Internal Combustion Engine MCQ with Answers Pdf Download

1. Engine pistons are usually made of aluminium alloy because it

A. Is lighter

B. Wear is less

C. Absorbs shocks

D. Is stronger

Answer: Option A

Solution:

Engine pistons are usually made of aluminium alloy because it Is lighter Aluminium alloy are used because they are lighter.

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2. The reason for supercharging in any engine is to

A. Increase efficiency

B. Increase power

C. Reduce weight and bulk for a given output

D. Effect fuel economy

Answer: Option C

Solution:

The reason for supercharging in any engine is to Reduce weight and bulk for a given output -A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power.

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3. Morse test can be conducted for

A. Petrol engines

B. Diesel engines

C. Multi cylinder engines

D. All of these

Answer: Option C

Solution:

Morse test can be conducted for Multi cylinder engines The purpose of Morse test is to obtain the approximate indicated power of a Multi cylinder engine. It consist of running the engine against the dynamo-meter at a particular speed, cutting out the firing of each cylinder in turn and noting the fall in BP each time while maintaining the speed constant.

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4. The cetane (C16H34) which is a straight chain paraffin, is assigned a cetane number of

A. 0

B. 50

C. 100

D. 120

Answer: Option C

Solution:

The cetane (C16H34) which is a straight chain paraffin, is assigned a cetane number of 100.

5. Alpha-methyl-naphthalene (C11H10) has a cetane number of

A. 0

B. 50

C. 100

D. 120

Answer: Option A

Solution:

Alpha-methyl-naphthalene (C11H10) has a cetane number of 0.

Internal Combustion Engine MCQ with Answers Pdf Download

6. The scavenging efficiency of a four stroke cycle diesel engine is

A. Below 50%

B. Between 50 and 85%

C. Between 85 and 95%

D. Between 95 and 100%

Answer: Option D

Solution:

A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power. The scavenging efficiency of a four stroke cycle diesel engine is Between 95 and 100%

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7. Scavenging is usually done to increase

A. Thermal efficiency

B. Speed

C. Power output

D. Fuel consumption

Answer: Option C

Solution:

Scavenging is a process of pushing exhaust gas out of the cylinder and drawing in fresh draught of air or air fuel mixture for the next cycle. Scavenging is usually done to increase power output

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8. Which of the following medium is compressed in a Diesel engine cylinder?

A. Air alone

B. Air and fuel

C. Air and lub oil

D. Fuel alone

Answer: Option A

Solution:

Air Alone is compressed in a Diesel engine cylinder

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9. Number of working strokes per min. for a four stroke cycle engine are _________ the speed of the engine in r.p.m.

A. Equal to

B. One-half

C. Twice

D. Four-times

Answer: Option B

Solution:

Number of working strokes per min. for a four stroke cycle engine are one half the speed of the engine in r.p.m.

10. Number of working strokes per min. for a two stroke cycle engine is _________ the speed of the engine in r.p.m.

A. Equal to

B. One-half

C. Twice

D. Four-times

Answer: Option A

Internal Combustion Engine MCQ with Answers Pdf Download

11. The thermodynamic cycle on which the petrol engine works, is

A. Otto cycle

B. Joule cycle

C. Rankine cycle

D. Stirling cycle

Answer: Option A

Solution:

The thermodynamic cycle on which the petrol engine works, is Otto cycle

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12. The thermal efficiency of petrol and gas engines is about

A. 15%

B. 30%

C. 50%

D. 70%

Answer: Option B

Solution:

The thermal efficiency of petrol and gas engines is about 30%

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13. The thermal efficiency of diesel engines is about

A. 15%

B. 30%

C. 50%

D. 70%

Answer: Option D

Solution:

The thermal efficiency of petrol and gas engines is about 30% and the thermal efficiency of diesel engines is about 70%.

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14. The size of inlet valve of an engine in comparison to exhaust valve is

A. More

B. Less

C. Same

D. More/less depending on capacity of engine

Answer: Option A

Solution:

The size of inlet valve of an engine in comparison to exhaust valve is more

15. A spark plug gap is kept from

A. 0.3 to 0.7 mm

B. 0.2 to 0.8 mm

C. 0.4 to 0.9 mm

D. 0.6 to 1.0 mm

Answer: Option A

Solution:

A spark plug gap is kept from 0.3 to 0.7 mm

Internal Combustion Engine MCQ with Answers Pdf Download

16. When crude oil is heated, then which of the following hydrocarbon is given off first?

A. Kerosene

B. Gasoline

C. Paraffin

D. Natural gas

Answer: Option D

Solution:

Heating oil is made from crude oil Heating oil is a petroleum product refined from crude oil. Heating oil and diesel fuel are closely related products called distillates. Heating oil is a distillate fuel sold mainly for use in boilers, furnaces, and water heaters. When crude oil is heated, then natural gas is given off first

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17. Which one of the following event would reduce volumetric efficiency of a vertical compression ignition engine?

A. Inlet valve closing after bottom dead center

B. Inlet valve closing before bottom dead center

C. Inlet valve opening before top dead center

D. Exhaust valve closing after top dead center

Answer: Option B

Solution:

Inlet valve closing before bottom dead center would reduce volumetric efficiency of a vertical compression ignition engine. -It should be quite clear that the volumetric efficiency decreases at higher rpm because the process of pushing the exhaust gases out and sucking the fresh charge inside cylinder gets lesser and lesser time.

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18. Which of the following does not relate to a compression ignition engine?

A. Fuel pump

B. Fuel injector

C. Governor

D. Carburettor

Answer: Option D

Solution:

carburettor is a device that mixes air and fuel for internal combustion engines in the proper air–fuel ratio for combustion.

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19. Which of the following does not relate to a spark ignition engine?

A. Ignition coil

B. Spark plug

C. Carburettor

D. Fuel injector

Answer: Option D

Solution:

Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector.

20. The output of a diesel engine can be increased without increasing the engine revolution or size in following way

A. Feeding more fuel

B. Heating incoming air

C. Scavenging

D. Supercharging

Answer: Option D

Solution:

A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power

Internal Combustion Engine MCQ with Answers Pdf Download

21. A gas engine has a swept volume of 300 cm^3 and clearance volume of 25 cm^3 . Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is

A. 248 cm^3

B. 252 cm^3

C. 264 cm^3

D. 286 cm^3

Answer: Option C

Solution:

Actual volume = swept volume × volumetric efficiency

= 300 × 0.88

= 264 cm^3

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22. The pressure at the end of compression, in diesel engines, is

A. 10 bar

B. 20 bar

C. 25 bar

D. 35 bar

Answer: Option D

Solution:

The pressure at the end of compression, in diesel engines, is approximately 35 bar

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23. The pressure at the end of compression, in petrol engines, is

approximately

A. 10 bar

B. 20 bar

C. 25 bar

D. 35 bar

Answer: Option A

Solution:

The pressure at the end of compression, in petrol engines, is approximately 10 bar

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24. Air fuel ratio for idling speed of a petrol engine is approximately

A. 1 : 1

B. 5 : 1

C. 10 : 1

D. 15 : 1

Answer: Option C

Solution:

Air fuel ratio for idling speed of a petrol engine is approximately 10 : 1

25. The specific fuel consumption per BH hour for a petrol engine is

approximately

A. 0.15 kg

B. 0.2 kg

C. 0.25 kg

D. 0.3 kg

Answer: Option C

Solution:

The specific fuel consumption per BH hour for a petrol engine is approximately 0.25 kg

Internal Combustion Engine MCQ with Answers Pdf Download

26. The specific fuel consumption per BHP hour for diesel engine is

approximately

A. 0.15 kg

B. 0.2 kg

C. 0.25 kg

D. 0.3 kg

Answer: Option B

Solution:

The specific fuel consumption per BHP hour for diesel engine is approximately 0.2 kg

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27. The maximum propulsive efficiency of a turbojet engine is at a speed of

A. 1000 km/h

B. 2000 km/h

C. 2400 km/h

D. 3000 km/h

Answer: Option C

Solution:

The maximum propulsive efficiency of a turbojet engine is at a speed of 2400 km/h

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28. The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of

A. Morse test

B. Prony brake test

C. Motoring test

D. Heat balance test

Answer: Option A

Solution:

Morse test can be conducted for Multi cylinder engines The purpose of Morse test is to obtain the approximate indicated power of a Multi cylinder engine. It consist of running the engine against the dynamo-meter at a particular speed, cutting out the firing of each cylinder in turn and noting the fall in BP each time while maintaining the speed constant.

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29. The air-fuel ratio of the petrol engine is controlled by

A. Fuel pump

B. Governor

C. Injector

D. Carburettor

Answer: Option D

Solution:

The air-fuel ratio of the petrol engine is controlled by carburettor

30. The air-fuel ratio in petrol engines is controlled by

A. Controlling valve opening/closing

B. Governing

C. Injection

D. Carburetion

Answer: Option D

Solution:

The air-fuel ratio in petrol engines is controlled by carburetion

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Internal Combustion Engine MCQ with Answers Pdf Download