Japan Engine Corporation (J-ENG) has completed the first full-scale ammonia-fueled engine, the 7UEC50LSJA-HPSCR, featuring a cylinder bore of 50 cm, seven cylinders, and a high-pressure SCR system, according to the company's release.
The project was developed under the New Energy and Industrial Technology Development Organization (NEDO)’s Green Innovation Fund Program for next-generation ships.
Between August 27 and August 30, 2025, J-ENG conducted land-based trial runs at its Akashi factory, witnessed by Nippon Yusen Kabushiki Kaisha (NYK Line), Japan Shipyard Co., Japan Marine United Corp., and ClassNK.
The tests included both ammonia-fueled and heavy oil dual-fuel modes, performance checks, and inspections.
According to the company, ClassNK approved the engine’s environmental performance and safety. The engine is scheduled to be shipped in October 2025 to Japan Marine United’s Ariake facility, where it will be installed on an ammonia-fueled ammonia carrier (AFMGC) currently under construction.
The vessel is expected to enter service in November 2026.
J-ENG previously conducted around 1,000 hours of testing with a single-cylinder ammonia engine at Mitsubishi Heavy Industries’ Nagasaki research site between May 2023 and September 2024.
The company started factory testing of the full-scale model in April 2025, followed by about 700 hours of additional testing over five months. These tests confirmed optimization of performance, prevention and monitoring of ammonia leaks, and operational safety for crews and vessels.
According to J-ENG, performance data showed that at 100% load with a 95% ammonia co-firing rate, nitrous oxide (N₂O) emissions were about 3 ppm, resulting in more than 90% reduction in greenhouse gas emissions compared to conventional fuels.
Nitrogen oxides (NOx) emissions were about half those of heavy oil engines, while unburned ammonia emissions after SCR were nearly zero. Thermal efficiency in ammonia-fueled mode was reported as equal to or higher than in heavy oil mode.
The company is also developing a 60 cm-bore ammonia-fueled engine in parallel, citing several ongoing projects. J-ENG plans to expand production of ammonia-fueled engines alongside heavy oil engines.
Supported by subsidies under the Ministry of the Environment and Ministry of Land, Infrastructure, Transport and Tourism’s program using GX Economic Transition Bonds, J-ENG has started construction of a new factory expected to begin operations in fiscal year 2028.
Japan Engine Corporation (J-ENG) is a Japanese corporation specializing in the design, development, and manufacture of large marine engines. It operates as a joint venture formed in 2017, with ownership by Mitsui E&S Co., Kawasaki Heavy Industries, and IHI Power Systems.