| BMW M51 | |
| Manufacturer: | BMW |
| Production: | 1991-2000 |
| Predecessor: | BMW M21 |
| Successor: | BMW M57 |
| Configuration: | Inline-6 |
| Displacement: | 2497cc |
| Bore: | 80mm |
| Stroke: | 82.8mm |
| Block: | Cast iron |
| Valvetrain: | SOHC 2 valves x cyl. |
| Compression: | 22.0:1 |
| Turbocharger: | Single turbo, tds-engines also have an intercooler |
| Fuelsystem: | Swirl-chamber-injection |
| Management: | Bosch DDE 2.1 |
| Fueltype: | Diesel fuel (DIN 51601) |
| Coolingsystem: | Water-cooled |
| Power: | NaNkW |
| Torque: | NaN0NaN0 |
| Weight: | 1320NaN0 |
The BMW M51 is an inline-6 cylinder Diesel engine produced by the Upper Austrian BMW plant in Steyr from July 1991 through February 2000. Its predecessor is the BMW M21, the successor is the BMW M57.
The M51 is a water-cooled and turbocharged inline six-cylinder diesel engine with a Bosch VP37-swirl-chamber-injection.[1] The displacement is 2497cc and the compression ratio is 22.0:1.
Some engine variants have an intercooler in addition to the turbocharger, they can be identified by the tds. The M51 is an engine made of cast iron, it has one chain driven overhead camshaft and two valves per cylinder. Compared to the M21 the M51 now has tappets and a hydraulic valve lash adjustment. The fuel injection in the first engines and all E36 models is controlled by the ECU Bosch DDE 2.1, which was replaced after the first technical revision by the DDE 2.2 This results in greater torque at lower revs. For lubrication SAE 5W-40 oil is used.
| Version | Power | Torque | Years | |
|---|---|---|---|---|
| M51D25 UL | at 4800 rpm | 2220NaN0 at 1900 rpm | 1991–1997 | |
| M51D25 OL | at 4800 rpm | 2600NaN0 at 2200 rpm | 1991–1996 | |
| Opel X25DT | at 4800 rpm[2] [3] [4] | 2500NaN0 at 1400 rpm | 1994–2001 | |
| M51D25TÜ UL | at 4800 rpm[5] [6] | 2300NaN0 at 1900 rpm | 1996–1998 | |
| M51D25TÜ OL | at 4800 rpm | 2800NaN0 at 2200 rpm | 1996–1998 | |
| M51D25TÜ OL | at 4600 rpm | 1998–2000 | ||
| M51D25M1 | at 4400 rpm | 2700NaN0 at 2300 rpm | 1995-2001 |
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