BMW M51


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.

Description

The M51 is a water-cooled and turbocharged inline six-cylinder diesel engine with a Bosch VP20-swirl-chamber-injection. The displacement is 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 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.
EnginePower outputTorqueYear
M51D25 UL @ 4800 rpm @ 1900 rpm1991–1997
M51D25 OL @ 4800 rpm @ 2200 rpm1991–1996
X25DT @ 4800 rpm @ 1400 rpm1994–2001
M51D25TÜ UL @ 4800 rpm @ 1900 rpm1996–1998
M51D25TÜ OL @ 4800 rpm @ 2200 rpm1996–1998
M51D25TÜ OL @ 4600 rpm @ 2200 rpm1998–2000
M51D25M1 @ 4400 rpm @ ? rpmuntil 1999

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