In 1955, shop test of the first Mitsubishi UE-type engine 9UEC75/150 was completed at Mitsubishi Heavy Industries Nagasaki Shipyard. It was the birth of Mitsubishi UE-type engine. In 1957, Kobe Diesel Co., Ltd. made a contract on the License Agreement with Mitsubishi UE-type engine production and became the first UE family member. In 1958, Kobe Diesel completed its first Mitsubishi UE-type engine 6UET45/75 (2,700HP) and this engine had made her debut as a main engine of “Kuroshio-Maru” (Kansai Line) which engaged with the Okinawa route service. For about 10 years then after, it was the time of struggle for both licensor and licensee who worked closely together to solve various troubles of the engines. Through these difficult times, and through the process of overcoming these troubles, reputation and trust towards the UE engines have been formed among the customers slowly but steadily. Due to its poor fuel economy, trunk piston type UET engine has disappeared some time back and only crosshead type UEC engine is being produced continuously.

Long-term enthusiastic approach, work and efforts of UE related engineers made Mitsubishi UE-type as one of the three major marine diesel engines (MAN B&W, WARTSILA and Mitsubishi) in the world. Furthermore, in 2004 CIMAC KYOTO CONGRESS, user’s working group reported that the failure rate of Mitsubishi UE was rather low than those of MAN B&W and WARTSILA. Consequently, Mitsubishi UE engine was highlighted worldwide due to its reliability. In latest new engine development like 45LSE, reliability first design concept is continuously applied. Recently Vietnamese and Chinese engine manufacturers newly became as UE family and further growth of Mitsubishi UE is very much expected.