Turning Diesel Over – OM 654
The OM 654 is the first Mercedes diesel engine to use all-aluminium construction, bringing down the weight of the engine by 17 per cent, from 202.8 kg to 168.4 kg. Steel pistons with stepped combustion bowls sit in 82-mm bores (-1.0 mm) and travel 92.3 mm (-6.7 mm). Total displacement of this new modular form of engine is 1,950 cc, down 193 cc on the old OM 651 2,143-cc unit. The spacing between cylinders is now 90 mm against 94 mm. Furthermore, fourth-generation common-rail direct injection is used.
In 220 d guise, the output is 143 kW (194 PS, at 3,800 rpm) and 400 Nm (peaking between 1,600 and 2,800 rpm), although Mercedes say that the peak specific output of the engine is rated at 90 kW (122 PS/litre). Juicy!
The new 350 d and 400 d iteration of the new S-Class will use six of these cylinders for a displacement of 2,925 cc, replacing the existing 3.0-litre V6 in a phased manner, starting with the new V/W/X222 S-Class.
