Ic Engine Interview Questions & Answers

  1. Question 1. What Are The Advantages Of Lubrication In Ic Engine?

    Answer :

    Following are the advantages of lubrication in IC Engine:

    • it reduces the wear and tear of the moving parts.
    • it damps down the vibration of the engine.
    • it cleans the moving parts.
    • it makes the piston gas tight. 
  2. Question 2. Why Have Eight Cylinders In An Engine? Why Not Have One Big Cylinder Of The Same Displacement Of The Eight Cylinders Instead?

    Answer :

    There are a couple of reasons why a big 4.0-liter engine has eight half-liter cylinders rather than one big 4-liter cylinder. The main reason is smoothness. A V-8 engine is much smoother because it has eight evenly spaced explosions instead of one big explosion. Another reason is starting torque. When you start a V-8 engine, you are only driving two cylinders (1 liter) through their compression strokes, but with one big cylinder you would have to compress 4 liters instead.

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  4. Question 3. What Causes White Smoke In Two Stroke Locomotive Engines?

    Answer :

    That is because of engine running too lean mixture (lack of fuel). This condition will lead to overheating and failure of the engine.

  5. Question 4. Why Efficiency Of Gas Turbines Is Lower Compared To I.c. Engines?

    Answer :

    In gas turbines, 70% of the output of gas turbine is consumed by compressor. I.C. engines have much lower auxiliary consumption. Further combustion temperature of I.C. engines is much higher compared to gas turbine.

  6. Question 5. What Do You Understand By Timed Cylinder Lubrication?

    Answer :

    For effective lubrication, lubrication oil needs to be injected between two piston rings when piston is at bottom of stroke so that piston rides in oil during upward movement. This way lot of lubrication oil can be saved and used properly.

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  8. Question 6. In Some Engines Glycerin Is Used In Place Of Water For Cooling Of Engine. Why?

    Answer :

    Glycerin has boiling point of 90°C which increases its heat carrying capacity. Thus weight of coolant gets reduced and smaller radiator can be used.

  9. Question 7. Why We Do Not Use Same Technology To Start Both Si /ci Engine?

    Answer :

    The S.I. or spark ignition engine uses petrol as a fuel and the C.I. or compression ignition engine uses diesel as a fuel. Both the fuels has different compression ratio.

    In SI engine the compression ratio is 8-12:1.

    In CI engine the compression ratio is 16-22:1.

     So in case of SI engine, the compression ratio is not sufficient for fuel to burn so a spark plug is used, whereas in ci engine, the compression ratio is so high that due to its internal heat the fuel is combusted so there is no need for a spark plug. So the technology used in SI engine is different from CI engine.

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  11. Question 8. Which Has More Efficiency: Diesel Engine Or Petrol Engines?

    Answer :

    Diesel engine has the better efficiency out of two.

  12. Question 9. What Is The Position Of Piston Ring?

    Answer :

    In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gap below the neck.

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  14. Question 10. What Is Ic Engine?

    Answer :

    The internal combustion engine converts chemical energy into useful mechanical energy by burning fuel.

    Chemical energy is released when the fuel-air mixture is ignited by the spark in the combustion chamber. The gas produced in this reaction rapidly expands forcing the piston down the cylinder on the power stroke.

  15. Question 11. What Is 2-stroke Engine?

    Answer :

    A Two-stroke engine is an internal combustion engine in which the piston’s two strokes are required to complete single thermodynamic cycle.

     2-STROKE engine is designed by DUGLAD CLERK in 1880, the suction, compression, expansion and exhaust takes place during 2-stroke of piston.

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  17. Question 12. What Is 4-stroke Engine?

    Answer :

    A four-stroke engine is an internal combustion engine in which the piston’s four separate strokes are required to complete single thermodynamic cycle.

     A 4-stroke engine is an internal combustion engine in which  the piston completes four separate strokes— intake, compression, power, and exhaust— during two separate revolutions of the engine’s crankshaft, and one single thermodynamic cycle.

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  19. Question 13. Definition Of Octane Number And Cetane Number?

    Answer :

    Octane No. – Octane number is defined as the percentage, by volume, of iso-octane in the mixture of iso-octane and h-heptane. It is the measure of rating of SI engine.

     Cetane No. – Cetane number is defined as the percentage, by volume, of n-cetane in the mixture of n-cetane and alpha methyl naphthalene. It is the measure of rating of CI engine.

  20. Question 14. Name The Main Steps Involve In 4-stroke Ic Engine?

    Answer :

    The steps involved here are:

    Intake stroke: The mixture of Air and Fuel are drawn in.

    Compression stroke: Fuel vapor and air are compressed and ignition takes place.

    Combustion stroke: Fuel combustion takes place and piston is pushed downwards.

     Exhaust stroke: Exhaust is driven out.

  21. Question 15. Among Two-stroke Engine And Four-stroke Engine Which Is Generally Preferred And Why?

    Answer :

    Two stroke engine is generally preferred. Because it has smaller size for the same output.

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  23. Question 16. During Idling Process, A Petrol Engine Requires Lean Or Rich Mixture?

    Answer :

    Lean mixture.

  24. Question 17. What Are The Applications Of Ic Engine?

    Answer :

    Automobiles, Aircraft vehicles, helicopters, Motorbikes, Boats and other locomotives.

    Major power plants and similar naval applications.

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  26. Question 18. Name The Fuel Used By Ic Engines?

    Answer :

    Petroleum:  Petroleum spirit, Petroleum diesel, liquefied petroleum gas(LPG), Compressed natural gas, Jet fuel ,Residual fuel.

    Coal: Methanol, Gasoline, Diesel fuel.

    Biofuels and Veg Oils:  Peanut oil and other veg oils, Biobutano, biodiesel, Dimethyl Ether, biogas, hydrogen.

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