Low revs high torque

New engine technology is claimed to make a new engine the most efficient truck engine in the world. Mercedes Benz has unveiled the next generation of its 13 litre engine range in Europe. The latest iteration of the OM 471 engine is based on the same basic engine block as other 13 litre Daimler engines around the world, including the Detroit DD 13.


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This evolution of the OM 471 comes four years after its introduction at the European launch of the new Actros, due in Australia next year. The Euro 6 compliant engine sees each of the various technologies included in the modern engine enhanced for improved performance. The initial launch of the new Actros in Australia will be fitted with the Euro 5 version of this engine, so we can expect to see this latest enhanced technology appearing later this decade.



Power ratings now go up to 530 hp, the X-Pulse fuel injection system has been improved, a new EGR valve has been introduced, as has an asymmetric turbo system. Mercedes Benz is claiming considerable fuel economy improvements for the new engine and is talking about oil change intervals out to 150,000 km.



New torque performance has been achieved, as a result of introducing the enhanced technology. The lower powered versions of the new engine will see torque topped up by an extra 200 Nm when the truck is in top gear. This should reduce down changing, thus decreasing fuel use, by enabling the truck to hang on to top gear longer.



Maximum power will be available from 1450 to 1800 rpm on the new engines and maximum torque, at 2600 Nm (1918 ft lb) on the top power engine, is on tap from 900 to 1450 rpm. Even at idling speed, at 600 rpm, the engine is still producing 1600 Nm of torque.



X-Pulse injection uses a common rail fuel system boosted with extra pressure by the injectors. Pressure in the rail will now increase to 1160 bar and injection pressure is to rise to 2700 bar, giving more precise control of injection event timing.



As part of the fuel saving strategy, the new engine is being offered in a truck with a rear axle ratio of 2.533. In this set up, with the truck running at 65 km/h the engine is still below 900 rpm but can use the 2200 Nm of torque to maintain performance.



The new EGR exhaust valve has been repositioned and can now be used to control both the level of exhaust gas recirculation but also the amount of exhaust gas redirected to the turbo, when a power boost is needed.


The engine also uses asymmetric injection strategies when regenerating the DPF. The EGR rate is increased as high as 50 per cent in to increase exhaust gas temperature flowing through the particulate filter. In order to avoid a high level of unburnt fuel, cylinders one to three get reduced fuel while four to six get a full fuel flow. Benz claim this strategy does not compromise power output or emissions levels.