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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.
101. 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
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.
105.The working medium of an air standard cycle has constant ___________ throughout the cycle.
(A) pressure
(B) volume
(C) specific heat
(D) mass
ans:C
106.It is assumed that all the processes of an air standard cycle are
(A) reversible
(B) irreversible
(C) adiabatic
(D) isothermal
ans:A
107.The compression ratio of the I.C. engine is
(A) the ratio of volumes of air in cylinder before compression stroke and after compression stroke.
(B) the volume displaced by piston per stroke and clearance volume in the cylinder.
(C) the ratio of pressure after compression and before compression.
(D) swept volume/cylinder volume.
ans:A
108.A petrol engine, during suction stroke, draws
(A) air only
(B) petrol only
(C) a mixture of petrol and air
(D) a mixture of petrol and air and oil
ans:C
109.In a four-stroke cycle engine, the sequence of operations is
(A) suction, compression, expansion, and exhaust
(B) suction, expansion, compression, and exhaust
(C) expansion, compression, suction, and exhaust
(D) compression, expansion, suction, and exhaust
ans:A
1-The following is (are) the volatile fuel(s).
Petrol
Alcohol
Benzol
All of the above
(Ans: d)
2-The function of induction system of Spark Ignition (SI) engine is to supply ______ to various cylinders of the engine.
Partly vaporized mixture of fuel and air
Fully vaporized mixture of fuel and air
Liquefied mixture of fuel and air
All of the above
(Ans: a)
3-The following factors affect the process of carburetion
Engine speed
The temperature of incoming air
The volatility of fuel
All of the above
(Ans: d)
4-Which of the following Air-fuel ratio is considered as rich mixture in Spark Ignition (SI) engine?
Below 11:1
Below 15:1
Below 20:1
Above 20:1
(Ans: a)
5-The fuel-air ratios in the range of _____ give maximum economy of fuel
12.5 to 13.5 : 1
14.5 to 15.5 : 1
16.5 to 17.5 : 1
19.5 to 20.5 : 1
(Ans: c)
6-The fuel consumption is least in
Idling range
No load running
Cruising range
High power range
(Ans: c)
7-The pressure in float chamber of carburetor is
1 atm
2 atm
3 atm
4 atm
(Ans: a)
8-The difference of level of tip of main nozzle and fuel level in float chamber of a simple carburetor is called
Nozzle lip
Nozzle dip
Throttle lip
Throttle dip
(Ans: a)
9-In carburetor, Choke is incorporated
Before the venturi
After the venturi
In the venturi
Any of the above
(Ans: a)
10-The following are the compensating devices used
Auxiliary air valve
Auxiliary port
Metering pin
All of the above
(Ans: d)
11-The following method provides the required air-fuel ratios in the economic and power range
Idling system
Accelerating pump
Metering pin method
Pressure reduction method
(Ans: d)
12-The following is (are) the modern carburetors used in automobiles
Solex carburetor
Cartex carburetor
S.U. carburetor
All of the above
(Ans: d)
13-At high altitudes, the automobile requires
Rich mixture
Lean mixture
Correct mixture
Any of the above
(Ans: b)
14-The first vehicle in India equipped with MPFI system in Indian automobile industry
Tata Indica
Daewoo Matiz
Maruti Alto
Chevrolet spark
(Ans: b)
15-‘MPFI’ stands for
Multi point fuel injection
Multi port fuel injection
Manifold point fuel injection
Manifold port fuel injection
(Ans: a)
16-In MPFI _____ is used to spray fuel into engine.
Engine vacuum
Suction pressure of engine
Electric pump
None of the above
(Ans: b)
17-The following is (are) the part(s) of Electronic Control Unit (ECU)
Injector control
Spark advance control
Idling control
All of the above
(Ans: d)
18-The vapour lock problem may be caused in
Pipes
Feed pump
Float chamber
All of the above
(Ans: d)
19. In battery ignition system, the energy required for producing spark is obtained from a _____________ battery.
a) 6 V to 12 V
b) 12 V to 24 V
c) 24 V to 30 V
d) none of the mentioned
20. The essential components of battery ignition system are
a) battery
b) ignition switch
c) ballast resistor
d) all of the mentioned
21. The essential components of battery ignition system are
a) ignition coil
b) contact breaker
c) capacitor
d) all of the mentioned
22. The essential components of battery ignition system are
a) distributor
b) spark plug
c) none of the mentioned
d) all of the mentioned
23. The battery is charged by a __________ driven by the engine.
a) shaft
b) axle
c) dynamo
d) none of the mentioned
24. A lead acid battery consists of a number of cells connected together in series and each having a nominal potential of 2 volts when fully charged.
a) True
b) False
25. The lead acid battery is used in ______________ duty commercial vehicles.
a) heavy
b) light
c) large
d) none of the mentioned
View Answer
26. The alkaline battery is used in ____________ duty commercial vehicles.
a) heavy
b) light
c) large
d) none of the mentioned
27. Battery is connected to the primary winding of the ignition coil through an ignition switch and blast resistor.
a) True
b) False
28. The ignition system can be turned ON or OFF, with the help of ignition switch.
a) True
b) False
29. A blast resistor is provided in parallel with the primary winding to regulate the primary current.
a) True
b) False
30. An eight cylinder engine running at 3000 rpm requires __________ spark per minute.
a) 1000
b) 3000
c) 12000
d) none of the mentioned
31. The function of the distributor is to distribute the ignition surges to the individual spark plug in the correct sequence and at the correct instants in time.
a) True
b) False
32. When the ignition switch is opened, the primary winding of the coil is connected to the positive terminal post of the storage battery.
a) True
b) False
33. The primary voltage increases as the engine speed increases due to the limitations in the current switching capability of the breaker system.
a) True
b) False
34. Swirl is the rotational flow of charge within the cylinder about the axis.
a) True
b) False
35. The _____________ is defined by the parallel portion of the piston and cylinder head which almost touch each other as the piston approaches T.D.C.
a) turbulence
b) swirl
c) quench area
d) none of the mentioned
36. ____________ consists of randomly dispersed vortices of different sizes which become superimposed into the air and petrol mixture flow stream.
a) Turbulence
b) Swirl
c) Quench area
d) None of the mentioned
37. The amount of vortex activity,and the disintegration of others, _____________ the turbulent flow with rising engine speed.
a) increases
b) decreases
c) remains same
d) none of the mentioned
38. The degree of turbulence increases _____________ with the piston speed.
a) indirectly
b) directly
c) linearly
d) none of the mentioned
39. Turbulence decreases the heat flow to the cylinder wall and in the limit excessive turbulence may extinguish the flame.
a) True
b) False
40. The flame propagation velocities range from
a) 10 to 15 m/s
b) 15 to 70 m/s
c) 20 to 80 m/s
d) 30 to 90 m/s
41. When ignition occurs the nucleus of the flame spreads with the whirling or rotating vortices in the form of ragged burning crust from the initial spark plug ignition site.
a) True
b) False
42. Swirl ratio is defined as the ratio of air rotational speed to crankshaft rotational speed.
a) True
b) False
43. Abnormal combustion knock produced by surface ignition in SI engines is not harmful as normal combustion knock.
a) True
b) False
44. In a spark ignition engine combustion which is initiated between the spark plug electrodes spreads across the combustible mixture.
a) True
b) False
45. A definite flame front is one which separates the fresh mixture from the products of combustion travels from the spark plug to the other end of the combustion chamber.
a) True
b) False
46. The process of autoignition has nothing to do towards engine knock.
a) True
b) False
47. In SI engine, ignition lag is reduced if the initial temperature and pressure are
a) decreased
b) increased
c) constant
d) none of the mentioned
48. Auto ignition refers to initiation of combustion without the necessity of a flame.
a) True
b) Fals
49. The effects of knocking are
a) noise and roughness
b) mechanical damage
c) carbon deposits
d) all of the mentioned
50. The effects of knocking are
a) increase in heat transfer
b) decrease in power output and efficiency
c) preignition
d) all of the mentioned
51. Increase of pressure increases the self ignition temperature and the induction period.
a) True
b) False
52. Low engine speeds will give low turbulence and low flame velocities and knock may occur at low speed.
a) True
b) False
53. Use of low octane fuel can eliminate detonation.
a) True
b) False
1. NOx is reduced in a CI engine by the use of EGR.
a) increased
b) reduced
c) unpredictable
d) none of the mentioned
2. EGR and lower combustion temperatures contribute to an ____________ in solid soot.
a) decreases
b) increases
c) same
d) none of the mentioned
3. Platinum and palladium are two main catalyst materials used for converters on CI engines.
a) True
b) False
4. Platinum and palladium catalyst promotes the removal of ____________ of the gaseous HC in the exhaust.
a) 30-80%
b) 40-90%
c) 50-100%
d) none of the mentioned
5. Platinum and palladium catalyst promotes the removal of _____________ of the gaseous CO in the exhaust.
a) 30-80%
b) 40-90%
c) 50-100%
d) none of the mentione
6. Diesel fuel contains sulphur impurities, and this leads to poisoning of the catalyst materials.
a) True
b) False
7. Traps are filter-like system often made of ceramic in the form of a monolith or mat, or metal wire mesh.
a) True
b) False
8. Traps typically remove _____________ of particulates in the exhaust flow.
a) 30-80%
b) 40-90%
c) 50-100%
d) 60-90%
9. Regeneration does not consists of combusting the particulates in the excess oxygen contained in the exhaust of the lean operating CI engine.
a) True
b) False
10. With greatly increased mixing efficiency and speeds, large regions of fuel-rich mixtures can be avoided when combustion starts.
a) True
b) False
Answer: a
Explanation: None.
11. In which of the following fuel injector is used?
a) Compression-ignition engines
b) Spark-ignition engines
c) Steam engines
d) Sterling engines
Answer: a
Explanation: In compression – ignition (CI) engines, only air is compressed in the cylinder and by means of fuel – injection system fuel is injected into the cylinder. In CI engines, compressed air temperature plays a main role in combustion.
12. At which stroke the fuel is injected in the CI engine?
a) Suction stroke
b) Compression stroke
c) Expansion stroke
d) Exhaust stroke
13. Which of the following is the port fuel – injection system?
a) D – MPFI
b) L – MPFI
c) GDI
d) TBI
14. What is the range of pressure is achieved in the injection pump?
a) 120 – 200 bar
b) 10 – 20 bar
c) 400 – 500 bar
d) < 10bar
15. In pneumatic governor, which of the following control the amount of vacuum applied to the diaphragm?
a) Spring
b) Accelerator pedal
c) Butterfly valve
d) Lever
16. A six-cylinder, four-stroke diesel engine develops a power of 200 kW at 2000 revolution per minute. The brake specific fuel consumption is 0.3 kg / kW – h. What is the time for injection if the injection takes place over 20° crank angle?
a) 1 millisecond
b) 2 milliseconds
c) 1.5 milliseconds
d) 1.66 milliseconds
17. What is the spray cone angle in the Pintle nozzle?
a) 60°
b) 15°
c) 25°
d) 45°
18. Which of the following is not the part of the injector assembly?
a) Needle valve
b) Nozzle
c) Diaphragm
d) Compressor spring
19. Which of the following is not the function of the fuel injection system?
a) Time the fuel injection
b) Filter the fuel
c) Atomize the fuel to fine particles
d) Control the engine speed
20. The cold start injector provides a lean air-fuel ratio.
a) True
b) False
21. The methods used on fuel injection are :
a) air injection
b) mechanical injection
c) solid fuel injection
d) all of the mentioned
22. Removal of air from the pipeline is termed as ____________ in injection system.
a) bleeding
b) wound
c) sweating
d) none of the mentioned
23. The usual types of diesel injectors are :
a) single hole injector
b) multi hole injector
c) long stem injector
d) all of the mentioned
24. In pre-chamber and swirl type of combustion system ______________ is used.
a) single hole injector
b) multi hole injector
c) long stem injector
d) pintle nozzle
25. _______________ is used to enable cold starting, with out the use of a heater plug.
a) Pintaux nozzle
b) Multi hole injector
c) Long stem injector
d) Pintle nozzle
26. If one or more nozzles are not spraying correctly then ________________ occurs.
a) dripping
b) misfiring
c) cold firing
d) none of the mentioned
27. Solid injection is also called ________________
a) air injection
b) mechanical injection
c) compression fuel injection
d) none of the mentioned
View Answer
28. Fuel is injected into the cylinder at the end of ______________ stroke.
a) suction
b) compression
c) expansion
d) exhaust
Answer: b
Explanation: Fuel is injected into the cylinder at the end of compression stroke and not at suction or expansion stroke.
29. The beginning and end of the injection should be sharp.
a) True
b) False
Answer: a
Explanation: None.
30. In _____________ injection system only one pump is sufficient for multi-cylinder engine.
a) air
b) mechanical
c) compression fuel
d) common rail
Answer: d
Explanation: None.
31. In a fuel-injection system, the amount of fuel delivered into the air stream going to the engine is controlled by a pump which forces the fuel under pressure.
a) True
b) False
Answer: a
Explanation: None.
32. The requirements met by the injection system are:
a) Proper atomization of fuel into very fine droplets
b) Proper spray pattern to ensure rapid mixing of fuel and air
c) Uniform distribution of fuel droplets throughout the combustion chamber
d) All of the mentioned
Answer: d
Explanation: None.
33. In an air injection system, __________ is forced into the cylinder by means of compressed air.
a) air
b) fuel
c) water
d) none of the mentioned
Answer: b
Explanation: In an air injection system, generally fuel is forced into the cylinder by means of compressed air.
34. Fuel injector is used for
a) Gas engines
b) CI engines
c) SI engines
d) None of the mentioned
Answer: b
Explanation: Fuel injector is used for CI engines and not for SI engine and gas engines.
35. Advantage of air injection system is
a) cheaper fuels can be used
b) mep is high
c) fine atomization and distribution of the fuel
d) all of the mentioned
Answer: d
Explanation: None.
36. Commonly used injection system in automobiles is
a) air injection
b) solid injection
c) combination of (a) and (b)
d) none of the mentioned
Answer: b
Explanation: None.
37. Fuel injection pressure in solid injection system is around
a) < 10 bar
b) 10-20 bar
c) 30-50 bar
d) 200-250 bar
Answer: d
Explanation: None.
38. Fuel filters do not use generally
a) oil
b) paper
c) cloth
d) felt
Answer: b
Explanation: Generally paper is not used as fuel filters.
39. Fuel is injected in a four-stroke CI engine
a) at the end of suction stroke
b) at the end of expansion stroke
c) at the end of compression stroke
d) at the end of exhaust stroke
Answer: c
Explanation: None.
40. Advantage of fuel injection in SI engine is
a) low initial cost
b) low maintenance requirements
c) increased volumetric efficiency
d) none of the mentioned
Answer: c
Explanation: None.
41. A six cylinder, four-stroke diesel engine develops 125 kW at 3000 rpm. Its brake specific fuel consumption is 200gm/kW h. Calculate the quantity of fuel to be injected per cycle per cylinder. Specific gravity of the fuel may be taken as 0.85.
a) 0.0545 cc/cycle
b) 0.545 cc/ cycle
c) 5.45 cc/cycle
d) none of the mentioned
Answer: a
Explanation: Fuel consumed/hour = bsfc x Power output
= 200 x 10-2 x 125 = 25 kg
Fuel consumption/cylinder = 25/6 = 4.17 kg/h
Fuel consumption/cycle = (Fuel consumption/minute)/nwhere n = N/2 for four-stroke cycle engines = (4.17/60)/(3000/2)
= 4.63 x 10-5 kg
= 0.0463 gm
Volume of fuel injected = 0.0463/0.85
= 0.0545 cc/cycle.
42. In CI engine, combustion occurs by the high temperature produced by the compression of the air.
a) True
b) False
Answer: a
Explanation: None.
43. In the CI engine, the intake is air alone and the fuel is injected at high pressure in the form of fine droplets at the start of compression.
a) True
b) False
Answer: b
Explanation: No, but actually, in the CI engine, the intake is air alone and the fuel is injected at high pressure in the form of fine droplets near the end of compression.
44. The phases of CI engine combustion are
a) ignition delay period
b) period of rapid combustion
c) period of controlled combustion
d) all of the mentioned
Answer: d
Explanation: The three phases of CI engine combustion are
a) ignition delay period
b) period of rapid combustion
c) period of controlled combustion.
45. The rate of pressure rise depends on the amount of fuel present at the end of delay period, degree of turbulence, fineness of atomization and spray pattern.
a) True
b) False
Answer: a
Explanation: None.
46. The factors affecting combustion in CI engine are
a) ignition quantity of fuel
b) injection pressure of droplet size
c) injection advance angle
d) all of the mentioned
Answer: a
Explanation: The factors affecting combustion in CI engine are
1) ignition quantity of fuel
2) injection pressure of droplet size
3) injection advance angle
4) compression ratio
5) intake temperature
6) jacket water temperature
7) intake pressure
8) engine speed
9) load and air to fuel ratio
10) engine size
11) type of combustion chamber.
47. The factors affecting combustion in CI engine are
a) compression ratio
b) intake temperature
c) jacket water temperature
d) all of the mentioned
Answer: a
Explanation: The factors affecting combustion in CI engine are
1) ignition quantity of fuel
2) injection pressure of droplet size
3) injection advance angle
4) compression ratio
5) intake temperature
6) jacket water temperature
7) intake pressure
8) engine speed
9) load and air to fuel ratio
10) engine size
11) type of combustion chamber.
48. The factors affecting combustion in CI engine are
a) intake pressure
b) engine speed
c) load and air to fuel ratio
d) all of the mentioned
Answer: a
Explanation: The factors affecting combustion in CI engine are
1) ignition quantity of fuel
2) injection pressure of droplet size
3) injection advance angle
4) compression ratio
5) intake temperature
6) jacket water temperature
7) intake pressure
8) engine speed
9) load and air to fuel ratio
10) engine size
11) type of combustion chamber.
49. Towards the end of the compression stroke when injection of the fuel into the combustion chamber commences, the quantity of fuel discharged is spread out over a predetermined period.
a) True
b) False
Answer: a
Explanation: None.
50. The rate of burning does not depends on the relative movement of the burning droplets to the surrounding air charge.
a) True
b) False
Answer: b
Explanation: In fact, the rate of burning depends on the relative movement of the burning droplets to the surrounding air charge.
51. In CI engines fuel is injected into the combustion chamber at about 15ºC ___________ TDC during compression stroke.
a) after
b) before
c) at
d) none of the mentioned
Answer: b
Explanation: None.
1-Lubricating oil
(A) Minimizes wear in moving parts
(B) Helps in keeping the parts cool
(C) Washes away and carries away dirt
(D) All of the above
(Ans: D)
2-Viscosity index (VI) is a measure for the change of viscosity with change in
(A) Temperature
(B) Pressure
(C) Volume
(D) All of the above
(Ans: A)
3-The following type of Lubrication system is used in two stroke engines
(A) Petroil (mist) system
(B) Wet sump system
(C) Dry sump system
(D) All of the above
(Ans: D)
4-In the following system, lubricating oil is carried in separate tanks from where it is fed to the engine
(A) Mist lubrication system
(B) Wet sump system
(C) Dry sump system
(D) Splash system
(Ans: C)
5-The following type of Lubrication system is used in Aircraft Engines
(A) Mist lubrication system
(B) Wet sump system
(C) Dry sump system
(D) Splash system
(Ans: C)
6-The following type(s) of Oil pump(s) is (are) used in Engine Lubrication system
(A) Gear type
(B) Rotor type
(C) Plunger type
(D) All of the above
(Ans: D)
7-The following is (are) oil pressure gauge(s)
(A) Pressure expansion type
(B) Electric type
(C) both (A) and (B)
(D) None of the above
(Ans: C)
8-The purpose of crankcase ventilation is to
(A) remove harmful particles from the engine
(B) provide proper lubrication to the engine
(C) provide air for combustion to the engine
(D) all of the above
(Ans: A)
9-The following part(s) is(are) lubricated by splash system
(A) Piston and piston rings
(B) Tappets
(C) Cams on camshaft
(D) All of the above
(Ans: D)
10-The following part is not lubricated by Pressure feed system
(A) Timing gears
(B) Valve rods and Push rods
(C) Rocker arms
(D) Main bearings of crankshaft
(Ans: B)
11.Which of the following parts are lubricated by splash system?
(A) Piston and piston rings
(B) Tappets
(C) Cams on camshaft
(D) All of the above
ans:D
12.Which of the following part is not lubricated by a pressure feed system?
(A) Timing gears
(B) Valve rods and Pushrods
(C) Rocker arms
(D) Main bearings of the crankshaft
ans:B
13.Mist lubrication system is used for ____________ stroke cycle engines.
(A) four
(B) two
(C) radial
(D) all of the above
ans:B
14.Splash system is suitable for
(A) low and medium speed engines
(B) high and medium speed engines
(C) only high-speed engines
(D) all of the above
ans:B
15.Wet sump lubrication system employs a large capacity oil sump at the base of the crank chamber, from which the oil is drawn by a ____ and delivered to various parts.
(A) low pressure oil pump
(B) high pressure oil pump
(C) oil pump
(D) vacuum pump
ans:A
16. Lubricating grease is a solid to semi-solid dispersion of a thickening agent in liquid lubricant.
a) True
b) False
17. Greases perform better than oils under conditions requiring
a) high bearing loads and shock loads
b) slow journal speed
c) temperature extremes
d) all of the mentioned
Answer: d
Explanation: Greases perform better than oils under conditions requiring
a) high bearing loads and shock loads
b) slow journal speed
c) temperature extremes
d) cleanliness or avoidance of splash
e) minimum attention
f) a seal against external contaminants
g) large bearing clearances.
18. Greases perform better than oils under conditions requiring
a) cleanliness or avoidance of splash
b) minimum attention
c) a seal against external contaminants
d) all of the mentioned
Answer: d
Explanation: Greases perform better than oils under conditions requiring
a) high bearing loads and shock loads
b) slow journal speed
c) temperature extremes
d) cleanliness or avoidance of splash
e) minimum attention
f) a seal against external contaminants
g) large bearing clearances.
19. The various types of greases used for lubrication are
a) calcium soap greases
b) sodium soap greases
c) aluminium soap greases
d) all of the mentioned
Answer: d
Explanation: The various types of greases used for lubrication are
a) calcium soap greases
b) sodium soap greases
c) aluminium soap greases
d) mixed soap greases
e) barium soap greases
f) lithium soap greases
g) pure petroleum greases.
20. Wet sump lubrication system employ a large capacity oil sump at the base of crank chamber, from which the oil is drawn by a low pressure oil pump and delivered to various parts.
a) True
b) False
Answer: a
Explanation: None.
21. Splash system is suitable for high and medium speed engines having moderate bearing load pressures.
a) True
b) False
Answer: b
Explanation: In fact, splash system is suitable for low and medium speed engines having moderate bearing load pressures.
22. Semi pressure system is a combination of splash and pressure systems.
a) True
b) False
Answer: a
Explanation: None.
23. Semi pressure system does not enables higher bearing loads and engine speeds to be employed as compared to splash system.
a) True
b) False
Answer: b
Explanation: Semi pressure system enables higher bearing loads and engine speeds to be employed as compared to splash system.
24. In full pressure system, oil from oil sump is pumped under pressure to the various parts requiring lubrication.
a) True
b) False
Answer: a
Explanation: None.
25. Full pressure sump lubrication system is generally adopted for high capacity engines.
a) True
b) False
Answer: b
Explanation: Dry sump lubrication system is generally adopted for high capacity engines.
26. The gasoline engine requires much ____________ air than a diesel engine.
a) less
b) more
c) equal
d) none of the mentioned
Answer: b
Explanation: As a gasoline engine works on a mixture of air and gasoline, therefore the gasoline engine requires much more air than a diesel engine.
27. The turbocharged diesel engine requires ____________ cooling air than naturally aspired diesel engines.
a) less
b) more
c) equal
d) none of the mentioned
Answer: a
Explanation: As the turbocharged engine produces less heat so, the turbocharged diesel engine requires less cooling air than naturally aspired diesel engines.
28. The heat flow to water jackets, on an average, is about ____________ for large engines.
a) 500 kJ/kW-h
b) 4200 kJ/kW-h
c) 5700 kJ/kW-h
d) none of the mentioned
Answer: b
Explanation: The heat flow to water jackets, on an average is about 4200 kJ/kW-h for large engines and it is about 500-5700 kJ/kW-h for small engines.
29. The heat flow to water jackets, on average, is about ____________ for small engines.
a) 500-6200 kJ/kW-h
b) 400-4200 kJ/kW-h
c) 500-5700 kJ/kW-h
d) none of the mentioned
Answer: c
Explanation: The heat flow to water jackets, on average, is about 500-5700 kJ/kW-h for small engines and is about 4200 kJ/kW-h for large engines.
30. What is the outlet cooling water temperature for large engines?
a) about 50ºC
b) 60 to 65ºC
c) 80ºC
d) none of the mentioned
Answer: a
Explanation: The outlet cooling water temperature for large engines is about 50ºC and the outlet cooling water temperature for medium engines is 60 to 65ºC.
31. What is the outlet cooling water temperature for medium engines?
a) about 50ºC
b) 60 to 65ºC
c) 80ºC
d) none of the mentioned
Answer: b
Explanation: The outlet cooling water temperature for medium engines is 60 to 65ºC and the outlet cooling water temperature for small engines is 80ºC.
32. What is the outlet cooling water temperature for small engines?
a) about 50ºC
b) 60 to 65ºC
c) 80ºC
d) none of the mentioned
Answer: c
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.
33. In thermo-syphon system, the radiator should be kept well above the engine, to provide a height for natural circulation.
a) True
b) False
Answer: a
Explanation: None.
34. Turbochargers are centrifugal compressors driven by the exhaust gas turbines.
a) True
b) False
Answer: a
Explanation: None.
35. A typical petrol engine may harness up to ____________ of the energy contained in the fuel supplied.
a) 20%
b) 30%
c) 40%
d) none of the mentioned
Answer: b
Explanation: Up to 30% of the energy contained in the fuel supplied is harnessed in a typical petrol engine.
36. ____________ of fuel energy is wasted as heat energy to friction, pumping and dynamic movement.
a) 7%
b) 9%
c) 16%
d) 38%
Answer: a
Explanation: Approximately 7% of fuel energy is wasted as heat energy to friction, pumping and dynamic movement and 9% of fuel energy is wasted as heat energy to surrounding air.
37. ____________ of fuel energy is wasted as heat energy to surrounding air.
a) 7%
b) 9%
c) 16%
d) 38%
Answer: b
Explanation: 9% of fuel energy is wasted as heat energy to surrounding air while 16% of fuel energy is wasted as heat energy to engine’s coolant system.
38. ____________ of fuel energy is wasted as heat energy to engine’s coolant system.
a) 7%
b) 9%
c) 16%
d) 38%
Answer: c
Explanation: 16% of fuel energy is wasted as heat energy to engine’s coolant system while approximately 7% of fuel energy is wasted as heat energy to friction, pumping and dynamic movement and 9% of fuel energy is wasted as heat energy to surrounding air.
39. ____________ of fuel energy is wasted as heat energy to outgoing exhaust gases.
a) 7%
b) 9%
c) 16%
d) 38%
Answer: d
Explanation: 38% of fuel energy is wasted as heat energy to outgoing exhaust gases and 16% of fuel energy is wasted as heat energy to engine’s coolant system while approximately 7% of fuel energy is wasted as heat energy to friction, pumping and dynamic movement and 9% of fuel energy is wasted as heat energy to surrounding air.
40. The turbocharger relies solely on extracting up to a third of the wasted energy passing out from the engine’s cylinders to impart power to the turbine wheel and compressor wheel assembly.
a) True
b) False
Answer: a
Explanation: The turbocharger relies solely on extracting up to a third of the wasted energy passing out from the engine’s cylinders to impart power to the turbine wheel and compressor wheel assembly.
41. Turbocharged engines produce lower cylinder volumetric efficiencies compared with the normally aspirated induction systems.
a) True
b) False
Answer: b
Explanation: In fact turbocharged engines produce higher cylinder volumetric efficiencies compared with the normally aspirated induction systems.
42. The compression of the charge entering the cells of the impeller depends upon the centrifugal force effect which decreases with the square of the rotational speed of the impeller wheel.
a) True
b) False
Answer: b
Explanation: In fact the compression of the charge entering the cells of the impeller depends upon the centrifugal force effect which increases with the square of the rotational speed of the impeller wheel.
43. When the engine is suddenly accelerated there will be a small time delay before the extra energy discharged into the turbine housing volute can speed up the turbine wheel.
a) True
b) False
Answer: a
Explanation: Yes, when the engine is suddenly accelerated there will be a small time delay before the extra energy discharged into the turbine housing volute can speed up the turbine wheel.
44. Supercharging of S.I engines is employed only for aircraft and racing car engines.
a) True
b) False
Answer: a
Explanation: Supercharging requires when speed is taken in consideration so, supercharging of S.I engines is employed only for aircraft and racing car engines.
45. ____________ in supercharging pressure increases the tendency to detonate and pre-ignite.
a) Decrease
b) Increase
c) Unpredictable
d) None of the mentioned
Answer: a
Explanation: Detonation and pre-ignition are increased by increase in supercharging pressure.
46. The supercharged petrol engines have a lower fuel consumption than naturally aspirated engines.
a) True
b) False
Answer: b
Explanation: Actually, the supercharged petrol engines have a greater fuel consumption than naturally aspirated engines.
47. Increased intake pressure and temperature reduces ignition delay and decreases flame speed.
a) True
b) False
Answer: b
Explanation: In fact, increased intake pressure and temperature reduces ignition delay and increases flame speed.
48. The increased flame speeds make the petrol engine more sensitive to fuel-air ratio and engine cannot run on strong mixtures without knock.
a) True
b) False
Answer: b
Explanation: Actually, the increased flame speeds make the petrol engine more sensitive to fuel-air ratio and engine cannot run on weak mixtures without knock.
49. Rich mixtures are used to control detonation, which further increases the specific fuel consumption of the engine.
a) True
b) False
Answer: a
Explanation: None.
50. The ignition timings and thermal load on the engine affect the knock limit of CI engine.
a) True
b) False
Answer: b
Explanation: No, in fact the ignition timings and thermal load on the engine affect the knock limit of SI engine.
51. The ignition must be retarded at high intake pressure and temperature.
a) True
b) False
Answer: a
Explanation: None.
52. The power developed by the turbocharger is not sufficient to drive the compressor, and overcome its mechanical friction.
a) True
b) False
Answer: b
Explanation: In fact, the power developed by the turbocharger is sufficient to drive the compressor, and overcome its mechanical friction.
53. The loss in piston work due to early opening of the exhaust valve is less than offset by better charging and scavenging of the engine.
a) True
b) False
Answer: b
Explanation: No, in fact, the loss in piston work due to early opening of the exhaust valve is more than offset by better charging and scavenging of the engine.
1. For which of the following engines a prony brake is used to measure brake power?
a) single cylinder engine
b) low speed engine
c) low power engine
d) variable speed engine
Answer: d
Explanation: Prony brake is used to measure the brake power of variable speed engines.
2. What does scavenging air mean?
a) Burnt air containing combustion products
b) Air sent under compression
c) Forced air for cooling the engine cylinder
d) Air used for forcing the burnt gases out of cylinder during the exhaust period
Answer: d
Explanation: Scavenging air is defined as the air used for forcing the burnt gases out of cylinder during the exhaust period.
3. ____________ is the basic requirement of a good combustion chamber.
a) Low volumetric efficiency
b) High compression ratio
c) Low compression ratio
d) High power output and high thermal efficiency
Answer: d
Explanation: The basic requirement of a good combustion chamber are:
i) High power output
ii) High thermal efficiency and low specific fuel consumption
iii) smooth engine operation
iv) reduced exhaust pollutants.
4. ____________ is the method of governing used in petrol engine.
a) Quality governing
b) Hit and mass governing
c) Quantity governing
d) All of the mentioned
Answer: a
Explanation: Quality governing is generally used in petrol engines as the quantity of air -fuel mixture flowing into the cylinder is varied accordingly and this may be done by decreasing the lift of the inlet valve or by throttling the mixture before it is made to enter the engine cylinder.
5. Hunting occurs due to which of the following?
a) Faulty governor
b) Poor control by the governor
c) Over control by the governor
d) Bad engine design
Answer: b
Explanation: Hunting occurs due to load variation and this is only when the governor is not controlled properly.
6. Maximum torque is generated by an engine when ______________
a) it runs at lowest speed
b) it develops maximum power
c) it consumes maximum fuel
d) it runs at maximum speed
Answer: a
Explanation: Maximum torque is generated by an engine when it runs at lowest speed while maximum power is developed when the engine rums at its maximum speed.
7. With an increase of the number of cylinders in a multicylinder engine the power to weight ratio ______________
a) decreases
b) increases
c) remains unaffected
d) none of the mentioned
Answer: c
Explanation: The power to weight ratio remains unaffected even after if the number of cylinders in a multicylinder is increased because as the number of cylinders increases, torque is smoother and less flywheel mass is needed.
8. Radiator tubes are generally made of______________
a) cast iron
b) steel
c) plastics
d) brass
Answer: d
Explanation: Brass is used to make radiator pipes due to its heat resistance capacities.
9. Automobile gears are generally made of ______________
a) cast iron
b) stainless steel
c) alloy steel
d) mild steel
Answer: c
Explanation: Steel mixed with copper, zinc and tin is used to make gears in automobiles.
10. ____________ is used to check the state of charge of a battery.
a) Battery charger
b) Hygrometer
c) Hydrometer
d) Battery eliminator
Answer: a
Explanation: Battery charger is used to check the state of charge of a battery while hygrometer is used to check the air humidity and hydrometer is used to check the specific gravity.
11.The mean effective pressure obtained from the engine indicator indicates the
(A) maximum pressure developed
(B) minimum pressure
(C) instantaneous pressure at any instant
(D) average pressure
ans:D
12.The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
(A) net efficiency
(B) efficiency ratio
(C) relative efficiency
(D) overall efficiency
ans:C
13.The basic measurement and testing parameters are
(A) friction power
(B) indicated power
(C) brake power
(D) all of the above
ans:D
14._____________ is the difference between indicated and brake power of an engine.
(A) Friction power
(B) Overall power
(C) Net power
(D) None of the mentioned
ans:A
15._____________ is also known as fuel rate extrapolation method.
(A) Morse test
(B) Motoring test
(C) Willan’s line method
(D) Retardation test
ans:C
16. Which of the following is one of the major exhaust emissions from CI engines compared to SI engines?
a) Oxides of nitrogen
b) Particulates
c) CO and CO2
d) Unburnt hydrocarbon
Answer: b
Explanation: Unburnt hydrocarbons are one of the major exhaust emissions from CI engines. The components in diesel fuel have higher molecular weight.
17. Which of the following causes the photochemical smog?
a) Excess O2
b) CO and CO2
c) Soot and particulate matter
d) NOx and HC
Answer: d
Explanation: NOx is one of the primary causes of photochemical smog. This smog is formed by the photochemical reaction of automobile exhaust and atmospheric air in the presence of sunlight.
18. What does the blue smoke in diesel engine indicate?
a) Unburnt oil
b) HC
c) NOx
d) CO
Answer: a
Explanation: Blue smoke comes out from the exhaust when there is unburnt oil in the diesel engine. A very thin layer of the oil gets deposited on the cylinder wall to provide the lubrication between the walls and the moving piston.
19. During which condition of the vehicle does NOx emission in SI engine will be lowest?
a) Cruising
b) Idling
c) Accelerating
d) Decelerating
Answer: b
Explanation: NOx emissions are lowest in SI engine during idling. NOx is created from nitrogen in the air. Nitrogen can also be found in fuel blends.
20. For what purpose is the Rhodium used?
a) To reduce CO and HC
b) To reduce NOx
c) To reduce CO
d) To reduce HC
Answer: b
Explanation: Rhodium is used to reduce NOx. It is used to clean vehicle emission. It is mixed with the other two metals – platinum and palladium.
21. Why is the fumigation technique used?
a) To control HC
b) To control NOx
c) To control CO
d) To control smoke
Answer: d
Explanation: The fumigation technique is used to control smoke. Fumigation is injecting gaseous or liquid fuel into the intake of air steam of CI engines. There are two types of smoke: hot smoke and cold smoke.
22. Why are lead compounds added in petrol?
a) Reduce knocking
b) Reduce HC emission
c) Reduce exhaust temperature
d) Increase power output
Answer: b
Explanation: The lead compounds are added in petrol to reduce the HC emission. The additive TEL (Tetraethyl Lead) was added to increase the octane number. The resulting lead in the engine exhaust was a poisonous pollutant.
23. Which of the following cannot be reduced by thermal converters?
a) CO
b) HC
c) Soot
d) NOx
Answer: d
Explanation: NOx emission cannot be reduced using a thermal converter. Thermal converters are high-temperature chambers through which the exhaust gas flows.
24. What can be reduced by using exhaust gas recirculation (EGR) effectively?
a) CO
b) NOx
c) HC
d) CO and HC
Answer: b
Explanation: The most effective way of reducing NOx emission is to hold combustion chamber temperatures down. Using this also reduces the thermal efficiency of the engine.
25. Three-way catalytic converters reduce the emission of CO, HC, and soot.
a) True
b) False
Answer: b
Explanation: Three-way catalytic converters reduce the emission of CO, NOx, and HC. They are chambers contain catalytic material. It promotes the oxidation of the emission contained in the exhaust flow.
26.Which of the following is one of the major exhaust emissions from CI engines compared to SI engines?
(A) Oxides of nitrogen
(B) Particulates
(C) Carbon monoxide and Carbon dioxide
(D) Unburnt hydrocarbon
ans:B
27.Why lead compounds added in petrol?
(A) Increase power output
(B) Reduce knocking
(C) Reduce exhaust temperature
(D) Reduce HC emission
ans:D
28.What can be reduced by using exhaust gas recirculation (EGR) effectively?
(A)
(B)
(C)
(D)
ans:B
29.What is the major difference between BS-IV and BS-VI norms?
(A) BS-IV fuels contain 80 ppm sulphur and BS-VI fuels contain 60 ppm sulphur
(B) BS-IV fuels contain 100 ppm sulphur and BS-VI fuels contain 90 ppm sulphur
(C) BS-IV fuels contain 50 ppm sulphur and BS-VI fuels contain 10 ppm sulphur
(D) BS-IV fuels contain 150 ppm sulphur and BS-VI fuels contain 110 ppm sulphur
ans:C
1. Advantage of gaseous fuel is that
a) it can be stored easily
b) it can mix easily with air
c) it can displace more air from the engine
d) all of the mentioned
Answer: b
Explanation: None.
2. Paraffins are generally represented by
a) CnHn
b) CnH2n
c) CnH2n+2
d) CnH2n-6
Answer: c
Explanation: Paraffins are generally represented by CnH2n+2 while olefins are generally represented by CnHn .
3. Paraffins have molecular structure of
a) chain saturated
b) chain unsaturated
c) ring saturated
d) ring unsaturated
Answer: a
Explanation: None.
4. Olefins are generally represented by
a) CnHn
b) CnH2n
c) CnH2n+2
d) CnH2n-6
Answer: a
Explanation: Olefins are represented by CnHn and paraffins are generally represented by CnH2n+2.
5. Hydrocarbons are decomposed into smaller hydrocarbons by
a) reforming
b) refining
c) cracking
d) polymerization
Answer: c
Explanation: Hydrocarbons are decomposed into smaller hydrocarbons by cracking while the molecular structure of the straight-run gasoline is changed by reforming.
6. The molecular structure of the straight-run gasoline is changed by
a) reforming
b) refining
c) cracking
d) boiling
Answer: a
Explanation: The molecular structure of the straight-run gasoline is changed by reforming and hydrocarbons are decomposed into smaller hydrocarbons by cracking.
7. For S.I. engines fuel most preferred are
a) aromatics
b) paraffins
c) olefins
d) napthenes
Answer: a
Explanation: For S.I. engines fuel most preferred are aromatics while for C.I. engines fuel most preferred are paraffins.
8. For C.I. engines fuel most preferred are
a) aromatics
b) paraffins
c) olefins
d) napthenes
Answer: b
Explanation: For C.I. engines fuel most preferred are paraffins and for S.I. engines fuel most preferred are aromatics.
9. In spark ignition engines, the knocking tendency can be decreased by
a) decreasing compression ratio
b) controlling intake throttle
c) controlling ignition timing
d) adding dopes like tetraethyl lead and ethylene dibromide
Answer: d
Explanation: None.
10. Detonation in petrol engines can be suppressed or reduced by the addition of small quantity of
a) lead nitrate
b) iso-octane
c) n-heptane
d) none of the mentioned
Answer: a
Explanation: None.
11. The ECU in the electronic control system, receives signals from the sensors and determines the opening time for the injectors land which also controls the injection volume.
a) True
b) False
Answer: a
Explanation: None.
12. When the engine is cold, the starting of the engine is usually not ___________
a) difficult
b) easy
c) all of the mentioned
d) none of the mentioned
Answer: b
Explanation: The starting of the engine is usually not easy when the engine is cold.
13. When a cold engine is started, it requires a _____________ mixture.
a) leaner
b) richer
c) chemically equal
d) none of the mentioned
Answer: b
Explanation: For starting a cold engine, generally a richer mixture is required.
14. The cold start injector is a type of solenoid valve to which power is supplied from a battery for the opening and closing of the valve inside, thus for injecting the fuel.
a) True
b) False
Answer: a
Explanation: None.
15. The duration of injection time is controlled by a timing switch.
a) True
b) False
Answer: a
Explanation: None.
16. The ignition switch is composed of a bi-metal element and an electric heater coil.
a) True
b) False
Answer: b
Explanation: No, but in fact, the timing switch is composed of a bi-metal element and an electric heater coil.
17. As the temperature is low, the _____________ valve speeds up the engine idle speed to fast idling.
a) nozzle
b) throttle
c) air
d) none of the mentioned
Answer: c
Explanation: At low temperature, the air valve speeds up the engine idle speed to fast idling and not the throttle or nozzle.
18. When the engine is cold, the _____________ plate will be in closed position.
a) nozzle
b) throttle
c) air
d) none of the mentioned
Answer: b
Explanation: Generally, when the engine is cold, the throttle plate will be in closed position and at low temperature, the air valve speeds up the engine idle speed to fast idling.
19. When the engine reaches the normal operating temperature, the valve closes completely and the air flow is cut-off from the _____________ valve.
a) nozzle
b) throttle
c) air
d) none of the mentioned
Answer: c
Explanation: Generally, when the engine reaches the normal operating temperature, the valve closes completely and the air flow is cut-off from the air valve.
20. A thermo wax valve operates depending on the temperature of the engine coolant.
a) True
b) False
Answer: a
Explanation: None.
21. The electronic fuel injection, eliminates majority of carburettor pressure loses and almost eliminates the requirement of manifold heating.
a) True
b) False
Answer: a
Explanation: None.
22. Manifold _____________ is eliminated due to the fuel being injected into or close to the cylinder and need not flow through the manifold.
a) heating
b) wetting
c) cooling
d) none of the mentioned
Answer: b
Explanation: Generally, manifold wetting is eliminated due to the fuel being injected into or close to the cylinder and need not flow through the manifold and not heating or cooling.
23. _____________ of fuel is independent of cranking speed and therefore starting will be easier.
a) Ignition
b) Atomization
c) Condensation
d) None of the mentioned
Answer: b
Explanation: Atomization of fuel is independent of cranking speed and therefore starting will be easier and ignition and condensation are not related to cranking speed.
24. Better atomization and _____________ will make the engine less knock prone.
a) ignition
b) vapourization
c) condensation
d) none of the mentioned
Answer: b
Explanation: Engine knock is dependent on poor atomization and vapourization conditions, so better atomization and vapourization will make the engine less knock prone.
25. Formation of ice on the _____________ plate is eliminated in electronic fuel injection.
a) throttle
b) nozzle
c) engine
d) none of the mentioned
Answer: a
Explanation: Generally, the formation of ice on the throttle plate is eliminated in electronic fuel injection and not of nozzle.
26. In an electronic fuel injection, variation of air-fuel ratio is almost negligible even when the vehicle takes different positions like turning, moving on gradients, uneven roads, etc.
a) True
b) False
Answer: a
Explanation: None.
27. In an electronic fuel injection, position of the injection unit is critical.
a) True
b) False
Answer: b
Explanation: No, in fact, in electronic fuel injection, position of the injection unit is not so critical and thereby the height of the engine can be less.
28. In an electronic fuel injection, the maintenance cost is?
a) low
b) high
c) nil
d) none of the mentioned
Answer: b
Explanation: Generally, in electronic fuel injection, the maintenance cost is high.
29. In an electronic fuel injection, the servicing is very ___________
a) difficult
b) easy
c) nil
d) none of the mentioned
Answer: a
Explanation: The servicing is very difficult in electronic fuel injection.
30. In an electronic fuel injection, there is a possibility of malfunctioning of some sensors.
a) True
b) False
Answer: a
Explanation: None.
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