With the market launch of common rail fuel injection for large-bore four-stroke diesel engines, MAN Diesel & Turbo set a milestone for even more efficient and clean combustion in every load range. Efforts towards optimisation in this regard were restricted in the past by the fact that the classic injection system is controlled by the camshaft and therefore directly linked to the engine speed. Only when extensive options for electronic control became available for large-bore diesel engines, new groundbreaking possibilities opened up for our engine developers. Common rail technology from MAN Diesel & Turbo now regulates the injection timing, the desired pressure and the required fuel quantity for four-stroke engines.
 
Unlike its equivalent in cars or commercial vehicles, common rail technology in large-bore diesel engines must be capable of operating with heavy fuel oil, which is similar to tar and therefore not exactly ideal for high-precision, electronically controlled injection. The fuel is therefore first heated to 150 degrees Celsius in order to attain the viscosity required for the process. The high proportion of corrosive content in heavy fuel oil also presented our engineers with additional challenges. All parts of the injection system need to be able to withstand high temperatures and the specific properties of heavy fuel oil over the long term without malfunction.
 
The reliability of the system is crucially important, as it is impossible to use a purely mechanical safeguard with an electronic system. For ships equipped with multiple propulsion engines, any malfunction can be bypassed in an emergency to ensure continued functioning of the system. However, if there is only one propulsion engine on board, the MAN Diesel & Turbo safety system comes into play. All sensors required for common rail, the power supply and the control modules are duplicated, so a malfunction in one area can never cause the whole engine to fail.

For the MAN B&W Diesel two-stroke engines another design principle for fuel injection has been selected. The so-called ME design also provides high pressure fuel injection at all engine speeds, electronically controlled injection timing and variable injection intensity during one injection called „rate shaping”.

Furthermore, the opening and closing times of the exhaust valve are also independently electronically controlled. All parameters are adjusted depending on engine load in order to optimise the NOx emissions and fuel consumption of the engine. The smaller bore two-stroke engines are for simplicity and initial cost reasons not equipped with variable exhaust valve timing. However, lack of exhaust valve timing can be compensated by application of a turbocharger with VTA technology.