Open main menu

The Mercedes-Benz OM629 is a 4.0 litres (3,996 cc) diesel-fuelled, 4-stroke, compression-ignition internal combustion 75° 32-valve V8 engine used in the 2000s. It is the world’s first aluminium V8 diesel engine.[1]

Mercedes-Benz OM629
Mercedes Benz GL420 CDi 4-Matic - Flickr - The Car Spy (19).jpg
Overview
ManufacturerMercedes-Benz
Production2005–2010
Layout
Configuration75° V8
Displacement4.0 L (3,996 cc)
Cylinder bore86 mm (3.39 in)
Piston stroke86 mm (3.39 in)
Block materialAluminium alloy
ValvetrainDOHC 4 valves x cyl.
Compression ratio17.0:1
Combustion
TurbochargerVariable-geometry
Fuel systemCommon rail
Fuel typeDiesel
Cooling systemWater cooled
Output
Power output225–235 kW (306–320 PS; 302–315 hp)
Torque output700–730 N⋅m (516–538 lb⋅ft)
Chronology
PredecessorMercedes-Benz OM628 engine

Contents

DesignEdit

The block features an aluminium crankcase and cylinder heads. It uses aluminium sand casting in bedplate construction (divided at the height of the crankshaft) with wet cylinder liners made of cast iron.

The main bearings are reinforced, cast in GGG ductile cast iron. Rather than the usual 90° "vee" angle between the cylinder banks, a 75° angle was chosen due to the space available to install the engine.[2] The consequence of this specific angle is free inertial forces of the first order. To compensate for this, the OM628 and OM629 use a balancer shaft located in the vee of the engine. To ensure even firing intervals the crankshaft uses split crank pins. The engine uses 97.0 mm cylinder spacing.

The engine uses dual overhead camshafts on each bank (‘quad-cam’) with four valves per cylinder, operated by hydraulic tappets. Each cylinder bank uses a variable geometry turbocharger. The compressed air from these is cooled by an air to water heat exchanger with an additional cold water circuit.

Compared to the OM628, the OM629 engine has an improved common-rail system,[3] and higher boost from the turbochargers. It displaces 4.0 L (3,996 cc) and produces between 225 to 235 kW (306 to 320 PS; 302 to 315 hp) at 3600 rpm, and 700 to 730 N⋅m (516 to 538 lb⋅ft) of torque between 2000–2600 rpm.

ModelsEdit

Engine Power @ rpm Torque @ rpm Years
OM629 225 kW (306 PS; 302 hp) 3,600 700 N⋅m (516 lb⋅ft) 2,000–2,600 2006–2010
231 kW (314 PS; 310 hp) 730 N⋅m (538 lb⋅ft) 2,200 2005–2009
235 kW (320 PS; 315 hp) 2006–2010

OM629 (225 kW version)Edit

OM629 (231 kW version)Edit

OM629 (235 kW version)Edit

ReferencesEdit

  1. ^ "Audi A8 3.3 TDI, BMW 740d, Mercedes S 400 CDI (German)". Auto Motor und Sport. Retrieved 2018-03-28.
  2. ^ "Mercedes-Benz OM628 and OM629 engines (2000-2010)". AustralianCar.Reviews. Retrieved 2018-03-28.
  3. ^ Chick, David. "Diesels Around The World: Mercedes-Benz". Diesel Army. Retrieved 2018-03-28.