HD Hyundai Marine Engine

HD Hyundai Marine Engine is a South Korean builder of large marine engines and components, headquartered in Changwon. It was formerly STX Engine / STX Heavy Industries. HD Korea Shipbuilding & Offshore Engineering (HD KSOE) took a 35.05% controlling stake, and the company took its current name in 2025 as HD Hyundai expanded its capacity for green engines.

Its engine business builds low-speed two-stroke engines under a technical alliance with Everllence SE (formerly MAN Energy Solutions). The programme covers G-type (G95ME-C10.6 to G45ME-C9.5), S-type (S90ME-C10.5 to S30ME-B9.5) and L35MC engines, with bores from 30 to 95 cm. The company reached 15 million horsepower of cumulative output in 2011. It was the first licensee to produce the 51/60DF engine for LNG carriers, and in December 2019 it ran sea trials of the first LPG dual-fuel (ME-LGIP) ship propulsion engine. Ammonia-fuelled ME engines are also in its plans.

The parts business builds turbochargers under licences from Everllence (since 1986), Mitsubishi Heavy Industries Marine Machinery & Equipment (since 2011) and Accelleron (from 2024). It also produces crankshafts, superalloy precision castings and gas turbine components.