Internal combustion engines and automobile engineering - Mechanical Engineering

Internal combustion engines and automobile engineering - Mechanical Engineering

1) The thermal efficiency of a two stroke petrol engine as compared to that of a four stroke petrol engine for same output, same speed and same compression ratio is

a) same
b) less
c) more
d) None of the above

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2) For an I.C. engine, the ratio of brake power to indicated power is called as

a) Relative efficiency
b) Mechanical efficiency
c) Thermal efficiency
d) None of the above

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3) The compression ratio for diesel engine ranges from

a) 5 to 8
b) 8 to 10
c) 10 to 15
d) 16 to 20

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4) For maximum power, the fuel air ratio should be

a) Rich
b) Lean
c) Chemically correct
d) None of these

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5) For better thermal efficiency of S.I. engine, the fuel air ratio should be

a) Rich
b) Lean
c) Chemically correct
d) None of these

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6) The principle of governing employed for petrol engines is

a) Quality governing
b) Quantity governing
c) Both (a) and (b)
d) None of the above

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7) Which of the following firing order is preferred in case of a 4 cylinder S.I. engine?

a) 1-2-3-4
b) 1-4-2-3
c) 1-3-2-4
d) 1-3-4-2

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8) The tendency to knock in case of S.I. engines increases with

a) Increase in compression ratio
b) Increase in inlet air temperature
c) Decrease in inlet air temperature
d) (a) and (b)
e) (a) and (c)

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9) The tendency to knock in case of C.I. engines increases with

a) Decrease in compression ratio
b) Increase in compression ratio
c) Increase in the inlet air temperature
d) None of the above

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10) Vapour lock is

a) Blocking of carburettor jets
b) Supply of air-fuel mixture containing liquid particles
c) Stoppage of fuel supply due to vaporisation of fuel in the supply line
d) All of the above

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11) Which among the following is used for the insulating body of a spark plug?

a) Glass
b) Silica
c) Alumina
d) Dolomite

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12) The spark advance is usually specified in terms of

a) Engine speed in rev./sec
b) Degrees of crank rotation
c) Time in seconds
d) None of these

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13) Scavenging is done to increase

a) Fuel consumption
b) Thermal efficiency
c) Power output
d) Speed

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14) What is the reason due to which the piston rings are plated with chromium, cadmium or phosphate?

a) To improve heat transfer
b) To prevent clogging
c) To reduce water and eliminate scuffing
d) To improve surface finish

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15) The phenomenon of pre-ignition ………………

a) Never occurs in diesel engines
b) Always occurs in petrol engines
c) Never occurs in diesel engines
d) Increases the power output of an engine

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16) What is swirl in C.I engines?

a) Directional movement of fuel spray
b) Radial motion imparted to fuel-air mixture
c) Circular motion imparted to gases after combustion
d) Circular motion imparted to suction air

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17) An increase in the mean effective pressure of a diesel engine with fixed compression ratio can be obtained with increase in

a) Back pressure
b) Charge density
c) Engine speed
d) Cut off ratio

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18) Which system of lubrication is used for motor cycles and scooters?

a) Splash lubrication
b) Forced lubrication system
c) Wet sump method
d) Mixing about 5% lub. oil with petrol

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19) For the same compression ratio ………………..

a) Diesel cycle is more efficient than Otto cycle
b) Otto cycle is more efficient than diesel cycle
c) Both diesel and Otto cycles are equally efficient
d) Compression ratio has no relation with efficiency

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20) In an automobile car where is the Hook’s joint used?

a) Between clutch and gear box
b) Between differential gear and wheels
c) Between flywheel and clutch
d) Between gear box and propeller shaft

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21) What is wheel base of a vehicle?

a) It is distance between front and rear axles
b) It is extreme length of the vehicle
c) It is distance between front tyres
d) It is width of tyres

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22) What should be the level of electrolyte in automobile’s battery?

a) Exactly at the level of the plates
b) 5-10 mm below the top of plates
c) 15 mm below the top of plates
d) 10-15 mm above top of plates

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23) If there is no king pin offset in a vehicle then ……………….

a) Starting steering effort will be zero
b) Starting steering effort will be high
c) Braking effort will be high
d) Wobbling of wheels will increase

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24) The tilt of the car wheels from the vertical is called

a) Castor
b) Camber
c) Slip angle
d) None of these

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25) Engine and braking torque cause

a) Longitudinal torsion
b) Lateral bending of side members
c) Distortion of frame to parallelogram shape
d) Bending of side members in vertical plane

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26) The front wheel drive as compared to wheel drive

a) Requires longer propeller shaft
b) Has a greater skidding tendency
c) Gives better riding performance
d) Provides increased tractive effort when going up steep gradient

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27) The function of a differential in an automobile is

a) It permits the two rear wheels to run independently
b) It permits the two rear wheels to have flexibility of relative speed, whenever it is required
c) It allows rear wheel movement
d) All of the above

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28) Smoky exhaust from a diesel engine is due to

a) Fuel injection is late
b) Presence of water in the fuel
c) Exhaust valve receives excess of lubricant oil
d) All of the above

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29) Fuel ignition accelerators are added in C.I. engines to

a) Increase delay period
b) Reduce combustion knock
c) Reduce smoky exhaust
d) None of these

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30) The minimum number of rings in a piston is

a) One
b) Two
c) Three
d) Four

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