BMW showcases new carbon fiber reinforced plastic production process with M3 CRT; process to produce components for i3 electric and i8 PHEV models
BMW M GmbH used the M Night Event in the lead-up to the Nürburgring 24-hour race to unveil the BMW M3 CRT (Carbon Racing Technology). The M3 CRT represents the worldwide debut of a new production process for carbon-fiber reinforced plastic (CFRP) components in the automotive industry. This process helps the sports car achieve a weight-to-power ratio of 3.5 kilograms per horsepower (7.7 lbs/hp).
The hood of the BMW M3 CRT and the bucket seats for the driver and front passenger are made from a cellular carbon honeycomb, which is produced in a globally unique process pioneered for the manufacture of body components for the battery-electric BMW i3 and plug-in hybrid BMW i8 models. (Earlier post.)
These new models—due to enter volume production in 2013 and equipped with electric and BMW ActiveHybrid drive system technology—will feature a body consisting entirely of CFRP in the passenger cell area. In a new development, the production process introduced for this purpose enables the cuttings left behind in the construction of the body to be reprocessed.
The basic material (made up of carbon fiber thread) can now be woven into CFRP mats of any size before being impregnated with synthetic resin and hardened in a similar way to the material used in the body of the BMW i3 and BMW i8.
For the BMW M3 CRT this allows the creation of a hood made from two CFRP moldings encasing an aramid honeycomb structure. This construction imbues the hood with the strength of a conventional steel equivalent, but at roughly a quarter of its weight. The weight saving over the aluminum hood of the standard BMW M3 Sedan is around 50%.
The material produced through this manufacturing technology is also used for the car’s bucket seats. Here, the CFRP layers are wrapped around a recycled-paper honeycomb, with a carbon layer made using conventional production technology added to visible areas. CFRP is also used to make both the rear spoiler of the BMW M3 CRT and an air-channeling element integrated into its front fascia.
This innovative manufacturing process opens up considerable potential for increased use of CFRP in series-produced cars as a means of lowering weight, BMW says.
BMW M3 CRT. The BMW M3 CRT is the latest in a series of exclusive high-performance sports cars optimized with the help of lightweight design. A V8 engine with customary M high-revving characteristics and maximum output of 331 kW/450 hp accelerates the BMW M3 CRT from 0 to 100 km/h in 4.4 seconds. The BMW M3 CRT will be produced by the BMW M GmbH factory in a limited run of 67 units. Due to the very limited worldwide volume, the BMW M3 CRT will not be homologated for sale in the USA.
Under the CFRP hood of the BMW M3 CRT lies a variant of the V8 engine developed exclusively for the BMW M3 with further increased displacement, output and maximum torque. Tuned for the BMW M3 GTS, the eight-cylinder engine develops 331 kW/450 hp from its 4,360 cc displacement. Maximum output is reached at 8,300 rpm, with peak torque of 440 N·m (325 lb-ft) on tap at 3,750 rpm. The engine incorporates some elements derived from motorsport, including a bedplate crankcase construction in a special aluminum-silicon alloy, individual throttle butterflies, a knock control system with ion current technology and a dynamically-optimized wet sump oil supply.
Transferring the engine’s power to the rear wheels is the M double clutch transmission (DCT) with Drivelogic developed for the BMW M3. The seven-speed M DCT Drivelogic unit also works according to a principle developed in motorsport, allowing an uninterrupted flow of power through gear changes to deliver extremely dynamic acceleration. Its shift characteristics have been tuned specially for the engine powering the BMW M3 CRT. Shift paddles on the steering wheel allow the driver to change gear manually with optimum ergonomics.
The electronic engine management of the BMW M3 CRT caps its top speed at 290 km/h (180 mph).