IC Engine: Objective Questions

IC Engine Objective Questions

Here are a few important Automobile Engineering or IC Engine Objective Questions with Answers for IES, GATE, ISRO, and DRDO Exams. You must practice these IC Engine Objective Questions before appearing for the exams.

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1. The method of determination of indicated power of a multi-cylinder SI engine is by the use of-

A. Morse test

B. Heat Balance test

C. Motoring test

D. Prony brake test

2. The presence of nitrogen in the process of combustion ensures that:

A. air is used for the combustion

B. incomplete combustion of fuels occur

C. complete combustion of a fuel occurs

D. dry products of combustion are analyzed

3. For the same maximum pressure and heat input, the most efficient cycle is-

A. Diesel Cycle

B. Otto Cycle

C. Brayton Cycle

D. Diesel Cycle

4. In a variable-speed SI engine, the maximum torque occurs at the maximum-

A. Brake Power

B. Speed

C. Volumetric Efficiency

D. Indicated Power

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5. The amount of CO2 produced by 1 kg of carbon on complete combustion is-

A. 3/11 kg

B. 3/8 kg

C. 8/3 kg

D. 11/3

6. Methane burns with a stoichiometric quantity of air. The air-fuel ratio by weight is-

A. 14.7

B. 1/4

C. 4

D. 17.4

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7. The Cetane Number of automotive diesel fuel used in India is-

A. range of 30 – 40

B. range of 41 – 50

C. range of 51 – 60

D. range of 61 – 70

8. Where does the mixing of fuel and air take place in the case of diesel engines?

A. Injector

B. Inlet manifold

C. Injection pump

D. Engine cylinder

9. Piston compression rings are made up of which one of these-

A. Aluminum

B. Bronze

C. Cast Iron

D. Brass

10. An I.C. engine has a bore and stroke each equal to 2 units. The total area to calculate heat loss from the engine can be taken as-

A. 4π

B. 8π

C. 12π

D. 2π

11. Air injection in I.C. Engine refers to the injection of –

A. Liquid Fuel only

B. Air only

C. Liquid fuel and Air

D. Supercharging Air

12. Pistons of Diesel Engine are usually cooled by-

A. Water

B. Air

C. Fuel Oil

D. Lubricating Oil

13. The volumetric efficiency of a well-designed SI Engine is in the range of (in %) –

A. 40-50

B. 55-65

C. 60-70

D. 70-90

14. Auto ignition time for petrol air-mixture is minimum when the ratio of the actual fuel-air ratio and the chemically correct fuel-air ratio is –

A. 0.8

B. 1

C. 1.2

D. 1.5

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15. The order of values of thermal efficiency of Otto, Diesel, and Dual Cycle is when they have equal compression ratio and heat rejection-

A. η_Otto > η_diesel > η_dual

B. η_Otto > η_dual > η_diesel

C. η_dual > η_Otto > η_dual

D. η_diesel > η_Otto > η_dual

16. The stoichiometric air-fuel ratio by volume for combustion of methane in air is-

A. 15:1

B. 17.16:1

C. 10.58:1

D. 9.52:1

17. The tendency of knocking in the CI Engine is reduced by

A. By decreasing the injection pressure

B. decreasing the jacket water temperature

C. injection of fuel just before TDC

D. high self-ignition temperature of fuel

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18. If the performance of diesel engines of different sizes, cylinder dimensions, and power rating are to be compared, which of these parameters can be used to compare-

A. Air fuel ratio

B. Swept volume

C. Volumetric efficiency

D. Specific brake fuel consumption

19. In some carburetors, a meter rod and economizer device are used for

A. power enrichment

B. idling

C. cold starting

D. accelerator

20. Which of the following cannot be caused by a hot spark plug?

1. Pre-ignition
2. Post-ignition
3. Detonation
4. Run-on-ignition

A. 1 only

B. 2 only

C. 1 and 4 only

D. 3 only

21. The discharge of hydrocarbons from petrol automobile exhaust is minimal when the vehicle is-

A. Cruising

B. Idling

C. Accelerating

D. Decelerating

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22. What do you mean by a higher Octane Number of SI fuel?

A. higher heating value

B. lower volatility

C. longer ignition delay

D. higher flash point

23. A gas engine has a swept volume of 300 cc and a clearance volume of 25 cc. Its volumetric efficiency is 0.88 and its mechanical efficiency is 0.99. The volume of the mixture taken in per stroke-

A. 254 cc

B. 264 cc

C. 282 cc

D. 284 cc

24. In the operation of 4-stroke diesel engines, the term ‘Squish‘ refers to

A. stripping of fuel from the core

B. injection of fuel in the pre-combustion chamber

C. discharge of gases from the pre-combustion chamber

D. entry of air into the combustion chamber

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25. A 40 kW engine has a mechanical efficiency of 80%. If the frictional power is assumed to be constant with load, what is the approximate value of the mechanical efficiency at 50% of the rated load-

A. 40%

B. 51%

C. 66%

D. 77%

26. The purpose of employing supercharging for an engine is-

A. to provide forced cooling

B. to inject excess fuel to cope with a higher load

C. to raise exhaust pressure

D. to supply an intake of air at a density greater than the density of the surrounding atmosphere

27. Which one of these fuels can be obtained by fermentation of vegetable matter-

A. Alcohol

B. Gasoline

C. Diesel

D. Benzene

28. Which of the following cannot be controlled by a three-way catalytic converter?

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A. CO Emission

B. HC Emission

C. SPM Emission

D. NOx

29.