Wartsila 31 engine has entered into Guiness book of world record for most fuel efficient 4-stroke diesel engine.
Specific fuel oil consumption is the key of fuel efficiency of engine, for Wartsila 31, it has been recorded as low as 165 g/kWh, which used to be as high as 175 -185 g/kWh ( Reference _ MAN Diesel and Wartsila WASA ) few years back.
It maintains outstanding performance across the complete operating range, this is important because the operating range of engines are wide due to kind of service they are used for.

Engine picture from Wartsila
Its modular design enables a significant reduction in maintenance time and costs, thereby improving power availability and reducing the need for parts.
The availability of spare part kit and sets as well as exchange units for maintenance significantly cuts down the maintenance time.
Wartsila providing long term maintenance agreement with owners to increase reliability, performance and financial predictability.
In place of conventional many small parts, there are fewer modular parts like fuel valve and fuel pumps which can be replaced as a whole unit thus saving time, less possibility of human error and thus failure.
One of the smallest footprints vs power ratio.
Performance data can be accessed remotely in real time enabling the experts and specialists to monitor and response promptly.
Installed in in various offshore, cruise & ferry, and in marine field where power requirement is from 4.2 to 9.8 MW. On ships it can be installed on container vessels where power requirement is high for reefer containers.
The engines are available in 3 version of fuel use Diesel, Dual-Fuel (DF) and Spark-Ignited Gas (SG).
