For the first time ever: an eight-cylinder in a BMW M3 Convertible.
After a great 15 years, the straight-six power unit featured in the two preceding generations of the BMW M3 and lauded several times over as the Engine of the Year has now found a worthy successor: For the first time all model variants of the new BMW M3 come with an eight-cylinder power unit.
The specifications of this all-new high-performance V8 clearly prove the competence of the engine specialists at BMW M GmbH derived directly from motorsport: Displacing 3,999 cc, the new V8 develops a supreme 309 kW/420 hp. Maximum torque of 400 Newton-metres or 295 lb-ft, in turn, comes at an engine speed of 3,900 rpm. And some 85 per cent of this maximum torque is readily available throughout the enormous engine speed range of 6,500 rpm.
The eight-cylinder nevertheless owes its most outstanding characteristics to the high-speed engine concept so typical of BMW M. Because revving all the way to 8,400rpm, the engine boasts truly shattering thrust and flexibility.
The experience of power and muscle is therefore simply unique all the way. Power is transmitted to the rear wheels by a six-speed manual gearbox and the all-new final drive.
This combination of engine and transmission provides a feeling of acceleration quite comparable in its spontaneity and ongoing surge of power to the dynamic potential of the most supreme high-performance thoroughbred sports cars.
Apart from specific output of 105 hp per litre, average fuel consumption of 12,9litres/100 kilometres (equal to 21 mpg imp) determined in the EU test cycle is a clear expression of the engineering art and outstanding skills of the engine development specialists at BMW M GmbH. Through this quality alone, the new BMW M3 Convertible ensures a standard of efficiency quite unique in the small segment of open high-performance sports cars.
Weighing just 202 kg or 445 lb, the V8 power unit of the new BMW M3 is a genuine lightweight. Indeed, it is even 15 kg or 33 lb lighter than the engine in the former model – a six-cylinder.
Production of components using know-how from Formula 1.
The engine block on the new eight-cylinder comes from BMW’s light-alloy foundry in Landshut just north of Munich, which also builds the engine blocks for the Formula 1 cars raced by the BMW Sauber F1 Team. The crankcase is made of a special aluminium-silicon alloy making conventional cylinder liners superfluous, since an appropriate cylinder surface is provided by the hard silicon crystals, the iron-coated pistons running directly in this uncoated, honed bore.
With high engine speeds and combustion pressure putting extremely great loads on the crankcase, the crankcase is compact and extra-strong in bedplate design, ensuring very precise and smooth running conditions for the crankshaft.
The forged crankshaft itself is extremely strong in terms of bending and torsional stiffness, while at the same time it only weighs about 20 kg or 44 lb.
Valve management by double- VANOS using engine oil pressure.
The V8 power unit within the engine compartment of the BMW M3 Convertible is equipped with variable double-VANOS camshaft control. Keeping valve adjustment times to a minimum, this technology reduces losses in the charge cycle and improves engine output, torque and response accordingly, with an appropriately positive influence on both fuel consumption and emissions.
A low-pressure version of double-VANOS has been developed especially for the new eight-cylinder to ensure ultra-short and fast adjustment timing even under normal engine oil pressure.
A separate throttle butterfly for each cylinder is the supreme technology not only on a racing engine when it comes to ensuring an immediate response at all times. Which is precisely why the new power unit features eight individual throttle butterflies, two adjuster motors each controlling four throttle butterflies on each row of cylinders. This guarantees a particularly smooth and sensitive response of the engine at low speeds combined with an immediate reaction as soon as the driver calls up more power on the gas pedal.
A smooth and consistent supply of lubricant to the eight-cylinder is ensured by the volume flow-controlled pendulum-slide cell pump delivering exactly the amount of oil required by the engine at any given point in time. Wet sump lubrication optimised for driving dynamics keeps the flow of lubricant consistent and sufficient even in extreme braking manoeuvres, with the system boasting two oil sumps – a small one upfront of the front axle subframe and a larger sump further back. A separate duocentric reflow pump, finally, serves to extract the oil from the front sump and pump it to the rear.