IC Engine MCQs (1–20)
1. The working cycle in case of a four-stroke engine is
completed in how many revolutions? A) 1
B) 2
C) 3
D) 4
Answer: B) 2
2. In a
diesel engine, the fuel is ignited by:
A) Spark plug
B) Compression
C)
Carburetor
D) Glow plug
Answer: B) Compression
3. The function of a carburetor
is to:
A) Mix air and fuel in correct ratio
B) Cool the engine
C) Supply oil
D)
Ignite the mixture
Answer: A) Mix air and fuel in correct ratio
4. The thermal
efficiency of a petrol engine is generally:
A) 20–30%
B) 30–40%
C) 50–60%
D)
60–70%
Answer: B) 30–40%
5. The compression ratio for petrol engines is
typically:
A) 4:1 to 6:1
B) 6:1 to 10:
C) 12:1 to 20:1
D) 20:1 to 25:1
Answer:
B) 6:1 to 10:1
6. Which of the following engine cycles is used in diesel
engines?
A) Otto
B) Carnot
C) Dual
D) Diesel
Answer: D) Diesel
7. Which part of
the engine is subjected to maximum temperature?
A) Piston
B) Exhaust valve
C)
Cylinder wall
D) Cylinder head
Answer: B) Exhaust valve
8. The air-fuel ratio
for a petrol engine under idling conditions is approximately:
A) 10:1
B) 12:1
C)
14.7:1
D) 18:1
Answer: A) 10:1
9. Detonation in petrol engines is also known as:
A) Pre-ignition
B) Knocking
C) Flash point
D) Flame propagation
Answer: B)
Knocking
10. In a 4-stroke engine, the number of power strokes per crankshaft
revolution is:
A) 1
B) 0.5
C) 2
D) 4
Answer: B) 0.5
11. Which gas is most
abundant in engine exhaust?
A) CO
B) CO₂
C) NOx
D) Hydrocarbons
Answer: B) CO₂
12. The function of a flywheel is to:
A) Store energy
B) Start engine
C) Filter
air
D) Maintain coolant
Answer: A) Store energy
13. The calorific value of
diesel is approximately:
A) 25,000 kJ/kg
B) 35,000 kJ/kg
C) 42,000 kJ/kg
D)
45,000 kJ/kg
Answer: D) 45,000 kJ/kg
14. Which stroke removes exhaust gases from
the cylinder?
A) Intake
B) Compression
C) Power
D) Exhaust
Answer: D) Exhaust
15. Pre-ignition is caused by:
A) Poor fuel
B) Overheating spark plug
C) High
compression
D) All of the above
Answer: D) All of the above
16. Supercharging in
IC engines results in:
A) Increased efficiency
B) Reduced noise
C) Decreased
pressure
D) Reduced temperature
Answer: A) Increased efficiency
17. The unit of
brake power is:
A) kWh
B) kW
C) HP
D) Both B and C Answer:
D) Both B and C
18. A
typical diesel engine has how many fuel injection nozzles per cylinder?
A) 1
B)
2
C) 3
D) 4
Answer: A) 1
19. Scavenging is associated with which type of engine?
A) 2-stroke
B) 4-stroke
C) Gas turbine
D) Rotary Answer:
A) 2-stroke
20. The
volumetric efficiency of IC engines generally ranges between:
A) 50–60%
B)
60–70%
C) 70–90%
D) 90–100%
Answer: C) 70–90%
Here are the next 20 IC Engine MCQs (Questions 21–40) with answers, designed for RRB JE Mechanical preparation:
IC Engine MCQs (21–40)
21. The function of a piston ring is to:
A) Transfer heat
B) Prevent gas leakage
C) Control oil
D) All of the above
Answer: D) All of the above
22. Compression ratio affects:
A) Power only
B) Efficiency only
C) Both power and efficiency
D) Emissions only
Answer: C) Both power and efficiency
23. The typical clearance volume in an IC engine is:
A) 5% of swept volume
B) 10% of swept volume
C) 20–30% of swept volume
D) 40–50% of swept volume
Answer: C) 20–30% of swept volume
24. Fuel injection in diesel engines occurs during:
A) Suction stroke
B) Compression stroke
C) Power stroke
D) Exhaust stroke
Answer: B) Compression stroke
25. The knocking tendency increases with:
A) Increase in compression ratio (in SI engine)
B) Decrease in inlet temperature
C) Use of anti-knock additives
D) Rich air-fuel mixture
Answer: A) Increase in compression ratio (in SI engine)
26. In CI engines, ignition delay is:
A) Time between injection and ignition
B) Time between compression and exhaust
C) Time of valve operation
D) Time of scavenging
Answer: A) Time between injection and ignition
27. The cetane number of diesel indicates:
A) Power
B) Ignition quality
C) Viscosity
D) Knocking
Answer: B) Ignition quality
28. The most suitable cooling method for stationary engines is:
A) Air cooling
B) Water cooling
C) Oil cooling
D) Natural cooling
Answer: B) Water cooling
29. Spark advance in SI engine is used to:
A) Start engine
B) Avoid pre-ignition
C) Complete combustion at TDC
D) Reduce temperature
Answer: C) Complete combustion at TDC
30. Which is not a part of the valve mechanism?
A) Camshaft
B) Rocker arm
C) Crankshaft
D) Push rod
Answer: C) Crankshaft
31. Volumetric efficiency decreases with:
A) Turbocharging
B) Valve overlap
C) Lower temperature intake
D) High engine speed
Answer: D) High engine speed
32. The stroke length is defined as the:
A) Distance piston moves per revolution
B) Crank radius
C) Total displacement per cycle
D) Distance piston moves between TDC and BDC
Answer: D) Distance piston moves between TDC and BDC
33. SI engine uses which ignition system?
A) Fuel injection
B) Compression ignition
C) Spark plug
D) Glow plug
Answer: C) Spark plug
34. Which engine has better part-load efficiency?
A) SI engine
B) CI engine
C) Gas turbine
D) Stirling engine
Answer: B) CI engine
35. Heat transfer from engine is highest in:
A) Power stroke
B) Compression stroke
C) Exhaust stroke
D) Suction stroke
Answer: A) Power stroke
36. Mean effective pressure (MEP) is an indicator of:
A) Volumetric efficiency
B) Indicated power
C) Fuel consumption
D) Cooling capacity
Answer: B) Indicated power
37. Which device is used to convert reciprocating motion to rotary motion in IC engines?
A) Crankshaft
B) Camshaft
C) Flywheel
D) Connecting rod
Answer: A) Crankshaft
38. An ideal Otto cycle consists of how many processes?
A) 2
B) 3
C) 4
D) 5
Answer: C) 4 (Two isentropic, two constant volume)
39. Turbocharging improves:
A) Fuel economy
B) Volumetric efficiency
C) Emissions
D) Lubrication
Answer: B) Volumetric efficiency
40. The ignition temperature of petrol is approximately:
A) 250°C
B) 350°C
C) 450°C
D) 550°C
Answer: B) 350°C
Here are the next 20 IC Engine MCQs (Questions 41–60) for your RRB JE prep:
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IC Engine MCQs (41–60)
41. Which type of engine is more efficient at part loads?
A) Spark Ignition
B) Compression Ignition
C) Gas turbine
D) Steam engine
Answer: B) Compression Ignition
42. Power output of an engine is directly proportional to:
A) Compression ratio
B) Swept volume
C) Engine speed
D) All of the above
Answer: D) All of the above
43. The specific fuel consumption of an engine is measured in:
A) kg/h
B) kg/kW
C) kg/kWh
D) g/kWh
Answer: C) kg/kWh
44. Which engine type uses glow plugs?
A) Petrol
B) Diesel
C) Gas turbine
D) Steam
Answer: B) Diesel
45. Knocking in diesel engines is due to:
A) Late burning
B) Detonation
C) Early ignition
D) Delay in ignition
Answer: D) Delay in ignition
46. The lubrication system used in two-stroke engines is:
A) Dry sump
B) Splash system
C) Wet sump
D) Petrol-oil mixture
Answer: D) Petrol-oil mixture
47. Crank angle is the angle:
A) Between piston and cylinder
B) Of rotation of crank during a stroke
C) Between valves
D) Between spark plug terminals
Answer: B) Of rotation of crank during a stroke
48. The turbocharger is driven by:
A) Engine crankshaft
B) Electric motor
C) Exhaust gases
D) Coolant pressure
Answer: C) Exhaust gases
49. The term “stoichiometric air-fuel ratio” refers to:
A) Lean mixture
B) Rich mixture
C) Chemically ideal mixture
D) Maximum power mixture
Answer: C) Chemically ideal mixture
50. The primary reason for cooling an engine is to:
A) Maintain lubrication
B) Avoid melting
C) Prevent knocking
D) Maintain working temperature
Answer: D) Maintain working temperature
51. The bore of an engine is the:
A) Stroke length
B) Cylinder diameter
C) Piston width
D) Valve size
Answer: B) Cylinder diameter
52. A naturally aspirated engine:
A) Uses a turbocharger
B) Uses a supercharger
C) Uses atmospheric air
D) Operates without combustion
Answer: C) Uses atmospheric air
53. A higher octane number means:
A) Lower knocking tendency
B) More energy
C) Higher volatility
D) Higher cost
Answer: A) Lower knocking tendency
54. Which cycle is most ideal for petrol engines?
A) Otto
B) Diesel
C) Rankine
D) Brayton
Answer: A) Otto
55. Blowby in IC engines refers to:
A) Backfire
B) Combustion gases escaping past piston rings
C) Air leak in carburetor
D) Fuel leak from injector
Answer: B) Combustion gases escaping past piston rings
56. If indicated power is greater than brake power, the difference is due to:
A) Friction losses
B) Cooling losses
C) Exhaust loss
D) Combustion inefficiency
Answer: A) Friction losses
57. The scavenging process is more efficient in:
A) 2-stroke engines
B) 4-stroke engines
C) Gas turbines
D) Diesel-electric systems
Answer: A) 2-stroke engines
58. The brake thermal efficiency is defined as:
A) BP/Input heat
B) IP/Input heat
C) FP/Output heat
D) BP × IP
Answer: A) BP/Input heat
59. In petrol engines, air-fuel mixture is supplied via:
A) Injector
B) Turbocharger
C) Carburetor
D) Governor
Answer: C) Carburetor
60. In CI engines, air is compressed to a pressure of about:
A) 5 bar
B) 15 bar
C) 30 bar
D) 50 bar
Answer: B) 15 bar
Here are the next 20 IC Engine MCQs (Questions 41–60) for your RRB JE prep:
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IC Engine MCQs (41–60)
41. Which type of engine is more efficient at part loads?
A) Spark Ignition
B) Compression Ignition
C) Gas turbine
D) Steam engine
Answer: B) Compression Ignition
42. Power output of an engine is directly proportional to:
A) Compression ratio
B) Swept volume
C) Engine speed
D) All of the above
Answer: D) All of the above
43. The specific fuel consumption of an engine is measured in:
A) kg/h
B) kg/kW
C) kg/kWh
D) g/kWh
Answer: C) kg/kWh
44. Which engine type uses glow plugs?
A) Petrol
B) Diesel
C) Gas turbine
D) Steam
Answer: B) Diesel
45. Knocking in diesel engines is due to:
A) Late burning
B) Detonation
C) Early ignition
D) Delay in ignition
Answer: D) Delay in ignition
46. The lubrication system used in two-stroke engines is:
A) Dry sump
B) Splash system
C) Wet sump
D) Petrol-oil mixture
Answer: D) Petrol-oil mixture
47. Crank angle is the angle:
A) Between piston and cylinder
B) Of rotation of crank during a stroke
C) Between valves
D) Between spark plug terminals
Answer: B) Of rotation of crank during a stroke
48. The turbocharger is driven by:
A) Engine crankshaft
B) Electric motor
C) Exhaust gases
D) Coolant pressure
Answer: C) Exhaust gases
49. The term “stoichiometric air-fuel ratio” refers to:
A) Lean mixture
B) Rich mixture
C) Chemically ideal mixture
D) Maximum power mixture
Answer: C) Chemically ideal mixture
50. The primary reason for cooling an engine is to:
A) Maintain lubrication
B) Avoid melting
C) Prevent knocking
D) Maintain working temperature
Answer: D) Maintain working temperature
51. The bore of an engine is the:
A) Stroke length
B) Cylinder diameter
C) Piston width
D) Valve size
Answer: B) Cylinder diameter
52. A naturally aspirated engine:
A) Uses a turbocharger
B) Uses a supercharger
C) Uses atmospheric air
D) Operates without combustion
Answer: C) Uses atmospheric air
53. A higher octane number means:
A) Lower knocking tendency
B) More energy
C) Higher volatility
D) Higher cost
Answer: A) Lower knocking tendency
54. Which cycle is most ideal for petrol engines?
A) Otto
B) Diesel
C) Rankine
D) Brayton
Answer: A) Otto
55. Blowby in IC engines refers to:
A) Backfire
B) Combustion gases escaping past piston rings
C) Air leak in carburetor
D) Fuel leak from injector
Answer: B) Combustion gases escaping past piston rings
56. If indicated power is greater than brake power, the difference is due to:
A) Friction losses
B) Cooling losses
C) Exhaust loss
D) Combustion inefficiency
Answer: A) Friction losses
57. The scavenging process is more efficient in:
A) 2-stroke engines
B) 4-stroke engines
C) Gas turbines
D) Diesel-electric systems
Answer: A) 2-stroke engines
58. The brake thermal efficiency is defined as:
A) BP/Input heat
B) IP/Input heat
C) FP/Output heat
D) BP × IP
Answer: A) BP/Input heat
59. In petrol engines, air-fuel mixture is supplied via:
A) Injector
B) Turbocharger
C) Carburetor
D) Governor
Answer: C) Carburetor
60. In CI engines, air is compressed to a pressure of about:
A) 5 bar
B) 15 bar
C) 30 bar
D) 50 bar
Answer: B) 15 bar
Here are the next 20 IC Engine MCQs (Questions 61–80) with answers:
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IC Engine MCQs (61–80)
61. The engine capacity is usually expressed in:
A) cm
B) cc
C) m³
D) cm²
Answer: B) cc
62. The component converting reciprocating motion to rotary motion is:
A) Camshaft
B) Crankshaft
C) Rocker arm
D) Valve
Answer: B) Crankshaft
63. Which of the following increases the engine's power output?
A) Increasing compression ratio
B) Increasing fuel injection pressure
C) Using a turbocharger
D) All of the above
Answer: D) All of the above
64. Specific fuel consumption decreases with:
A) Decreased load
B) Increased speed
C) Increased load
D) High friction
Answer: C) Increased load
65. In an IC engine, combustion occurs in:
A) Intake manifold
B) Outside the cylinder
C) Inside the cylinder
D) Exhaust manifold
Answer: C) Inside the cylinder
66. The purpose of a silencer is to:
A) Cool exhaust gas
B) Reduce exhaust noise
C) Increase speed
D) Enhance combustion
Answer: B) Reduce exhaust noise
67. What is the purpose of a governor in an engine?
A) Increase speed
B) Control temperature
C) Regulate fuel supply
D) Filter oil
Answer: C) Regulate fuel supply
68. Lean mixture has:
A) More fuel
B) Less fuel
C) More oil
D) More air
Answer: D) More air
69. The clearance volume is located between:
A) Piston and crank
B) Cylinder head and piston at TDC
C) Piston rings
D) Valve and rocker
Answer: B) Cylinder head and piston at TDC
70. Otto cycle efficiency depends on:
A) Engine size
B) Speed
C) Compression ratio
D) Fuel injection
Answer: C) Compression ratio
71. Which of the following determines octane rating?
A) Knock resistance
B) Viscosity
C) Density
D) Flash point
Answer: A) Knock resistance
72. Which stroke in a 4-stroke engine consumes power?
A) Power stroke
B) Compression stroke
C) Suction stroke
D) Exhaust stroke
Answer: B) Compression stroke
73. Which type of engine uses both constant volume and constant pressure heat addition?
A) Otto
B) Diesel
C) Dual cycle
D) Rankine
Answer: C) Dual cycle
74. Which device regulates engine temperature?
A) Radiator
B) Thermostat
C) Water pump
D) Fan
Answer: B) Thermostat
75. The compression stroke increases:
A) Temperature only
B) Pressure only
C) Both pressure and temperature
D) Volume
Answer: C) Both pressure and temperature
76. Engine knocking is more common in:
A) High-octane fuels
B) Low compression engines
C) High-speed engines
D) Low-octane fuels
Answer: D) Low-octane fuels
77. For better volumetric efficiency, the intake valve should:
A) Close early
B) Open late
C) Close after BDC
D) Stay always open
Answer: C) Close after BDC
78. Which of the following components opens and closes engine valves?
A) Crankshaft
B) Camshaft
C) Flywheel
D) Governor
Answer: B) Camshaft
79. Diesel engines usually operate at:
A) High RPM
B) Constant temperature
C) Lean mixture
D) Rich mixture
Answer: C) Lean mixture
80. The component that stores rotational energy is:
A) Valve
B) Crankshaft
C) Flywheel
D) Piston
Answer: C) Flywh
Here’s the final set of 20 IC Engine MCQs (Questions 81–100) for your RRB JE exam prep:
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IC Engine MCQs (81–100)
81. Turbocharger increases:
A) Fuel economy
B) Engine volume
C) Power output
D) Valve size
Answer: C) Power output
82. Flash point of fuel is the temperature at which it:
A) Catches fire spontaneously
B) Emits enough vapor to ignite
C) Explodes
D) Becomes liquid
Answer: B) Emits enough vapor to ignite
83. Which fuel has the highest calorific value?
A) Petrol
B) Diesel
C) LPG
D) Hydrogen
Answer: D) Hydrogen
84. Diesel engine has no:
A) Fuel injector
B) Carburetor
C) Piston
D) Cylinder
Answer: B) Carburetor
85. Engine firing order affects:
A) Engine balance
B) Combustion
C) Fuel quality
D) Valve timing
Answer: A) Engine balance
86. The exhaust valve opens at:
A) Top dead center
B) Bottom dead center
C) Before BDC
D) After TDC
Answer: C) Before BDC
87. In SI engines, knocking occurs near:
A) Spark plug
B) Cylinder wall
C) Crankcase
D) Injector
Answer: B) Cylinder wall
88. The function of the oil filter is to:
A) Cool oil
B) Remove dirt from oil
C) Lubricate cylinder
D) Increase oil pressure
Answer: B) Remove dirt from oil
89. Valve overlap helps in:
A) Fuel economy
B) Cooling
C) Better scavenging
D) Lubrication
Answer: C) Better scavenging
90. During suction stroke, the pressure inside the cylinder is:
A) Higher than atmosphere
B) Equal to atmosphere
C) Lower than atmosphere
D) Zero
Answer: C) Lower than atmosphere
91. A multi-cylinder engine has:
A) One piston
B) Multiple pistons
C) One crankshaft only
D) No flywheel
Answer: B) Multiple pistons
92. TDC refers to:
A) Total displacement cycle
B) Top dead center
C) Thermal dead center
D) Throttle down control
Answer: B) Top dead center
93. Fuel injector in diesel engines operates under:
A) Vacuum
B) Low pressure
C) Atmospheric pressure
D) High pressure
Answer: D) High pressure
94. A rich mixture contains:
A) Less air
B) More air
C) Only fuel
D) More oil
Answer: A) Less air
95. Which one is not a stroke of 4-stroke engine?
A) Suction
B) Combustion
C) Compression
D) Exhaust
Answer: B) Combustion
96. The volumetric efficiency is highest when the intake air is:
A) Hot
B) Cold
C) Humid
D) Dry
Answer: B) Cold
97. Which engine has lower specific fuel consumption?
A) Petrol
B) Diesel
C) Gas
D) Steam
Answer: B) Diesel
98. The component transmitting motion from camshaft to valve is:
A) Piston
B) Connecting rod
C) Tappet
D) Crank
Answer: C) Tappet
99. The stroke volume is:
A) Total cylinder volume
B) Clearance volume
C) Swept volume
D) Dead volume
Answer: C) Swept volume
100. Engine efficiency is highest when:
A) Load is zero
B) Engine runs cold
C) Engine runs hot and loaded
D) Engine runs at high speed
Answer: C) Engine runs hot and loaded
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You're now equipped with 100 important IC Engine MCQs for RRB JE! Let me know if you'd like a PDF version, quiz format, or topic-wise explanations.
