The development of the L21/31 engine is a continuance of the logical development in the strategy initiated with introduction of L16/24 and L27/38 as the new generation of MAN B&W.

Compact size

The L21/31 propulsion package is lower and shorter than the other long-stroke engines in its power class, optimizing the combination of engine, flexible coupling and gear box.

The turbocharger is located on the engine's aftend box utilizing the space above the compact gear box, resulting in a very low exhaust gas outlet flange position.

Low overhual height

Low dismantling height for cylinder head, piston and cylinder liner is ensured thanks to the marine head connecting rod.

The engine front-end box incorporates built-on cooling water pumps, thermostatic valves, lub. oil pump, lub. oil cooler and automatic lub. oil filter.100%PTO is possible from either end of the engine and another PTO is optional on the front-end box for drive of seawater pump or similar.

Robust design

The engine is designed for reliability. A sturdy engine frame and connecting rods of marine head design are some of the parameters which secure long overhaul intervals.

Main data

*D-Min center distance for twin engine installation.

Low maintenance

The L21/31 is designed for low daily maintenance and major overhaul can be carried out with a minimum of resources due to the cylinder unit concept.

Environment friendly

The L21/31 meets the IMO NOx emission limits.