BMW automotive engine families listed as M20. Specifications below retain the source's separate family and variant labels.
Family specifications
BMW M20 engine
| Field | Reported value |
|---|---|
| Production | 1977–1993 |
| Configuration | Straight-6 |
| Displacement | 2.0 L (1,991 cc) 2.3 L (2,316 cc) 2.5 L (2,494 cc) 2.7 L (2,693 cc) |
| Cylinder bore | 80 mm (3.15 in) 84 mm (3.31 in) |
| Piston stroke | 66 mm (2.60 in) 75 mm (2.95 in) 76.8 mm (3.02 in) 81 mm (3.19 in) |
| Cylinder block material | Cast iron |
| Cylinder head material | Cast aluminum alloy |
| Valvetrain | SOHC |
| Fuel type | Petrol |
| Predecessor | None |
| Successor | BMW M50 |
Variant specifications
Models
| Version | Displacement | Power | Torque | Bore | Stroke | Compression Ratio | Years | Notes |
|---|---|---|---|---|---|---|---|---|
| M20B20 | 1,991 cc (121.5 cu in) | 90 kW (122 PS; 121 hp) at 6,000 rpm | 163 N⋅m (120 lb⋅ft) at 4,000 rpm | 80 mm (3.15 in) | 66 mm (2.60 in) | 9.2:1 | 1977-1982 | Solex 4A1 variant |
| M20B20 | 1,991 cc (121.5 cu in) | 92 kW (125 PS; 123 bhp) at 5,800 rpm | 170 N⋅m (125 lb⋅ft) at 4,000 rpm | 80 mm (3.15 in) | 66 mm (2.60 in) | 9.0:1 (catalyst) 9.8:1 (non-catalyst) | 1982-1984 | L-Jetronic fuel injection with "200" head |
| M20B20 | 1,991 cc (121.5 cu in) | 92 kW (125 PS; 123 bhp) at 5,800 rpm | 174 N⋅m (128 lb⋅ft) at 4,000 rpm | 80 mm (3.15 in) | 66 mm (2.60 in) | 9.0:1 (catalyst) 9.8:1 (non-catalyst) | 1984-1987 | LE-Jetronic fuel injection with "731" head |
| M20B20 | 1,991 cc (121.5 cu in) | 95 kW (129 PS; 127 bhp) at 6,000 rpm | 164 N⋅m (121 lb⋅ft) at 4,300 rpm | 80 mm (3.15 in) | 66 mm (2.60 in) | 8.8:1 | 1986-1992 | Motronic 1.1/1.3 engine management Compression ratio reduced to accommodate emissions controls and unleaded gasoline |
| M20B23 | 2,316 cc (141.3 cu in) | 105 kW (143 PS; 141 bhp) at 5,300 rpm | 190 N⋅m (140 lb⋅ft) at 4,500 rpm | 80 mm (3.15 in) | 76.8 mm (3.02 in) | 9.5:1 | 1977-1982 | K-Jetronic fuel injection |
| M20B23 | 2,316 cc (141.3 cu in) | 102 kW (139 PS; 137 bhp) at 5,300 rpm | 205 N⋅m (151 lb⋅ft) at 4,000 rpm | 80 mm (3.15 in) | 76.8 mm (3.02 in) | 9.0:1 (catalyst) 9.8:1 (non-catalyst) | 1982-1983 | L-Jetronic |
| M20B23 | 2,316 cc (141.3 cu in) | 110 kW (150 PS; 148 bhp) at 6,000 rpm | 205 N⋅m (151 lb⋅ft) at 4,000 rpm | 80 mm (3.15 in) | 76.8 mm (3.02 in) | 9.0:1 (catalyst) 9.8:1 (non-catalyst) | 1983-1987 | LE-Jetronic |
| M20B25 | 2,494 cc (152.2 cu in) | 126 kW (171 PS; 169 bhp) at 5,800 rpm | 226 N⋅m (167 lb⋅ft) at 4,000 rpm | 84 mm (3.31 in) | 75 mm (2.95 in) | 9.4:1 | 1985-1990 | For markets that did not require a catalytic converter |
| M20B25 | 2,494 cc (152.2 cu in) | 125 kW (170 PS; 168 hp) at 5,800 rpm | 226 N⋅m (167 lb⋅ft) at 4,300 rpm | 84 mm (3.31 in) | 75 mm (2.95 in) | 8.8:1 | 1987-1993 | For markets that required a catalytic converter |
| M20B27 | 2,693 cc (164.3 cu in) | 90 kW (122 PS; 121 hp) at 4,250 rpm | 230 N⋅m (170 lb⋅ft) at 3,250 rpm | 84 mm (3.31 in) | 81 mm (3.19 in) | 9.0:1 | 1982-1987 | For markets that required a catalytic converter |
| M20B27 | 2,693 cc (164.3 cu in) | 92 kW (125 PS; 123 hp) at 4,250 rpm | 240 N⋅m (177 lb⋅ft) at 3,250 rpm | 84 mm (3.31 in) | 81 mm (3.19 in) | 11.0:1 | 1982-1985 | For markets that did not require a catalytic converter Early high compression variant |
| M20B27 | 2,693 cc (164.3 cu in) | 95 kW (129 PS; 127 hp) at 4,250 rpm | 240 N⋅m (177 lb⋅ft) at 3,250 rpm | 84 mm (3.31 in) | 81 mm (3.19 in) | 10.2:1 | 1985-1987 | For markets that did not require a catalytic converter Compression ratio reduced to mitigate knocking |
| M20B27 | 2,693 cc (164.3 cu in) | 95 kW (129 PS; 127 hp) at 4,800 rpm | 240 N⋅m (177 lb⋅ft) at 3,200 rpm | 84 mm (3.31 in) | 81 mm (3.19 in) | 8.5:1 | 1988 | "Super" Eta engine Motronic 1.1 |
Recorded vehicle applications
M20B20
- 1977–1981 E12 5 Series 520/6 (carburettor)
- 1977–1982 E21 3 Series 320/6 (carburettor)
M20B20KE
- 1981–1982 E28 5 Series 520i (K-Jetronic)
M20B20LE
- 1982–1984 E28 5 Series 520i ( L-Jetronic )
- 1982–1984 E30 3 Series 320i (L-Jetronic)
- 1984–1987 E28 5 Series 520i (LE-Jetronic)
- 1984–1987 E30 3 Series 320i (LE-Jetronic)
M20B20 (Motronic)
- 1986–1987 E28 3 Series 520i (Motronic)
- 1987–1992 E30 3 Series 320i (Motronic)
- 1988–1990 E34 5 Series 520i (Motronic)
- 1989–1992 Bertone Freeclimber (Freeclimber I)
M20B23
- 1977–1982 E21 3 Series 323i (K-Jetronic)
- 1982–1984 E30 3 Series 323i (L-Jetronic)
- 1984–1987 E30 3 Series 323i (LE-Jetronic)
M20B25
- 1985–1993 E30 3 Series 325i
- 1989–1990 E34 5 Series 525i
- 1988–1991 Z1
M20B27
- 1982–1987 E30 3 Series 325e, 325e
- 1982–1988 E28 5 Series 525e (called 528e in North America)
- 1989–1992 E30 3 Series 325iS (only available in South Africa)
- 1989–1992 Bertone Freeclimber (Freeclimber I)
BMW automotive engine directory
Design, development and variant notes
The 'little six' M20 has an iron block, aluminium cross-flow head and a belt-driven single overhead camshaft. Its smaller bore spacing and different mounting angle distinguish it from the larger M30.
Early 2.0-litre and 2.3-litre versions used different fuelling systems, including carburettor and Bosch K-Jetronic arrangements. The M21 diesel was developed from the M20 architecture.
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 M20. Wikipedia contributors; CC BY-SA 4.0. Source revision oldid 1384599794; accessed 2026-11-10.