More than 95 % of the world’s trade goes by sea and there are approximately 86,000 ocean going merchant ships over 100 gt in operation. About 97 % of them are propelled by large-bore, highly supercharged diesel engines. State-of-the-art four-stroke diesel engines with maximum availability do not only have to be reliable, maintenance-friendly and highly efficient, but compliant with ever increasing market re-quirements including lower emissions.