiber with load-charge optimized ram tubes. The mechanics have been adjusted to meet the extreme demands of GT and endurance racing: as a result, the BMW P65 has a steel crankshaft, forged skirt pistons, high-performance steel conrods and a dry sump lubrication system. This allows the engine to achieve 500 bhp, depending of the diameter of the air restrictor.

Due to this the BMW M3 GT2 is capable of sprinting from 0 to 60 mph in just 3.4 seconds. With 500 ccm per cylinder and the stroke to bore ratio of 72.5 x 92 millimeters, the engine meets the ideal requirements of demanding engine designers. The cylinder block is designed with a bedplate lower section and made of a special aluminum alloy. The unit’s dimensions, capacities, number of components and extremely light weight make it the perfect engine to use on the race track.

Intelligent control systems are at work in the BMW M3 GT2. Via two bus systems, the POWER400 control unit operates such functions as headlamps and taillights, wipers, etc. Traditional relays and fuses are thus eliminated, realizing considerable weight savings, improved reliability and ease of operation. The functions of the BMW P65 engine are managed by an ECU408 electronic control unit, developed in-house by BMW Motorsport. This unit uses two high-performance micro-processors to control the individual cylinder injection and ignition, the BMW Motorsport Lambda controller and the engine data memory system, among other things.

The ECU408 monitors the “Quick Shift” function of the six-speed sequential gearbox on the BMW M3 GT2, which suppresses the ignition when changing gear, thus allowing even faster gear changes. The compact transmission unit is positioned on the rear axle to allow optimal weight distribution. The driver is assisted by a mechanical limited slip differential and traction control.

The engineers also have upgraded the chassis system. The front and rear axles on the BMW M3 GT2 have an increased wheel castor angle, enlarged track width and greater wheel camber than its series counterpart. The shock absorbers can be adjusted five ways and tubular stabilizer bars can be used to set up the car for a specific track.

Weight optimization plays a significant role in the development of a racing car. Building on the road model’s lightweight construction and carbon fiber roof, the BMW Motorsport engineers consequently realized further weight savings in the BMW M3 GT2. The use of high-tech carbon fiber reinforced plastics (CFRP) played a crucial role in achieving a low weight of just 1,150 kilograms. The BMW M3 GT2’s roof, front and rear aprons, hood, deck lid, rear spoiler, front wing, and flared rear wheel arches are all made of carbon fiber.

The aerodynamics of the BMW M3 GT2 were fine-tuned using computational fluid dynamics (CFD). It was also possible to optimize the geometry and kinematics of the chassis and determine the most efficient placements for axle attachment points. At the same time, elaborate calculation programs also made it possible to simulate distortion of the chassis under extreme strain. Using extensive investigations in the wind tunnel, the engineers were able to verify the results of the CFD calculations before starting to build particular components. As a result of the experience gained during the Formula One project, maximum reliability and precision during these wind tunnel tests could be applied.

A sophisticated air conditioning system keeps the drivers comfortable, when they are at the wheel of the BMW M3 GT2. At the Le Mans 24-hour race, for example, regulations stipulate that temperatures in the cockpit must not exceed 32 degrees Celsius. Following a pit stop this temperature needs to be reached again within eight minutes. In order to design the cooling as effectively as possible and minimize cooling requirements, the passenger compartment was limited by inserting a plastic screen behind the driver seat.

Only one aspect has had a higher priority for the BMW Motorsport engineers when developing the car than performance: driver safety. A safety cell made from extremely rigid, precision steel tubing is used in the BMW M3 GT2. This is welded into the unibody steel construction and effectively protects the driver in the event of a collision. The development and design of the safety cell, which is produced by experts at the BMW Plant Regensburg, takes place using CAD constructions and computer-aided simulations. BMW Motorsport is certified by the FIA as a CAD institute for safety cells.

On the track, the drivers are strapped into a new safety seat, developed by BMW Motorsport, using a six-point harness. In the case of an accident, both seat and driver can be lifted out of the car through the roof. Also, drivers are protected by HANS (Head-and-Neck Support), energy-absorbing foam in hollow sections, and crash pads in the doors.

While high-performance compound brakes ensure excellent deceleration in the BMW M3 Coupé, the brakes in the BMW M3 GT2 have a fixed-caliper design. The aluminum brake calipers consist of six pistons on the front wheels and four pistons on the rear wheels. The inner-vented grey-cast iron brake discs on the BMW M3 GT2 have a diameter of 380 mm at the front and 332 mm at the rear.

As development partner of BMW Motorsport, Dunlop equips the BMW M3 GT2 with high-performance racing tires, which optimally transfer the acceleration and braking torque to the track and are able to withstand extreme lateral forces. The tire manufacturer has been involved in the development of the GT sports car right from the beginning. The BMW M3 GT2 takes to the track on 18-inch wheels with aluminum rims.

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