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Wärtsilä
8V31
Guinness World Record holder as the world's most efficient 4-stroke diesel engine. Designed for both propulsion and power generation.
4480.0 kW
Power
Engine Specifications
8
Cylinders
310 mm
Bore
430 mm
Stroke
4,480 kW
MCR Power
750.0 rpm
MCR RPM
165.0 g/kWh
SFC
4-stroke
Stroke Type
Family: Wartsila Wartsila 31
· Tier: IMO Tier II
· Fuel: HFO, MDO
Other Cylinder Configurations 3
Components & Design
Dual-Fuel System (Gas Mode)
Wartsila
W31 Gas Admission Valve (GAV)
Low-pressure gas admission valve per cylinder. Overhaul at 12,000 hrs. Leak test after every overhaul.
Lead time: 6 wk
18.0 kg
Dual-Fuel System (Gas Mode)
Wartsila
W31 Pilot Fuel System (DF variant)
Micro-pilot diesel injection for gas mode ignition. Pilot fuel consumption <1% of total energy. Overhaul pilot injector at 8,000 hrs.
Lead time: 6 wk
35.0 kg
Dual-Fuel System (Gas Mode)
Wartsila
W31 Pre-Chamber Assembly (DF)
Pre-chamber ensures stable ignition of lean gas-air mixture. Inspect at 8,000 hrs. Replace inserts at 16,000 hrs.
Lead time: 6 wk
8.0 kg
Fuel Pump (Jerk-Type / Common Rail)
Wartsila / L'Orange
W31 Common Rail Injection Unit
Common rail pressure up to 2200 bar. Rail and injector overhaul at 12,000 hrs. Monitor rail pressure stability.
Lead time: 8 wk
120.0 kg
Technical Data
Cylinder power
610 kW/cyl (diesel)
Mean effective pressure (BMEP)
30 bar
SFOC (diesel)
167.7 g/kWh (optimal point)
Weight (8V31)
~57.1 tonnes (dry, diesel)
Weight (16V31)
~89–92.5 tonnes (dry, diesel)
Piston speed
10.75 m/s
Turbocharging
Two-stage turbocharging with intercooling
Fuel injection
Common rail direct injection
Valve layout
2 inlet, 2 exhaust valves per cylinder
unified from engine model
True
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Common failures & inspection points
Low-load operation: Poor combustion, carbon deposit accumulation in cylinders, turbocharger fouling, economizer fouling. Wärtsilä offers Slow Steaming Upgrade K
Cylinder liner wear and scuffing (general 4-stroke diesel pattern, not W31-specific): Exacerbated by inadequate lubrication oil film, excessive cylinder tempera
Fuel injection system: Common rail system generally robust; however, HP fuel pump overhaul intervals are extended to 24,000 hrs (vs. 12,000 in prior-gen engines
Scavenge space deposit accumulation and fire risk (class-wide diesel phenomenon): Carbonized lube oil and unburnt fuel residues accumulate in scavenge space. Ex
Type-general inspection and maintenance points for this equipment category — not model-specific.
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Equipment Model #38952
· ✓ still in production