Wärtsilä 31SG

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Wärtsilä 31SG

Designed to set a new benchmark in efficiency and overall emissions performance in connection with Hybrid solutions

The development of this engine is a direct result of Wärtsilä's on-going commitment to reduce the greenhouse gas emissions of its gas engines by 15%, by 2020 (from 2015 levels).

The Wärtsilä 31SG is available in 8 to 16 cylinder configurations and has a power output ranging from 4.2 to 8.8 MW, at 720 and 750 rpm. The launch of the Wärtsilä 31SG 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.

Key benefits

The Wärtsilä 31 retains its high efficiency and environmental values throughout the entire lifecycle of the vessel.

  • Available in Diesel, Dual Fuel (DF) and Pure Gas (SG) versions.
  • Lowest fuel consumption over a wide operating range.
  • Highest cylinder power in its segment, 650 kW/cylinder (Diesel).
  • Full output available for a broad range of gas qualities down to methane number 70 (DF & SG).
  • 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 is guaranteed through extensive validation and Wärtsilä’s vast manufacturing experience.
  • Supported by Wärtsilä’s extensive global service network.

Download Wärtsilä 31 brochure


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 Methane Number Calculator

Wärtsilä 31SG Product guide and 3D models and drawings

Get technical data and system proposals for designing W31SG marine engine installations.

Wärtsilä 31


FAQs Wartsila 31SG

Why is Wärtsilä launching the pure gas engine for the marine market now?
How is the pure gas engine different from the dual fuel engine?
Is the pure gas engine replacing the dual fuel engine?
When should the pure gas (SG) engine be selected instead of the dual fuel (DF) engine?
What are the environmental benefits of the pure gas engine vs. the dual fuel engine?
Is the pure gas engine suitable for heavier gases with a lower methane number?
How does the single-fuel pure gas engine comply with the redundancy requirements of the marine sector?
What are the benefits of a pure gas-hybrid application?
When is the Wärtsilä 31SG ready for delivery for marine applications?
Does Wärtsilä have plans for other pure gas engines for the marine market?

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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...

Press releases

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