# Internal Combustion Engine MCQ (Multiple Choice Questions)

1. Indicated power of a 4-stroke engine is equal to ___________
a) 4pLAN
b) pLAN/2
c) pLAN
d) 2pLAN

Explanation: Indicated power of a 4-stroke engine is equal to pLAN/2.
where p = mean effective pressure,
L = stroke
A = area of piston and
N = rpm of engine.

2. The thermal efficiency of diesel engines is about ___________
a) 65%
b) 50%
c) 80%
d) 70%

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

3. What is the combustion in spark ignition engine?
a) heterogeneous
b) laminar
c) homogeneous
d) none of the mentioned

Explanation: The combustion in spark ignition engine is homogeneous while the combustion in compression ignition engine is heterogeneous.

4. The following volume of air is required for consuming 1 litre of fuel by a four stroke engine is?
a) 5-6m3
b) 9-10m3
c) 2.5m3
d) 1m3

Explanation: 9-10m3 volume of air is required for consuming 1 litre of fuel by a four stroke engine.

5. The major loss in a S.I. engine is due to ____________
a) variation in specific heat and chemical equilibrium
b) pumping
c) exhaust blow down
d) incomplete combustion

Explanation: The major loss in a S.I. engine is due to variation in specific heat and chemical equilibrium while the major loss in a C.I. engine is loss due to incomplete combustion.

6. What is the firing order of a six stroke I.C. engine?
a) 1-5-3-4-2-6
b) 1-3-6-5-2-4
c) 1-4-2-5-6-3
d) 1-6-2-5-4-3

Explanation: The firing order of a six stroke I.C. engine is 1-5-3-4-2-6 and the firing order in the case of four cylinder in-line I.C. engine is 1-3-4-2.

7. Which of the following is the most preferred S.I. engines fuel?
a) napthenes
b) olefins
c) aromatics
d) paraffins

Explanation: For S.I. engines fuel most preferred are aromatics while for C.I. engines fuel most preferred are paraffins.

8. Which of the following statement is not correct with respect to alcohols as alternate fuel in IC engines?
a) alcohol contains about half the heat energy of gasoline/litre
b) alcohol does not vaporize as easily as gasoline
c) alcohols are corrosive in nature
d) anti-knock characteristics of alcohol is poor

Explanation: Anti-knock characteristics of alcohol is good.

9. Which of the following is the anti-knock for compression ignition engines?
a) amyl nitrate
b) naphthene

Explanation: Amyl nitrate is the anti-knock for compression ignition engines.

10. Which of the following does not relate to spark ignition engine?
a) Spark plug
b) Carburetor
c) Fuel injector
d) Ignition coil

Explanation: Fuel injector is not related to spark ignition engine as there is no fuel injection in spark ignition engine.

11. Which is the most effective air cleaner in the case of diesel engines?
a) whirl type
b) oil bath type
c) wet type
d) dry type

Explanation: Oil bath type is the most effective air cleaner in case of diesel engines.

12. An SI engine sometimes continues to run for a very small period even after the ignition is switched off. This phenomenon is called?
a) throttling
b) idling
c) dieseling
d) none of the mentioned

Explanation: Dieseling is the phenomenon in which an SI engine sometimes continues to run for a very small period even after the ignition is switched off.

13. Which are the most important requirements of an automobile carburetor?
a) ensuring full torque at low speeds
b) good fuel economy
c) absence of racing of the engine under idling conditions
d) all of the mentioned

Explanation: The important requirements of automobile carburetors are
i) ease of starting the engine, particularly under low ambient conditions
ii) ability to give full power quickly after starting the engine
iii) equally good and smooth engine operation at various loads
iv) good and quick acceleration of the engine
v) developing sufficient power at high engine speeds
vi) simple and compact in construction
vii) good fuel economy
viii) absence of racing of the engine under idling conditions
ix) ensuring full torque at low speeds

14. The number of holes in a multi-hole nozzle, varies from ___________
a) 4 to 8
b) 4 to 18
c) 4 to 12
d) none of the mentioned

Explanation: The number of holes in a multi-hole nozzle, lies between 4 to 18 depending on the size and requirement of the engine.

15. Gasoline engines are _____________ than diesel engines.
a) lighter
b) unpredictable
c) heavier
d) none of the mentioned

Explanation: In comparison to diesel engine, gasoline engines are heavier.

16. Formation of ice on the _____________ plate is eliminated in electronic fuel injection.
a) engine
b) throttle
c) nozzle
d) none of the mentioned

Explanation: Generally, the formation of ice on the throttle plate is eliminated in electronic fuel injection and not of nozzle.

17. The timing of injection has to be advanced as the speed _____________
a) increases
b) stables
c) decreases
d) none of the mentioned

Explanation: The timing of injection is directly dependent on engine speed, so it has to be advanced as the speed increases.

18. The ignition timing is affected by _____________
a) engine speed
b) mixture strength
c) compression ratio
d) all of the mentioned

Explanation: The ignition timing is affected by
i) compression ratio
ii) engine speed
iii) mixture strength
iv) combustion chamber design
v) throttle opening
vi) engine temperature
vii) type of fuel.

19. Which of the following factors affecting combustion in the CI engine?
a) intake temperature
b) jacket water temperature
c) compression ratio
d) all of the mentioned

Explanation: The factors affecting combustion in CI engine are
i) ignition quantity of fuel
ii) injection pressure of droplet size
iv) compression ratio
v) intake temperature
vi) jacket water temperature
vii) intake pressure
vii) engine speed
ix) load and air to fuel ratio
x) engine size
xi) type of combustion chamber.

20. Blow by losses are reduced as the engine speed is ____________
a) reduced
b) unpredictable
c) increased
d) none of the mentioned

Explanation: Blow by losses are indirectly proportional to engine speed and it is reduced as the engine speed is increased.

21. The mechanical friction ___________ with increase in speed.
a) reduces
b) unpredictable
c) increases
d) none of the mentioned

Explanation: Mechanical friction is directly proportional to engine speed, so mechanical friction increases with an increase in speed.

22. Which of the following is the outlet cooling water temperature for small engines?
a) 60 to 65ºC
b) 80ºC
d) none of the mentioned

Explanation: The outlet cooling water temperature for small engines is 80ºC while the outlet cooling water temperature for medium engines is 60 to 65ºC and the outlet cooling water temperature for small engines is 80ºC.

23. The weight per B.P. of air-cooled engine is ___________ than that of water-cooled engine.
a) less
b) unpredictable
c) greater
d) none of the mentioned

Explanation: In comparison with water-cooled engine, the weight per B.P. of air-cooled engine is less.

24. Which of the following is/are the correct sequence of the decreasing order of brake thermal efficiency of the three given basic types of engines?
a) 4-stroke S.I. engine, 4-stroke C.I. engine, 2-stroke S.I. engine
b) 4-stroke C.I. engine, 4-stroke S.I. engine, 2-stroke S.I. engine
c) 4-stroke S.I. engine, 2-stroke S.I. engine, 4-stroke C.I. engine
d) 2-stroke C.I. engine, 4-stroke C.I. engine, 4-stroke S.I. engine

Explanation: The brake thermal efficiency of the three given basic types of engines decreases in the order 4-stroke C.I. engine, 4-stroke S.I. engine, 2-stroke S.I. engine.

25. For which of the following engines a prony brake is used to measure brake power?
a) low speed engine
b) variable speed engine
c) single cylinder engine
d) low power engine

Explanation: Prony brake is used to measure the brake power of variable speed engines.

26. Which one of the following event would reduce the volumetric efficiency of a vertical compression ignition engine?
a) exhaust valve closing after top dead center
b) inlet valve closing after bottom dead center
c) inlet valve closing before bottom dead center
d) inlet valve opening before top dead center

Explanation: Volumetric efficiency of a vertical compression ignition engine is reduced by closing inlet valve before bottom dead center.

27. Which of the following is the main aim of an engine management system to achieve?
a) low levels of gaseous and particulate emissions
b) high reliability and durability with lowest possible initial cost
c) high power output and torque
d) all of the mentioned

Explanation: The main aims of an engine management system is to achieve
i) high reliability and durability with lowest possible initial cost
ii) high power output and torque
iii) low levels of gaseous and particulate emissions
iv) low fuel consumption
v) low noise levels and vibrations.

28. The ignition timings and thermal load on the engine affect the knock limit of _____________ engine.
a) CI
b) SI
c) Both SI & CI
d) None of the mentioned

Explanation: The ignition timings and thermal load on the engine affect the knock limit of SI engine while there is no such case in CI engine.

29. Which of the following engines will have a heavier flywheel than the remaining ones?
a) 30 kW four stroke diesel engine running at 750 r.p.m
b) 30 kW two stroke diesel engine running at 750 r.p.m
c) 30 kW four stroke petrol engine running at 1500 r.p.m
d) 30 kW two stroke petrol engine running at 1500 r.p.m

Explanation: The flywheel in a four stroke petrol engine is heavier than in a two stroke petrol engine and there is no flywheel in a diesel engine.

## Chapterwise Multiple Choice Questions on Internal Combustion Engine

Our 1000+ MCQs focus on all topics of the Internal Combustion Engine subject, covering 100+ topics. This will help you to prepare for exams, contests, online tests, quizzes, viva-voce, interviews, and certifications. You can practice these MCQs chapter by chapter starting from the 1st chapter or you can jump to any chapter of your choice.

## 1. MCQ on Introduction to Internal Combustion Engine

The section contains IC Engine multiple choice questions and answers on engine performance parameters.

## 2. IC Engine MCQ on Air Standard Cycles and their Analysis

The section contains IC Engine questions and answers on air standard cycles, carnot and stirling cycles, otto and dual cycles, diesel cycles and comparison of otto, diesel and dual cycles.

## 3. IC Engine Multiple Choice Questions on Fuel Air and Actual Cycles and their Analysis

The section contains IC Engine MCQs on fuel air cycle, dissociation, actual cycle, air cycle and fuel cycles, effect of operating variables.

## 4. Internal Combustion Engine Multiple Choice Questions on Conventional and Alternate Fuels

The section contains IC Engine multiple choice questions and answers on fuels quality and its ratings, alternate fuels, ci engine, gaseous fuels, hydrogen engine and dual fuel operations.

## 5. Internal Combustion Engine MCQ on Carburetion

The section contains IC Engine questions and answers on carburetion, air fuel mixtures, automotive engines, carburetor parts and its types, altitude compensation and modern carburetors.

## 6. IC Engine MCQ on Mechanical Injection Systems

The section contains IC Engine MCQs on injection systems and pumps, fuel injector, nozzle and fuel injection in si engine.

## 7. IC Engine Multiple Choice Questions on Electronic Injection Systems

The section contains IC Engine multiple choice questions and answers on gasoline injection, electronic injection system, electronic control systems, injection timing and group gasoline injection system.

## 8. Internal Combustion Engine Multiple Choice Questions on Ignition

The section contains IC Engine questions and answers on requirements and battery of ignition systems, magneto ignition systems, ignition timing and energy parameters and spark mechanism.

## 9. IC Engine MCQ on Combustion and Combustion Chambers

The section contains IC Engine MCQs on combustion, abnormal combustion, combustion in si and ci engine, knocking in si engine and delay period.

## 10. MCQ on Engine Friction and Lubrication

The section contains IC Engine multiple choice questions and answers on engine and mechanical friction, lubrication types and properties, classification and mechanisms of lubricating systems.

## 11. IC Engine Multiple Choice Questions on Heat Rejection and Cooling

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## 12. Multiple Choice Questions on Engine Emissions and their Control

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## 13. IC Engine MCQ on Measurements and Testing/Performance Parameters and Characteristics

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## 14. Multiple Choice Questions on Engine Electronics

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## 15. Internal Combustion Engine Multiple Choice Questions on Supercharging

The section contains IC Engine MCQs on supercharging and its effects and turbocharging.

## 16. Multiple Choice Questions on Two Stroke Engines

The section contains IC Engine multiple choice questions and answers on terminologies and definations, scavenging process and pumps, two stroke engine and its advantages, si and ci engines, advantages of four stroke engines.

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