BMW automotive engine families listed as M42. Specifications below retain the source's separate family and variant labels.
Family specifications
BMW M42
| Field | Reported value |
|---|---|
| Manufacturer | BMW |
| Production | 1989–1996 |
| Configuration | Naturally aspirated straight-4 |
| Displacement | 1.8 L (1,796 cc) |
| Cylinder bore | 84 mm (3.31 in) |
| Piston stroke | 81 mm (3.19 in) |
| Cylinder block material | Cast iron |
| Cylinder head material | Aluminium |
| Valvetrain | DOHC , 16V |
| Compression ratio | 10.0:1 |
| Fuel system | Fuel injection |
| Fuel type | Petrol |
| Predecessor | BMW M40 |
| Successor | BMW M44 |
Variant specifications
Versions
| Engine | Displacement | Power | Torque | Year |
|---|---|---|---|---|
| M42B18 | 1,796 cc (109.6 cu in) | 100 kW (136 PS; 134 hp) at 6,000 rpm | 172 N⋅m (127 lb⋅ft) at 4,600 rpm | 1989-1992 ( E30 ) |
| M42B18 | 1,796 cc (109.6 cu in) | 103 kW (140 PS; 138 hp) at 6,000 rpm | 175 N⋅m (129 lb⋅ft) at 4,500 rpm | 1992-1996 ( E36 ) |
Recorded vehicle applications
M42B18
- 1989–1991 E30 318is
- 1990–1992 E30 318i (only North American models)
- 1992–1995 E36 318i (only North American and South African models)
- 1991–1995 E36 318is
- 1994–1995 E36 318ti
BMW automotive engine directory
Design, development and variant notes
The M42 combines an iron block and aluminium head with a chain-driven twin-cam, 16-valve layout and hydraulic tappets. It uses Bosch Motronic M1.7 with a separate ignition coil pack; late engines gained a variable-length DISA intake.
From September 1993 BMW changed the timing-chain idler gear to a curved guide and revised the front casing. The source also describes upper oil-pan bolt loosening on the E30's two-piece sump arrangement; inspect the actual installation before drawing conclusions.
Variant dimensions and compression
These values are associated with the named variant and source qualifier; equipment and market specifications can differ. A dash means the value is not listed here.
| Variant | Bore (mm) | Stroke (mm) | Compression ratio | Source qualifier |
|---|---|---|---|---|
| M42B18 | 84 | 81 | — | — |
Data adapted from the cited Wikipedia revision by Wikipedia contributors under CC BY-SA 4.0. Production dates and fitments reflect that revision; verify the exact engine code, market and vehicle before applying a specification.
Sources
Curated reference notes. Applicability follows the cited sources; hardware testing by this wiki is not implied.
- Wikipedia: List of BMW engines. Wikipedia contributors; CC BY-SA 4.0. Source revision oldid 1382309748; accessed 2026-11-10.
- Wikipedia: BMW M42. Wikipedia contributors; CC BY-SA 4.0. Source revision oldid 1372840469; accessed 2026-11-10.
Further Wikipedia-sourced details
The following additional information is drawn from the cited Wikipedia revision by Wikipedia contributors, available under CC BY-SA 4.0. An open-ended date reflects the source snapshot, not confirmed current production or fitment.
Additional technical and variant notes
S42B20 is a racing development, not the ordinary M42B18 road engine. The article describes 1,999 cc, individual throttles, two injectors per cylinder and dry-sump lubrication, with quoted outputs rising from 206 kW in 1994 to 235 kW in 1997.