1. Self Ignition temperature(SIT) of iso-octane fule(C8H18) is_________ than the SIT of n_heptane fuel(C7H16)
Correct : A. higher
2. autoignition in petrol engine means
Correct : C. ignition of mixture without flame front reaches to it
3. Abnormal combustion in SI engine relates to
Correct : B. rapid release of energy in some part of combustion chamber without flame front
4. Detonation in SI engines takes place when
Correct : D. both a and c
5. Detonation in SI engine may result into
Correct : D. all of the above
6. Pre-igntion can occur
Correct : B. petrol engine
7. A spark plug should be located at the
Correct : A. center of cylinder head
8. Use of two spark plugs in middle of cylinder head causes detonation tendancy to
Correct : B. reduce
9. Detonation in SI engine may be decreased by
Correct : D. all of the above
10. Increased load on engine may_______ the detonation in SI engine
Correct : A. increase
11. SI engines are
Correct : B. never over loaded
12. Which of the following factor decreases detonation in SI engines
Correct : D. fuels with high s. i.t.
13. To reduce detonation the charge away from spark plug should have
Correct : D. all of the above
14. Compression ratio in SI engine is kept lower than diesel engine
Correct : B. to avoid preignition
15. Slightly rich mixture (5 to 10%) will ______ knocking in SI engines
Correct : A. increase
16. A compact engine having design to promote turbulence will________ detonation tendancy
Correct : B. decrease
17. The objectives of SI engine design are
Correct : D. none of the above
18. The combustion chamber of S.I. Engine should have progressively reduced volume of charge from point of igintion
Correct : C. to reduce pressure rise of end gases
19. Exhaust valves of the SI engine should be
Correct : D. both a and b
20. Combustion chambers of SI engines are developed into hemispherical shapes since
Correct : D. both b and c
21. T-head combustion chambers used by ford in the past are not suitable for modern SI engines because
Correct : D. all of the above
22. Which factor in the design of combustion chamber to avoid knocking and detonation in SI engine is not applicable
Correct : A. long flame travel
23. Detonation and Knocking in SI engine can be controlled by
Correct : A. retarding the spark timing
24. A well designed combustion chamber of petrol engine is the one which has
Correct : C. high thermal output and efficiency
25. which is not applicable to Ricardo combustion chamber design
Correct : C. large mass of end charge
26. Modern SI engine use F head combustion chamber because of
Correct : D. all of the above
27. If n heptane in a mixture of iso octane and n-heptane by volume is 30%.Its octane rating is
Correct : B. 70
28. Iso octane in a fuel for petrol engine
Correct : A. reduces auto-ignition
29. To assign knock rating of fuels for SI engines the fuels are considered as
Correct : B. 2,2,4 trimethyl pentane and n-heptane
30. If a fuel for SI engine has high octane rating it shows that fuel has
Correct : D. higher ignition delay
31. Highest usefuel compression ratio relates to
Correct : C. the engine can be run without detonation
32. Petrol available in the market has octane rating as
Correct : C. 70 to 80
33. Ignition quality of SI engine fuels is expressed as
Correct : A. octane rating
34. HUCR represents the compression ratio at which
Correct : C. engine can run without detonation
35. Performance number gives rating of fuel with
Correct : D. octane number more than 100
36. Performance number=
Correct : D. knock limited imep of test fuel /knock limited imep of iso octane
37. Toluene and heptane are reference fuels used in
Correct : C. toluene rating
38. Performance number of iso-octane is
Correct : B. 100
39. The maximum compression ratio which can be used without knocking is
Correct : B. hucr
40. Ideal fuel for SI engine should have
Correct : B. high sit
41. Which is not true about L-head combution chamber?
Correct : A. high rate of combustion
42. Main drawback of T-head combution chamber is
Correct : D. permits less compression ratio
43. In T-head combution chamber, spark plug is located
Correct : C. near exhaust valve
44. Which is not true about I-head combution chamber?
Correct : B. non-uniform pressure rise
45. Main drawback of F-Head combution chamber is
Correct : D. difficult manufacturing
46. For petrol engine the method of governing is
Correct : C. quantity governing
47. Economizer is used to provide enriched mixture during
Correct : D. full throttle opening
48. When the throttle is suddenly opened, the mixture from the simple carburettor tends to become
Correct : B. lean
49. The choke in automobile carburettor system is meant for supplying
Correct : B. rich mixture
50. Modern carburettor provide the correct qaulity of air-fuel mixture during
Correct : D. all conditions
51. The essential conditions for combution are
i) The presence of combustible mixture
ii) Initiation by any means like spark plug is not required
iii) Stabilization and propagation of flame in the combution chamber
Out of these following is correct
Correct : B. i and iii
52. In the rich mixtures used for automobile applications……
Correct : A. fuel quantity is more than stoichiometric quantity
53. In the Lean mixtures used for automobile applications…..
Correct : B. air quantity is more than stoichiometric quantity
54. Stoichiometric air fuel ratio suggests…..
Correct : C. correct quantity of fuel-air ratio which gives complete combution
55. Practical limits of fuel air ratio for combution in SI engines is…..
Correct : A. 0.11 to 0.05
56. Practical limits for air fuel ratio in SI engines provides…..
Correct : B. range of air fuel ratio to get combustion close to stoichiometric conditions in si engine
57. Ignition limits in the SI engine depends upon….
Correct : A. mixture ratio and temperature
58. Maximum pressure obtained in normal SI engine during motoring is about…..
Correct : C. 8 bar
59. Pressure during motoring in SI engine compared to CI engine is….
Correct : A. less
60. Maximum pressure in SI engine is about…..
Correct : D. 30 bar
61. Approximate temperature produced by spark plug is…..
Correct : D. 10,000 deg.celsius
62. The preparation phase in SI engine will last for about…..
Correct : A. 20 deg. of crank rotation
63. The peak pressure in SI engine will be observed when crank position is….
Correct : B. about 10 deg. after tdc
64. The peak temperature in SI engine will be observed when crank position is….
Correct : B. about 10 deg. after tdc
65. On P.Ѳ. Diagram, start of second phase in the combustion of SI engine is indicated by….
Correct : D. separation of combustion curve from motoring curve
66. On P.Ѳ. Diagram, separation of combustion curve from motoring curve in SI engine takes place…
Correct : A. when crank angle is about 10 deg. before tdc
67. On P.Ѳ. Diagram, first measurable rise of pressure in SI engine takes place approximately….
Correct : B. when crank angle is about 10 deg. after tdc
68. Which phase of combustion takes place during expansion stroke…..
Correct : D. after burning
69. During propagation of flame in SI engine crank rotates by about….
Correct : A. 20 deg.
70. During afterburning phase in SI engine crank rotates by about…
Correct : C. 170 deg.
71. Gap size in spark plug electrodes in about….
Correct : B. 1 to 2 mm
72. As compared to level of fuel in float chamber, the carburettor nozzle opening is at……level
Correct : B. higher
73. SI engines in which diesel is used as a fuel will……
Correct : A. not run at all
74. If diesel is used in SI engine, it will not run. What is the correct reason?
Correct : C. less volatility
75. Performance number of SI engine fuel
Correct : B. relates to the fuels having octane number more than 100
76. The maximum resistance to detonation is by the fuel
Correct : A. iso octane
77. A dope or additive is a compound when added in fuel have an effect on
Correct : C. anti knock characteristic
78. Which of the following are dopes for SI engine fuels
Correct : D. all of the above
79. Addition of ethyl bromide in TEL helps in
Correct : C. prevents lead deposits
80. Now a days a unleaded petrol is in the market because
Correct : C. lead deposits are poisonous
81. Stoichiometric air-fuel ratio of petrol engine is roughly
Correct : C. 15/1
82. Venturi in the carburettor results in
Correct : B. increase of air velocity
83. The choke is closed when the engine is
Correct : C. cold
84. Lean air mixture is required during
Correct : D. cruising
85. The limits of air-fuel for SI engine are
Correct : A. 8/1 to 18/1
86. In a SI engine for maximum power, relative fuel-air ratio is
Correct : B. 1.2
87. For maximum thermal efficincy, the fuel-air ratio mixture in SI engines should be
Correct : A. lean
88. During starting petrol engines require
Correct : C. rich mixture
89. Economizer is used to provide enriched mixture during
Correct : D. full throttle opening
90. When the throttle is suddenly opened, the mixture from the simple carburettor tends to become
Correct : B. lean
91. Precise petrol injection system is
Correct : D. manifold or port injection system
92. The choke in automobile meant for supplying
Correct : B. rich mixture
93. Modern carburettor provide the correct quality of air-fuel mixture during
Correct : D. all conditions
94. A simple carburettor supplies rich mixture during
Correct : C. cruising
95. Combustion is defined as
Correct : A. chemical combination of hydrogen and carbon in the fuel and oxygen in the air
96. Combustion is defined as
Correct : C. both a and b
97. Favourable conditions for combustion are
Correct : D. all of the above
98. Favourable conditions for combustion are
Correct : D. both a and c
99. Favourable conditions for combustion are: 1. The presence of combustible mixture 2. Initiation by any means like spark plug is not required 3. Stabilization and propagation of flame in the combustion chamber. Out of these following is correct
Correct : B. i and iii
100. In the rich mixturers used for automobile applications
Correct : A. fuel quantity is more than stoichiometric quantity