OM473

Mercedes-Benz opened its Euro VI heavy-duty range with the OM 471 in March 2011 and closed it with this engine, which entered series production at the Mannheim works in September 2013, a few months before the standard took effect. The architecture is shared and scaled up: a cast-iron block, a cylinder head of compacted graphite iron held down by 38 bolts, steel pistons in wet liners, and two hollow composite camshafts driven by a gear train at the flywheel end. X-Pulse injection lifts roughly 900 bar of rail pressure to 2,100 bar inside each injector.

The feature that defines it is turbocompounding. A second turbine downstream of the turbocharger takes what is left in the exhaust and returns it through a shaft and a hydrodynamic coupling to the gear drive, and so to the crankshaft. Ratings run from 380 to 460 kW — 517 to 625 hp — with 2,600 to 3,000 N·m from 1,100 rpm and rated speed as low as 1,600. The decompression engine brake is worth up to 460 kW. It went into the Actros, Arocs and Antos, and the SLT heavy-haulage tractors rated to 250 tonnes.