BMW M40
| BMW M40 engine | |
|---|---|
| Overview | |
| Manufacturer | BMW |
| Production | 1987–1994 |
| Layout | |
| Configuration | Naturally aspirated straight-4 |
| Displacement |
|
| Cylinder bore | 84 mm (3.31 in) |
| Piston stroke | 72 mm (2.83 in) 81 mm (3.19 in) |
| Cylinder block material | Cast iron |
| Cylinder head material | Aluminium |
| Valvetrain | SOHC |
| Combustion | |
| Fuel system | Fuel injection |
| Management | Bosch Motronic 1.3 or 1.7 |
| Fuel type | Petrol |
| Cooling system | Water cooled |
| Chronology | |
| Predecessor | BMW M10 |
| Successor | BMW M43 |
The BMW M40 is an SOHC straight-four petrol engine which was produced from 1987–1994. 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, 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, and the E36 versions use Bosch Motronic 1.7.
Following the introduction of the BMW M43 engine in 1991, the M40 began to be phased out.