The MAN L32/44CR is a medium-speed, four-stroke trunk-piston marine engine produced by MAN Energy Solutions in Augsburg, Germany, with a 320 millimetre cylinder bore and a 440 millimetre piston stroke. The “CR” designation denotes common-rail electronic fuel injection, distinguishing the L32/44CR from the older mechanically injected L32/40 that it succeeded as MAN’s flagship 32-bore medium-speed product. The engine is offered in L6, L7, L8, L9, V12, V14, V16, V18, and V20 cylinder configurations with rated outputs from approximately 3,000 kilowatts to 11,000 kilowatts.
Cylinder data and outputs
The current L32/44CR rating produces approximately 560 kilowatts per cylinder at 720 or 750 revolutions per minute, depending on application and frequency requirements. Brake mean effective pressure approaches 27 bar in the latest production version, supported by Miller-cycle valve timing, two-stage turbocharging on selected variants, and the precision of common-rail injection. Configurations from L6 through V20 cover the 3 to 11 megawatt range with significant overlap with MAN’s smaller 28/33D and 23/30 products at the lower end and the larger 48/60 at the upper end.
Common-rail fuel injection
The defining feature of the L32/44CR relative to the L32/40 it replaced is the common-rail electronic fuel injection system. Common-rail decouples injection pressure and timing from engine speed, enabling:
- Independent control of injection timing, pressure, and rate-shaping at each cylinder.
- Improved part-load efficiency through optimised injection at lower loads.
- Lower particulate and NOx emissions through better fuel atomisation and combustion control.
- Multiple injection events per cycle including pilot, main, and post-injection for emission control or thermal load management.
The MAN common-rail system on the 32/44CR uses a high-pressure pump driven from the engine, accumulator pressure of approximately 1,500 bar, and electronically controlled injectors at each cylinder. The system is similar in architecture to the common-rail used on MAN’s 35/44 and 48/60 products.
Dual-fuel and methanol variants
MAN has introduced derivative dual-fuel and methanol variants of the L32/44 platform:
- L35/44DF: a dual-fuel variant with slightly different bore and stroke (350 mm bore, 440 mm stroke), capable of operating on liquefied natural gas in lean-burn Otto cycle with diesel pilot injection. Widely deployed on LNG-fuelled cargo vessels, ferries, and offshore vessels.
- L32/44CR-LGIM methanol variant: capable of operating on methanol with a small pilot diesel injection, supporting decarbonisation pathways using renewable methanol.
Fuel and emissions
The standard L32/44CR runs on heavy fuel oil, marine diesel oil, low-sulphur fuel oil, and biofuel blends. IMO Tier II compliance is standard. Tier III compliance requires either selective catalytic reduction (typically MAN’s own SCR product) or operation in dual-fuel gas mode on the L35/44DF derivative. The methanol variant supports operation on grey, blue, or green methanol with corresponding lifecycle emission characteristics.
Applications
The L32/44CR is widely deployed across:
- Container ship and bulk carrier auxiliary gensets at the upper output end.
- Ro-pax and ferry main propulsion in mechanical or diesel-electric configurations.
- Offshore supply vessels and platform supply vessels, frequently in dual-fuel L35/44DF variant.
- Cruise ship gensets in V12 to V20 configurations.
- Naval auxiliary gensets on frigates, replenishment ships, and amphibious vessels.
- FPSO and offshore platform power generation.
- Land-based power plants in the 3 to 200 megawatt range.
Predecessor and successor context
The L32/44CR succeeded the mechanically injected L32/40 in new orders from approximately 2008 onward, with the older engine remaining in service in large installed numbers. Below the 32/44CR sits the smaller L23/30, L21/31, L27/38, and L28/32H products in the MAN four-stroke range. Above it sits the L48/60 and V51/60DF dual-fuel flagship four-strokes. Together these products span MAN Energy Solutions’ complete medium-speed range from approximately 1 to 20 megawatts.
Production and service
The L32/44CR is built at MAN Energy Solutions’ Augsburg works, with selected components and licensed production from MAN partners in Korea, Japan, and China. MAN’s PrimeServ aftermarket organisation supports the engine globally, with service centres on every major shipping route. The engine has undergone progressive output and efficiency upgrades since its introduction, with the current rating significantly above the original specification.