Cylinder block
B284 is a fluid-cooled, 6-cylinder V engine made of an aluminum alloy. Then engine has a 60° angle between the cylinder banks, 4 valves per cylinder and 2 overhead camshafts per bank. The engine is a cross-flow type, i.e. with intake ducts on one side and exhaust ducts on the other side of the combustion chambers. The cylinder liners are steel and are cast in the cylinder block. The cylinders are completely surrounded by coolant, including between the cylinders. The four main bearing caps are mounted with six bolts each. Two of the six bolts are so-called cross bolts, constituting an important part of the stability in the bottom of the cylinder block. The thrust bearing is located at the third main bearing cap.
Scheme 971
Scheme 972
In order to reduce the amount of air mixed in the oil in the crankcase, return oil is led from the cylinder heads in ducts that lead to the oil sump. Thus, the return oil does not come in contact with moving parts such as the crankshaft and connecting rods.
The cylinder block also houses bored oil ducts to supply oil to bearings, the turbocharger and the cam phasing mechanism.
Scheme 973
Scheme 974
The cylinder head is made of aluminum and has four valves per cylinder. The combustion chambers are pentroof type. Two camshafts are mounted in the cylinder head with four bearing caps. The bearing cap closest to the camshaft sprocket has cast ducts for transferring oil to the CVCP pinion of the intake camshaft.
The cylinder heads also house a position sensor for the intake camshaft and valves for CVCP control.