Crank Case

CRANKCASE


The crankcase of the M5 is similar to the M62 engine and is manufactured from Alusil as aluminum alloy pressure die-casting. The cylinder walls are finished by honing only. The water cooling passageways of the block incorporate a connection in the "V" of the block for an oil/water heat exchanger.

The bore of the block is increased from 62mm (M62) to 94 mm. This along with an increased stroke of 6.3 mm gives the M5 engine a displacement of 5 liters. There is 3 mm between the cylinder bores of the engine.

CRANKCASE VENTILATION

Crankcase ventilation is controlled by the current pressure (vacuum) in the intake manifold. Blowby gasses that are produced when the engine is running are collected in the crankcase and flow into the manifold through two cyclone separators. The separators are mounted at the left and right sides at the front of the timing case. Any liquid in the blowby gasses is separated and flows back directly to the oil sump through a return hose.

The crankcase ventilation system is completely sealed. Hose clamps are used at all connections to ensure that the system does not contain any leaks. Care must be taken when servicing the system as sections of the pipes and hoses are covered by the accessory drive belts.

CRANKSHAFT/CON RODS/PISTONS

The crankshaft is forged steel with five main bearings and the thrust on number five bearing.

The connecting rods are cracked steel, similar to the sintered rods used on the M 62 engine. The mating surfaces of the rod and cap form a rough surface (interference fit) that allows the elimination of the centering sleeves. All con rods are produced with the same weight class by forging counterweights on both the bearing and pin ends. The rods are then machined until they are the same weight class.

The pistons are short skirt design and are coated with a Ferrostan/tin alloy for use with the Alusil block (similar to the M62). The piston height is 51.1 mm with a diameter of 94 mm. There is no thermal control strips in the pistons. The pistons are cooled with S62 specific spray jets, mounted in the crankcase. the compression ratio is 11:1 and requires super unleaded fuel for optimum performance.

The pistons for cylinder bank 1 - 4 are different from cylinder bank 5 - 8 due to the off set for the con rods. The relevant cylinder bank number is engraved into the piston crown using laser technology.