MAN L51/60DF

The MAN L51/60DF is a four-stroke, medium-speed, dual-fuel engine from MAN Energy Solutions, not a two-stroke. The numbers give a 510 mm bore and 600 mm stroke, L marks the inline cylinder arrangement, and DF marks dual fuel: it runs LNG on the lean-burn Otto cycle with a pilot oil ignition, or fully on liquid fuel. Built in 6L to 9L configurations rated roughly 5,850 to 9,000 kW, it is used for propulsion and gensets on gas carriers, ferries, and offshore units. In gas mode it meets NOx Tier III under MARPOL Annex VI Reg 13 without after-treatment, the standard advantage of lean-burn dual-fuel four-strokes.