Wärtsilä 31

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Wärtsilä 31

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.

Key benefits

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.


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.

Wärtsilä 31 Product guide and 3D models and drawings

Get technical data and system proposals for designing W31 marine engine installations.

Wärtsilä 31


  • 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 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.

  • Icebreaker for FSUE Atomflot

    “We are convinced that Wärtsilä, with its long and good reputation as an engine builder, is able to build a reliable and efficient engine. Another feature in favour of the Wärtsilä 31 was the connection to the CBM (Condition-Based Maintenance) system. It is an advantage to us that Wärtsilä can monitor the engine operation online and, if necessary, provide us with instant advice.” FSUE Atomflot, Head of diesel-electric icebreakers, Alexander Degterev

    FSUE Atomflot


UNIC automation system enables Wärtsilä 31 performance
26 APR 2017 Article
6 min read

Next generation UNIC automation system enables Wärtsilä 31 performance

With its long history of technology leadership in advanced controls for...
Orders stream in for Wärtsilä 31
28 MAR 2018 Article
3 min read

Orders stream in for Wärtsilä 31

The demand for what the Guinness Book of World Records calls ‘the world’s most efficient 4-stroke engine’, the...
Modularisation hand in hand with manufacturability
29 MAY 2018 Article
5 min read

Modularisation hand in hand with manufacturability

The development of the new Wärtsilä 31 engine provided the perfect opportunity to exploit the...
Wärtsilä 31
1 JUN 2015 Article
7 min read

Wärtsilä 31 – the most efficient engine in the world

The Wärtsilä 31 marine engine sets the standard for energy efficiency. It has the lowest fuel...
Dual fuel engines hero image
26 APR 2017 Article
25 min read

Common rail fuel injection rules the waves

Very few marine engines are awarded a Guinness World Record. Thanks to Wärtsilä’s common rail injection...

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