Wärtsilä 31

The Wärtsilä 31 is the first of a new generation of medium speed engines, designed to set a new benchmark in efficiency and overall emissions performance.

The Wärtsilä 31 is available in 8 to 16 cylinder configurations and has a power output ranging from 4.7 to 9.8 MW, at 720 and 750 rpm. The launch of the Wärtsilä 31 introduces a 4-stroke engine having the best fuel economy of any engine in its class. At the same time, it maintains outstanding performance across the complete operating range. Its modular design enables a significant reduction in maintenance time and costs, thereby improving power availability and reducing the need for spare parts.

Wärtsilä 31 is recognised by Guinness World Records as the world's most efficient 4-stroke diesel engine

    The Wärtsilä 31 retains its high efficiency and environmental values throughout the entire lifecycle of the vessel.
    • Lowest fuel consumption over a wide operating range.
    • Highest cylinder power in its segment, 610 kW/cylinder.
    • Available in Diesel, Dual Fuel (DF) and Pure Gas (SG) versions.
    • Meets the coming IMO Tier 3 regulations when operating on gas, and with an SCR when using diesel fuel. The SCR has a minimal effect on fuel consumption.
    • Reliability guaranteed through extensive validation and Wärtsilä’s vast manufacturing experience.
    • Supported by Wärtsilä’s extensive global service network.
    Technical data
    Wärtsilä 31 IMO Tier II or III
    Cylinder bore 310 mm Fuel specification: Fuel oil
    Piston stroke 430 mm 700 cSt/50°C 7200 sR1/100°F
    Cylinder output 610 kW/cyl ISO 8217, category ISO-F-RMK 700 ISO-F-DMA, ISO-F-DMB, ISO-F-DMZ ,ULSF
    Speed 750 rpm  
    Mean effective pressure 30.1 bar Gas: Methane number ³ 80
    Piston speed 10.75 m/s SFOC 170,6 g/kWh at ISO conditions

    Rated power
    Engine type kW
    8V31 4880
    10V31 6100
    12V31 7320
    14V31 8540
    16V31 9760
    Engine platform A* A B C F Weight (tons)
    Wärtsilä 8V31 6175 6114 3205 3113 1496 56.7
    Wärtsilä 10V31 6813 6754 3205 3113 1496 62.0
    Wärtsilä 12V31 7900 7840 2628 3500 1496 73.0
    Wärtsilä 14V31 8540 8480 2660 3500 1496 81.0
    Wärtsilä 16V31 9130 9070 2660 3500 1496 89.0
    W31 technical data W

    The Wärtsilä 31 is designed to be suitable for a broad range of ship types and applications, both as a main propulsion engine and in diesel electric configurations, or as an auxiliary engine. It can be optimised for running either at constant speed or along a propeller curve. In the Offshore sector, the Wärtsilä 31 is a perfect solution for OSV´s and drilling or semi-submersible vessels, where operational flexibility, high power density, long intervals between overhauls, and high levels of safety are of paramount importance.


    • Car and passenger ferry for Mols-Linien
      A new 158 metre long car and passenger ferry being built for Danish operator Mols-Linien, will be powered by two 8-cylinder Wärtsilä 31 main engines.“The selection of this particular engine was based on the unique efficiency for the required output, and also the favourable maintenance intervals it allows.” Mols-Linien A/S - Technical Director Flemming Kristensen

      Car and passenger ferry for Mols-Linien

    • Fishing vessel for Peter Hepsø Rederi AS
      The fishing vessel will be powered by the Wärtsilä 31 engine and a complete propulsion system from Wärtsilä. “... a new vessel that will represent the future of the fishing fleet. Wärtsilä’s propulsion solution provides the efficiency and environmental sustainability we needed for the ship,” Audhild Hepsø, General Manager, Peter Hepsø Rederi AS.

      Fishing vessel for Peter Hepsø Rederi AS

    • Fishing Trawler for Strand Senior AS
      The vessel will feature the Wärtsilä 31 engine and propulsion machinery. “We wanted to build a new vessel that represents the future. For this reason we have emphasised high efficiency and environmental sustainability, and Wärtsilä was the obvious choice to meet these aims.” Strand Havfiske AS – Managing Director Janne-Grethe Strand Aasnæs.

      Fishing Trawler for Strand Senior AS

    • FSUE Atomflot
      The new generation icebreaker Aker ARC 124 will feature three 8-cylinder Wärtsilä 31 engines.
      "This new icebreaker, powered by Wärtsilä 31 engines, will be the most technologically advanced ship of its kind in the whole world.”
      FSUE Atomflot First Deputy Director General – Chief Engineer Mustafa Kashka

      FSUE Atomflot

    Press releases

    Product hologram


    Wärtsilä 31 - the most efficient engine in the world

    Welcome to a brand-new generation of engines. The Wärtsilä 31 is setting a new standard for energy efficiency, delivering the lowest level of fuel consumption of any four-stroke engine worldwide.
    20 October 2015
    • Twentyfour7. article

    Wärtsilä engine in Guinness World Records

    The recently launched Wärtsilä 31 engine has achieved a Guinness World Records title for the most efficient...
    2 June 2015
    • News

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