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MAN Energy Solutions
9L21/31
The MAN 9L21/31 is a medium‑speed, 9‑cylinder, four‑stroke trunk piston main engine delivering up to 1 800 kW at 1000 rpm, notable for its high power‑to‑weight ratio and flexible fuel capability (HFO, MDO/MGO, biofuels and methanol retrofit).
1800.0 kW
Power
Engine Specifications
9
Cylinders
210 mm
Bore
310 mm
Stroke
4-stroke
Stroke Type
Components & Design
Component data being added…
Technical Data
Swept volume per cylinder
10.74 L / 10.7 dm³
Compression ratio
15.5:1
Maximum combustion pressure
200 bar
Specific Fuel Oil Consumption (SFOC)
183-192 g/kWh (more precise values: 183 g/kWh at 85% load, 180 g/kWh part-load optimized, 189-192 g/kWh depending on configuration)
Specific lubrication oil consumption
<0.8 g/kWh
Power per cylinder
220 kW
Stroke/Bore ratio
1.48:1
Turbocharging system
MAN TCR constant pressure with Jet Assist and intercooling
Power-to-weight ratio
18.4-22.5 kg/kW
Emission compliance
IMO Tier II + IMO Tier III (mit MAN SCR)
power kw
1800
rpm
1000
fuel type
HFO/MDO
configuration
L
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Common failures & inspection points
Piston ring stiction and breakage due to carbon deposits in grooves - Rings may seize and rupture causing severe liner damage. Residue buildup between ring groo
Cylinder liner scuffing and wear due to inadequate lubrication film - occurs when lubricant breaks down between piston rings and liner, leading to micro-welding
Exhaust valve deposits and carbon buildup - Salt deposits in fuel increase combustion space fouling. L21/31 design includes valve rotators to ensure even temper
Water contamination in fuel system - Four-stroke fuel-injected engines rely entirely on fuel for high-pressure pump lubrication; water kills the fuel pump faste
Turbocharger fouling and excessive play - Turbocharger inspection required for fouling, bearing play exceeding limits, or oil leakage (class-wide issue for all
Type-general inspection and maintenance points for this equipment category — not model-specific.
Suppliers & Spare Parts
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Equipment Model #123249
· ✓ still in production