BMW automotive engine families listed as M21. Specifications below retain the source's separate family and variant labels.
Family specifications
BMW M21
| Field | Reported value |
|---|---|
| Manufacturer | BMW Motoren GmbH Steyr |
| Production | 1983–1991 |
| Configuration | Straight-6 |
| Displacement | 2.4 L (2,443 cc) |
| Cylinder bore | 80 mm (3.15 in) |
| Piston stroke | 81 mm (3.19 in) |
| Cylinder block material | Cast iron |
| Valvetrain | SOHC 2 valves x cyl. |
| Compression ratio | 22.0:1 |
| Turbocharger | Garrett T03 ('td' versions), None ('d' versions) |
| Fuel system | Swirl chamber injection , distributor fuel injection pump |
| Fuel type | Diesel fuel 45 CN (DIN 51601) |
| Cooling system | Water-cooled |
| Power output | 63–85 kW (84–114 hp) |
| Torque output | 152–220 N⋅m (112–162 lb⋅ft) |
| Predecessor | None |
| Successor | M51 |
Variant specifications
Models
| Engine | Aspiration | Power | Torque | Redline | Dates built |
|---|---|---|---|---|---|
| M21D24 | Turbo-diesel | 85 kW (115 PS; 113 hp) at 4800 rpm | 210 N⋅m (155 lb⋅ft) at 2400 rpm | 5350 rpm | 1983.09–1987.08 |
| M21D24 | Turbo-diesel | 85 kW (115 PS; 113 hp) at 4800 rpm | 220 N⋅m (162 lb⋅ft) at 2400 rpm | 5350 rpm | 1987–1992 (DDE) |
| M21D24 | Natural | 63 kW (86 PS; 85 hp) at 4600 rpm | 152 N⋅m (112 lb⋅ft) at 2500 rpm | 5150 rpm | 1985.09–1989 1989–1992 (DDE) |
BMW automotive engine directory
Design, development and variant notes
The M21 derives from the M20 petrol architecture but uses indirect swirl-chamber diesel injection, an iron block, strengthened internal components and a belt-driven camshaft.
Both turbocharged and naturally aspirated versions were made. From 1987 an electronically controlled Bosch injection pump was introduced on updated engines; the source distinguishes these from earlier mechanically controlled pumps.
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 M21. Wikipedia contributors; CC BY-SA 4.0. Source revision oldid 1372467812; accessed 2026-11-10.