W?rtsil? 50DF

Designed to give high output with fuel flexibility, low emissions, efficiency & reliability

The engine can be run on either natural gas, light fuel oil (LFO), or heavy fuel oil (HFO), and can smoothly switch between fuels whilst operating. It is designed to provide the same output regardless of the fuel.

The Wärtsilä 50DF engine operates on the lean-burn principle. Lean combustion enables a high compression ratio, which in turn increases engine efficiency, reduces peak temperatures, and therefore also reduces NOx emissions.

Both the gas admission and pilot fuel injection are electronically controlled. The engine functions are controlled by an advanced automation system that allows optimal running conditions to be set, independent of the ambient conditions or fuel type.


    Fuel flexibility

    The technology enables the engine to be operated on either natural gas, light fuel oil (LFO), or heavy fuel oil (HFO), and switching between fuels can take place seamlessly during operation, without loss of power or speed. This ensures safety and continuous installation operability. The Wärtsilä 50DF engine is designed to have the same output regardless of the fuel used.

    One of the reasons for the strong success of this particular engine over the alternatives is its superior propulsion efficiency. The clear environmental advantages that operating on gas allows, is another factor in the success of this technology. When operating in gas mode, the nitrogen oxide (NOx) emissions are at least 85 percent below those specified in the current IMO regulations, and CO2 emissions are some 25 percent less than those of a conventional marine engine running on diesel fuel. Additionally, the sulphur oxide (SOx) and particle emissions are negligible at almost zero percent.

    Technical data
    Wärtsilä 50DF IMO Tier III
    Cylinder bore 500 mm Fuel specification: Fuel oil
    Piston stroke 580 mm 700 cSt/50°C     7200 sR1/100°F
    Cylinder output 950, 975 kW/cyl
    Speed 500, 514 rpm ISO 8217
    Mean effective pressure 20.0 bar ISO-F-DMX, DMA & DMB
    Piston speed 9.7, 9.9 m/s BSEC 7150 kJ/kWh at ISO cond.
    BSGC 7110 kJ/kWh at ISO cond.
    Dimensions (mm) and weights (tonnes)
    Engine type A B C D F Weight
    6L50DF 8115 3 475 3 270 4 000 1 455 96
    8L50DF 10 230 3 920 3 505 4 000 1 455 128
    9L50DF 11 140 3 920 3 505 4 000 1 455 148
    12V50DF 10 410 4 055 3 810 3 600 1 500 175
    16V50DF 13 085 4 400 4 730 3 600 1 500 220
    18V50DF 14 180 4 400 4 730 3 600 1 500 240


    Rated power
    Engine type Engine kW (50Hz) Gen. kW (50Hz) Engine kW (60Hz) Gen. kW (60Hz)
    6L50DF 5700 5500 5850 5650
    8L50DF 7600 7330 7800 7530
    9L50DF 8550 8250 8775 8470
    12V50DF 11400 11000 11700 11290
    16V50DF 15200 14670 15600 15050
    18V50DF 17100 16500 17550 16940
    Generator output based on a generator efficiency of 96.50 %

    Wärtsilä’s advanced dual-fuel technology was first launched in the early 1990s for use in land-based power plant applications. The first marine installation of the 50DF engine came a decade later.

    The fitting of Wärtsilä 50DF engines onboard the first LNG Carriers in 2006 set a trend in the industry. Since that introduction, 65 percent of all new LNG Carriers have been fitted with Wärtsilä dual-fuel engines.

    In addition to its success in the LNG Carrier market, the Wärtsilä 50DF engine is increasingly being considered by owners and operators throughout the shipping industry. For example, in the cruise and ferry sector, where it is often necessary to operate in Emission Control Areas (ECAs), there is growing awareness of the advantages of operating on gas.

    Similarly, vessels serving the offshore oil and gas industry are increasingly being fitted with Wärtsilä dual-fuel engines. The need for flexibility, fuel efficiency, and compliance with stricter environmental regulations, are the drivers behind this trend.

    Methane Number

    W?rtsil? Methane Number Calculator

    We have developed this tool for ship owners and operators to calculate the Methane Number of the fuel gas.
    The calculation result indicates whether or not the given gas quality is suitable for use in W?rtsil? dual fuel engines.

    Methane CH4
    Iso-butane (2-Methylpropane)i-C4H10
    Iso-pentane (2-Methylbutane)i-C5H12
    Neo-pentane (2,2-Dimethylpropane) neo-C5H12
    Mix-hexaneMix C6H14
    Mix-heptaneMix C7H16
    Carbondioxide C02
    Nitrogen N2
    Hydrogen sulfideH2S
    Total mol%
    W?rtsil? Methane number (WMN)
    Propane Knock Index (PKI)
    The calculation tool is owned by W?rtsil? and is made for customer use and is for guidance only. Changes in the tool is reserved at any time.


    • Provalys
      When taken into service in 2006, the 154,000 m3 LNG carrier Provalys was the largest LNG carrier in existence.

      This modern LNG carrier has clearly demonstrated the advantages of gas fuel propulsion, made possible by W?rtsil?’s pioneering efforts in dual-fuel engine technology.


    • JS INEOS Insight
      "The delivery of the first in this series of the Dragon class vessels marks the beginning of a new era in the transportation of liquefied gases. The highly advanced technological solutions that W?rtsil? provides makes these ships the most modern and environmentally sustainable gas carriers ever built,"
      Steffen Jacobsen, CEO, Evergas.

      JS INEOS Insight

    • P-63 FPSO
      The P-63, the first FPSO to utilize gas engines to produce more than 100 MWe of power, is one of the new units coming on stream in 2013 helping to increase oil production for Petrobras.

      P-63 FPSO

    • Viking Grace
      A new era in ferry operations was established in 2013 with the launch of the world’s largest Ro-Pax ferry operating on LNG fuel.

      This vessel features four W?rtsil? 50DF dual-fuel engines and a complete W?rtsil? LNGPac system that includes the storage tanks, the fuel supply system, and all equipment needed for bunkering and related safety and automation systems.

      Viking Grace

    Press releases


    LNG Vessels advance in North America

    Totem Ocean Trailer Express is one of the latest North American shipping companies to opt for W?rtsil?’s...
    2 July 2014
    • Twentyfour7. article

    Grace on the waves

    Not for 20 years has a new cruise ferry been brought into service between Finland and Sweden, but Viking Line’s new...
    22 May 2013
    • Twentyfour7. article

    The W?rtsil? Gas Valve Unit Enclosed...

    W?rtsil?’s dual-fuel engine technology is...
    17 May 2013
    • In Detail article

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