8UEC50LSII
The Mitsubishi 8UEC50LSII is an eight‑cylinder, low‑speed two‑stroke diesel main engine delivering up to 15 200 kW at 127 rpm, distinguished by its large 500 mm bore/2050 mm stroke geometry and modern exhaust‑valve design for high fuel efficiency.
Engine Specifications
Inspector Detail
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Designation decoded
8UEC50LSII – Mitsubishi 8-Zylinder, Unified Exhaust-valve Crosshead, 500 mm Bohrung, Langhub, Super-Mark-II-Ausführung (LSII). Zweitakt-Kreuzkopfmotor mit verbesserter LSII-Technologie.
Background
The UEC50LSII is the Mark II further development of the LS series with 500 mm bore and 1600 mm stroke. The LSII series offers improved combustion chamber geometry compared to the LSE, optimized injection and further reduced specific fuel consumption. The 8-cylinder arrangement ensures excellent mass balance and low-vibration operation.
Calculated metrics
Inspector checklist
- Laufbuchsenverschleiß mittels Innenmessgerät dokumentieren
- Piston ring condition and gap measure
- Scavenge ports inspect for carbon buildup and deformation
- SIP-Zylinderschmierdüsen auf freien Durchgang prüfen
- Check valve seat and spindle for corrosion and burn-off
- Hydraulische Ventilbetätigung auf Dichtheit kontrollieren
- Ventildrehvorrichtung (Rotocap) auf Funktion testen
- Check injection pump plungers and cylinders for wear
- Test nozzle opening pressure and spray pattern
- Kraftstoff-Hochdruckleitungen auf Ermüdungsrisse inspizieren
- Kreuzkopflager-Spiel mit Fühlerlehre messen
- Pleuelschrauben mittels hydraulischer Vorspannung kontrollieren
- Check sliding shoes and guide surfaces for scoring
- Axiallager-Spiel des Turboladers messen
- Check compressor wheel for erosion and fouling
- Ladeluftkühler Druckabfall messen
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust gas temperature per cylinder | 340–420 °C | Differenz >30 °C zwischen Zylindern deutet auf Verbrennungsanomalie hin |
| Pmax (Zünddruck) | ±3 bar vom Sollwert | Excess indicates injection timing deviation or compression loss |
| Spülluftdruck | 2.0–3.2 bar depending on load | Reduced pressure means turbocharger or cooler problems |
| Schmieröldruck Hauptleitung | 3,5–5,0 bar | Pressure drop indicates bearing or pump wear |
| Zylinderöl-Feedrate | 0,7–1,1 g/kWh | Increased consumption signals liner or ring wear |
| Turbolader-Drehzahl | Gemäß Herstellerkurve ±3% | Deviation indicates fouling or bearing damage |
Common Failure Modes
Expert tips
- 💡 The LSII variant features optimized combustion chamber geometry – when setting injection timing, always use the LSII-specific Technical File, not the LS/LSE values.
- 💡 8-cylinder UEC engines offer the best natural mass balance of all cylinder configurations – nevertheless check damper silicone oil fill at each class renewal.
- 💡 Bei Kolbenziehung die Laufbuchsen-Spülschlitzkanten auf Abrundung kontrollieren – scharfe Kanten führen zu vorzeitigem Kolbenringbruch.
Related components
Classification & regulatory
Comply with MARPOL Annex VI and IMO Tier II limits. NOx Technical File for LSII series contains modified injection parameters compared to LS/LSE. IACS UR Z10.5 crankshaft deflection measurements at each intermediate survey. Consult classification society for operating hour extensions.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 44
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Borescope inspection of exhaust valve seats for scratches/wear, dye penetrant test for cracks, leakage measurements (valve should hold pressure under compressed air for 15 min)
Liner surface inspection for scratches/grooves, piston run gemietlich measurement, lubricant flow rate check (wrong parameters for part load operation)
Measure pressure drop across cooler, check air temperature after cooler, inspect drainage separator for water accumulation
Tägliche Kurbelgehäuse-Ölprobe auf Weißmetall-Partikel (>0.5 mm mit glatter Oberfläche beidseitig = Überbelastung), Lagerspiel-Kontrolle per Schieblehre
Check crankshaft bearing flanges with magnifying glass for cracks; crankshaft deflection measurement via dial gauge (indicator set: <0.1 mm critical)
Type-general inspection and maintenance points for this equipment category — not model-specific.
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