Engine Block
The engine block of the N74 engine is a new design. It is similar to the N63 engine concept, but with a cylinder bank angle of 60° and the following features:
- Block made of an aluminum alloy (Alusil)
- Closed deck crankcase design
- Honed cylinder liners
- Lowered side walls (deep skirt) with main bearing caps
- Double main bearing bolting with additional side wall connection.
The closed-deck design and the bolt connections of the cylinder heads in the bottom of the cylinder housing ensure high rigidity and low deformation of the exposure-honed cylinder liners.
The crankcase with lowered side walls (deep skirt) has double main bearing bolting with additional side wall connections by means of threaded support sleeves and bolts designed to absorb the lateral forces from the crankshaft common on the V-engine configuration.
There are coolant passages to cool the (hot zone) area between the cylinders. In order to keep the pumping losses in the crankcase to a minimum, there are one to six ventilation holes below each of the main bearing seats.
The use of separate channels for the oil return from the cylinder heads and for crankcase ventilation reduces the amount of oil in the blow-by gases.
As on the N63 engine, the torque converter is bolted onto the flywheel through an opening in the converter housing with six bolts positioned at an angle of 30°. This makes it easier to replace the transmission.