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Mechanical Engineering :: Internal Combustion Engines

  1. Supercharging is the process of

  2. A.

     Supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere

    B.

     Providing forced cooling air

    C.

     Injecting excess fuel for raising more loads

    D.

     Supplying compressed air to remove combustion products fully


  3. A carburettor is used to supply

  4. A.

     Petrol, air and lubricating oil

    B.

     Air and diesel

    C.

     Petrol and lubricating oil

    D.

     Petrol and air


  5. The fuels in order of decreasing knock tendency for spark ignition engines are

  6. A.

     Paraffin, aromatic, napthene

    B.

     Paraffin, napthene, aromatic

    C.

     Napthene, aromatics, paraffin

    D.

     Napthene, paraffin, aromatic


  7. The knocking tendency in compression ignition engines for a given fuel will be

  8. A.

     Enhanced by decreasing compression ratio

    B.

     Enhanced by increasing compression ratio

    C.

     Dependent on other factors

    D.

     None of the above


  9. Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows

  10. A.

     Using additives in the fuel

    B.

     Increasing the compression ratio

    C.

     Adherence to proper fuel specification

    D.

     Avoidance of overloading


  11. Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to

  12. A.

     Cylinder walls being too hot

    B.

     Overheated spark plug points

    C.

     Red hot carbon deposits on cylinder walls

    D.

     Any one of these


  13. If the compression ratio in I.C. engine increases, then its thermal efficiency will

  14. A.

     Decrease

    B.

     Increase

    C.

     Remain same

    D.

     None of these


  15. The minimum cranking speed in case of petrol engine is about

  16. A.

     Half the operating speed

    B.

     One fourth of operating speed

    C.

     250 - 300 rpm

    D.

     60 - 80 rpm


  17. The injection pressure in a diesel engine is about

  18. A.

     10 bar

    B.

     100 bar

    C.

     150 bar

    D.

     500 bar


  19. The specific fuel consumption per B.P. hour for a petrol engine is about

  20. A.

     0.2 kg

    B.

     0.25 kg

    C.

     0.3 kg

    D.

     0.35 kg