BMW has revealed details of the M Performance twin-turbo V12 gasoline engine that will power the new M760Li xDrive.
The 6,592cc unit produces 600ps at 5,500rpm and maximum torque of 800Nm from 1,500rpm, with a 0-100km/h time of 3.9 seconds and a limited top speed of 250km/h, which can be optionally increased to a higher limit of 305km/h.
Fuel consumption in the V12 7 Series application is 12.6 l/100km (18.7mpg) and CO2 emissions are 294g/km.
The engine is an upgraded in-house version of the N74B66 unit that has seen action in the Rolls-Royce Ghost, Wraith and Dawn. The new unit has been tweaked mainly for the purpose of improving fuel consumption.
The engine uses two mono-scroll turbochargers, high-precision fuel injection and double-vanos variable camshaft timing to extract performance.
BMW says that the turbochargers are as efficient as possible thanks to a compact arrangement on the outside of the 60° angled cylinders. The company says that their positioning provides the ideal platform for short, straight and therefore flow-efficient pipe connections between the exhaust system and the turbochargers.
The precision injectors are positioned centrally in the cylinder head to precisely measure out fuel and spray it into the chamber at up to 200 bar of pressure. The fuel is dispersed according to an ideal model calculated in complex processes, allowing for extremely consistent and clean combustion.
BMW says that the process has a positive effect on emissions and engine acoustics, and the mixture cooling brought about by the directly injected fuel also allows a higher compression ratio than that achieved by a turbocharged engine with manifold injection.
The double-vanos continuously variable camshaft timing means the engine can run under part loads with a high level of residual gas and reduced throttle losses, maximizing fuel efficiency. The V12’s oil supply to the M Performance 12-cylinder engine has been similarly optimized. Its volume flow-controlled pump operates only when required and is therefore extremely efficient.
A focus on maximizing rigidity on the all-aluminum block was realized by using a closed-deck structure combined with bolts holding the cylinder head down on the floor plate of the crankcase to ensure maximum stability on the cylinder liners.
Double bolts on the main bearings with an additional connection to the side panels through threaded support bushes and bolts reduce the influence of lateral forces from the crankdrive on the crankcase.
Further components of the engine block that serve to reduce vibrations and noise to an absolute minimum are iron-coated aluminum pistons, forged connecting rods assembled using the cracking process, and a likewise forged crankshaft.
February 17, 2016