Wärtsilä 20DF Dual‑Fuel Marine Engine
Engine Summary
- Power Range: 876 – 1,665 kW
- Speed Range: 1,000 – 1,200 rpm
- Fuel Type: Dual-Fuel: Natural gas (LNG) / MDF (HFO as back-up fuel only)
- Cylinder Configuration: 6L, 8L, 9L (in-line)
- Max Power: 1,665 kW (9L20DF, 1,200 rpm)
Engine Information
Engine Family: Wärtsilä 20DF
Engine Type: Dual-Fuel Engine
Description
The Wärtsilä 20DF is a compact, medium-speed dual-fuel marine engine designed for operation on natural gas (LNG) and liquid fuel. It combines proven diesel engine architecture with lean-burn gas combustion and allows switching between fuel modes during operation.
Available in 6L, 8L and 9L in-line configurations with 876–1,665 kW at 1,000–1,200 rpm, it meets IMO Tier III in gas mode and Tier II in liquid fuel mode. The 20DF is used in generating sets and as a mechanical drive in smaller vessels such as ferries, tugs and small cargo ships.
As a member of the Wärtsilä 20 engine family, it offers a reliable and flexible solution for marine propulsion and onboard power generation.
Compatible Filters
Specifications
- Rated Speed: 1,000 / 1,200 rpm
- Fuel Consumption: Gas mode: 8,180 – 8,370 kJ/kWh; liquid fuel mode: 195 – 197 g/kWh (100 % load)
- Max Torque: approx. 13,750 Nm (9L at 1,000 rpm, calculated from rated power and speed)
Dimensions & Weight
- Length: 3,218 – 4,401 mm (6L – 9L)
- Width: 1,690 – 1,860 mm (6L – 9L)
- Height: approx. 2,391 mm (6L – 9L, wet sump)
- Dry Weight: 9.3 – 13.4 t (6L – 9L, main engines)
Compliance
- Emission Standards:
IMO NOx: Tier III in gas mode, Tier II in liquid fuel mode
SCR-ready version: Tier III also in liquid fuel mode
Accessories
Standard Accessories
- Lubrication-oil system — Engine-driven main oil pump and wet sump
- Cooling-water system — Separate HT and LT circuits with engine-driven pumps and charge air cooler
- Pneumatic starting system — Compressed-air start at 30 bar
- Pilot-fuel system — Engine-driven pilot fuel pump for micro-pilot ignition
- Turbocharger — Turbocharged engine design
Optional Accessories
- SCR-ready version — Engine version prepared for an SCR system, achieving IMO Tier III also in liquid fuel mode
Further optional equipment depends on the project and vessel. Please refer to the manufacturer’s documentation for the scope of supply.
Warranty
- Warranty Period: Varies by project and contract
- Warranty Conditions: Terms are defined in the supply contract with the manufacturer. Please refer to the manufacturer's documentation.
Additional Notes
- Dual-fuel operation — Runs on natural gas (LNG) or liquid fuel and can switch between the two during operation
- Pilot-fuel ignition — A small quantity of pilot fuel (about 3–4 g/kWh at full load) is required for ignition in gas mode
- Fuel oil — Liquid fuel operation is based on MDF; heavy fuel oil is accepted only for the back-up fuel system and cannot be used as pilot fuel
- Gas quality — Full output in gas mode requires a methane number of 80 or above; gases with a lower methane number can only be used at reduced output
- Gas pressure — Minimum fuel gas pressure at the engine inlet is 520–550 kPa(a) at a lower heating value of 36 MJ/m³N; lower heating values require a higher pressure
- Reference conditions — Technical data refer to ISO 15550 conditions (100 kPa, 25 °C ambient air, 30 % relative humidity, 25 °C charge air coolant) with manufacturer tolerances
- Inclination — Marine engines are designed for permanent list up to 15° and trim up to 5°, with temporary roll up to 22.5° and pitch up to 7.5°
- Load limits — Maximum engine output is 100 % in gas mode and 110 % in liquid fuel mode; the engine transfers to liquid fuel mode automatically in case of overload
- Loading temperatures — Minimum HT water temperature 60 °C (preferably 70 °C), minimum lubricating oil temperature 40 °C, and 45 °C receiver temperature when starting in gas mode
- Low-load operation — Below 20 % load on HFO or below 10 % load on MDF or gas, continuous operation is limited to 100 hours, followed by one hour at minimum 70 % load
- Start-up — A stand-by generator reaches nominal speed in 50–70 seconds; the engine can be started with gas mode selected once the pilot fuel check is completed
- SCR operation — Fuel consumption in SCR operation is guaranteed only with a Wärtsilä SCR system
- Dimensions and weights — Values refer to main engines; dimensions and weights of generating sets depend on the generator and flexible coupling
- Data basis — Values are based on the Wärtsilä 20DF Product Guide (2018 edition) and may differ for later engine versions
Data basis — Technical values are based on the Wärtsilä 20DF Product Guide (2018 edition). Application examples are based on Wärtsilä product information.