The BMW M40 is an SOHCstraight-fourpetrol engine which was produced from 1987–1994.[1][2] It served as BMW's base model four-cylinder engine and was produced alongside the higher performance BMW M42 DOHC four-cylinder engine from 1989 onwards.
Compared with its M10 predecessor, the M40 uses a belt-driven camshaft,[3] and hydraulic tappets. Like the M10, the M40 uses an iron block and an aluminium head. Fuel injection for the E30 versions is Bosch Motronic 1.3,[4] and the E36 versions use Bosch Motronic 1.7.[5][6]
Following the introduction of the BMW M43 engine in 1991, the M40 began to be phased out.
The M40B16 is a 1,596 cc (97.4 cu in) version of the M40, which has a bore of 84 mm (3.3 in) and a stroke of 72 mm (2.8 in).[7] It produces 73 kW (98 hp) and 142 N⋅m (105 lb⋅ft).[8]
The M40B18 is a 1,796 cc (109.6 cu in) version of the M40, which has a bore of 84 mm (3.3 in) and a stroke of 81 mm (3.2 in).[7] It produces 83 kW (111 hp) and 163 N⋅m (120 lb⋅ft).[6]