We have the first technical details of the new BMW M3 sedan and M4 coupe – both will be powered by a 3.0 litre S55B30 twin-turbo straight-six that develops around 430 hp and more than 500 Nm of torque, outstripping the outgoing V8-powered M3's figures by over 30%.
The engine is mated to an optional seven-speed M DCT with DriveLogic and launch control. The Active M diff is now electrically-actuated, constantly varying the locking effect. M Dynamic Mode - a sub-function of DSC - is present as well.
Boasting direct injection, Valvetronic and Double Vanos tech, the motor can rev up to 7,500 rpm. It features a closed-deck crankcase design, allowing increased rigidity and cylinder pressures. The cylinder bores feature a twin-wire arc-sprayed coating instead of liners, saving weight.
Also, a forged, torsionally-rigid crankshaft provides increased torque-carrying capacity. Its reduced rotating masses improve throttle response and acceleration. Fuel consumption and emissions are down by about 25%, while the vehicles themselves weigh under 1,500 kg.
Keeping things cool, apart from the main radiator, are radiators for the high- and low-temperature circuits, turbocharger and gearbox, plus a temperature-stabilising electric water pump and an indirect intercooler.
Under strong lateral acceleration, a magnesium oil sump with a special cover limits oil movement, while an oil extraction pump and a sophisticated oil return system ensure circulation is uninterrupted. Electrically-controlled flaps in the twin tailpipes provide the soundtrack, while minimising back pressure and giving feedback on engine load.
Suspension is taken care of by a double-joint spring strut front axle and a five-link rear axle. The control arms, wheel carriers and axle subframes are made out of aluminium, while an aluminium stiffening plate, CFRP front strut brace and extra bolted joints between the axle subframe and body sills all help to increase rigidity.
The electromechanical steering and optional Adaptive M suspension both offer Comfort, Sport and Sport+ settings. M compound brakes are standard; for even greater stopping power, carbon ceramic brakes are available as an option.
Large front air intakes, exposed CFRP components and the rear diffuser are as much about function as form. Reducing unwanted lift are the front apron, smooth underbody and 'Gurney' rear spoiler lip (integrated spoiler lip on the M4), while the Air Curtain and M gills with Air Breather minimise turbulence in the front wheel arches.
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