Akasaka Diesels

Akasaka Diesels Limited is a Japanese marine engine manufacturer based in Yaizu, Shizuoka Prefecture. The company was founded in 1933. It became a licensee for Mitsubishi UE low-speed two-stroke engines in 1960, and that licence has since passed to Japan Engine Corporation (J-ENG).

Akasaka builds two groups of engines. The first is its own four-stroke diesels for direct-drive propulsion. The Type AT, AX and A engines cover about 749–3,309 kW at 210–320 rpm for coastal cargo ships and tankers. The Type K, E, AH and U engines cover about 956–2,942 kW at 350–720 rpm for fishing vessels, training ships, ferries and government vessels. The second group is licence-built J-ENG UEC two-stroke engines (types LSE, LSII, LSJ and LSH) covering about 1,655–11,040 kW for coastal and short-sea cargo ships and tankers.

In 2026 Akasaka's J-ENG licence was renewed to include ammonia-fuelled engines, and licences for methanol and hydrogen are reported to be pending. The company also markets the NEPHRON oil purifier system.