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.

BMW M51
Overview
ManufacturerBMW
Production1991-2000
Layout
ConfigurationInline-6
Displacement2.5 L; 152.4 cu in (2,497 cc)
Cylinder bore80 mm (3.15 in)
Piston stroke82.8 mm (3.26 in)
Block materialCast iron
ValvetrainSOHC 2 valves x cyl.
Compression ratio22.0:1
Combustion
TurbochargerSingle turbo, tds-engines also have an intercooler
Fuel systemSwirl-chamber-injection
ManagementBosch DDE 2.1
Fuel typeDiesel fuel (DIN 51601)
Cooling systemWater-cooled
Output
Power output85–105 kW (114–141 hp)
Torque output222–280 N⋅m (164–207 lb⋅ft)
Dimensions
Dry weight132 kg (291 lb)
Chronology
PredecessorBMW M21
SuccessorBMW M57

Description

The M51 is a water-cooled and turbocharged inline six-cylinder diesel engine with a Bosch VP20-swirl-chamber-injection.[1][2][3] The displacement is 2.5 L; 152.4 cu in (2,497 cc) 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.[2] The M51 is an engine made of cast iron, it has one chain driven overhead camshaft[4] and two valves per cylinder.[2][4] Compared to the M21 the M51 now has tappets and a hydraulic valve lash adjustment.[2] 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.[4] This results in greater torque at lower revs.[4] For lubrication SAE 5W-40 oil is used.[5]

VersionPowerTorqueYears
M51D25 UL85 kW (114 hp)
at 4800 rpm		222 N⋅m (164 lb⋅ft)
at 1900 rpm		1991–1997
M51D25 OL105 kW (141 hp)
at 4800 rpm		260 N⋅m (192 lb⋅ft)
at 2200 rpm		1991–1996
Opel X25DT[lower-alpha 1]96 kW (129 hp)
at 4800 rpm[6][7][8][9]		250 N⋅m (184 lb⋅ft)
at 1400 rpm		1994–2001
M51D25TÜ UL85 kW (114 hp)
at 4800 rpm[10][11]		230 N⋅m (170 lb⋅ft)
at 1900 rpm		1996–1998
M51D25TÜ OL105 kW (141 hp)
at 4800 rpm[4]		280 N⋅m (207 lb⋅ft)
at 2200 rpm		1996–1998
M51D25TÜ OL105 kW (141 hp)
at 4600 rpm[4]		1998–2000
M51D25M1[lower-alpha 2]100 kW (134 hp)
at 4400 rpm[12]		270 N⋅m (199 lb⋅ft)
at 2300 rpm		1995-2001
  1. For Opel Omega B only
  2. For Range Rover P38 DSE 2.5 LP2 only.

Applications:

See also

References
  1. BMW E38 7 Series 725 tds Technical data
  2. Die BMW-Sportdiesel: Von 524td E28 über 530d E39 bis BMW M550d F10 (german)
  3. "BMW M41 and M51 Diesel Engines". www.unixnerd.demon.co.uk. Archived from the original on 10 October 2016.
  4. Etzold: So wird's gemacht: pflegen – warten – reparieren. Band 102, BMW 5er E39 Delius Klasing Verlag. Pages 12 and 13 (german)
  5. Übersicht der Motorölqualitäten. Page 7 (german)
  6. "Vauxhall V94 - Omega B confidential launch guides". vauxpedianet.uk2sitebuilder.com. Retrieved 2 October 2021.
  7. Opel Omega B 2.5 TD 96 kW 130 PS - Motor: 25DT, X25DT, X25TD - Eco Optimierung / Leistungssteigerung (german)
  8. "Detailed specs review of 1995 Opel Omega 2.5 TD model for Europe". www.automobile-catalog.com. Retrieved 14 August 2021.
  9. "Opel Omega 2.5 TD CD Manual 4 doors specs". www.Cars-Data.com. Retrieved 14 August 2021.
  10. "Die BMW Turbodiesel". bmw-grouparchiv.de. Retrieved 30 September 2021.
  11. "Betriebsanleitung zum Fahrzeug. [BMW 5er Limousine/touring (E39)]". bmw-grouparchiv.de. Retrieved 30 September 2021.
  12. Automobile Catalogue: 1997 Range Rover 2.5 DSE (model for Europe ) specifications & performance data review.
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