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MAN Energy Solutions
7K90MC-C8
The MAN 7K90MC-C8 is a high‑power, 7‑cylinder, low‑speed two‑stroke main engine designed for large ocean-going vessels, featuring camshaft‑controlled fuel injection and constant‑pressure turbocharging.
66150.0 kW
Power
Engine Specifications
7
Cylinders
900 mm
Bore
2500 mm
Stroke
66,150 kW
MCR Power
76.0 rpm
MCR RPM
2-stroke
Stroke Type
Family: MAN B&W MC/MC-C
· Tier: Tier II
· Fuel: HFO, VLSFO, MDO
Inspector Detail
✓ verified
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Designation decoded
7 stands for 7 cylinders, K for Short-Stroke, 90 for 900 mm bore, MC-C for the MAN B&W MC Compact series, 8 for Mark 8.
Background
The K90MC-C8 is the short-stroke variant of the 90-class bore with a 2,500 mm stroke and S/B 2.78. Large engines in this bore class are typically used in VLCCs, large bulkers and large container ships. The K variant suits higher propeller speeds, possibly with a gearbox.
Calculated metrics
Stroke To Bore Ratio
2.778
Inspector checklist
Running gear & tribology
- Cylinder liners: very large running surface at 900 mm bore — systematic wear measurement at a minimum of 8 positions
- Piston rings: lower lateral pressures at S/B 2.78 — wear tends to be more even, but high thermal load due to the large bore
- Cylinder lubrication: pay particular attention to even distribution across all quills at the 900 mm bore
Crosshead & stuffing box
- Crosshead bearing: large bearing dimensions — temperature and oil film monitoring
- Stuffing box: sealing rings for the 900 mm piston rod — availability and condition
- Piston rod deflection at docking, check roundness
Control & hydraulics
- Camshaft drive and timing accuracy
- Exhaust valve: large valve dimensions — actuating cylinder and hydraulic pressure
- Injection pumps: high injection quantities on a large engine — nozzle condition critical
Scavenge air & exhaust system
- Scavenge air box: walk-in at 900 mm bore — systematic inspection of all ports
- Turbocharger: possibly 2-TC configuration on a large engine — inspect both units
- Exhaust duct and economiser for fouling and soot fire risk
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust gas temperature after cylinder | 330-400 °C at MCR | Spread >15 °C with K-type → investigate more closely |
| Scavenge air pressure | 2.8-3.5 bar | Drop → check turbocharger/cooler |
| Pmax | ±3 bar cylinder balance | Deviation → timing |
| Cooling water temperature | 80-85 °C | Check single-cylinder deviation |
| Lube oil pressure | 3.5-4.5 bar | Pressure drop → check system |
Common Failure Modes
Uneven cylinder lubrication at 900 mm bore
Symptoms: Local dry area on the liner, scuffing marks, uneven wear pattern
Causes: Blocked quills, Uneven oil pressure in the distribution, Incorrect quill positioning after liner replacement
Preventive: Check each quill individually for flow, assess oil distribution on the liner running surface at piston pull
Exhaust valve burning
Symptoms: Rising exhaust gas temperature, erosion at the valve seat
Causes: Vanadium/sodium corrosion, Rotocap defect, Thermal overload
Preventive: Check valve rotation, regrind seat, shorten inspection interval with HFO operation
Turbocharger fouling with 2-TC configuration
Symptoms: Asymmetric charge pressure between the turbochargers
Causes: Uneven exhaust distribution, Different fouling levels, Throttle valve malfunction
Preventive: Clean both turbochargers synchronously, regularly log pressure differential
Expert tips
- 💡 At 900 mm bore, the cylinder cover is very heavy (>20 t) — verify crane capacity and lifting equipment before every piston pull
- 💡 K-type with S/B 2.78 has a shorter stroke and tends toward higher speed — camshaft loading is higher than S/L variants, perform chain box inspection at shorter intervals
- 💡 On the 7-cylinder K90, pay particular attention to vibration analysis — an unfavorable firing order can excite torsional vibrations in the shaft line
Related components
Turbocharger (both, for 2-TC configuration)
Scavenge air cooler (large area, fouling tendency)
Shaft line and thrust bearing
Foundation bolts and engine foundation (large inertial forces)
Classification & regulatory
IMO Tier I compliant. Combustion optimization required for Tier II. Observe EEDI requirements for newbuildings. MARPOL Annex VI — VLSFO or scrubber for ECA operation.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 50
5L35MC-C8
5 cyl
· 6,450 kW
5L42MC-C8
5 cyl
· 10,100 kW
5L60MC-C8
5 cyl
· 21,000 kW
5L70MC-C8
5 cyl
· 31,150 kW
5L80MC-C8
5 cyl
· 42,000 kW
5S26MC-C8
5 cyl
· 3,700 kW
5S35MC-C8
5 cyl
· 7,650 kW
5S42MC-C8
5 cyl
· 12,950 kW
5S46MC-C8
5 cyl
· 15,500 kW
5S50MC-C8
5 cyl
· 18,650 kW
5S60MC-C8
5 cyl
· 28,250 kW
5S65MC-C8
5 cyl
· 35,000 kW
5S70MC-C8
5 cyl
· 40,400 kW
5S80MC-C8
5 cyl
· 51,000 kW
5S90MC-C8
5 cyl
· 64,350 kW
6K80MC-C8
6 cyl
· 43,500 kW
6K90MC-C6
6 cyl
· 30,780 kW
6K90MC-C8
6 cyl
· 56,700 kW
6K98MC-C8
6 cyl
· 85,020 kW
6L35MC-C8
6 cyl
· 7,740 kW
6L42MC-C8
6 cyl
· 12,120 kW
6L60MC-C8
6 cyl
· 25,200 kW
6L70MC-C8
6 cyl
· 37,380 kW
6L80MC-C8
6 cyl
· 50,400 kW
6S26MC-C8
6 cyl
· 4,440 kW
6S35MC-C8
6 cyl
· 9,180 kW
6S42MC-C8
6 cyl
· 15,540 kW
6S46MC-C8
6 cyl
· 18,600 kW
6S50MC-C8
6 cyl
· 22,380 kW
6S50MC-C8.2
6 cyl
· 9,960 kW
6S60MC-C8
6 cyl
· 33,900 kW
6S65MC-C8
6 cyl
· 42,000 kW
6S65MC-C8.2
6 cyl
· 16,440 kW
6S70MC-C8
6 cyl
· 48,480 kW
6S80MC-C8
6 cyl
· 61,200 kW
6S90MC-C8
6 cyl
· 77,220 kW
7K80MC-C6
7 cyl
· 28,980 kW
7K80MC-C8
7 cyl
· 50,750 kW
7K98MC-C7.1
7 cyl
· 40,040 kW
7K98MC-C8
7 cyl
· 99,190 kW
7L35MC-C8
7 cyl
· 9,030 kW
7L42MC-C8
7 cyl
· 14,140 kW
7L60MC-C8
7 cyl
· 29,400 kW
7L70MC-C8
7 cyl
· 43,610 kW
7L80MC-C8
7 cyl
· 58,800 kW
7S35MC-C8
7 cyl
· 10,710 kW
7S42MC-C8
7 cyl
· 18,130 kW
7S46MC-C8
7 cyl
· 21,700 kW
7S50MC-C8
7 cyl
· 26,110 kW
7S60MC-C8
7 cyl
· 39,550 kW
Components & Design
Component data being added…
Technical Data
unified from engine model
True
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Suppliers & Spare Parts
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Maritime Network →Manuals
-
operating
MAN B&W MC/MC-C Engine Operating Manual (OM-MC-C)MAN Energy Solutions
-
maintenance
MAN B&W MC/MC-C Maintenance Manual (MM-MC-C)MAN Energy Solutions
-
spare_parts
MAN B&W MC/MC-C Illustrated Parts Catalogue (IPC-MC-C)MAN Energy Solutions
-
project_guide
MAN B&W Project Guide MC/MC-C (PG-MC-C)MAN Energy Solutions
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Equipment Model #38241
· ✓ still in production