The bearing covers for the main crankshaft bearings are of grey cast iron, and are bolted to the crankcase, as well as on the sides, for high rigidity. (ausmotive.com)
As opposed to the 3.0 in the X4 xDrive35i, this mill gets forged steel crankshaft, pistons with a modified top ring, new crankshaft bearings and high performance spark plugs. (autoweek.com)