MAN B&W ME-C Electronic Control Overview

Background

For most of the twentieth century, slow-speed marine two-stroke engines used mechanical timing: a camshaft, geared from the crankshaft at half engine speed, lifted exhaust valves through pushrods and rocker arms, and pumped fuel injectors at fixed crank angles. Mechanical timing was reliable, simple to maintain, and adequate for the relatively narrow operating envelope of mid-century shipping. But it had two fundamental limitations: timing was fixed at design, and individual cylinders could not be balanced through software.

In the 1990s, MAN Energy Solutions (then MAN B&W Diesel) developed the ME (Mechanical Electronic) platform to replace mechanical timing with electronic control. The first ME engine, a 12K90ME, was prototyped through 2003 and entered commercial service in 2004 on the Maersk Burnham. Since then, electronic control has spread across the entire MAN B&W slow-speed catalogue. By 2020 essentially all new-build large MAN B&W engines were ME-C variants, with the older MC (Mechanical Camshaft) variants relegated to the smaller end of the catalogue and to specialised applications.

In June 2025 MAN Energy Solutions rebranded globally to Everllence. The product family retains the “MAN B&W” designation as the brand for the slow-speed two-stroke engines, now marketed under the Everllence company name. References in this article to “MAN Energy Solutions” or “MAN-ES” describe the same corporate entity now operating as Everllence.

The “ME-C” suffix denotes “Compact” and refers to the family’s compact engine room footprint compared to the mechanical-camshaft predecessors. Variants of ME-C include:

• ME-C for liquid fuel operation (HFO, LSFO, MGO)
• ME-GI (Gas Injection) for high-pressure gas injection (typically LNG)
• ME-LGI (Liquid Gas Injection) for methanol and LPG
• ME-GA (Gas Ammonia) for ammonia, in development

The architecture is shared across these variants, with fuel-specific changes confined to fuel valves, fuel supply systems, and software.

System architecture

Hydraulic power supply (HPS)

The ME-C hydraulic power supply is a high-pressure pump unit that supplies system oil at typically 250 to 350 bar. The HPS consists of:

• Multiple parallel high-pressure pumps, sized for full engine load with redundancy
• Pressure regulation valves
• Accumulators to absorb pulsations
• Filtering and water separation
• Cooling

The HPS is housed adjacent to the engine and is bolted to the engine frame. Hydraulic supply pipes run to each cylinder, providing the actuation power for fuel and exhaust valves.

Hydraulic control unit (HCU)

Each cylinder has a hydraulic control unit (HCU) mounted directly on the cylinder cover or close to it. The HCU contains:

• The exhaust valve actuator, with its servo valves and position sensors (see exhaust valve actuation)
• The FIVA (Fuel Injection Valve Activator) for the fuel injectors
• Pressure intensification stages where required
• Local hydraulic accumulators
• Sensor mounts

The HCU is a self-contained module that can be removed and replaced as a unit during overhaul.

Engine control system (ECS)

The engine control system (ECS) is the electronic brain of the engine. It comprises:

• A central ECS computer (often duplicated for redundancy)
• Cylinder control units (CCUs) one per cylinder
• Engine interface unit (EIU) for bridge and remote control communication
• Auxiliary control units for ancillary functions (cylinder lubrication, turbochargers, etc.)
• A network of digital signals connecting the components

The ECS receives operator commands (load setpoint, mode selection) from the bridge or engine control room, reads sensor inputs (crank angle, exhaust temperatures, scavenge pressure, ambient temperature), computes the appropriate timing and fuel quantity for each cylinder, and triggers the HCU actuators at the right crank angles.

Crankshaft sensor

A high-resolution crank angle sensor (typically 1024 pulses per revolution or higher) is mounted at the engine’s flywheel end. The sensor provides the timing reference for all engine actions. Precise crank angle measurement enables timing accuracy of better than 0.1 crank degrees.

Fuel injection

Common rail architecture

ME-C engines use a common rail fuel injection system. The common rail is a high-pressure pipe running along the engine’s length, charged by HPS-driven fuel pumps. Each cylinder’s fuel injector connects to the rail through the FIVA actuator on its HCU.

Fuel pressure

Common rail pressure is typically 800 to 1,000 bar for HFO and LSFO operation. Pressure can be varied by the ECS to adjust fuel atomisation as a function of engine load, optimising spray quality and combustion efficiency.

Variable injection timing (VIT)

The FIVA actuator controls fuel injection timing through a software-defined timing map. The injection timing varies as a function of:

• Engine load
• Ambient inlet temperature
• Fuel mode (HFO, LSFO, MGO, gas)
• Operator-selected mode (economy, performance, low-NOx)
• Cylinder balancing offsets

Variable injection timing was the first major operational benefit of ME-C: at low load, injection is advanced for better thermal efficiency; at high load, retarded for lower NOx and reduced peak pressures.

Variable exhaust valve closing (VEC)

The exhaust valve closing timing is similarly software-controlled. Combined VIT and VEC provide a two-dimensional timing map that allows the engine to be tuned to different operating regimes by software change rather than mechanical retiming.

Fuel mode switching

ME-GI, ME-LGI, and similar dual-fuel variants can switch between fuel modes during operation:

Liquid fuel mode

In liquid fuel mode, the engine operates on HFO, LSFO, MGO, or biofuels through the standard liquid fuel injectors. Common rail pressure, injection timing, and exhaust valve timing are tuned for liquid combustion.

Gas/methanol/LPG mode

In gas mode (ME-GI), high-pressure gas is injected through dedicated gas injectors using a separate fuel valve assembly. A small pilot injection of liquid fuel ignites the gas charge in dual-fuel diesel cycle operation. ME-LGI engines burn liquid methanol or LPG through similarly arranged injectors.

Mode switching

Switching between modes is performed by the ECS in real time, with timing, fuel quantity, and ignition pilot all adjusted automatically. Switching can occur at any operating load above a minimum threshold. Mode switches typically take a few minutes to complete safely.

Cylinder balancing

Software-driven balancing

The ECS individually adjusts injection timing, injection quantity, and exhaust valve timing for each cylinder. Balancing offsets correct for:

• Manufacturing variation between cylinders
• Different cylinder load conditions in the engine room
• Wear-driven changes in cylinder performance
• Fuel quality variation cylinder-to-cylinder (rare but possible)

Performance feedback

The ECS uses indicator pressure measurements (cylinder pressure transducers) and exhaust temperature measurements to verify cylinder balance and adjust offsets. Modern ME-C engines run continuous electronic indicator measurements, providing cycle-by-cycle pressure data to the control system.

Manual operator override

Operators can manually adjust cylinder balancing offsets, typically through the engine control room interface. Manual overrides may be needed during commissioning, after major overhauls, or to compensate for unusual operating conditions.

Tier II and Tier III compliance

Tier II (NOx 14.4 g/kWh)

ME-C engines as standard meet IMO Tier II NOx limits through optimised combustion: high-pressure injection, careful timing, and tuned scavenge swirl. No exhaust aftertreatment is required.

Tier III (NOx 3.4 g/kWh in ECAs)

ECA Tier III compliance requires either:

• EGR (Exhaust Gas Recirculation), recirculating a fraction of exhaust gas back to the inlet to dilute oxygen and lower flame temperature. ME-C engines integrate EGR through the standard ECS.
• SCR (Selective Catalytic Reduction), an exhaust aftertreatment system. ME-C engines work with SCR through the ECS managing the SCR injection profile and reagent dosing.

Both options are available across the ME-C catalogue. Operator’s choice depends on capex, ECA exposure, and other ship-design considerations.

Operational characteristics

Load-up ramp

When changing from low to high load, the ECS implements a load-up ramp that gradually increases fuel quantity and adjusts timing to avoid thermal shock and to keep the turbocharger within stable operating bounds. Load-up ramps are typically 5 to 15 minutes from idle to full load.

Slow steaming

ME-C engines operate well at slow steaming loads (down to roughly 25 percent MCR). Below this, scavenge air supply becomes problematic, and operators may need auxiliary blowers running to maintain adequate scavenge pressure.

Emergency operation

If a cylinder must be cut out due to fault, the ECS can isolate that cylinder’s fuel and continue running on the remaining cylinders. Engine output is reduced proportionally, but operation continues. This is particularly valuable on long voyages where in-port repair is the only alternative.

Degraded operation

If a sensor fails, the ECS can switch to a degraded operation mode using estimated values for the missing sensor. Engine continues running with reduced control quality until the sensor is repaired.

Maintenance characteristics

HCU overhaul

The hydraulic control units (HCUs) are removed and overhauled at major intervals (typically every 16,000 to 24,000 hours). During overhaul, the FIVA, exhaust valve actuator, servo valves, and seals are inspected and replaced as needed.

Common rail maintenance

The common rail itself is largely maintenance-free. The high-pressure fuel pumps that charge the rail require regular service (every 8,000 to 16,000 hours).

ECS maintenance

The electronic control system is largely maintenance-free in normal operation. Software updates may be installed as the engine model evolves; sensor recalibration is performed periodically.

Spare parts

Critical ECS components (CCUs, EIUs, sensors) are typically held as spares aboard the ship for emergency replacement. Major HPS pumps and HCUs may also be carried as spares for long voyages.

Comparison with WinGD X-DF

WinGD’s X-DF family is the parallel platform from the other major slow-speed two-stroke manufacturer. The two platforms are functionally similar:

The principal architectural difference is in gas injection: MAN B&W uses high-pressure gas injection (~300 bar), while WinGD’s X-DF uses low-pressure (Otto-cycle) gas operation with diesel pilot ignition. The high-pressure approach burns more efficiently and has lower methane slip; the low-pressure approach simpler gas supply systems and lower capex.

Related Calculators

• Common Rail Fuel Pressure Calculator
• Variable Injection Timing Calculator
• Engine Load Up Ramp Calculator
• Cylinder Balancing Offset Calculator
• Specific Fuel Oil Consumption Calculator

See also

• Exhaust Valve Actuation in Two-Stroke Marine Engines
• Two-Stroke Marine Diesel Engine Fundamentals
• Crosshead Diesel Engine Architecture Overview
• Cylinder Bore and Stroke Selection Criteria for Marine Engines

References

• MAN Energy Solutions. (2023). ME-C Engine Operation and Maintenance Manual. MAN Energy Solutions.
• MAN Energy Solutions. (2023). ME-GI Operation and Maintenance Manual. MAN Energy Solutions.
• MAN Energy Solutions. (2022). The ME Engine Story. MAN Energy Solutions.
• Woodyard, D. (2009). Pounder’s Marine Diesel Engines and Gas Turbines (9th ed.). Butterworth-Heinemann.
• Lloyd’s Register. (2022). Guidance Notes for Electronically Controlled Marine Engines.