7S70ME-GI10
The MAN 7S70ME-GI10 is a high‑power 2‑stroke low‑speed dual‑fuel main engine delivering up to 56 560 kW at 91 rpm, capable of running on HFO, VLSFO, MDO or LNG with instant fuel switching.
Engine Specifications
Inspector Detail
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Designation decoded
{'7': 'Number of cylinders: 7', 'S': 'Super-long-stroke – stroke/bore ratio approx. 4.0', '70': 'Cylinder bore 700 mm', 'ME': 'Electronically controlled two-stroke engine (MAN Electronic)', 'GI': 'Gas Injection – high-pressure gas injection (approx. 300 bar, diesel cycle)', '10': 'Design version / Mark number 10'}
Background
The 7S70ME-GI10 is a powerful super-long-stroke two-stroke engine with 700 mm bore and high-pressure gas injection for large LNG-powered ships such as Aframax/Suezmax tankers and medium-sized container ships. In the MAN portfolio it is positioned as a proven dual-fuel solution in the upper-mid power range. The 7-cylinder configuration requires particular attention to torsional vibration.
Calculated metrics
Inspector checklist
- Cylinder liners at 700 mm bore – compare and document wear patterns in gas and diesel operation
- Check piston rings for wear, end gap and gas blow-by formation
- Check piston crown for erosion, thermal crack formation and condition of gas sealing surfaces
- Alpha Lubricator – BN25 in gas operation, BN40-70 in diesel operation, ensure correct dosing
- Pay particular attention to scuffing risk after fuel switchover
- Check ELGI gas injection valves for tightness and function testing at 300 bar
- Inspect double-wall piping system for leaks, corrosion and mechanical integrity
- Evaluate and compare HP compressor operating data (pressure, temperature, vibration)
- Monitor sealing oil system – pressure, consumption and oil quality
- Function-test safety valves and emergency shutdowns
- Check FIVA valves for response behaviour and hydraulic tightness
- HPS/HCU – check system pressure, oil level, filter condition and accumulator charge pressure
- EICU – read out fault memory, document software version
- Calibrate cylinder pressure sensors and check reading plausibility
- Test gas/diesel switchover and all safety interlocks
- Turbocharger at 700 mm bore – inspect bearings, compressor wheel, turbine wheel and seals
- Compare exhaust temperature profiles in gas and diesel operation
- Check charge air cooler for fouling, corrosion and condensate drainage
- Check scavenge air duct for oil mist and deposits
- Check crosshead bearing for wear and bearing clearance – 700 mm bore with 2800 mm stroke generates significant loading
- Check crosshead pin and guide rails for scoring marks
- Check stuffing box for gas tightness – safety-critical in ME-GI operation
- Inspect oil scraper rings and telescopic pipe seals
- Check torsional vibration damper for function, oil level and temperature
- Compare vibration measurements with manufacturer reference values – 7-cylinder configuration has increased risk
- Document the barred speed range and verify compliance
- Compare torsional vibration record with operating data
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Gas injection pressure | 280–320 bar | Pressure drop indicates HP compressor wear or gas valve leakage |
| Exhaust temperature after cylinder (gas operation) | 340–420 °C | Spread >50 °C between cylinders indicates uneven gas distribution |
| Exhaust temperature after cylinder (diesel operation) | 360–440 °C | Individual deviation indicates injector nozzle or valve fault |
| Pmax (firing pressure) | 145–170 bar (load-dependent) | Low Pmax in gas operation can indicate a pilot oil ignition problem |
| Pilot oil share | 3–8% of total energy | Increased share indicates ignition problems in gas operation |
| Cylinder oil dosing | 0.6–0.8 g/kWh (gas operation) | Incorrect dosing leads to scale deposits or increased wear |
| Scavenge air pressure | 2.3–3.7 bar (load-dependent) | Too low indicates turbocharger problem or cooler fouling |
| Torsional vibration amplitude | Per manufacturer specification (7-cylinder S-type) | Elevated values require immediate inspection of the vibration damper |
Common Failure Modes
Expert tips
- 💡 The 7-cylinder configuration at 700 mm bore requires particular attention to torsional vibration – strictly observe the barred speed range and inspect the vibration damper regularly.
- 💡 Consistently use BN25 cylinder oil in gas operation – switch promptly to a higher BN value on fuel change to diesel and document the transition phase.
- 💡 Methane is lighter than air – at 700 mm bore and 7 cylinders the gas volumes are substantial. Gas detectors at ceiling level and in double-wall spaces have highest priority.
Related components
Classification & regulatory
['IMO Tier II – NOx emission limits, Tier III achievable with EGR or SCR', 'IGC Code – mandatory regulations for gas-fuelled ships', 'SOLAS Chapter II-1 – fire protection and safety requirements for dual-fuel installations', 'MARPOL Annex VI – SOx/NOx emission limits, LNG operation significantly eases ECA compliance', 'Classification society – observe 7-cylinder torsional vibration approval and special conditions']
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 36
Components & Design
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Technical Data
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