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Sulzer
6RTA48T
The Sulzer 6RTA48T is a six‑cylinder low‑speed two‑stroke diesel main engine delivering up to 7 920 kW at 124 rpm, known for its compact size relative to power output and proven RTA family reliability.
7920.0 kW
Power
Engine Specifications
6
Cylinders
480 mm
Bore
1900 mm
Stroke
7,920 kW
MCR Power
124.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: Sulzer RTA
· Tier: IMO Tier I
· Fuel: HFO, MDO
Inspector Detail
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Designation decoded
6RTA48T: Sulzer reversible turbocharged Typ A, 480 mm Bohrung, 6 Zylinder, T=Tanker/kompakte Bauweise. Zweitakt-Kreuzkopfmotor mit Zahnrad-Nockenwellenantrieb (konventionelle Nockenwellensteuerung).
Background
The 6RTA48T is the base version of the Sulzer RTA48T programme with 480 mm bore and 1900 mm stroke. As a compact tanker variant it offers a good power-to-weight ratio for small to medium commercial ships. The 6-cylinder arrangement ensures favourable torsional vibration behaviour without critical speed ranges.
Calculated metrics
Stroke To Bore Ratio
3.958
Inspector checklist
Cylinders and cylinder liners (CLU)
- Measure liner bore diameter on all 6 cylinders and document ovalization
- Check CLU sealing surfaces and cooling water seals for condition
- Measure piston ring end gap and wear height
- Inspect scavenge ports for deposits and edge rounding
Fuel injection and VIT
- Check VIT calibration and compare setpoints with EIAPP certificate
- Check fuel injection nozzle opening pressure and spray pattern
- Test fuel pumps for delivery rate and plunger wear
Camshaft and control drive
- Camshaft gear drive – check flank clearance and tooth contact pattern
- Visually inspect cam profiles for pitting and abrasion
- Nockenwellenlager-Spiel dokumentieren
Pulse Lubricating System
- Check fuel injection per cylinder and verify uniformity
- Check distribution valves and supply lines for function and tightness
- Zylinderöl-TBN gegen aktuellen Brennstoff-Schwefelgehalt bewerten
Turbocharger and charge air system
- Abgastemperaturspreizung zwischen Zylindern kontrollieren (Soll: 340-420°C)
- Check turbocharger bearing clearance and compressor wheel condition
- Inspect charge air cooler for fouling and corrosion
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust gas temperature per cylinder | 340-420 °C | Deviation >15°C between cylinders indicates fuel injection or compression problems |
| Pmax (Zünddruck) | Nennwert ±3 bar | Deviations indicate VIT misalignment, fuel injection timing error or valve leakage |
| Kühlwassertemperatur Zylinder | 80-95 °C Austritt | Elevated values may indicate cylinder liner cracks or cooling jacket deposits |
| Spülluftdruck | Gemäß Betriebskennfeld | Excessively low pressure indicates turbocharger or charge air cooler problems |
| Zylinderöl-Verbrauchsrate | Gemäß Sulzer Pulse System Vorgabe | Deviations indicate metering error or increased piston ring wear |
Common Failure Modes
Laufbuchsen-Mikroanfressungen (Micro-Seizure)
Symptoms: Vertikale Riefen auf der Laufbuchsenoberfläche, erhöhter Zylinderölverbrauch, Kompressionsverlust
Causes: Unzureichende Zylinderschmierung in der Einlaufphase, Load increase too rapid after overhaul, Schlechte Kolbenring-Anlage
Preventive: Einlaufprogramm gemäß Herstellervorgabe strikt einhalten, Pulse Lubricating System auf erhöhte Dosierung während Einlaufphase einstellen
Abgasventil-Undichtigkeit
Symptoms: Erhöhte Abgastemperatur am betroffenen Zylinder, Pmax-Abfall, sichtbare Blow-by-Spuren am Ventilsitz
Causes: Valve seat erosion due to poor fuel quality, Ventilspindel-Drehvorrichtung (Rotocap) defekt, Überschreitung der Ventilstandzeit
Preventive: Grind valve seat during overhaul, check Rotocap function regularly, replace valves at manufacturer's interval
Turbolader-Verschmutzung (Fouling)
Symptoms: Abfallender Ladedruck, steigende Abgastemperaturen an allen Zylindern, Turbolader-Drehzahlabfall
Causes: Unzureichende Turbolader-Waschwasserreinigung, Betrieb mit stark rückstandshaltigem Schweröl, Ladeluftkühler-Verschmutzung
Preventive: Turbocharger wet cleaning at prescribed intervals, dry wash at part load, clean charge air cooler regularly
Expert tips
- 💡 Base version RTA48T without B-suffix has older piston ring specifications – if wear problems occur, check whether upgrade to B-version piston rings is possible and recommended.
- 💡 Camshaft gear drive (not chain-driven like MAN B&W) – when comparing with MAN engines, note the different drive type and corresponding service intervals.
Related components
VIT-Stellantrieb
Pulse Lubricating System
Zahnrad-Nockenwellenantrieb
Fuel injection nozzles and fuel pumps
Exhaust valves and Rotocap
Turbocharger and charge air cooler
Piston and piston rings
Kreuzkopflager
Classification & regulatory
The engine is subject to NOx emission regulations in accordance with MARPOL Annex VI. VIT parameters must correspond with the EIAPP certificate. Cylinder oil TBN must be adapted to the respective Fuel Sulphur Limit Regulation (SECA/ECA). Class survey requirements for service intervals and wear limits must be observed.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 50
5RTA48T
5 cyl
· 6,600 kW
5RTA48T-B
5 cyl
· 7,150 kW
5RTA52
5 cyl
· 7,350 kW
5RTA52U
5 cyl
· 7,850 kW
5RTA58T
5 cyl
· 10,150 kW
5RTA58T-B
5 cyl
· 10,800 kW
5RTA62
5 cyl
· 10,100 kW
5RTA62U
5 cyl
· 11,000 kW
5RTA62U-B
5 cyl
· 12,000 kW
5RTA72
5 cyl
· 16,000 kW
5RTA72U
5 cyl
· 17,000 kW
5RTA72U-B
5 cyl
· 18,000 kW
5RTA82T
5 cyl
· 16,600 kW
5RTA84T
5 cyl
· 19,100 kW
5RTA84T-D
5 cyl
· 22,600 kW
6RTA48T-B
6 cyl
· 7,920 kW
6RTA52
6 cyl
· 8,820 kW
6RTA52U
6 cyl
· 9,420 kW
6RTA58T
6 cyl
· 12,180 kW
6RTA58T-B
6 cyl
· 12,960 kW
6RTA62
6 cyl
· 12,120 kW
6RTA62U
6 cyl
· 13,200 kW
6RTA62U-B
6 cyl
· 14,400 kW
6RTA72
6 cyl
· 19,200 kW
6RTA72U
6 cyl
· 20,400 kW
6RTA72U-B
6 cyl
· 21,600 kW
6RTA82T
6 cyl
· 19,920 kW
6RTA84C
6 cyl
· 22,920 kW
6RTA84T
6 cyl
· 22,920 kW
6RTA84T-D
6 cyl
· 27,120 kW
6RTA96C
6 cyl
· 32,940 kW
6RTA96C-B
6 cyl
· 34,320 kW
7RTA48T
7 cyl
· 9,240 kW
7RTA48T-B
7 cyl
· 10,010 kW
7RTA52
7 cyl
· 10,290 kW
7RTA52U
7 cyl
· 10,990 kW
7RTA58T
7 cyl
· 14,210 kW
7RTA58T-B
7 cyl
· 15,120 kW
7RTA62
7 cyl
· 14,140 kW
7RTA62U
7 cyl
· 15,400 kW
7RTA62U-B
7 cyl
· 16,800 kW
7RTA72
7 cyl
· 22,890 kW
7RTA72U
7 cyl
· 23,800 kW
7RTA72U-B
7 cyl
· 25,200 kW
7RTA82T
7 cyl
· 23,240 kW
7RTA84C
7 cyl
· 26,740 kW
7RTA84T
7 cyl
· 26,740 kW
7RTA84T-D
7 cyl
· 31,640 kW
7RTA96C
7 cyl
· 38,430 kW
7RTA96C-B
7 cyl
· 40,040 kW
Components & Design
Component data being added…
Technical Data
unified from engine model
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Maritime Network →Manuals
-
operating
Sulzer RTA Operating ManualWärtsilä Switzerland (historical Sulzer)
-
maintenance
Sulzer RTA Maintenance ManualWärtsilä Switzerland (historical Sulzer)
-
spare_parts
Sulzer RTA Spare Parts CatalogueWärtsilä Switzerland (historical Sulzer)
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Equipment Model #38638
· ✓ still in production