1.
The expansion of fuel in a four stroke cycle diesel engine
A. Starts at 15° before top dead center and ends at 30° after top dead center
B. Starts at top dead center and ends at 30° after top dead center
C. Starts at 15° after top dead center and ends at 30° before bottom dead center
D. May start and end anywhere
Answer: C
2. In a diesel engine, the duration between the time of injection and ignition, is
known as
A. Pre-ignition period
B. Delay period
C. Period of ignition
D. Burning period
Answer: B
3. The effective inhibitor of pre-ignition is
A. Alcohol
B. Water
C. Lead
D. None of these
Answer: B
204. A diesel engine has
A. One valve
B. Two valves
C. Three valves
D. Four valves
Answer: C
5. The pressure inside the cylinder is _________ the atmospheric pressure during the
exhaust stroke.
A. Equal to
B. Below
C. Above
D. None of these
Answer: C
6. A carburetor is used to supply
A. Petrol, air and lubricating oil
B. Air and diesel
C. Petrol and lubricating oil
D. Petrol and air
Answer: D
7. Morse test can be conducted for
A. Petrol engines
B. Diesel engines
C. Multi cylinder engines
D. All of these
Answer: C
8. High speed compression engines operate on
A. Otto cycle
B. Diesel cycle
C. Dual combustion cycle
D. All of these
Answer: C
9. The theoretically correct mixture of air and petrol is
A. 10 : 1
B. 15 : 1
C. 20 : 1
D. 25 : 1
Answer: B
10. A diesel engine has compression ratio from
A. 6 to 10
B. 10 to 15
C. 15 to 25
D. 25 to 40
Answer: C
11. In order to mix air and petrol in the required proportion and to supply it to the
engine during suction stroke, then _________ is employed.
A. Fuel pump
B. Injector
C. Carburetor
D. None of these
Answer: C
12. The ratio of the brake power to the indicated power is called
A. Mechanical efficiency
B. Overall efficiency
C. Indicated thermal efficiency
D. Volumetric efficiency
13. The cetane (C₁₆H₃₄) which is a straight chain paraffin, is assigned a cetane
number of
A. 0
B. 50
C. 100
D. 120
14. The thermodynamic cycle on which the petrol engine works, is
A. Otto cycle
B. Joule cycle
C. Rankine cycle
D. Stirling cycle
15. The correct mixture strength (by weight) for petrol is about
A. 14.6 : 1
B. 18.5 : 1
C. 20.4 : 1
D. 22.6 : 1
16. 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%
17. If the speed of the engine is increased, the indicated power will
A. Increase
B. Decrease
C. Remain same
D. None of these
18. The specific fuel consumption per B.P. hour for a petrol engine is about
A. 0.2 kg
B. 0.25 kg
C. 0.3 kg
D. 0.35 kg
19. The injector nozzle of a compression ignition engine is required to inject fuel at a
sufficiently high pressure in order to
A. Inject fuel in a chamber of high pressure at the end of compression stroke
B. Inject fuel at a high velocity to facilitate atomization
C. Ensure that penetration is not high
D. All of the above
20. A fuel of cetane number 40 has the same ignition quality as a mixture of
A. 40% cetane and 60% alpha methyl naphthalene
B. 40% alpha methyl naphthalene and 60% cetane
C. 40% petrol and 60% diesel
D. 40% diesel and 60% petrol
21. The two reference fuels used for cetane rating are
A. Cetane and iso-octane
B. Cetane and alpha-methyl naphthalene
C. Cetane and normal heptane
D. Cetane and tetra ethyl lead
22. In petrol engines, the delay period is of the order of
A. 0.001 second
B. 0.002 second
C. 0.003 second
D. 0.004 second
23. A diesel engine is _________ as compared to petrol engine, both running at rated
load.
A. Equally efficient
B. Less efficient
C. More efficient
D. None of these
24. The pressure at the end of compression, in petrol engines, is approximately
A. 10 bar
B. 20 bar
C. 25 bar
D. 35 bar
25. The turbine of the turboprop engine is __________ that of the turbojet engine.
A. Same as
B. Smaller than
C. Bigger than
D. None of these
Answer: C(15)
26. A higher compression ratio causes
A. Pre-ignition
B. Increase in detonation
C. Acceleration in the rate of combustion
D. Any one of these
Answer: D
28. 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: A
29. The air standard efficiency of an I.C. engine depends on
A. Fuel used
B. Speed of engine
C. Compression ratio
D. None of these
Answer: C
30. Alpha-methyl-naphthalene (C₁₁ H₁₀) has a cetane number of
A. 0
B. 50
C. 100
D. 120
Answer: A
31. The increase in intake temperature of internal combustion engines will _________
efficiency.
A. Have no effect on
B. Increase
C. Decrease
D. None of these
Answer: C
32. The thermal efficiency of a petrol engine is _________ as compared to diesel
engine.
A. Same
B. Less
C. More
D. None of these
Answer: B
33. The thermal efficiency of diesel engines is about
A. 15%
B. 30%
C. 50%
D. 70%
Answer: D
34. The ignition quality of diesel oil is expressed by
A. Cetane number
B. Octane number
C. Calorific value
D. None of these
Answer: A
35. If petrol is used in a diesel engine, then
A. Low power will be produced
B. Efficiency will be low
C. Higher knocking will occur
D. Black smoke will be produced
Answer: C
36. In a coil ignition system of petrol engines, a condenser is connected across the
contact breaker in order to
A. Prevent sparking across the gap between the points
B. Cause more rapid break of the primary current, giving a higher voltage in the
secondary circuit
C. Both (A) and (B)
D. None of the above
Answer: C
37. The _________ engines can work on very lean mixture of fuel.
A. Spark ignition
B. Compression ignition
C. Both (A) and (B)
D. None of these
Answer: B
38. A diesel engine, during suction stroke, draws
A. Air only
B. Diesel only
C. A mixture of diesel and air
D. None of these
Answer: A
39. Antiknock for compression ignition engines is
A. Napthene
B. Tetra ethyl lead
C. Amyl nitrate
D. Hexadecane
Answer: C
40. 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: A
41. The cetane number of diesel oil, generally available, is
A. 20 to 25
B. 25 to 30
C. 30 to 40
D. 40 to 55
Answer: D
42. A petrol engine has compression ratio from
A. 6 to 10
B. 10 to 15
C. 15 to 25
D. 25 to 40
Answer: A
43. The brake power is the power available
A. In the engine cylinder
B. At the crank shaft
C. At the crank pin
D. None of these
Answer: B
44. The normal heptane (C₇H₁₆) is given a rating of ________ octane number.
A. 0
B. 50
C. 100
D. 120
Answer: A
45. The knocking in diesel engines may be prevented by
A. Reducing the delay period
B. Raising the compression ratio
C. Increasing the inlet pressure of air
D. All of these
Answer: D
46. The air-fuel ratio of the petrol engine is controlled by
A. Carburetor
B. Injector
C. Governor
D. None of these
Answer: A
247. If the compression ratio in I.C. engine increases, then its thermal efficiency will
A. Decrease
B. Increase
C. Remain same
D. None of these
Answer: B
48. The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5
will be
A. 25%
B. 50%
C. 70%
D. 100%
Answer: B
49. The octane number of petrol, generally available, is
A. 20 to 40
B. 40 to 60
C. 60 to 80
D. 80 to 100
Answer: D
50. The object of supercharging the engine is
A. To reduce mass of the engine per brake power
B. To reduce space occupied by the engine
C. To increase the power output of an engine when greater power is required
D. All of the above
