BMW V12 engine

2010-11-26T18:01:45Z

75.176.11.92: BMW V12 Engine

A BMW V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft.[1]

Since each cylinder bank is essentially a straight-6, this configuration has perfect primary and secondary balance no matter which V angle is used and therefore needs no balance shafts. A V12 with two banks of six cylinders angled at 45°, 60°, 120°, or 180° from each other has even firing with power pulses delivered twice as often per revolution as, and is smoother than a straight-6 because there is always even positive net torque output with little variation. This allows for great refinement in a luxury car. In a racing car, the rotating parts can be made much lighter and thus more responsive, since there is no need to use counterweights on the crankshaft as is needed in a 90° V8 and less need for the inertial mass in a flywheel to smooth out the power delivery. In a large displacement, heavy-duty engine, a V12 can run slower than smaller engines, prolonging engine life.

*Used in the Mclaren F1 angled at 60° and other Series of Cars.

BMW has made 5 and 6-liter engines for the 7 Series and 5-liter engines for the 8 Series model cars. BMW Motorsport also made a 5.6-liter unit for the 850 CSi. All 5-liter 12-cylinder engines are 2 valve per cylinder units, while the new 6-liter engine has 4 valves per cylinder.

BMW has made 5 and 6-liter engines for the 7 Series and 5-liter engines for the 8 Series model cars. BMW Motorsport also made a 5.6-liter unit for the 850 CSi. All 5-liter 12-cylinder engines are 2 valve per cylinder units, while the new 6-liter engine has 4 valves per cylinder.

7 Series
The latest 7 Series models with V-12 power are the 760. This DOHC engine has 322.4 Kw / 438.00 BHP @ 6000.00 RPM with torque of Nm / 444.00 Ft-lbs @ 3950.00 RPM.

12-cylinder engine

The E38 750iL, offered through 2001, was powered by a V-12 of 5.4 liters with single overhead camshafts and 2 valves per cylinder. The engine's output was 326 horsepower.

The V-12 powering the new 760Li is a new design with 6.0 liters of displacement, dual overhead camshafts (per cylinder bank) and 4 valves per cylinder. Designated the N73, it is also related to the N62 V-8 engine that powers the two 745 models.

The V-12 configuration has long been recognized as an ultimate power plant concept, suited for top-class vehicles. According to BMW, its physics are ideal: 12 cylinders arranged in a 60° "vee" of two cylinder banks are perfectly balanced; combined with the relatively even power pulses of so many cylinders, this results in an extremely smooth propulsion unit.

Direct Fuel Injection

BMW's N73 is the first direct-injected V-12 engine ever offered in a production automobile, and the first direct-injected gasoline engine to meet contemporary emission control standards.

Direct fuel injection means injection of the fuel directly into the combustion chamber, rather into the intake port as is the norm. It has been chosen and developed by BMW's power train engineers to boost power output and fuel efficiency to higher levels than could be achieved with conventional fuel injection.

BMW's system operates on a stoichiometrically optimum fuel-air mixture and can be emission-controlled by conventional, proven 3-way catalyst technology. By contrast, other direct-injection concepts currently under development in the auto industry (such as lean-burn or stratified-charge) can achieve greater fuel-efficiency gains than the concept chosen by BMW, but these depend on unproven "deNOx" catalyst technology and require sulfur-free fuel, which is not universally available.

Checkered Flag

BMW's highest performance V-12 was made for the McLaren F1 sports car.

McLaren Engine
Model BMW S70/2
Type 6.1 liter, 48 valve V-12 with aluminum block and heads, 627 bhp
Bore and stroke 3.38 x 3.41 in (86 x 87 mm)
Displacement 370 cubic in, 6064 cc
Compression ratio 10.5:1
Engine control system Bosch Motronic with port fuel injection
Emissions controls 3-way catalytic converter feedback fuel-air-ratio control auxiliary air pump
Valve gear Chain-driven double overhead cams, 4 valves per cylinder, hydraulic lifters, variable intake timing
Power (SAE net) 618 bhp @ 7400 rpm
Torque (SAE net) 479 ft-lb @ 4000 rpm
Redline 7500 rpm

The McLaren F1 with the BMW S70 engine had a 0-60 mph time of 3.1 seconds and a top speed of 230-240 mph. The McLaren set the world speed record of 240.1 mph for the fastest production car in March 1998.

The engine for the McLaren F1 LM model produced 680 hp and 520 ft-lbs of torque! Issued in honor of the McLaren F1's that won the 1995 LeMans race, the LM's set a 0-100-0 mph world record for a production car by ripping through the tach in a gut wrenching 11.5 seconds while traveling a distance of only 828.4 feet!

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BMW V12 engine