The MAN 48/60 (and its current production derivative the 48/60CR) is a large-bore medium-speed four-stroke trunk-piston marine and stationary diesel engine produced by MAN Energy Solutions, with a 480 millimetre cylinder bore and a 600 millimetre piston stroke. The engine is the upper-bore offering in MAN’s medium-speed four-stroke portfolio, sitting above the 32/40, 35/44, 40/54, and 46DF in cylinder size, and is selected for the largest single-engine main propulsion and power-plant applications. Cylinder configurations range from L6 to V18, with rated outputs from approximately 7,200 kilowatts to 22,000 kilowatts.
Cylinder data and outputs
The 48/60CR has a swept volume per cylinder of approximately 108.5 litres and produces 1,200 kilowatts per cylinder at 500 to 514 revolutions per minute under the current rating. Common-rail injection (the CR suffix) was introduced on the 48/60 platform in the 2000s and is now standard on all current production. The CR injection system delivers fuel at pressures up to 1,800 bar with electronically controlled injection timing and rate shaping, supporting compliance with stricter emission regulations and improved part-load fuel efficiency.
Configurations available include L6, L7, L8, L9 in-line and V12, V14, V16, V18, giving an output band of approximately 7,200 kilowatts (L6) to 21,600 kilowatts (V18) at 500 revolutions per minute. The brake mean effective pressure has progressively risen from approximately 21 bar in the original 1980s 48/60A through 24 bar in the 48/60B and to over 25 bar in the present 48/60CR.
Fuel and emissions
The 48/60CR runs on heavy fuel oil, marine diesel oil, and low-sulphur fuel oils as standard. The 51/60DF dual-fuel variant (a derivative with the same architecture but slightly larger 510 millimetre bore) operates on liquefied natural gas with diesel pilot ignition, delivering IMO Tier III compliance in gas mode without aftertreatment. SCR (selective catalytic reduction) is the standard NOx aftertreatment for IMO Tier III compliance on the diesel-only 48/60CR.
The platform has been extended to ammonia and methanol-ready variants for the post-2030 fleet. MAN announced a methanol-ready 48/60 variant in 2024 with provisions for retrofit to dual-fuel methanol service, and an ammonia-ready 48/60 variant in 2025 with provisions for ammonia injection equipment installation.
Applications
The 48/60 is the dominant medium-speed engine for the largest cruise ships, naval auxiliary ships, and FPSO power plants. Notable application categories include:
- Cruise ship integrated power plants, where four to six L9 or V12 units feed diesel-electric propulsion and hotel loads on cruise vessels above 100,000 gross tonnes.
- FPSO main power generation, where multiple V configurations supply combined process and propulsion power on Brazilian, West African, and North Sea floating production platforms.
- Naval auxiliary ships and large amphibious vessels, where the high single-engine output supports Combined Diesel-Electric and Mechanical (CODLAG and similar) configurations.
- Stationary baseload and peaking power plants in markets where fuel oil or natural gas plants of 20 to 200 megawatts are economical.
48/60 history
The 48/60 family entered production in the late 1980s as the successor to MAN’s earlier large-bore medium-speed engines. The 48/60B with electronic engine management was introduced in the 1990s, and the 48/60CR with common-rail injection followed in the 2000s. The engine has been continuously updated with improved combustion chamber geometry, valve materials, and turbocharging systems supplied principally by Accelleron (formerly ABB Turbo Systems) and MAN’s own TCA series turbochargers.
Service and support
MAN Energy Solutions PrimeServ supports the 48/60 globally with a dedicated large-engine service organisation, condition monitoring through PrimeServ Assist, and component overhaul depots in Augsburg, Frederikshavn, Copenhagen, Singapore, Houston, and several Chinese ports. The engine’s bore size and weight (a V18 unit weighs approximately 350 tonnes) place it in the heaviest-handling category for engine room construction and major overhauls, with major component lifts requiring specialist crane provision.