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Daimler announces third generation OM 471 heavy-duty diesel engine

9 April 2022

Daimler Truck has announced the launch of the third generation of its OM 471 heavy-duty commercial vehicle engine. The updated six-cylinder in-line diesel engine will be available from October 2022.

The third generation OM 471 achieves better fuel efficiency, by up to 4%, thanks to optimized combustion, application-oriented turbochargers, and reduced friction. The geometry of the piston recess, the injection nozzle design, and the parameters of the cylinder head relevant for gas exchange have all been optimized. The compression ratio has been increased from 18.3:1 to 20.3:1, leading to more efficient combustion with a peak ignition pressure of 250 bar.

Third generation OM 471 heavy-duty diesel engine

The third generation OM 471 comes with two new turbochargers, developed and manufactured in-house. The first turbocharger variant, optimized for fuel consumption, is intended for use in long-distance haulage with an engine rated at up to 350 kW (476 hp). The second turbocharger variant is designed for high performance and a high engine braking force. It is intended for use in the heavy-duty and construction sector with an engine rating of up to 390 kW (530 hp). For the lower and medium performance levels of the OM 471, the maximum fuel saving compared with the previous generation is up to 4%, and for the upper performance levels up to 3.5%.

For the purpose of friction reduction, the third-generation OM 471 has a newly developed engine oil pressure control valve. It is installed behind the engine oil pump and in front of the oil thermostat. An electrical actuator enables characteristics map-controlled use of the pressure-reducing valve. Available reductions in engine oil pressure are determined in a complex matrix that takes into account all engine components and their specific requirements, such as lubrication or cooling. A newly-developed engine oil with low viscosity enhances oil pressure control—it improves fuel efficiency without reducing oil change intervals or increasing the wear on affected engine components.

The exhaust gas aftertreatment system has been completely revamped and adapted to the new combustion and control system of the OM 471. The system limits the engine backpressure and also increases the uniformity index of the AdBlue, which leads to improved NOx conversion and lower fuel consumption. NOx sensors, a closed and adaptive NOx closed-loop control circuit, and a predictive SCR temperature model are used to improve emission stability. The engine is compliant with Euro VI-E emission standards, which call for effective emission reductions over the entire normal service life of a vehicle.

The engine will be manufactured at the Mercedes-Benz Mannheim plant—a center of competence for heavy-duty commercial vehicle engines from Daimler Truck.

Source: Daimler