Marine Commercial - News Release

Yanmar Completes Development of the Cleaner and Highly Reliable 6EY26DF Dual-Fuel Engine for Vessels

July 25, 2016
Yanmar Co., Ltd.

6EY26DF dual-fuel engine

Yanmar Co., Ltd. has completed development of a new, reliable dual-fuel engine for vessels that enables the user to switch to and from liquefied natural gas (LNG) and diesel fuel during operation. The new International Maritime Organization (IMO) Tier 3 regulations, introduced in January this year, require an 80% reduction of nitrogen oxides (NOx) emissions from the Tier 1 levels, and a 20% improvement of CO2 emissions by 2020; representing an annual tightening of emissions for vessels. With the flexibility to operate using both LNG which offers superior environmental benefits and easy to obtain diesel fuels, the dual-fuel engine has drawn considerable attention in recent years as a solution that easily passes the demanding Tier 3 emissions controls.

While advanced electronic control is typically required for utilization of two different fuel types, the EY26DF employs high-precision air flow technology that optimizes combustion conditions delivering stability and reliability when in operation. From here on, Yanmar will continue its efforts towards expanding its dual-fuel engine line-up for vessels, delivering optimal solutions for a wide range of customers.

1. 6EY26DF Engine Features

Fuel Flexibility

  • Switch between LNG and diesel fuel mode even under full engine loads
  • No power limitations even for LNG—a fuel source which sometimes causes knocking in other engines due to it having a low methane concentration

Advanced Engine Control

  • Utilizing Yanmar's innovative technology to control the air-fuel ratio*1 and its knock detection system, the 6EY26DF delivers stability in gas mode.
  • Ignition with the micro-pilot injection system, when in gas mode, is as effective as a diesel engine

Cleaner Operation and Greater Thermal Efficiency in Gas Mode

  • Compared to the same-class EY26 diesel engine, the 6EY26DF delivers 84% NOx, 25% CO2, and 99% Sox and PM reductions, meeting IMO Tier 3 standards
  • Gas mode exceeds Yanmar's current diesel engine thermal efficiency ratios at 46.8%

2. 6EY26DF Specifications

Model 6EY26DF
Rated power (kW) 1533
Rated speed (min-1) 750
No. of cylinders 6
Bore x stroke (mm) 260 x 385
Mean effective pressure (MPa) 2.0
Fuel Heavy fuel oil for vessels, LNG(36.0 to 40.6 MJ/Nm2)
  • ※1:Optimal air flow (air-fuel ratios) for combustion can vary with load fluctuations and methane concentrations. Additionally, as diesel and LNG air and fuel requirements differ, it’s crucial that the engine is equipped with a device for optimizing air-fuel ratios
  • ※2:By injecting minute quantities of diesel fuel, the LNG ignites speeding up combustion

About Yanmar

With beginnings in Osaka, Japan in 1912, Yanmar was the first ever to succeed in making a compact diesel engine of a practical size in 1933. Moving on, with industrial diesel engines as the cornerstone of the enterprise, Yanmar has continued to expand its product range, services, and expertise to deliver total solutions as an industrial equipment manufacturer. As a provider of small and large-size engines, ag machines and facilities, construction equipment, energy systems, marine, machine tools, and components — Yanmar’s global business operations span seven domains.

On land, out at sea, and in the midst of the city, Yanmar’s Mission of “providing sustainable solutions focused on the challenges customers face, in food production and harnessing power, thereby enriching people’s lives for all our tomorrows,” stands testament to Yanmar’s determination in providing us with “a sustainable future.” For more information, visit Yanmar Co., Ltd. at its worldwide website at


Public Relations Group
Brand Communication Division, Yanmar

  • Note: Information contained in the news release is valid at the time of publication and may differ from the most recently available information.