Japan Engine Corporation (J-ENG) reports that it has finalised development of its 2-stroke, dual-fuel ammonia engine, the 7UEC50LSJA-HPSCR, which completed performance verification tests in August 2025.
The engine – under development since 2023, as part of a NEDO-funded project with partners NYK Line, Nihon Shipyard, Japan Marine United Corporation (JMU) and ClassNK – will be installed aboard an ammonia-fuelled medium gas carrier at JMU Ariake Shipyard in October 2025. This newbuild is expected to commence operations in 2026.
The new engine is a 50cm-bore, 7-cylinder model, with a high-pressure SCR system for exhaust aftertreatment. The August verification tests saw the engine put through its paces in both ammonia and HFO operation modes, with ClassNK handling certification related to environmental performance and safety.
J-ENG comments: “[We] previously conducted approximately 1,000 hours of test runs on a single-cylinder ammonia-fuel test engine at the Mitsubishi Heavy Industries Research & Development Center at Nagasaki between May 2023 and September 2024.” Insights gained from those test runs informed the manufacture of the first full-scale commercial version of the 7UEC50LSJA-HPSCR, which began ammonia fuel trials in April 2025. In the five months since, the engine has undergone 700 hours of tests, focusing on factors such as leak prevention and monitoring, for the safety of the crew. J-ENG adds that, at 100% engine load and 95% ammonia fuel content, the engine was observed to reduce greenhouse gas emissions by more than 90%.
Additionally, J-ENG says it is developing a 60cm-bore ammonia-fuelled engine, and plans to open a new engine-building factory in 2028.
