Wärtsilä 20DF
The advantages of fuel flexibility in a small unit, also used for generating set applications
With the Wärtsilä 20DF, Wärtsilä is extending the benefits of dual-fuel (DF) technology to cover the entire power range. The engine offers ship owners and operators a compact unit that brings all the advantages of fuel flexibility to auxiliary applications, such as generating sets or as the prime mover in smaller vessels.
Based on the well proven and reliable Wärtsilä 20 diesel engine introduced in the early 1990s, fuel flexibility means the engine can be optimized for constant speed generating sets, as well as variable speed mechanical drives, for main engine applications.
Fuel flexibility
The Wärtsilä 20DF is a medium-speed dual-fuel engine that can be run on either natural gas, marine diesel oil (MDO), or heavy fuel oil (HFO). The engine can smoothly switch from gas to MDO/HFO and vice versa during operation without power interruption.
The Wärtsilä dual-fuel (DF) main and auxiliary engines allow the ships to operate on liquefied natural gas (LNG), which minimises their environmental footprint. Fuel flexibility, a primary benefit of the Wärtsilä DF engine technology, means that conventional marine diesel fuels can also be used if required. The switch between fuel types is made seamlessly without loss of power or speed.
The use of Wärtsilä’s dual-fuel engine technology enable vessels to sail without restrictions in Sulphur Emission Control Areas (SECAs) and Nitrogen Emission Control Areas (NECAs). Natural gas is the most environmentally sound fuel today, and it fulfils current actual and known future marine emissions legislation.
Applications
Installed alongside Wärtsilä 34DF or 50DF main propulsion machinery, a Wärtsilä 20DF generating set completes the multi-fuel engine room concept. Compact and light, the Wärtsilä 20DF is intended for use in those vessel types where the Wärtsilä 20 is currently installed.
As well as being an ideal mechanical-drive prime mover in smaller applications, such as small cargo vessels, ferries or tug boats, it is also an excellent choice for harbour generating set applications in a wide range of vessel types.

Wärtsilä 20DF | IMO Tier III |
Cylinder bore |
200 mm |
Fuel specification: |
Piston stroke |
280 mm |
Fuel oil |
700 cSt/50oC |
Cylinder output |
185 kW/cyl |
|
7200 sR1/100 F |
Speed |
1200 rpm |
ISO 8217, category ISO-F-DMX, DMA & DMB |
Mean effective pressure |
21.0 bar |
BSEC 7700 kJ/kWh at ISO cond. |
Piston speed |
11.2 m/s |
Rated power |
Engine type |
kW |
6L20DF |
1 110 |
8L20DF |
1 480 |
9L20DF |
1 665 |
Dimensions (mm) and weights (tonnes) |
Engine type |
A* |
A |
B |
C |
D |
F |
Weight |
6L20DF |
3 254 |
3 210 |
1 705 |
1 829 |
1 800 |
624 |
9.5 |
8L20DF |
3 973 |
3 890 |
1 705 |
1 963 |
1 800 |
624 |
11.2 |
9L20DF |
4 261 |
4 195 |
1 705 |
1 963 |
1 800 |
624 |
11.8 |
|