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MAN Energy Solutions
MAN L21/31
Der MAN L21/31 ist MANs Standard-Hilfsdiesel für Generatorantrieb auf Handelsschiffen. Direkter Konkurrent zum Wärtsilä 20. Auf Schiffen mit MAN 2-Takt-Hauptmaschine oft als Paket spezifiziert.
750-1,980 kW (5-9L)
Capacity
HFO / VLSFO / MGO
Medium
Engine Specifications
5L, 6L, 7L, 8L, 9L
Cylinders
210 mm
Bore
310 mm
Stroke
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 (genauere Werte: 183 g/kWh bei 85% Last, 180 g/kWh Part-Load optimiert, 189-192 g/kWh je nach Konfiguration)
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 mit Jet Assist und Interkühlung
Power-to-weight ratio
18.4-22.5 kg/kW
Emission compliance
IMO Tier II + IMO Tier III (mit MAN SCR)
type
4-Stroke Medium-Speed Auxiliary Engine
sfoc g kwh
192
tier
IMO Tier II
variant count approx
5
period start year
2005
drive type
Generator Drive
construction
Trunk piston, inline
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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.
Service & Maintenance
Standard MAN 4-Stroke intervals.
Suppliers & Spare Parts
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Maritime Network →Replacement Parts
MAN PrimeServ global.
Equipment Model #38026
· ✓ still in production