New four-cylinder petrol engine (M 264): Specific output and agility on a par with a sports car

A two-litre four-cylinder engine with a specific output of up to 100 kW: the new Toptype petrol engine from Mercedes-Benz (internal code: M 264) advances into output regions previously reserved for high-displacement six-cylinder machines. At the same time, it consumes significantly less fuel than a comparable six-cylinder engine. The engine's special features include twin-scroll turbochargers and belt-driven 48 V starter-alternator (BSA). The M 264 will celebrate its debut next year.

A specific output of around 100 kW per litre almost puts the M 264 on a par with full-blooded sports car engines. In the interests of high power output and spontaneous engine response, Mercedes-Benz has opted for twin-scroll turbocharging, as in the Mercedes-AMG M 133 engine. Unlike conventional systems, a twin-scroll turbocharger merges the exhaust gas ducts of cylinder pairs in the flow-optimised manifold. This turbocharging concept with systematic cylinder flow separation produces high torque in the low-rpm range together with high specific output.

A further-improved intake manifold with extremely short air paths and an exceptionally compact compressor housing additionally ensure spontaneous engine response and fast reactions to accelerator pedal movements. The twin-scroll turbocharger has an electric wastegate actuator, which allows fast changes of the charge-air pressure.

Further efficiency measures include intake CAMTRONIC, a newly developed electric 48 V water pump and a friction loss reduction package.

The M 264 is combined with a 48 V electrical system, which is used for the belt-driven starter-alternator (BSA) and the electric water pump. The BSA is also responsible for fuel-saving hybrid functions:

  • Easy start: virtually imperceptible starting and acceleration of the engine
  • Boost in the engine-speed range up to 2500 rpm
  • Energy recovery up to 12.5 kW
  • Shifting of the load point: the engine can be operated in a more favourable area of the engine map; load increase/reduction depending on the state of charge of the battery
  • Coasting with engine off
  • iECO: extended stop/start with intelligent engine shutoff even at low speeds

At the very top of the list of requirements for developers were comfort and NVH (noise, vibration, harshness). Plastic engine mounts and the BSA contribute to exemplary refinement, as do numerous insulation measures. These include insulation of the engine block and extensive covering of the engine with an acoustic insert as well as further NVH optimisation in relation to the injection hydraulics. To guarantee excellent exhaust emissions, use is made of tried-and-tested piezo injectors with good mixture preparation, a further-improved combustion chamber and a particulate filter for petrol engines.

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