Mercedes-Benz M 256 petrol engine

Mercedes Benz
M 256
Manufacturer:	Mercedes Benz
Production period:	since 2017
Style:	Inline engine , six-cylinder
Engines:	3.0 liters (2999 cc)
Previous model:	M 276

The M 256 is a newly developed gasoline engine from Mercedes-Benz , which was launched in 2017. It is a six-cylinder in - line engine with turbocharging and an additional electric compressor. It is assembled at the engine plant Stuttgart-Untertürkheim . 

The M 256 is a successor of the M 276 and part of a new, modular engine generation that includes 4 and 6 cylinder diesel engines as well as 4 and 6 cylinder gasoline engines. By identical Zylinderhubraum (about 500 cm³) and distance a high number of identical parts is achieved. 

The first use of the engine was in 2017 in the facelift of the S-Class ( class 222 ).The displacement of the six-cylinder in - line engine is 2999 cc with a bore of 83 mm and a stroke of 92.4 mm, with a cylinder spacing of 90 mm. The compression ratiois 10.5. 

The change of charge is controlled by four valves per cylinder ( four-valve technology ) and two overhead camshafts driven by a timing chain .

The basic engine is extremely compact in terms of its cylinder spacings (90 mm) and the bore (83 mm) in the longitudinal direction. With this planning of a web thickness of only 7 mm, it can be seen that an expansion of this type of engine which is frequently used earlier in other series is not provided and can only be achieved by increasing the stroke, if at all.

The engine has an exhaust gas turbocharger and - depending on the engine variant - an electrically driven auxiliary compressor from BorgWarner , which should improve the response of the engine. The electric compressor accelerates within 300 milliseconds to 70,000 revolutions per minute and thus ensures a fast build up of the required charge pressure. 

Behind the turbine of the turbocharger first a three-way catalyst is used. In addition, a particulate filter is fitted as standard in the underbody of the vehicle . Thus, the M 256 one of the first gasoline engine with a particulate filter.Furthermore, for the first time, an integrated intercooler is used, which is placed between the throttle valve and intake bridge.

The M 256 completely dispenses with a conventional belt drive for driving the auxiliary units , which shortens the installation length of the motor. Instead, the electric coolant pump and the electric air conditioning compressor are supplied from the new 48 V electrical system. 

A central component of the new engine is the integrated starter generator (ISG), which takes over both the function of the generator and the starter and also works on the 48 V level. The ISG can support the engine with a maximum of 16 kW (22 hp) and 250 Nm of torque (" boosting " from the 48-volt accumulator), for example during kick-down, and also performs other hybrid functions such as recuperation (recovery of a part of the Kinetic energy when braking in the 48 V accumulator) or sailing . He also helps the internal combustion engine by load point shift in a favorable map rangeto operate. Thus, every vehicle equipped with the M 256 becomes a mild hybrid .

Versions

The M 256 is offered in several performance levels.

M 256 E30 DEH LA GR 

M 256 E30 DEH LA G