Turbocharger / Supercharger — Most Asked Questions
16 questions asked about turbocharger / supercharger across the General and Fn 4b papers, heaviest first.
Learn the system first
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1 Air cooler checks
Answer
Charge-air coolers earn power and life: check deposits, clean both sides, pressure-test and retube past 10% failed.
- Purpose first: cool dense charge air burns more fuel at lower thermal load with better scavenging.
- Inspect air side for lime, scale and oil sludge; clean waterside with soft tube brushes and oil side by reverse chemical circulation.
- Pressure-test hydraulically at 1.5 times working pressure after cleaning.
- Retube past 10% failed tubes; watch air temperatures and pressure drops to catch fouling early.
Surveyor follow-up: scavenge temperature climbing with seawater flow normal — air side, water side or tubes, and what proves it?
Full theory: Charge Air Cooler & Scavenge Air System — Density Thermodynamics, Fouling Diagnostics & Condensate Control -
2 Turbocharger filter how to know it's dirty
Also asked: “Turbocharger filter how to know it’s dirty”, “Turbo charger filter fouled how will you know?”
Answer
A dirty turbocharger filter shows as pressure drop: downstream suction pressure falls against trial figures, then surging starts.
- Watch suction pressure downstream of the filter against test-bed figures at the same load.
- Rising pressure drop with falling scavenge pressure and climbing exhaust temperatures marks the choke.
- Fouled nozzle rings, turbine blades and scavenge ports join the same story with back-pressure climbing.
- Clean or renew at the book pressure, then prove recovery on gauges before full load.
Surveyor follow-up: pressure drop normal yet surging persists — filter, nozzle ring or scavenge ports, and what do you open first?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
3 types of turbocharging
Also asked: “type of turbo charger”, “Types of turbocharging and explain fully”
Answer
Turbocharging splits pulse versus constant pressure, single versus two-stage: pulse for response, constant for efficiency, two stages for boost.
- Pulse groups cylinders with non-interfering exhausts into separate manifold branches for sharp turbine kicks.
- Constant pressure feeds one big manifold steadily — smoother, simpler, slightly slower to answer.
- Single-turbo sets dominate constant-pressure plants but leave no standby and answer load changes slowly.
- Two-stage with intercooling nears isothermal compression for the highest pressure ratios at best efficiency.
Surveyor follow-up: pulse manifold cracked and blanked as one big pipe — response, efficiency or both, and what breaks next?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
4 List precaution in use of charge air cooler, with a sketch briefly the construction part of air cooler and onboard maintenance to maintain efficiency
Answer
Sketch tube stack in a box with water inside and air outside: check deposits, clean both sides, test at 1.5 times working pressure.
- Construction is finned tube nests with water boxes and end covers splitting multi-pass flow.
- Precautions are venting air locks, guarding against freezing and watching pressure drops climb.
- Clean waterside wet with tube brushes and flushing, oilsides by reverse chemical circulation for hours.
- Hydraulic-test after cleaning, retube past 10% failed, log drops and temperatures every watch.
Surveyor follow-up: scavenge temperature climbing with seawater flow normal — air side, water side or tubes?
Full theory: Charge Air Cooler & Scavenge Air System — Density Thermodynamics, Fouling Diagnostics & Condensate Control -
5 A turbocharger is so needed to provide that extra air required for the proper combustion. This leads to an advantage in the efficiency and power of the engine
Also asked: “• A turbocharger is so needed to provide that extra air required for the proper combustion. This leads to an advantage in the efficiency and power of the engine”
Answer
Turbochargers burn waste into power: exhaust drives more air in, so the same engine burns more fuel cleanly.
- Exhaust energy spins the turbine, and the blower forces scavenge air above atmospheric pressure.
- Extra air burns fuel fully for more power per cylinder, higher thermal efficiency and lower specific consumption.
- The same power fits a smaller, lighter engine, cutting cost per horsepower and engine-room weight.
- Every kilowatt to the turbocharger is recovered waste heat — superchargers taxed the crankshaft instead.
Surveyor follow-up: same power wanted from a smaller engine — more boost, more fuel, or both, and what limits it?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
6 Deposits reduce overall efficiency of turbocharger
Also asked: “• Deposits reduce overall efficiency of turbocharger”
Answer
Deposits throttle both wheels: nozzle fouling chokes gas in, impeller fouling chokes air out — wash them off.
- Soot and salt cake nozzle rings and turbine blades, dropping pressure ratio and mass flow together.
- Oily dust and soot film the blower impeller — tenths of a millimetre cost visible boost.
- Water-wash the blower at full load warm with the fixed dose over seconds, repeating only after ten minutes.
- Blow granules through the turbine side or chemical-clean sulphurous crust that water leaves behind.
Surveyor follow-up: boost still low after a blower wash with dry exhaust trunking — air side again or turbine side now?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
7 state two reasons for fitting an exhaust gas turbocharger to an engine
Answer
Fit the turbocharger for power and economy: more air per cylinder and cheaper power per tonne.
- Raised scavenge pressure burns more fuel per cycle for higher output from the same frame.
- Longer expansion with free exhaust energy lifts thermal efficiency and trims specific fuel consumption.
- Pulse or constant-pressure manifolding feeds one or two turbochargers per six cylinders to keep pulses apart.
- Compact power follows — same output from a smaller engine room with a lower price per horsepower.
Surveyor follow-up: two turbochargers on a six-cylinder two-stroke — pulse pairing or spare cover, and why paired?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
8 What type of turbocharger u have?
Answer
Answer with your turbocharger’s gas path: pulse or constant-pressure volute around an axial or radial wheel set.
- Pulse types sit close to cylinders with small-bore pipes keeping exhaust pulses sharp on the turbine.
- Constant-pressure types share a big manifold that smooths pulses for steady turbine drive.
- Axial wheels suit big slow engines; radial compressor-turbine sets suit compact medium-speed sets.
- Quote maker, frame, cylinders fed and washing gear — “pulse VTR on six cylinders” beats “turbocharger”.
Surveyor follow-up: two turbochargers close-coupled on a six-cylinder two-stroke — pulse-paired or spare cover, and why?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
9 Turbocharger , how it is lubricated
Also asked: “Type of turbocharger and it's lubrication”
Answer
Turbochargers drink engine oil under pressure: forced feed in, gravity drain out, header tank cover for rundown.
- Plain journal bearings take pressurised engine oil in volume enough to cool as well as lubricate.
- Integral pump-and-sump roller sets run their own oil with an 8000-hour life on resilient damped mountings.
- Header or gravity tanks keep oil flowing while the rotor coasts down after a supply failure.
- Thrust pads hold the rotor axially toward the compressor with labyrinth glands sealing gas from oil.
Surveyor follow-up: oil supply failed with the rotor still spinning down on a hot engine — header tank, cooler or standby pump first?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
10 Efficiency of turbocharger how will u get to know (rough estimation without any calculation
Answer
Estimate a turbocharger on the running numbers: boost pressure against the exhaust temperature it is eating, plus sound and smoke.
- The true efficiency is hard to measure because the unit is a gas turbine and a compressor in one, driven by waste heat.
- Rough estimation comes from the boost delivered against the exhaust gas temperature available and the power being made.
- A dirty machine shows it in the readings — low boost for the load, high exhaust temperature, and smoke at the air filter.
- Surge, speed, bearing temperature and the wash condition complete the picture — no single gauge tells the whole story.
Surveyor follow-up: boost low for the load with the exhaust temperature high and the filter clean — is it the turbine, the air side or the load?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
11 Engine running – How to know Air cooler efficiency
Answer
Air cooler efficiency shows as the approach: scavenge air inlet against the seawater outlet at the same load and condition.
- Read the air inlet temperature and the seawater outlet temperature and compare them at a steady load.
- A closing approach means the cooler is clean; a widening one means the air side or water side is fouled.
- Sea chest strainers, the impeller and the air filter are the first checks when the approach moves.
- Cross-check with the booster outlet temperature — rising inlet temperature at the same boost confirms a charge problem.
Surveyor follow-up: approach widening with clean filters and clean sea chests — is it the cooler core, the scale or the thermocouple?
Full theory: Charge Air Cooler & Scavenge Air System — Density Thermodynamics, Fouling Diagnostics & Condensate Control -
12 Maker of turbocharger. Lubrication of ME turbocharger
Answer
The turbocharger is lubricated from the engine system under pressure, and the oil drains back — a float feed is the other arrangement.
- One method uses the engine lubricating oil, supplied under pressure to the bearings, from which it drains back to the sump.
- The other is the float-feed arrangement: oil delivered to the shaft end and carried into the bearings by the rotating shaft.
- A sight glass, filter and drain tank are in the line, so the supply is watched, filtered and kept full of oil.
- A starving turbo bearing shows first as a rising bearing temperature and low lube oil pressure, before any noise.
Surveyor follow-up: turbo sight glass empty twice on the same watch — is it the feed pump, the drain or the sight glass?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
13 Monometer se pata chal jayega turbocharger ka air filter dirty hai toh
Answer
Yes — a dirty compressor inlet shows as low charging pressure and a poor acceleration, both readable on one gauge.
- A restricted air filter chokes the compressor inlet, so charging pressure falls below its normal value for the load.
- The engine then accelerates slowly and exhaust temperature runs low, because less air means less fuel can be burnt.
- Charge air temperature also behaves oddly, and blowing down the compressor shows the restriction by feel and sound.
- So the monometer points at it, and the filter and the cooler element check confirms it — the gauge names the symptom, not the cause.
Surveyor follow-up: charge pressure low with a clean filter and a hot cooler — where else can the same reading come from?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation -
14 To reduce air temperature & increase density of charge air
Answer
The charge-air cooler takes the heat out after the turbocharger: cooler air is denser, so the same cylinder takes a fuller charge of air.
- Charge air leaving the turbocharger is hot from compression; the cooler brings it down before it enters the cylinder.
- Cooler air is denser for the same pressure, so volumetric efficiency rises and the mass of air burnt per cycle increases.
- A steaming economiser reverses the water flow to hold the temperature gradient level and stop steam forming in the tubes.
- It lowers the metal temperature as well, which is why the cooling water on an aftercooler is a cooling medium in its own right.
Surveyor follow-up: charge air inlet temperature rising with the cooler clean — is the bypass open, the pump weak or the air filter choked?
Full theory: Charge Air Cooler & Scavenge Air System — Density Thermodynamics, Fouling Diagnostics & Condensate Control -
15 Turbocharger manfacturer name
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16 Types of Turbocharging, which is used where & why?
Also asked: “Types of turbocharging, which is used where, advantages/disadvantage of each”
Answer
Two systems: exhaust turbocharging from the engine’s own waste gas, and mechanical supercharging off the crankshaft — the first for power, the second for response.
- Exhaust turbocharging recovers waste heat, so it costs no engine power and gives a rising pressure ratio with load.
- Mechanical supercharging is driven off the crankshaft, so it costs fuel but responds instantly and does not surge at low load.
- Pulse turbocharging takes each cylinder’s exhaust separately; constant pressure mixes them in a common manifold.
- Large two-strokes use pulse or constant-pressure sets; high-response duties and older designs use the blower or auxiliary engine air supply.
Surveyor follow-up: surge at part load with a pulse set on a low-speed engine — pulse, constant pressure, or the speed?
Full theory: Marine Turbochargers: Aerodynamics, Bearings, Washing & Surge Mitigation
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