## Applied Thermodynamics Multiple Choice Questions

1. Power available at output shaft is called
A. i.p.
B. b.p.
C. f.p.
D. unavailable power

2. Mechanical losses in engine equal to
A. b.p/i.p
B. i.p./b.p
C. i.p./b.p.
D. b.p./i.p

3. Best method to measure indicated mean effective pr (imep) is by
A. mechanical indicator
B. electronic indicator
C. electrical indicator
D. all are equal efficient

4. Indicator diagram is used to measure
A. imep
B. speed
C. temperature
D. f.p.

5. Aim of engine testing is
A. to get specified information
B. to justify rating of engine
C. to validate design data
D. all the above

6. Heat losses in an engine are indicative of
A. thermal efficiency of engine
B. indicated power
C. brake power
D. none of the above

Answer: A thermal efficiency of engine

7. Power developed within the cylinder is called
A. i.p.
B. b.p.
C. f.p.
D. unavailable power

8. Indicator diagram is the plot of_____on cartesian co-ordinates.
A. p-v
B. p-t
C. t-v
D. t-p

9. Mechanical indicators are suitable to measure imp in case of
A. low speed engine up to 1500 rpm
B. medium speed engines (1500-3000)
C. high speed engines more than 3000 rpm
D. none of the above

Answer: A low speed engine up to 1500 rpm

10. If a= net area of diagram in mm², l= length of indicator diagram in cm & k= spring constant in N/m²/m the imp in bar equals
A. (a/l)xk
B. (a/l) x k x 10ˉ⁹
C. (a/l) x k x 10ˉ⁶
D. (a/l) x k x 10ˉ³

Answer: B (a/l) x k x 10ˉ⁹

11. Engine indicator is used to measure
A. bmep
B. imep
C. b.p
D. i.p

12. If work developed by the engine per cycle is W, then the indicated mean effective pr equals to
A. w
B. w / stroke volume
C. w / length of stroke
D. w x stroke volume

Answer: B w / stroke volume

13. Best method to measurement of B.P. is
A. rope brake dynamometer
B. prony brake dynamometer
C. hydraulic dynamometer
D. all are equal

14. Which of the dynamometer cannot be used for measurement of B.P. at high speeds
A. prony brake
B. hydraulic
C. swing field
D. none of the above

15. Which of the following dynamometer is suitable to measure B.P. of an aircraft
A. prony brake
B. hydraulic
C. swinging field
D. eddy current

16. F.P.______with increase in speed
A. increases
B. remains same
C. decreases
D. can not say

17. Which is the best way to measure F.P. of an I.C., engine
A. willan\s line method
B. morse test
C. motoring test
D. all are the equal effective

18. Willan’s line method for determining F.P. is applicable to
A. c.i engines
B. engine runs at constant speed
C. both A & B
D. none of the above

Answer: C both A & B

19. I.P. of engine can be determined by
A. willan’s line method
B. morse test
C. motoring test
D. none of the above

20. Increase in F.P. of an engine causes
A. reduced b.p.
C. increased s.f.c.
D. all the above

21. Morse test in multi cylinder engine is used to determine
A. mechanical efficiency
B. thermal efficiency
C. air standard l efficiency
D. relative l efficiency

22. Which is assumed constant in determining F.P. by Willan’s line method.
A. mechanical efficiency
B. beake thermal efficiency
C. indicated thermal efficiency
D. none of the above

23. The range of mechanical efficiency for automobile is
A. 0-30%
B. 30-50%
C. 70-80%
D. 90-100%

24. The measurement of frictioned power by Willans line is applicable only to
A. c.i engine at a particualr speed
B. s.i engine at a particular speed
C. any engine at a particular speed only
D. none of the above

Answer: A c.i engine at a particualr speed

25. morse test is applicable only to
A. single cylinder c.i engines
B. single cylinder s.i engine
C. multi cylinder c.i engine
D. single and multi cylinder c.i and s.i engine

Answer: C multi cylinder c.i engine

26. the most accurate method of determining friction power is by
A. willins line
B. morse test
C. motoring test
D. measurement of brake and indicated power

Answer: D measurement of brake and indicated power

27. in the air base method of measuring air flow, the air base is provided to
A. damp out the pulsations
B. have constant temprature
C. have constant flow
D. provide constant velocity of flow

28. the air box/ swept volume ratio should be in the range for single cylinder engine
A. 10-100%
B. 200-300%
C. 500-600%
D. 10

29. the best method of measuring speed is by
A. mechanical tachometer
B. electric tachometer
C. magnetic pickup
D. none of the above

30. flame ionization detector is used for measuring
A. hc
B. co
C. nox
D. co2

31. chemilumme scence analyzer is used for measuring
A. hc
B. co
C. nox
D. co2

32. non dispersive infrared analyzer is widely accepted instrument for measuring
A. unburned hydrocarbons
B. carbone monoxide
C. carbone dioxide
D. nox

33. if n is theorem, number of power stroke per minute in a four stroke enigne is
A. n/2
B. n
C. 2n
D. 4n

34. if n is the rpm, number of power strokes per min in a two stroke engine is
A. n/2
B. n
C. 2n
D. 4n

35. mechanical effficiency is the ratio of
A. frictional power to brake power
B. frictional power to indicated power
C. brake power to indicated power
D. indicated power ot frictional power

Answer: C brake power to indicated power

36. volumetric efficiency is a measure of
A. power of the enigne
B. speed of the engine
C. brathing capacity of the engine
D. pressure rise in the cylinder

Answer: C brathing capacity of the engine

37. thermal efficiency varries
A. inversely as specific fuel consumption
B. directly as specific fuel consumption
C. as square as specific fuel consumption
D. as root as specific fuel consumption

Answer: A inversely as specific fuel consumption

38. the spark timing and combustion rate should be should be such that
A. one half of the total pressure occurs at tdc
B. ignition delay is reduced
C. peak pressure occurs at tdc
D. none of the above

Answer: A one half of the total pressure occurs at tdc

39. indicated power is directly proportional to
A. air consumption
B. torque
C. cylinder peak pressure
D. none of the above

40. the brake thermal efficiecny of SI engine is in the range of
A. 35%-60%
B. 25%-35%
C. 60%-80%
D. none of the above

41. the boiling point of a four cylinder engine is 30 with all cylinder firing and 20 with one cylindr cut
A. 0.6
B. 0.75
C. 0.8
D. none of the above

42. The bore and stroke of a single cylinder four stroke engine are 100 mm and 160 mm resp. if the brake torqe is 50NM, the brake mean effective pressure is
A. 5 bar
B. 7-6bar
C. 10bar
D. 15bar

43. the volumetric efficiecy of a well disigned engine is the
A. 30-40%
B. 40-60%
C. 60-70%
D. 75-90%

44. if the performance of SI engine manufacturer having different capacities sizes and system are to be compared , the common parameter would be
A. engine cylinder diameter
B. b.h.p
C. speed
D. mean effective pressure

45. mores test is conducted on
A. single cylinder c.i engines
B. multi cylinder engine
C. vcc engine
D. horizontle engine

46. endurance test for IC engine is conducted for
A. 100hrs
B. 200hrs
C. 400hrs
D. 500hrs

47. which of the following factor will not assist in improving thermal efficiency of a compression ignition engine
A. fine atomisation and even distribution of fuel
B. miniumum heat loss during combustion
C. clear exhaust
D. high surgace to volume ratio

Answer: D high surgace to volume ratio

48. which statement is correct
A. morese test can be conducted on petrol engine
B. morese test can be conducted on diesel engine
C. morese test can be conducted only on multicylinder engine
D. morese test can be conducted on crf engine

Answer: C morese test can be conducted only on multicylinder engine

49. rope brake dynamometer falls under the category of
A. hydraulic dynamometer
B. transmission type dynamometer
C. mechanical friction type dynamometer
D. torsion type dynamometer

Answer: C mechanical friction type dynamometer

50. prony brakes are used for testing
A. small engine
B. large capasity engine
C. highspeed engine
D. slow speed engine

51. which of the following is performed for supercharging of ic engine
A. roots blower
B. axial compressor
C. sliding vane type compressor
D. reciprocationg compressor

52. from the engine indicator diagram we obtain
A. indicatecd mean effective pressure
B. brake mean effective pressure
C. mechanical efficiency
D. relative efficiecy

Answer: A indicatecd mean effective pressure

53. the more accurate dynamometer is
A. prony brake type
B. hydraulic type prony
C. swinging field type
D. eddy current type

54. the most commonly used dynamometer on account of its simplicity of construction is the
A. brake type
B. hydraulic type prony
C. swinging field type
D. eddy current type

55. brake mean effective pressure in an engine depends upon its
A. speed only
B. torque only
C. speed and torque
D. speed and power

56. brake thermal efficiecny of si engine usually varies between
A. 25-30%
B. 30-60%
C. 60-80%
D. more then 80%

57. the brake power is the
A. power availabale at the output of the shaft
B. energy developed inside the cylinder block
C. energy lost dude to friction
D. none of the above

Answer: A power availabale at the output of the shaft

58. the total power developed by the combustion of the fuel is
A. bp
B. ip
C. fp
D. none of the above

59. mean effective pressure is the pressure
A. pressure acting on the crank shaft
B. which is acting on the piston through out the power stroke
C. pressure required to inject the fuel in the combustion chamber
D. none of the above

Answer: B which is acting on the piston through out the power stroke

60. fuel air ratio is
A. mass of fuel to mass of air
B. reciprocal of air fuel ratio
C. which affects the combustion phenomenon
D. all of the abov e

Answer: D all of the abov e

61. specific fuel consumption is
A. amount of fuel consumed per unit power developed per hour
B. amount of fuel consumed per unit indicated power developed per hour
C. amount of fuel consumed per hour
D. all of the above

Answer: A amount of fuel consumed per unit power developed per hour

62. heat balance sheet indicates
A. amount of heat energy consumed in the combustion chamber
B. brake up of the total energy input in to different parts
C. amount of energy lost through the exhaust
D. all of the above

Answer: B brake up of the total energy input in to different parts

63. the frictional power is
A. bp+ip
B. bp-ip
C. bpxip
D. none of the above

64. identify the correct statement
A. power friction means less brake power
B. lower friction means high barke power
C. higher friction means high brake power
D. none of the above

Answer: B lower friction means high barke power

65. power out put of an engine can be increased by
A. speed
B. compression ratio
C. use of two stroke cycle
D. all of the above

Answer: D all of the above

66. power out put of an engine can be increased by
A. speed
B. charge density
C. compression ratio
D. all of the above

Answer: D all of the above

67. increasing the power out put by increasing the compression ratio is limited by
A. weight to power ratio
B. utilization of energy in fuel
C. air fuel ratio
D. hucr

68. increase in speed to improve B.P is limited by
A. maximum volumetric efficienccy
B. robust engine
C. fuel suply
D. all of the above

Answer: D all of the above

69. utilization of energy in exhaust gases causes power output to
A. increases
B. remains same
C. decreases
D. can not say

70. increase in charge density will
A. increases volumetric efficiency
B. power out put
C. both a & b
D. none of the above

Answer: C both a & b

71. supercharging is a process of increasing the
A. pressure in the cylinder
B. suction pressure of charge
C. temprature of the charge
D. charge density

72. supercharging is essential for
A. stationary engine
B. marine engine
C. aircraft engine
D. none of the above

73. power out put of static engine at high alitude compared to power out put at sea level is
A. higher
B. lower
C. same
D. can not predict

74. objective of superchargin are
A. increase power output
B. reduces weight to power ratio
C. compansate loss of power at high altitudes
D. all of the above

Answer: D all of the above

75. which is not the objectve of supercharging
A. to increase power out put
B. to increase weight to power ratio
C. to increase charge density at high alitude
D. none of the above

Answer: B to increase weight to power ratio

76. an exhaust gas driven blower/ compressor to increase charge density is called
A. supercharger
B. turbocharger
C. both a & b
D. none of the above

Answer: D none of the above

77. a blower/compressor driven by engine shaft to increase charge density is called
A. supercharger
B. turbocharger
C. both a & b
D. none of the above

Answer: D none of the above

78. power out put of an engine compared to turbocharge is
A. more
B. same
C. less
D. can not say

79. which is not a supercharger
A. centrifugal compressor
B. root blower
C. vane blower
D. pump

80. compressed air of turbochar is cooled in aftercooler before supply to engine because it
A. reduceses density of air
B. increases volumetric efficiency
C. increases density of air
D. both b and c

Answer: D both b and c

81. efficiency of turbocharged engine compared to naturally aspirated engine is
A. more
B. same
C. less
D. can not predict

82. a free piston engine has
A. gear driven supercharger
B. a turbocharger
C. coupled engine, compressor and turbine supercharge
D. gear driven supercharger and separate power turbine

Answer: D gear driven supercharger and separate power turbine

83. Reason for not using very high suction pressure in an engine with the help of supercharger / turbocharger are
A. increased weight
B. increased detonation in si engine
C. increased fp and bearing load
D. all of the above

Answer: D all of the above

84. Reason for not using very high suction pressure in an engine with the help of supercharger / turbocharger are
A. high mean wall and exhaust gas temprature
B. increased detonation in si engine
C. increased weight
D. all of the above

Answer: D all of the above

85. superchargin is usually is not employed in si engine in the following cases
A. static or mobile enigne
B. static engine at high altitude
C. aero enignes at the time of take off
D. none of the above

Answer: A static or mobile enigne

86. superchargin in ci engine is limited by
A. peak pressure and temprature in cylinder
B. mean cylinder wall tempratuer
C. load on bearing and fuel economy
D. all of the above

87. A theory in which chain carriers are formed in one step and destroyed in the next step relate to the theory of combustion as
A. preferencial burning of carbon
B. chain reaction theory
C. hydroxylation theory
D. none of the above

88. Time interval between instant the spark is given and the point a tiny flame appears is called
A. igniton lag
B. ignition delay period
C. ignition delay angle
D. either \a\ or b\

Answer: D either \a\ or b\

89. Angle tuned by crank between the point of spark and formation of flame is called
A. igniton lag
B. ignition delay period
C. ignition delay angle
D. either \a\ or b\

90. In a vertical engine, the crank angle before TDC at the instant spark is given is called
A. igniton lag
B. ignition delay period
C. ignition delay angle

91. The travel of flame speed (m/s) in the S.I. combustion chamber is approximately
A. 5 to 15
B. 15 to 35
C. 35 to 50
D. > 50

92. Ignition lag in S.I. engine reduces due to
A. increase in pressure,temperature and compression ratio
B. decrease in pressure,temperature and compression ratio
C. decrease in residual gases
D. both a and c

Answer: D both a and c

93. Minimum ignition lag is obtained when
A. rich mixture(5 to 10%)
B. stoichiometric mixture
C. lean mixture
D. very rich mixture(15 to 30%)

Answer: A rich mixture(5 to 10%)

94. Ignition delay period with increase in speed
A. increases
B. decreases
C. remains same
D. none of the above

95. Ignition delay angle________with increase in speed
A. increases
B. decreases
C. remains same
D. none of the above

96. The speed of the flame propagation increases with increase in
A. compression ratio
B. suction pressure and temperatur
C. slightly rich mixtures
D. all of the above

Answer: D all of the above

97. Increase in turbulence________the flame speeds
A. increases
B. decreases
C. doesn\t affect
D. none of the above

98. Increase in speed of the engine________the flame speeds
A. increases
B. decreases
C. doesn\t affect
D. none of the above

99. Increase in the size of similar engines__________the crank angle turned during flame travel across the cylinder
A. increases
B. decreases
C. doesn\t affect
D. none of the above

100. Flame speed in combustion chamber during flame travel are
A. high at beginning and at the end whereas low in the middle
B. low at beginning and end and high in the middle
C. constant throught
D. cannot predict

Answer: B low at beginning and end and high in the middle

101. Self Ignition temperature(SIT) of iso-octane fule(C8H18) is_________ than the SIT of n_heptane fuel(C7H16)
A. higher
B. lower
C. same
D. cannot predict

102. autoignition in petrol engine means
A. ignition of fuel due to spark
B. ignition of mixture at the end of compression stroke
C. ignition of mixture without flame front reaches to it
D. none of the above

Answer: C ignition of mixture without flame front reaches to it

103. Abnormal combustion in SI engine relates to
A. rapid and uniform rate of pressure rise due to combustion
B. rapid release of energy in some part of combustion chamber without flame front
C. both a and b
D. none of the above

Answer: B rapid release of energy in some part of combustion chamber without flame front

104. Detonation in SI engines takes place when
A. end part of charges reaches to sit and its delay period is over
B. the flame front reaches to end of the part of the charge
C. the flame front doesn\t reach to end part of the charge
D. both a and c

Answer: D both a and c

105. Detonation in SI engine may result into
A. loss of the power and efficiency
B. pre-ignition
C. failure of spark plug
D. all of the above

Answer: D all of the above

106. Pre-igntion can occur
A. diesel engine
B. petrol engine
C. both in petrol and diesel engines
D. none of the above

107. A spark plug should be located at the
B. near the inlet valve
C. near the exhaust valve
D. none of the above

108. Use of two spark plugs in middle of cylinder head causes detonation tendancy to
A. increases
B. reduce
C. remains same
D. none of the above

109. Detonation in SI engine may be decreased by
A. reduction in suction pressure and temperature
B. reducing cr
C. reduction in coolant temperature
D. all of the above

Answer: D all of the above

110. Increased load on engine may_______ the detonation in SI engine
A. increase
B. decrease
C. have no effect
D. none of the above

111. SI engines are
C. both a and b
D. it does not matter

112. Which of the following factor decreases detonation in SI engines
A. increased cr
C. larger sized engine
D. fuels with high s. i.t.

Answer: D fuels with high s. i.t.

113. To reduce detonation the charge away from spark plug should have
A. low density
B. high ignition delay period
C. lean mixture
D. all of the above

Answer: D all of the above

114. Compression ratio in SI engine is kept lower than diesel engine
A. to reduce its weight
B. to avoid preignition
C. to improve its thermal efficiency
D. none of the above

115. Slightly rich mixture (5 to 10%) will ______ knocking in SI engines
A. increase
B. decrease
C. have no effect
D. none of the above

116. A compact engine having design to promote turbulence will________ detonation tendancy
A. increase
B. decrease
C. have no effect
D. none of the above

117. The objectives of SI engine design are
A. high length of flame travel
B. low speed of the flame travel
C. high surface area to volume
D. none of the above

Answer: D none of the above

118. The combustion chamber of S.I. Engine should have progressively reduced volume of charge from point of igintion
A. to increase rate of combustion
B. to improve power output
C. to reduce pressure rise of end gases
D. none of the above

Answer: C to reduce pressure rise of end gases

119. Exhaust valves of the SI engine should be
A. kept away from the end charge of the mixture
B. cooled by water jacket
C. kept near from the end charge of the mixture
D. both a and b

Answer: D both a and b

120. Combustion chambers of SI engines are developed into hemispherical shapes since
A. it has better appearance
B. reduce length of flame travel
C. reduces heat losses
D. both b and c

Answer: D both b and c

121. T-head combustion chambers used by ford in the past are not suitable for modern SI engines because
A. needs two cam shafts to operate each valve
B. has long flame travel
C. high surface to volume ratio
D. all of the above

Answer: D all of the above

122. Which factor in the design of combustion chamber to avoid knocking and detonation in SI engine is not applicable
A. long flame travel
B. exhaust valves away from end gas
C. cooling of exhaust valve
D. small bore

123. Detonation and Knocking in SI engine can be controlled by
A. retarding the spark timing
B. reduction in speed
C. increase in surface to volume ratio
D. none of the above

Answer: A retarding the spark timing

124. A well designed combustion chamber of petrol engine is the one which has
A. low volumetric efficiency
B. high compression ratio
C. high thermal output and efficiency
D. none of the above

Answer: C high thermal output and efficiency

125. which is not applicable to Ricardo combustion chamber design
A. provides high turbulence
B. reduce length of travel
C. large mass of end charge

Answer: C large mass of end charge

126. Modern SI engine use F head combustion chamber because of
A. provides high turbulence
B. provides shorter flame travel
C. low surface to volume ratio
D. all of the above

Answer: D all of the above

127. If n heptane in a mixture of iso octane and n-heptane by volume is 30%.Its octane rating is
A. 30
B. 70
C. 50
D. none of the above

128. Iso octane in a fuel for petrol engine
A. reduces auto-ignition
B. promotes auto-ignition
C. has no effect on autoignition
D. none of the above

129. To assign knock rating of fuels for SI engines the fuels are considered as
A. alpha methyl napthelene and iso-octane
B. 2,2,4 trimethyl pentane and n-heptane
C. alpha- methyl napthelene and n-heptane
D. none of the above

Answer: B 2,2,4 trimethyl pentane and n-heptane

130. If a fuel for SI engine has high octane rating it shows that fuel has
A. high volatility of fuel
B. high calorific value
C. lower ignition delay
D. higher ignition delay

131. Highest usefuel compression ratio relates to
A. maximum power
B. maximum efficiency
C. the engine can be run without detonation
D. none of the above

Answer: C the engine can be run without detonation

132. Petrol available in the market has octane rating as
A. 40 to 50
B. 51 to 75
C. 70 to 80
D. 86 to 100

133. Ignition quality of SI engine fuels is expressed as
A. octane rating
B. volatility rating
C. api gravity rating
D. none of the above

134. HUCR represents the compression ratio at which
A. power output
B. fuel comsumption is minimum
C. engine can run without detonation
D. none of the above

Answer: C engine can run without detonation

135. Performance number gives rating of fuel with
A. octane number less than 1
B. octane number more than 1
C. octane number less than 100
D. octane number more than 100

Answer: D octane number more than 100

136. Performance number=
A. knock limited imep of test fuel – knock limited imep of iso octane
B. knock limited imep of test fuel + knock limited imep of iso octane
C. knock limited imep of test fuel x knock limited imep of iso octane
D. knock limited imep of test fuel /knock limited imep of iso octane

Answer: D knock limited imep of test fuel /knock limited imep of iso octane

137. Toluene and heptane are reference fuels used in
A. octane rating
B. heptane rating
C. toluene rating
D. d.n.rating

138. Performance number of iso-octane is
A. 1
B. 100
C. zero
D. 50

139. The maximum compression ratio which can be used without knocking is
A. hcr
B. hucr
C. pn
D. on

140. Ideal fuel for SI engine should have
A. low sit
B. high sit
C. low cv
D. less volatility

A. high rate of combustion
B. more tendency to detonate
C. permits low compression ratio
D. requires less maintenance

Answer: A high rate of combustion

142. Main drawback of T-head combution chamber is
A. more maintenance
B. permits more compression ratio
C. more flame travel
D. permits less compression ratio

Answer: D permits less compression ratio

143. In T-head combution chamber, spark plug is located
A. near intake valve
B. centrally
C. near exhaust valve
D. near injector

A. higher volumetric efficiency
B. non-uniform pressure rise
C. permits higher compression ratio
D. less flame travel

145. Main drawback of F-Head combution chamber is
A. improper positioning of spark plug
B. more knocking tendency
C. less efficiency
D. difficult manufacturing

146. For petrol engine the method of governing is
A. hit and miss governing
B. quality governing
C. quantity governing
D. none of the above

147. Economizer is used to provide enriched mixture during
A. starting
B. idling
C. cruising
D. full throttle opening

148. When the throttle is suddenly opened, the mixture from the simple carburettor tends to become
A. rich
B. lean
C. stoichiometric
D. not affected

149. The choke in automobile carburettor system is meant for supplying
A. lean mixture
B. rich mixture
C. stoichiometric mixture
D. weak mixture

150. Modern carburettor provide the correct qaulity of air-fuel mixture during
A. starting
B. idling
C. cruising
D. all conditions

151. 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
A. all correct
B. i and iii
C. ii and iii
D. i and ii

152. In the rich mixtures used for automobile applications……
A. fuel quantity is more than stoichiometric quantity
B. air quantity is more than stoichiometric quantity
C. both the quantities are same
D. fuel quantity is more than the air quantity

Answer: A fuel quantity is more than stoichiometric quantity

153. In the Lean mixtures used for automobile applications…..
A. fuel quantity is more than stoichiometric quantity
B. air quantity is more than stoichiometric quantity
C. both quantities are same
D. fuel quantity is more than the air quantity

Answer: B air quantity is more than stoichiometric quantity

154. Stoichiometric air fuel ratio suggests…..
A. correct quantity of fuel-air ratio which gives more economy
B. correct quantity of fuel-air ratio which gives more power
C. correct quantity of fuel-air ratio which gives complete combution
D. all of the above

Answer: C correct quantity of fuel-air ratio which gives complete combution

155. Practical limits of fuel air ratio for combution in SI engines is…..
A. 0.11 to 0.05
B. 0.2 to 0.1
C. 0.05 to 0.033
D. 0.2 to 0.033

156. Practical limits for air fuel ratio in SI engines provides…..
A. range of air fuel ratio which gives comfortable working of si engine
B. range of air fuel ratio to get combustion close to stoichiometric conditions in si engine
C. range of air fuel ratio for obtaining maximum power in si engine
D. all of the above

Answer: B range of air fuel ratio to get combustion close to stoichiometric conditions in si engine

157. Ignition limits in the SI engine depends upon….
A. mixture ratio and temperature
B. volumetric efficiency and temperature
C. engine size and volumetric efficiency
D. mixture ratio and engine size

Answer: A mixture ratio and temperature

158. Maximum pressure obtained in normal SI engine during motoring is about…..
A. 2 bar
B. 15 bar
C. 8 bar
D. 40 bar

159. Pressure during motoring in SI engine compared to CI engine is….
A. less
B. more
C. same
D. none of the above

160. Maximum pressure in SI engine is about…..
A. 10 bar
B. 70 bar
C. 50 bar
D. 30 bar

161. Approximate temperature produced by spark plug is…..
A. 5,000 deg.celsius
B. 20,000 deg.celsius
C. 2,000 deg.celsius
D. 10,000 deg.celsius

162. The preparation phase in SI engine will last for about…..
A. 20 deg. of crank rotation
B. 40 deg. of crank rotation
C. 30 deg. of crank rotation
D. 10 deg. of crank rotation

Answer: A 20 deg. of crank rotation

163. The peak pressure in SI engine will be observed when crank position is….
A. about 10 deg. before tdc
B. about 10 deg. after tdc
C. at tdc
D. at bdc

164. The peak temperature in SI engine will be observed when crank position is….
A. about 10 deg. before tdc
B. about 10 deg. after tdc
C. at tdc
D. at bdc

165. On P.Ѳ. Diagram, start of second phase in the combustion of SI engine is indicated by….
A. separation of velocity line from compression line
B. constant pressure
C. fall of pressure
D. separation of combustion curve from motoring curve

Answer: D separation of combustion curve from motoring curve

166. On P.Ѳ. Diagram, separation of combustion curve from motoring curve in SI engine takes place…
A. when crank angle is about 10 deg. before tdc
B. when crank angle is about 10 deg. after tdc
C. when crank angle is about 10 deg. before bdc
D. when crank angle is about 10 deg. after bdc

167. On P.Ѳ. Diagram, first measurable rise of pressure in SI engine takes place approximately….
A. when crank angle is about 10 deg. before tdc
B. when crank angle is about 10 deg. after tdc
C. when crank angle is about 10 deg. before bdc
D. when crank angle is about 10 deg. after bdc

168. Which phase of combustion takes place during expansion stroke…..
A. ignition lag
B. preparation phase
C. propagation of flame
D. after burning

169. During propagation of flame in SI engine crank rotates by about….
A. 20 deg.
B. 40 deg.
C. 30 deg.
D. 10 deg.

170. During afterburning phase in SI engine crank rotates by about…
A. 20 deg.
B. 190 deg.
C. 170 deg.
D. 10 deg.

171. Gap size in spark plug electrodes in about….
A. 10 to 20 mm
B. 1 to 2 mm
C. 0.01 mm to 0.1 mm
D. none of the above

Answer: B 1 to 2 mm

172. As compared to level of fuel in float chamber, the carburettor nozzle opening is at……level
A. same
B. higher
C. lower
D. fluctuating

173. SI engines in which diesel is used as a fuel will……
A. not run at all
B. run with detonation
C. run normally
D. run with less efficiency

Answer: A not run at all

174. If diesel is used in SI engine, it will not run. What is the correct reason?
A. low compression ratio
B. more density
C. less volatility
D. low burning point

175. Performance number of SI engine fuel
A. corresponds to octane rating
B. relates to the fuels having octane number more than 100
C. either a or b
D. none of the above

Answer: B relates to the fuels having octane number more than 100

176. The maximum resistance to detonation is by the fuel
A. iso octane
B. n heptane
C. alpha methyl nonane
D. cetane

177. A dope or additive is a compound when added in fuel have an effect on
A. decreasing compression ratio
B. increasing self ignition temperature
C. anti knock characteristic
D. none of the above

178. Which of the following are dopes for SI engine fuels
A. tel
B. tml
C. phenol
D. all of the above

Answer: D all of the above

179. Addition of ethyl bromide in TEL helps in
A. improving anti knock characteristics
B. reducing anti knock characteristics
D. none of the above

180. Now a days a unleaded petrol is in the market because
A. it has better anti knock property
B. it is cheaper as compared to leaded petrol
D. it is highly refined petrol

181. Stoichiometric air-fuel ratio of petrol engine is roughly
A. 18/1
B. 25/1
C. 15/1
D. 10/1

182. Venturi in the carburettor results in
A. decrease of air velocity
B. increase of air velocity
C. decrease of fuel flow
D. increase of manifold vacuum

Answer: B increase of air velocity

183. The choke is closed when the engine is
A. accelerating
B. hot
C. cold
D. idling

184. Lean air mixture is required during
A. idling
B. starting
C. accelerating
D. cruising

185. The limits of air-fuel for SI engine are
A. 8/1 to 18/1
B. 8/1 to 50/1
C. 25/1 to 50/1
D. 50/1 to 100/1

186. In a SI engine for maximum power, relative fuel-air ratio is
A. 1.5
B. 1.2
C. 0.8
D. 0.6

187. For maximum thermal efficincy, the fuel-air ratio mixture in SI engines should be
A. lean
B. rich
C. stoichiometric
D. may be lean or rich

188. During starting petrol engines require
A. stoichiometric mixture
B. lean mixture
C. rich mixture
D. any air-fuel ratio is alright

189. Economizer is used to provide enriched mixture during
A. starting
B. idling
C. cruising
D. full throttle opening

190. When the throttle is suddenly opened, the mixture from the simple carburettor tends to become
A. rich
B. lean
C. stoichiometric
D. not affected

191. Precise petrol injection system is
A. direct injection
B. sequential injection
C. both
D. manifold or port injection system

Answer: D manifold or port injection system

192. The choke in automobile meant for supplying
A. lean mixture
B. rich mixture
C. stoichiometric mixture
D. weak mixture

193. Modern carburettor provide the correct quality of air-fuel mixture during
A. starting
B. idling
C. cruising
D. all conditions

194. A simple carburettor supplies rich mixture during
A. starting
B. idling
C. cruising
D. acceleration

195. Combustion is defined as
A. chemical combination of hydrogen and carbon in the fuel and oxygen in the air
B. chemical combination of hydrogen and carbon in the fuel and nitrogen in the air
C. chemical combination of hydrogen and carbon in the fuel and both oxygen and nitrogen in the air.
D. all the above.

Answer: A chemical combination of hydrogen and carbon in the fuel and oxygen in the air

196. Combustion is defined as
A. rapid oxidation to liberate energy in the form of heat
B. its a chemical reaction of contents of fuel and oxygen in the air to produce energy in the form of heat.
C. both a and b
D. only a

Answer: C both a and b

197. Favourable conditions for combustion are
A. the presence of combustible mixture
B. some means of initiation of combustion
C. stabilization and propagation of flame in the combustion chamber
D. all of the above

Answer: D all of the above

198. Favourable conditions for combustion are
A. the presence of combustible mixture
B. initiation by any means like spark plug is not required
C. stabilization and propagation of flame in the combustion chamber
D. both a and c

Answer: D both a and c

199. 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
A. all are correct
B. i and iii
C. ii and iii
D. i and ii

200. In the rich mixturers used for automobile applications
A. fuel quantity is more than stoichiometric quantity
B. air quantity is more than stoichiometric quantity
C. both the quantities are same
D. fuel quantity is more than the air quantity.

Answer: A fuel quantity is more than stoichiometric quantity

201. In the Lean mixturers used for automobile applications
A. fuel quantity is more than stoichiometric quantity
B. air quantity is more than stoichiometric quantity
C. both the quantities are same
D. fuel quantity is more than the air quantity.

Answer: B air quantity is more than stoichiometric quantity

202. Stoichiometric air fuel ratio suggests
A. correct quantity of fuel -air ratio which gives more economy
B. correct quantity of fuel -air ratio which gives more power
C. correct quantity of fuel -air ratio which gives complete combustion
D. all of the above

Answer: C correct quantity of fuel -air ratio which gives complete combustion

203. Practical limits of air fuel ratio for combution in SI engines is
A. 9 to 21
B. 5 to 10
C. 20 to 30
D. 5 to 30

204. Practical limits of fuel air ratio for combution in SI engines is
A. 0.11 to 0.05
B. 0.2 to 0.1
C. 0.05 to 0.033
D. 0.2 to 0.033

205. Practical limits for air fuel ratio in SI engines provides
A. range of air fuel ratio which gives comfortable working of si engine
B. range of air fuel ratio to get combustion close to stochiometric conditions in si engine
C. range of air fuel ratio for obtaining maximum power in si engine
D. all of the above

Answer: B range of air fuel ratio to get combustion close to stochiometric conditions in si engine

206. SI engine is also called as
A. petrol engine
B. gasoline engine
C. spark ignition engine
D. all of the above

Answer: D all of the above

207. SI engine is also called as
A. auto ignition engine
B. compression ignition engine
C. otto engine
D. diesel engine

208. Ignition limits in the SI engine depends upon
A. mixture ratio and temperature
B. volumetric efficiency and temperature
C. engine size and volumetric efficiency
D. mixture ratio and engine size

Answer: A mixture ratio and temperature

209. Correct sequence of combustion stages in SI engine is
A. propagation of phase,ignition phase and after burning
B. preparation phase,propagation of flame and after burning
C. propagation of phase,preparation phase and after burning
D. after burning,propagation of phase and preparation phase

Answer: B preparation phase,propagation of flame and after burning

210. Maximum pressure pobtained in SI engine duering motoring is about
A. 2 bar
B. 15 bar
C. 8 bar
D. 40 bar

211. Pressure during motoring in SI engine compared to CI engine is
A. less
B. more
C. same
D. none of the above

212. Maximum pressure in SI engine is about
A. 10 bar
B. 70 bar
C. 50 bar
D. 30 bar

213. SI engine contains homogeneous mixture of
A. only vaporized fuel and oxygen
B. fuel and air
C. vaporized fuel,air and residual gases
D. vaporized fuel,oxygen and residual gases

Answer: C vaporized fuel,air and residual gases

214. Approximate tempearture between electrodes of spark plug is
A. 5,000 deg. celsius
B. 20,000 deg. celsius
C. 2,000 deg. celsius
D. 10,000 deg. celsius

215. Flame advancement from the start of formation of first nucleus of combustion depends on
A. temperature of flame front itself, density of surrounding mixture and temperature inside of cylinder.
B. only temperature of flame front itself,
C. temperature of flame front itself and density of surrounding mixture
D. only pressure and temperature inside cylinder

Answer: A temperature of flame front itself, density of surrounding mixture and temperature inside of cylinder.

216. The preparation phase in SI engine will take about
A. 20 deg. of crank angle
B. 40 deg of crank angle
C. 30 deg. of crank angle
D. 10 deg. of crank angle

Answer: A 20 deg. of crank angle

217. The peak pressure in SI engine will be observed when crank angle is
A. about 10 deg. before tdc
B. about 10 deg. after tdc
C. at tdc
D. at bdc

218. The first phase of combustion in SI engine is named as
A. ignition lag
B. preparation phase
C. both a and b
D. none of the above

Answer: C both a and b

219. In the ignition lag phase of SI engine following things happens
A. growth and development of semi propagating nucleus of flame.
B. its just temperature rise phase
C. its just pressure rise phase.
D. all of the above

Answer: A growth and development of semi propagating nucleus of flame.

220. Ignition lag in SI engine depends on following parameters
A. only b
B. nature of fuel,pressure and temperature
C. temperature coefficient, proportion of exhaust gases
D. both b and c

Answer: D both b and c

221. Temperature Coeficient of the fuel is
A. relation between temperature ,the rate of acceleration of oxidation or burning and pressure
B. relation between temperature and the rate of acceleration of oxidation or burning.
C. relation between temperature and the rate of acceleration of oxidation or burning.
D. relation between temperature and pressure.

Answer: B relation between temperature and the rate of acceleration of oxidation or burning.

222. Ignition lag phase is also
A. mechanical process
B. mechanical and chemical process
C. chemical process
D. none of the above

223. Start of second phase in the combustion of SI engine is indicated by
A. separation of velocity line from compression line on p-Ө diagram.
B. constant pressure on p-Ө diagram.
C. fall of pressure p-Ө diagram.
D. separation of combustion curve from motoring curve on p-Ө diagram.

Answer: D separation of combustion curve from motoring curve on p-Ө diagram.

224. Separation of combustion curve from motoring curve in SI engine takes place
A. when crank angle is about 10 deg. before tdc
B. when crank angle is about 10 deg. after tdc
C. when crank angle is about 10 deg. before bdc
D. when crank angle is about 10 deg. after bdc

225. First measurable rise of pressure in SI engine takes place approximately
A. when crank angle is about 10 deg. after tdc
B. when crank angle is about 10 deg. before tdc
C. when crank angle is about 10 deg. before bdc
D. when crank angle is about 10 deg. after bdc

226. Maximum heat energy is liberated during
A. ignition lag
B. preparation phase
C. propagation of flame
D. after burning

227. Which phase of combustion takes place during expansion stroke
A. ignition lag
B. preparation phase
C. propagation of flame
D. after burning

228. During propagatuion of flame in SI engine crank rotates by about
A. 20 deg.
B. 40 deg.
C. 30 deg.
D. 10 deg.

229. During afterburning phase in SI engine crank rotates by about
A. 20 deg.
B. 190 deg.
C. 170 deg.
D. 10 deg.

230. During combustion in SI engine heat is liberated due to reassociation of molecules in
A. ignition lag
B. preparation phase
C. propagation of flame
D. after burning

231. Gap size in spark plug electrodes is about
A. 10 to 20mm
B. 1 to 2 mm
C. 0.01 mm to 0.1 mm
D. none of the above

Answer: B 1 to 2 mm

232. A-fuel mixture in the SI engine is prepared
A. in the clearance volume in cylinder of engine
B. can be prepared anywhere outside the cylinder
C. prepared in the carburetor outside the cylinder
D. prepared in the carburetor inside the cylinder

Answer: C prepared in the carburetor outside the cylinder

233. Volatility property of the fluid helps in
A. increasing vaporization of fuel
B. decreasing vaporization of fuel
C. can increase or decrease vaporization
D. none of the above

Answer: C can increase or decrease vaporization

234. During combustible mixture preparation process fuel droplets are vaporized in
A. carburetor
B. carburetor and intake manifold
C. carburetor, intake manifold and cylinder
D. all of the above

Answer: C carburetor, intake manifold and cylinder

235. Maximum fuel economy occurs on the side of following air fuel ratio
A. small value of air-fuel ratio
B. large value of air-fuel ratio
C. depends on the working condition of si engine
D. none of the above

Answer: B large value of air-fuel ratio

236. The important factors which significantly affects process of carburetion are
A. time available for preparation of mixture
B. the temperature of intake air in the intake manifold
C. design of the induction system and combustion chamber
D. all of the above

Answer: D all of the above

237. The important factors which significantly affects process of carburetion are
A. time available for preparation of mixture
B. the temperature of exhaust gases in the exhaust manifold
C. design of the induction system and combustion chamber
D. both a and d

Answer: D both a and d

238. For high speed S I engines following things occurs
A. less time available for mixture preparation
B. more time available for mixture preparation
C. it varies with fuel properties
D. all of the above

Answer: A less time available for mixture preparation

239. Volatility of the fuel affects following processes in S I engine
A. mixing of fuel with air
B. vaporization and distribution of fuel
C. both a and b
D. none of the above

Answer: C both a and b

240. Stoichiometric condition in S I Engine is such that
A. it creates some pollutants with combustion of fuel and air mixture
B. it gives complete combustion of the air fuel mixture
C. exact quantity of the air is mixed with fuel to burn mixture effectively
D. both b and c

Answer: D both b and c

241. When SI engine is Idling
A. leaner mixture is required
B. mixture close to stoichiometric condition is needed
C. richer mixture is required
D. it may vary with atmospheric condition

Answer: C richer mixture is required

242. Idling condition of the SI engine is
A. when engine is running but no power out put from crank shaft
B. when engine is running but power is produced from crankshaft
C. when engine is not running but power out put from crank shaft
D. only crankshaft is rotating

Answer: A when engine is running but no power out put from crank shaft

243. When SI Engine is idling mixture enrichment is done
A. to produce maximum power which is required during idling.
B. for compensating diluted mixture in the cylinder because of exhaust gases in the cylinder which remains in previous stroke.
C. both a and b
D. none of the above

Answer: B for compensating diluted mixture in the cylinder because of exhaust gases in the cylinder which remains in previous stroke.

244. For full load on S I engine following changes should be made in mixture prparation
A. mixture should be prepared with fuel quantity increased
B. mixture should be prepared with fuel quantity decreased
C. mixture should be prepared with fuel and air quantity decreased
D. mixture should be prepared with fuel and air quantity increased

Answer: A mixture should be prepared with fuel quantity increased

245. During cruising of S I engine
A. richer mixture is required
B. leaner mixture is required
C. both of the above
D. nothing is right

Answer: B leaner mixture is required

246. With increasing Air-Fuel ratio in S I engine Maximum power
A. increases in the leaner region of the mixture
B. decreases in the richer region of the mixture
C. first increases up to a point at which maximum power is obtained and then it is decreases on the leaner side of the mixture
D. all of the above

Answer: C first increases up to a point at which maximum power is obtained and then it is decreases on the leaner side of the mixture

247. Maximum efficiency from the S I engine can be obtained
A. at any air fuel ratio
B. depends on working condition of the engine
C. leaner mixture region compared to stoichiometric conditions
D. in the region of richer air-fuel ratio compared to stoichiometric conditions

Answer: D in the region of richer air-fuel ratio compared to stoichiometric conditions

248. Fuel economy from the engine can be expected
A. when engine is running at normal speed
B. when engine is running at very very low speed
C. when engine is running at high speed
D. when engine is running at very very high speed

Answer: A when engine is running at normal speed

249. Fuel economy should not be expected in SI engine for which following cases
A. when vehicle is climbing on hills
B. when engine is pulling large quantity water from well
C. both a and b
D. only a

Answer: C both a and b

250. Cruising speed of S I engine is
A. high speed working condition of an engine
B. normal working condition of an engine
C. full load working condition of an engine
D. all of the above

Answer: B normal working condition of an engine

251. For Full throttle valve opened condition of an S I engine
A. we get less brake horse power
B. we get only required brake horse power
C. brake horse power is changing
D. we get maximum brake horse power

Answer: D we get maximum brake horse power

252. Air-fuel mixture required for condition of best fuel economy and maximum power is
A. same at all working conditions of an engine
B. same at a region close to stoichiometric conditions
C. is different at all working conditions of an engine
D. none of the above

Answer: D none of the above

253. For proper working of S I engine, I . There is always combustible range II. No proper combustible range can be decided III. Richer mixture is always prepared IV. Leaner mixture is always prepared
A. statements i, ii and iii are correct
B. statement ii is correct
C. statement i is correct
D. all statements are correct

Answer: C statement i is correct

254. For producing maximum power excess fuel burning leads to
A. incomplete combustion
B. more co is formed
C. more co2 is formed
D. both a and b

Answer: D both a and b

255. Carburator is used to
A. meter air-fuel quantity
B. increase air-fuel quantity
C. decrease air-fuel quantity
D. mix air-fuel.

256. Carburetor is designed
A. to get easy combustion in engine
B. to meter the liquid quantity to prepare the required air-fuel mixture which varies with load on engine
C. it supporting device in piping
D. it is a acting as a fuel and air mixer

Answer: B to meter the liquid quantity to prepare the required air-fuel mixture which varies with load on engine

257. In S I Engine homogeneous mixture is prepared in
A. combustion chamber
B. intake manifold
C. carburetor
D. exhaust valve

258. Air- fuel ratio must be changed with following conditions of an SI engine
A. starting
B. warm up
C. acceleration
D. all of the above

Answer: D all of the above

259. Steady operating conditions of an SI engine is
A. continuous operation of engine at constant speed and for constant load on engine
B. continuous operation of engine at constant speed and for changing load on engine
C. continuous operation of engine at changing speed and for constant load on engine
D. none of the above

Answer: A continuous operation of engine at constant speed and for constant load on engine

260. For normal power range following air fuel ratio is prefered
A. 22 to 1
B. 17 to 1
C. 5 to 1
D. 2 to 1

261. During cruising range of operation of SI engine throttle position is opened by
A. 0 to 20%
B. 20 to 78 %
C. 90 % to 100%
D. all the ranges are suitable

Answer: B 20 to 78 %

262. During normal operating condition of engine load on engine shoud be

263. During maximum power requirement rich mixture provided also has advantage of
A. decreasing temperature of exhaust manifold which is overheated at high load
B. reducing flame temperature and the cylinder temperature
C. avoids detonation because of prevention of overheating of exhaust valve
D. all of the above

Answer: D all of the above

264. Multi cylinder engines needs air-fuel ratio which is
A. same as single cylinder engines
B. leaner than the single cylinder engines
C. richer than the single cylinder engines
D. always close to stoichiometric conditions

Answer: C richer than the single cylinder engines

265. In multi cylinder engines, cylinder close to carburetor receives
A. richer mixture
B. leaner mixture
C. stoichiometric condition mixture
D. none of the above

266. In multi cylinder engines,cylinder away from carburetor receives
A. richer mixture
B. leaner mixture
C. stoichiometric condition mixture
D. none of the above

267. In multi cylinder engines,in all the cylinders I. Air-fuel ratio is same, II.Air-fuel ratio is different
A. only i is true
B. only i is false
C. both i and ii are true
D. none of the above

Answer: B only i is false

268. Transient condition of SI engine is
A. idling
B. cruising
C. starting
D. maximum power range

269. Transient condition of SI engine is I. Starting II. Acceleration III. Idling IV. Deceleration V. Warming up
A. only i and ii
B. only i,ii, iv and v
C. only iii
D. all i,ii,iii,iv and v

Answer: B only i,ii, iv and v

270. Transient conditions in SI engine occurs because of
A. evaporation of fuel is incomplete
B. quantity of fuel in intake manifold may be increasing or decreasing
C. distribution of fuel to various cylinders may be different
D. all of the above

Answer: D all of the above

271. Transient conditions in SI engine occurs because of
A. evaporation of fuel is incomplete
B. quantity of fuel in intake manifold may be increasing or decreasing
C. both a and b
D. none of the above

Answer: C both a and b

272. Transient conditions in SI engine occurs because of
A. more mixing of fuel and air
B. quantity of fuel in intake manifold may be increasing or decreasing
D. none of the above

Answer: B quantity of fuel in intake manifold may be increasing or decreasing

273. Transient conditions in SI engine occurs because of
A. cold days starting problems
B. quantity of fuel in intake manifold may be increasing or decreasing
D. all of the above

Answer: D all of the above

274. Petrol is mixture of hydrocarbons having
A. same boiling points
B. different boiling points
C. more boiling points
D. none of the above

275. Petrol having high vapour pressures and low boiling points are called
A. light ends
B. heavy ends
C. bulky ends
D. low ends

276. Petrol fuel which is more volatile are called
A. heavy ends
B. more ends
C. light ends
D. bulky ends

277. When 10% of fuel is vaporised it is called
A. 90 per cent point
B. 10 per cent point
C. any point
D. 110 per cent point

Answer: B 10 per cent point

278. During starting, richer mixture is sent through carburetor because
A. it is transient condition
C. it provides heavy ends of fuel in cylinder
D. it provides light ends of fuel in cylinder

Answer: C it provides heavy ends of fuel in cylinder

279. When 100% of fuel is vaporised it is called
A. 100 per cent point
B. 10 per cent point
C. end point
D. 110 per cent point

280. During cold starting, richer mixture is provided
A. because lean mixture is created in cylinder because of less vapourized fuel availability in air.
B. because lean mixture is created in cylinder because of less fuel availability in air.
C. because lean mixture is created in cylinder because of more air availability in same quantity of fuel.
D. all of the above

Answer: A because lean mixture is created in cylinder because of less vapourized fuel availability in air.

281. During cold starting problems
A. vaporized fuel in carburetor is condensed in intake manifold, cylinder and piston top
B. vaporized fuel in carburetor is condensed in intake manifold, carburetor itself
C. vaporized fuel in carburetor is condensed in carburetor, cylinder and piston top
D. vaporized fuel in carburetor is condensed in intake manifold, cylinder and carburetor

Answer: A vaporized fuel in carburetor is condensed in intake manifold, cylinder and piston top

282. During cold starting problems air-fuel mixture sent to engine is
A. 2 to 3 times normal amount of fuel
B. 5 to 10 times normal amount of fuel
C. 10 to 20 times normal amount of fuel
D. 1 to 2 times normal amount of fuel

Answer: B 5 to 10 times normal amount of fuel

283. During cold starting problems air – fuel ratio required is
A. 30 to 1
B. 10 to 1
C. 3 to 1
D. 2 to 3

284. Petrol engines are
A. quality governed
B. mechanically governed
C. quantity governed
D. all of the above

285. Pump which provide additional fuel quantity during acceleration is called as
A. liquid pump
B. vapor pump
C. fuel pump
D. acceleration pump

286. During acceleraton lean mixture is reached in cylinder because
A. more quantity of fuel is vaporized but not sent in cylinder during working of the cylinder
B. during acceleration intake manifold is supporting the working of carburetor as more and more fuel is sent to intake manifold instantly from the carburetor
C. because more fuel is consumed during acceleration and hence we send leaner mixture
D. fuel lags behind in intake manifold as vaporized fuel is passed in the cylinder and more fuel is collected in intake manifold which is not vaporized during subsequent strokes as during normal working conditions of engine

Answer: D fuel lags behind in intake manifold as vaporized fuel is passed in the cylinder and more fuel is collected in intake manifold which is not vaporized during subsequent strokes as during normal working conditions of engine

287. Acceleration term refers to
A. increasing speed of engine
B. increasing speed of throttle valve opening or closing
C. increasing speed of choke valve opening or closing
D. increasing speed of fuel flow

Answer: A increasing speed of engine

288. Requirements of carburetor are
A. to meter the liquid in such a quantity that air-fuel ratio is changed according to steady and transient working conditions of an engine
B. to prepare homogeneous air-fuel mixture
C. to provide rich mixture during idling and acceleration
D. all of the above

Answer: D all of the above

289. Simple carburetor doesn’t have which of the following element in its arrangement
A. float chamber
B. auxiliary air port
C. venturi
D. throttle valve

290. Carburetor depression is a
A. velocity difference
B. temperature difference
C. pressure difference
D. none of the above

291. Pressure at throat section of venturi in simple carburetor is
A. above atmospheric pressure
B. atmospheric pressure
C. it is any pressure
D. below atmospheric pressure

292. Carburetor depression is pressure difference between
A. pressure in float chamber and at float section in venturi
B. pressure in float chamber and at throttle valve section in jet tube
C. pressure in venturi section and at float section in venturi
D. pressure in float chamber and at inlet section in jet tube

Answer: A pressure in float chamber and at float section in venturi

293. Simple carburetor can be used for following applications
A. engine running at constant speed with load varying on engine
B. engine running at constant speed without load varying on engine
C. engine running at varying speed without load varying on engine
D. engine running at very very low speed without load varying on engine

Answer: B engine running at constant speed without load varying on engine

294. Jet tube in simple carburetor is also called as
A. choke tube
B. venturi tube
C. both a and b
D. only a

Answer: C both a and b

295. Nozzle lip is
A. level difference between level of fuel in throttle valve and level of fuel in float chamber
B. it is tip of main jet
C. it is pressure difference
D. level difference between level of tip of main jet and level of fuel in float chamber

Answer: D level difference between level of tip of main jet and level of fuel in float chamber

296. Nozzle lip is provided in simple carburetor
A. to avoid overflow of liquid fuel from float chamber
B. to get proper working of simple carburetor
C. to maintain proper vapor quantity produced in simple carburetor
D. to maintain liquid level in float chamber

Answer: A to avoid overflow of liquid fuel from float chamber

297. Minimum cross section in venturi is caleed as
A. main jet area
B. throat
C. venturi area
D. float

298. Main suction or vacuum is created in simple carburetor at
A. float chamber
B. choke valve section
C. throat section
D. throttle valve section

299. Fuel quantity in the all the types of carburetors is mainly controlled with the help of which of the following device
A. throat
B. needle valve
C. choke valve
D. throttle valve

300. Which of the following device is directly connected to accelerator in vehicle
A. throttle valve
B. throat
C. needle valve
D. choke valve

301. During cold starting problems in winter seasons in india
A. throat section is closed
B. choke valve is closed
C. throttle valve is closed
D. main jet is closed

Answer: B choke valve is closed

302. Pressure at the throat at fully open position of throttle condition lies in between
A. 1 to 2 mm hg below atmospheric pressure
B. 10 to 20 mm hg below atmospheric pressure
C. 4 to 5 mm hg below atmospheric pressure
D. 0.5 to 2 mm hg below atmospheric pressure

Answer: C 4 to 5 mm hg below atmospheric pressure

303. Throttle valve is placed on which side of venturi
A. on atmospheric air side
B. at venturi
C. before venturi
D. after venturi

304. At high speed of engine and for fully open position of throttle valve.
A. more air-fuel mixture it send to cylinder.
B. less air-fuel mixture it send to cylinder.
C. more air mixture it send to cylinder.
D. less fuel mixture it send to cylinder.

Answer: A more air-fuel mixture it send to cylinder.

305. Drawbacks of simple carborator are
A. it provides richest mixture when speed engine is high.
B. it provides leanest mixture when speed engine is less.
C. both a&b
D. none of the above.

306. In case of simple carburetor for high speed engines too rich mixture is created because of following reason
A. more vacuum at throttle section
B. less air from atmosphere
C. less vacuum at throat
D. too high vacuum at throat

Answer: D too high vacuum at throat

307. In the simple carburetor which of the following modification is necessory for increasing air flow to compenset for rich mixture
A. compensating jet
B. emulsion tube
C. back suction control
D. all of the above

Answer: D all of the above

308. During idling condition of SI engine mixtue is diluted because of exhaust gases presence in cylinder, so fuel is provided in venturi tube
A. at throat section because of suction created at that point
B. after throttle valve because of suction created at that point
C. after throat section because of suction created at that point
D. after choke valve because of suction created at that point

Answer: B after throttle valve because of suction created at that point

309. Idle adjust in idling arrangement is used mainly to control the
A. petrol bleed
B. fuel bleed
C. air bleed
D. mixture bleed

310. __________ is the process of preparation of mixture of fuel and air before admission to cylinder.
A. mixing
B. carburettion
C. evaporation
D. condensation

311. Which of the following is not the part of fuel induction system.
A. fuel filter and fuel pump
B. carburettor
C. throttle valve
D. spark plug

312. The function of carburettor is,
A. to control a:f ratio
B. to control amount of mixture
C. to control both a and b
D. none of the above

Answer: D none of the above

313. The function of carburettor is to control,
A. speed
B. a:f ratio
C. a:f ratio and quantity of mixture
D. none of the above

Answer: D none of the above

314. The process of carburettion depends on
A. speed of engine
B. temperature of suction air
C. volatility of fuel
D. all of the above

Answer: D all of the above

315. Volatile fuels with heating in intake manifolds will
A. decrease volumetric efficiency
B. decrease power output
C. supply rich mixture
D. both a and b

Answer: D both a and b

316. Time available in seconds for process of carburettion at about 4000 rpm is about
A. 0.0075 to 0.01
B. 0.01 to 0.02
C. 0.03 to 0.04
D. none of the above

317. Increased temperature of inlet air, causes volumetric efficency of engine to
A. increase
B. decrease
C. remains same
D. same of the above

318. A carburettor is used in case of
A. gas engines
B. petrol engines
C. diesel engines
D. none of the above

319. The chemically correct mixture for petrol is approximately
A. 1970-01-01 12:01:00
B. 1970-01-01 15:01:00
C. 1970-01-01 17:01:00
D. 1970-01-01 18:01:00

320. Mixture requirements at different load and speeds of petrol engine are
A. starting and idling
B. acceleration
D. all of the above

Answer: D all of the above

321. Cruishing range as percentage of designed load refers to
A. 0 to 20
B. 20 to 75
C. 80 to 100
D. none of the above

322. Idling of engine refers to
D. none of the above

323. To develop maximum power, mixture supplied is
A. rich
B. chemically correct
C. lean
D. none of the above

324. To have minimum specific fuek consumption ot to achieve maximum economy of fuel, mixture supplied is
A. rich
B. chemically correct
C. lean
D. none of the above

325. Engine at the time of starting and idling needs mixture which is,
A. rich
B. chemically correct
C. lean
D. none of the above

326. At low load running (zero to 20% load of rated power) engine requires mixture which is,
A. rich
B. chemically correct
C. lean
D. none of the above

327. During sudden acceleration, engine requires
A. rich mixture
B. chemically correct mixture
C. lean mixture
D. may be lean or rich mixture

328. Mixture requirements by the engine part load running ( cruising range) is,
A. rich
B. chemically correct
C. lean
D. cant say

329. A:F ratio needed during maximum power is
A. 12 to 13.5:1
B. 1970-01-01 15:01:00
C. 16 to 17.5:1
D. 18 to 20:1

330. A:F ratio needed for minimum specific fuel consumption of S.I. engine is,
A. 12 to 14:1
B. 1970-01-01 15:01:00
C. 16.5 to 17.5:1
D. 18 to 20:1

331. A:F ratio needed at the time of starting and idling is
A. 11 to 12:1
B. 13 to 15:1
C. 16 to 18:1
D. 18 to 20:1

332. A:F ratio required for low load running in the range of zero to 20% load is,
A. 12 to 14:1
B. 15 to 17:1
C. 17 to 20:1
D. none of the above

333. A:F ratio used during part load running cruising range from
A. 11 to 14:1
B. 1970-01-01 15:01:00
C. 16 to 17.5:1
D. 18 to 20:1

334. A petrol engine is ____________
A. quality governed
B. quantity governed
C. both a and b
D. none of the above

335. The tip of main nozzle with reference to petrol level in float chamber is
A. at the same level
B. at higher level
C. at lower level
D. none of the above

336. During idling of engine of engine, it requires
A. lean fuel-air mixture
B. no fuel in air
C. stoichiometric air-fuel ratio
D. rich mixture

337. Which of the following is not the requirement of a good carburettor?
A. prepare a:f ratio as required during starting, idling, no load running, cruising, maximum power
B. prepare non-homogeneous (heterogeneous) mixture
C. energy is supplied to change fuel from liquid to vapour form
D. supply rich mixture during acceleration

Answer: B prepare non-homogeneous (heterogeneous) mixture

338. Which is not the drawback of a simple carburettor,
A. it provides required air-fuel ratio at all throttle position
B. it provides increasing richness of a:f ratio as speed increases
C. it provides very lean mixture at low speeds which is not adequate to ignite the mixture
D. all of the above

Answer: A it provides required air-fuel ratio at all throttle position

339. A choke in the carburettor is
A. kept in closed closed position when cold starting the engine
B. kept in open position when cold starting the engine
C. not required since the carburettor can produce a:f ratio during cold starting
D. none of the above

Answer: A kept in closed closed position when cold starting the engine

340. During no load (idling) running of engine, the throttle valve is kept slmodt in closed position. A simple carburettor will provide
A. rich mixture
B. stoichiometric mixture
C. extreamly lean mixture
D. none of the above

341. The idle jet does not supply fuel during
A. idling
C. both a and b
D. none of the above

342. Which of the following is not the requirement of the carburetor
A. prepare af ratio as required during starting, idling, maximum power and acceleration
B. prepare non homogeneous mixture
C. energy is supplied to change fuel from liquid to vapour form
D. supply rich mixture during acceleration

Answer: B prepare non homogeneous mixture

343. Which is not drawback of simple carburetor?
A. it provides required air fuel ratio at all throttle position
B. it supplies increasingly rich mixture as speed increases
C. it provides very lean mixtures at low speeds
D. none of the above

Answer: D none of the above

344. A choke in the carburetor is
A. kept in closed position when cold starting the engine
B. kept in open position when cold starting the engine
C. not required since carburetor can produce required af ratio during cold starting
D. none of the above

Answer: A kept in closed position when cold starting the engine

345. During no load running of the engine, the throttle valve is kept almost closed. A simple carburetor will provide
A. rich mixture
B. stoichiometric mixture
C. extremely lean mixture
D. none of the above

346. Compensating devices are provided in carburetor
A. to vary quantity of mixture according to the load on the engine
B. to supply af ratio always as needed by economy running
C. to vary af ratio according to various operating conditions
D. to supply rich mixtures during acceleration only

Answer: B to supply af ratio always as needed by economy running

347. An emulsion tube or air bleed method is used in modern carburetor
A. to maintain air fuel ratio at all speeds
B. to increase af ratio with decrease in load
C. to decrease af ratio with increase in speed
D. none of the above

Answer: A to maintain air fuel ratio at all speeds

348. A carburetor which is installed above intake manifold and flow ofmixture is assited by gravity is called
A. up draught carburetor
B. down draught carburetor
C. side draught carburetor
D. none of the above

349. Carburetor which uses horizontal draft tube is called
A. up draught carburetor
B. down draught carburetor
C. side draught carburetor
D. none of the above

350. Actual air fuel ratio supplied by carburetor at high altitudes compared to sea level
A. lean
B. rich
C. same
D. can’t say

351. Which is not the advantage of gasoline injection as compared to carburetor
A. exact af ratio at all loads
B. same mixture strengths to all cylinders
C. economy of fuel during idling and low load running
D. low volumetric efficiency

352. Which is not a method of fuel injection in SI engine
A. directly into the cylinder before the end of compression stroke
B. in to the inlet manifold during suction stroke
C. near inlet port during suction stroke
D. directly into the cylinder in high pressure injection system

Answer: A directly into the cylinder before the end of compression stroke

353. Continuous port fuel injection refers to injection of fuel
A. near the inlet port
B. near the inlet manifold
C. directly into the cylinder
D. none of the above

Answer: A near the inlet port

354. In continuous inlet manifold injection system, the fuel is injected at a pressure of refers to injection of fuel
A. 1.2 bar
B. 1.5 bar
C. 2 bar
D. 3 bar

355. GDI refers to injection of fuel
A. near the inlet port
B. into the intake manifold
C. directly into the cylinder
D. none of the above

Answer: C directly into the cylinder

356. Which of the following is not the advantage of GDI
A. high volumetric efficiecy
B. low emissions
C. ease of cold starting
D. high initial cost

357. In MPFI injection system
A. each cyclider has separate fuel injector
B. injectors are mounted on the inlet ports
C. fuel from fuel tank is pumped under pressure
D. all of the above

Answer: D all of the above

358. Which is not an advantage of MPFI system?
A. uniform air fuel ratio to each cylinder
B. ease of cold starting
C. low sfc
D. elaborate arrangement of components

Answer: D elaborate arrangement of components

359. If flame travel from point of ignition upto end of combustion chamber without change in speed, the combustion is called
A. auto ignition
B. normal
C. abnormal
D. none of the above

360. The combustion of mixture without a flame front is called
A. auto ignition
B. normal
C. abnormal
D. none of the above

361. The throttle valve is placed in a draft tube
A. on atmospheric side of the venturi
B. on engine side of the venturi
C. at the venturi
D. none of the above

Answer: B on engine side of the venturi

362. The choke valve is placed in a draft tube
A. on atmospheric side of the venturi
B. on engine side of the venturi
C. at the venturi
D. none of the above

Answer: A on atmospheric side of the venturi

363. The venturi is the portion in a draft tube
A. converging section
B. diverging section
C. minimum cross secional area
D. all of the above

Answer: C minimum cross secional area

364. The main jet of the main metering system is situated
A. above the level of the petrol in float chamber
B. below the level of the petrol in float chamber
C. at the same level
D. any arrangement can be possible

Answer: A above the level of the petrol in float chamber

365. The nozzle lip is the level difference between
A. venturi and level of petrol in float chamber
B. venturi and throttle valve
C. throttle valve and choke valve
D. none of the above

Answer: A venturi and level of petrol in float chamber

366. The use of vent on a float chamber ensures
A. filling of petrol if level of petrol goes down
B. leak off connection for overflow case
C. maintaining atmospheric pressure in float chamber
D. none of the above

Answer: C maintaining atmospheric pressure in float chamber

367. The carburetion does not perform this function
A. atomization
B. vaporization
C. mixing air and fuel in right proportion
D. increasing the temperature of the mixture near to its ignition point

Answer: D increasing the temperature of the mixture near to its ignition point

368. The carburetor depression is
A. the pressure drop because of whch air is sucked inside
B. the pressure drop because of which fuel is sucked
C. the pressure drop because of charge is taken inside the cylinder
D. all of the above

Answer: B the pressure drop because of which fuel is sucked

369. Operating the choke in cold starting means
A. closing the choke valve
B. opening the choke valve
C. opening the throttle valve more
D. closing the throttle valve

Answer: A closing the choke valve

370. In idling system, the idling port opens in a draft tube of carburetor on
A. venturi side of throttle valve
B. on engine side of throttle valve
C. exactly at the front of throttle valve
D. none of the above

Answer: B on engine side of throttle valve

371. Stoichiometric air fuel ratio of petrol is aproximately
A. 1970-01-01 10:01:00
B. 1970-01-01 12:01:00
C. 1970-01-01 15:01:00
D. 1970-01-01 18:01:00

372. Equivalence ratio means
A. actual fuel air ratio to stoichiometric fuel air ratio
B. stoichiometric fuel air ratio to actual fuel air ratio
C. mass of fuel to mass of air
D. mass of air to mass of fuel

Answer: A actual fuel air ratio to stoichiometric fuel air ratio

373. If air fuel ratio is greater than 16:1 then ixture is
A. lean
B. chemically correct
C. rich
D. perfect

374. The function of the venturi in the carburetor is
A. to decrease fuel flow
B. to increase fuel flow
C. to decrease air velocity
D. to increase air velocity

Answer: D to increase air velocity

375. To get maximum power aim is
A. to use all fuel in combustion chamber
B. to utilize all oxygen in combustion chamber
C. to get more economy
D. to get less fuel consumption

Answer: B to utilize all oxygen in combustion chamber

376. If the bonnet space is limited, the carburetor used is
A. updraught
B. downdraught
C. horizontal draught
D. slant draught

377. In constant choke carburetor or open choke carburetor ___________ is kept constant.
A. air flow area
B. fuel flow area
C. both air and fuel flow areas
D. pressure drop

Answer: C both air and fuel flow areas

378. A venturi of fixed dimension is used in
A. constant choke carburetor
B. constant vacuum carburetor
C. multiple venturi carburetor
D. multijet carburetor

379. In ______________ carburetor, pressure drop is kept constant.
A. constant choke carburetor
B. constant vacuum carburetor
C. multiple venturi carburetor
D. multijet carburetor

380. If the equivalence ratio is greater than one then, mixture is
A. lean
B. chemically correct
C. rich
D. perfect

381. Fuel flow rate as per demand is varied by varying pressure difference in _____ carburetor.
A. su
B. apha
C. solex
D. none of the above

382. Fuel flow area is varied in ____________ carburetor.
A. solex
B. zenith
C. carter
D. su

383. In this carburetor, air lifts fuel droplets against gravity.
A. updraught
B. downdraught
C. side draught
D. cross draught

384. If inlet temperature of air increases ___________
A. efficiency of ic engine increases but power output decreases
B. efficiency of ic engine decreases but power output increases
C. both efficiency and power output decrease
D. both efficiency and power output increase

Answer: C both efficiency and power output decrease

385. Chemixally correct air fue ratio of octane is
A. 13.14:1
B. 15.14:1
C. 17.14:1
D. 1.17:14

386. Which air fuel ratio gives maximum power for SI engine
A. 1970-01-01 15:01:00
B. 1970-01-01 18:01:00
C. 1970-01-01 08:01:00
D. 1970-01-01 12:01:00

387. Which air fuel ratio gives minimum BSFC
A. 1970-01-01 15:01:00
B. 1970-01-01 16:01:00
C. 1970-01-01 19:01:00
D. 1970-01-01 12:01:00

388. Rich mixture is required during
A. idling and cruising
B. cruising and acceleration
C. idling and cruising and acceleration
D. idling and acceleration

389. The choke is used when engine is
A. cold
B. hot
C. accelerating
D. idling

390. SI engines use mixtures having AF ratio between
A. 4:1 to 24:1
B. 3:1 to 17:1
C. 15:1 to 80:1
D. 1:1 to 5:1

391. For SI engine for maximum power, relative fuel air ratio should be
A. 0.6
B. 0.8
C. 1
D. 1.2

392. Lean mixture is required during
A. idling and cruising
B. cruising and starting
C. cruising only
D. cruising, starting and idling

393. For maximum thermal efficiency aim is to
A. use all the oxygen present in combustion chamber
B. use all the fuel present in combustion chamber
C. to get maximum pressure in the cylinder
D. to get maximum temperature in the cylinder

Answer: B use all the fuel present in combustion chamber

394. The mixture requirements during staarting and idling are
A. rich and rich
B. rich and lean
C. lean and lean
D. lean and rich

395. For maximum economy mixture should be
A. rich
B. lean
C. stoichiometric
D. inert

396. The pressure difference between float chamber and throat is
A. nozzle lip
B. nozzle dip
C. carburetor depression
D. potential difference

397. When choke is closed, suction presssure is applied on
A. air intake
B. nozzle
C. both air intake and nozzle
D. every where

398. Economiser system comes into action during
A. cruising
B. idling
C. starting
D. full throttle condition

399. During cruising, mixture provided by simple carburetor is
A. increasingly rich
B. increasingly lean
C. constant chemically correct
D. sometimes rich, sometimes lean

400. During acceleration, mixture provided by simple carburetor is
A. increasingly rich
B. increasingly lean
C. lean
D. chemically correct

401. During idling, mixture provided by simple carburetor is
A. increasingly rich
B. increasingly lean
C. lean
D. chemically correct

402. The fuction of the choke is to provide
A. lean mixture
B. some mixture
C. rich mixture
D. stoichiometric mixture

403. Simple carburetor provides correct quality of mixture
A. at all operating conditions
B. during acceleration only
C. during cruising only
D. only at one throttle position

Answer: D only at one throttle position

404. The correct expression for nozzle lip is
A. tip height – fuel surface height
B. tip height – throat height
C. throat height – float chamber height
D. fuel surface height

Answer: A tip height – fuel surface height

405. The tip of the nozzle is kept
A. at the same level as that of fuel in float chamber
B. at level above the fuel level in float chamber
C. at level below the fuel level in float chamber
D. sometimes above, sometime below the fuel level in float chamber

Answer: B at level above the fuel level in float chamber

406. The drawbacks of carburetor includes
A. non uniform distribution in multi cylinder engines
B. less breathing capacity
C. slow response to change in operating conditions
D. all of the above

Answer: D all of the above

407. MPFI means
A. metal point fuel injection
B. multi point fuel injection
C. metal power fuel injection
D. multiple pin fuel injection

Answer: B multi point fuel injection

408. In port injection system, location of injector is
A. inside cylinder near intake port
B. near carburetor
C. inside intake manifold near intake port
D. inside cylinder near exhaust port

Answer: C inside intake manifold near intake port

409. In carburetor, choke is located on which side of the venturi?
A. engine side
B. air filter side
C. at the venturi
D. any where

410. In carburetor, throttle valve is located on which side of the venturi?
A. engine side
B. air filter side
C. at the venturi
D. any where

411. In complete caruretor, idling passage opens in a draft tube at which position?
A. engine side of throttle valve
B. venturi side of throttle valve
C. at the venturi
D. none of the above

Answer: A engine side of throttle valve

412. The cold start injector provides
A. stoichiometric mixture
B. rich mixture
C. lean mixture
D. heating of fuel

413. Ignition lag, spreading of flame and after burning are the stages observed during combustion in
A. petrol engines
B. diesel engines
C. pi engines
D. turbocharged engines

414. The combustion will not start immediately after spark because of
A. flame propogation
B. after burning
C. ignition lag
D. motoring

415. The time interval between formation of spark and appreciable pressure rise is
B. ignition lag
C. propogation lag
D. burning lag

416. A motoring curve is plotted when
A. when the vehicle is not running
B. when engine is running at no load condition
C. the cycle is taking place due to combustion of fuel
D. the cycle is not fired

Answer: D the cycle is not fired

417. Which of the following is not necessary condition for starting of combustion process in SI engines?
A. compression of charge
B. presence of fuel
C. presence of oxygen
D. formation of spark

418. Effect of spark in SI engines is____
A. ionisation of gases
B. rise in volume
C. rise in pressure
D. rise in temperature

419. In SI enginesmaximum amount of fuel is burnt during the stage____
A. pre-burning
B. ignition lag
C. flame propagation
D. after burning

420. In SI engines the flame travels in____
A. spherical shape
B. circular shape
C. linear direction
D. sinusoidal pattern

421. In D-MPFI system the quantity sensed is ____
A. pressure
B. volume
C. temperature
D. mixture flow rate

422. The D-MPFI system responds to vacuum sensed in____
A. carburettor
B. intake manifold
C. exhaust manifold
D. piston

423. L-MPFI ststem responds to____
A. pressure
B. volume
C. temperature
D. flow rate

424. Arrange the phases of combustion in ascending order according to amount heat evolved in each phase
A. ignition lag, after burning, flame propagation
B. ignition lag, flame propagation, after burning
C. after burning, flame propagation, ignition lag
D. after burning, ignition lag, flame propagation

Answer: A ignition lag, after burning, flame propagation

425. In SI engines flame speed decreases with increase in
A. intake temperature
B. peak temperature
C. compression ratio
D. residual gases

426. In SI engines, Maximum flame speed is obtained when equivalance ratio is___
A. less than 1
B. between 1 to 1.1
C. between 1.1 to 1.2
D. greater than 1.2

Answer: C between 1.1 to 1.2

427. With increase in compression ratio, flame travels
A. faster
B. slower
C. with same speed
D. with fluctuations

428. In SI engines flame speed always increases with____
A. turbulence
B. air-fuel ratio
C. residual gases
D. compression ratio

429. With increase in speed, the crank angle required for flame propagation___
A. increases
B. decreases
C. remains same
D. cant predict

430. If cooling water temperature is decreased flame speed___
A. increases
B. decreases
C. remains same
D. cant predict

431. Increasing cooling water temperature in SI engines, kncocking tendency_____
A. increases
B. decreases
C. remains same
D. cant predict

432. To reduce knocking, the fuel in SI engine should have ____ self ignition temperature
A. low
B. high
C. any
D. automatic

433. Detonation in SI engine means
A. sudden ignition of charge before delay period is over
B. pre-ignition of charge before the spark
C. auto-ignition of charge before the spark
D. auto-ignition of charge after the delay period is over

Answer: D auto-ignition of charge after the delay period is over

434. Knocking in SI engine occurs when___
A. flame reaches the unburnt charge before delay period is over
B. flame reaches after the delay period is over
C. spark is produced before charge coming in
D. spark is produced several times

Answer: B flame reaches after the delay period is over

435. Pre-ignition takes place when____
A. flame reaches the unburnt charge before delay period is over
B. ignition takes place after spark
C. ignition starts before spark
D. flame travels very fast

Answer: C ignition starts before spark

436. Larger combustion chambers
A. increase detonation
B. decrease detonation
C. do not affect detonation
D. cant say

437. To prevent knocking flame propagation should be
A. retareded
B. accelerated
C. sinusoidal
D. upfront

438. To reduce knocking in SI engines, self ignition temperature of fuel should be ____
A. high
B. low
C. varying
D. constant

439. Which of the following is not an effect of increased intake temperature?
A. less delay period
B. higher flame speed
C. more knocking tendency
D. does not affect anything

Answer: D does not affect anything

440. As load increases, the knocking tendency of SI engines____
A. increases
B. decreases
C. cant predict
D. remains same

441. As the speed of flame travel increases, detonation___
A. increases
B. decreases
C. cant predict
D. remains same

442. AS distance of flame travel increases, detonation
A. increases
B. decreases
C. cant predict
D. remains same

443. Detonation tendency is maximum for air:fuel ratio___
A. 8:1 to 10:1
B. 10:1 to 12:1
C. 12:1 to 14;1
D. 16:1 to 18:1

444. To reduce detonation, the spark plugh should be located
A. near to intake valve
B. at the corner
C. centrally
D. neat piston

445. Which is not a probable location of preignition?
A. spark plugh tip
B. exhaust valve
C. remote corner of chamber
D. intake valve

446. Knocking in SI engines will be less if
A. delay period is less and flame speed is high.
B. delay period is less and flame speed is less
C. delay period is high and flame speed is high
D. delay period is high and flame speed is less

Answer: C delay period is high and flame speed is high

447. In SI engines, to aviod knock, combustion chamber should have___
A. small bore
B. large bore
C. large flame path
D. large ratio of flame path to bore

448. Octane rating is___
A. measure of fuel resistance to knock in ci engines
B. measure of fuel assistance to knock in si engines
C. measure of fuel assistance to knock in ci engines
D. measure of fuel resistance to knock in si engines

Answer: D measure of fuel resistance to knock in si engines

449. For octane rating a standard reference fuel consists of
A. iso-octane only
B. n-heptane only
C. combination of 2,2,4 trimethyl pentane and n-heptane
D. combination of iso heptane and n-octane

Answer: C combination of 2,2,4 trimethyl pentane and n-heptane

450. 2,2,4 trimethyl pentane has octane number equal to
A. 1
B. 0
C. 100
D. 120

451. n-heptane has octane number equal to
A. 0
B. 1
C. 100
D. 120

452. Octane number 60 means, the fuel has antiknock proper equal to fuel from by
A. 60% of n-octane 40% of petrol
B. 60% of iso octane and 40% n-heptane
C. 60% of iso octane and 40% of eptrol
D. 60% of iso octane and 40% of tel

Answer: B 60% of iso octane and 40% n-heptane

453. Dopes are___
A. chemical which will increase knocking tendency of fuel
B. chemical which will decrease knocking tendency of fuel
C. chemical which will decrese exhaust from engine
D. chemical which will increse exhaust from engine

Answer: B chemical which will decrease knocking tendency of fuel

454. RON means ____
B. research oxygen number
D. research octane number

455. MON means ___
A. metal oxygen number
B. motor oxygen number
C. metal octane number
D. motor octane number

456. RON is calculated at___
A. low speed and low temperature
B. high speed and low temperature
C. low speed and high temperature
D. high speed and high temperature

Answer: A low speed and low temperature

457. Which is correct expression?
A. ron=sensitivity-mon
B. sensitivity=ron/mon
C. sensitivity=ron-mon
D. sensitivity=mon/ron

458. Sensitivity shows
A. change in eprformance of fuel under test condition and practical condition
B. change in octane number
C. ratio of octane number of ideal fuel and actual fuel
D. ratio of octane number of actual fuel to ideal fuel.

Answer: A change in eprformance of fuel under test condition and practical condition

459. Higher sensitivity of fuel shows___
A. better performance under serve conditions.
B. poor oerformance under serve conditions
C. better emissions under serve conditions
D. less emissions under serve conditions

Answer: B poor oerformance under serve conditions

460. A 4-cylinder, 4-stroke petrol engine has,swept volume=0.001cubic meter and N=4200rpm. The power developed within the enigne cylinder is
A. 35kw
B. 140kw
C. 2100kw
D. nonenone of the above

461. B.P of a four cylinde, four stroke engine is measured by brake dynamometer which develops a torque of 1000N-M at 4200rpm. The B.P is about
A. 440kw
B. 1760kw
C. 4.4×105 kw
D. none of the above

462. In an eight cylinder engine the fuel suplied was 4000kg in 2 hours and the out put is 8000KW. Its bsfc is about
A. 0.5kg/kwh
B. 1kg/kwh
C. 0.25kg/kwh
D. 0.125kg/kwh

463. brake thermal efficiency of ci engine is about
A. 20-28%
B. 30-40%
C. 40-50%
D. more then 50%

464. four cylinder engine , the indicated power is 100KW and brake power is 20KW/cylinder . Its mechanical efficiency is about
A. 0.2
B. 0.4
C. 0.8
D. none of the above

465. brke mean effective pressure and indicated mean effective pressure of an ic engine are 8br and 10 bar resp. the mechanical efficiency of an engine when runnign at 4000 rpm is
A. 0.8
B. 1.25
C. 80
D. none of the above

466. an engine develops 12KW and frictional power is 4KW . The mechanical efficiency is about
A. 0.67
B. 0.33
C. 0.75
D. none of the above

467. an engine develops 100 Kw wihing the cylinder using fuel having calrofic value of 40000kj/kg with brake thermal efficiency 0.24 and mechanical efficiency 0.8. the fuel consumprion in kg/s…………….?
A. 30
B. 1/120
C. 0.3
D. 37.5

468. A four cylinde si engine develops 100 kw running at a constant speed . When eginition of each cylinder is cut-off successively at the same speed , the BP is 71, 70, 71, 72 KW. The FP of engine and mechanical efficiency are
A. 116kw, 51.3%
B. 16kw, 86.2%
C. 29kw, 77.5%
D. none of the above

469. a vertical single cylinder four stroke diesel engine has a bore of 80mm and stroke of 100mm resp. it is water cooled and develops a torque of 305 N-m . What is the mean effective pressure …………?
A. 2.285 bar
B. 5.875 bar
C. 6.325 bar
D. 7.835 bar

470. a diesel engine consumes 5 grams fuel per second and develops a brake power 75KW. It has a mechanical efficiency of 85%. What would be the bsfc………?
A. 0.055 g/kw s
B. 0.033 g/kw s
C. 0.066 g/kw s
D. 0.088 g/kw s

471. a diesel engine consumes 5 grams fuel per second and develops a brake power 75KW. It has a mechanical efficiency of 85%, bsfc is 0.066 g/KW s . What would be the isfc….?
A. 0.683 kg/kwh
B. 0.204 kg/kwh
C. 0.106 kg/kwh
D. 0.108 kg/kwh

472. a four stroke gas engine has a bor of 20cm and stroke of 35 cm . What would be the swept volume of the engine
A. 6863.93 cc
B. 5853.93 cc
C. 5369.93 cc
D. 7853.93 cc

473. a diesel engine consumes at the rate of 5.5gm/ses and develops a power of 75KW . If the mechanical efficiency is 85% and calorific value is 44 MJ/kg. what would be the bsfc
A. 0.074 g/kws
B. 0.087 g/kws
C. 0.587 g/kws
D. 0.596 g/kws

474. a six cylinder gasoline engine operates on four stroke cycle. It runs at the speed of 4100rpm and develops a torque of 160N-m. what would be the brake power of the engine ……..?
A. 58.53kw
B. 68.66 kw
C. 35.33kw
D. all are the equal effective

475. a sic cylinder gasoline engine operates on a four stroke cycle. The bore of each cylinder is 80mm and the stroke is 100 mm. it runs at a speed of 4100 rpm and develops a brake power of 68.66Kw………what would be the brake mean effective pressure…………….?
A. 5.23bar
B. 2.37bar
C. 6.66bar
D. none of the above

476. a six cylinder gasoline engine operates on the four stroke cycle . The bore of each cylinder is 80 mm and stroke is 100mm. What would be the compression ratio of the engine if clearnce volume per cylinder is 70cc
A. 7.63
B. 8.18
C. 9.68
D. 5.28

477. if the compression ratio of otto cycle is 8.18, what would be the air standard efficiency
A. 0.325
B. 0.658
C. 0.428
D. 0.568

478. if the compression ration of otto cycle is 8.18 and brake thermal efficiency of actual cyle is 29.03%……..what would be the relative efficienct
A. 0.51109
B. 0.6103
C. 0.3105
D. 0.2908

479. a six cylinder four stroke petron engine having a bore of 90 mm and stroke of 100mm and runs at a speed of 2500 rpm. What would be the indicated power
A. 53.239kw
B. 18.368kw
C. 67.593kw
D. 55.235kw

480. a six cylinder four stroke petrol engine develops a indicated power of 67.593 KW with indicated mean specific fuel consumption os 0.3kg/Kwh. What would be the mas flow rate of the fuel in kg/hr
A. 25.369
B. 18.658
C. 20.278
D. 19.365

481. the air standard efficiecny of engine is 0.42647 and corsponding relative efficiecny is 0.55. what would be the corsponding indicated thermal efficiency
A. 0.2346
B. 0.4621
C. 0.3256
D. 0.3325

482. what would be the brake power of the engine, if the net brake load on the engine is 1470 N, effective brake corcumeference is of 4m and engine runs at the speed of 233.33rpm
A. 22.583kw
B. 24.689kw
C. 26.589kw
D. none of theabove

483. if the brake power and indicated power of an engine are 22.286 KW and 56.589KW, what would be mecanicale efficiency of an engine ………..?
A. 0.75
B. 0.78
C. 0.79
D. 0.86

484. what would be the number of powe strokes per min ……..? If a six cylinder four stroke engine runs at 233.33 rpm and the number of missed powe stroke is 8.33 per min
A. 105.33
B. 107.33
C. 108.66
D. none of the above

485. actual number of stroke per min will be equll to
A. theroricl stroke per min + missed stroke per min
B. theroricl stroke per min x missed stroke per min
C. theroricl stroke per min – missed stroke per min
D. none of the above

Answer: C theroricl stroke per min – missed stroke per min

486. a four cylinder petrol engine with 70mm bore and 100 mm stroke length working on four stroke pricniple develops a torque 140 N-m at 4000 rpm……what would be the brake power of the engine ……?
A. 58.65kw
B. 63.25kw
C. 48.35kw
D. 33.32kw

487. what would be the brake thermal efficiency of the engine, if the brake power of the engine is of 58.65KW, fuel consumption is 14kg/hr and the calrofic value of the fuel is 42500kj/kg
A. 0.3548
B. 0.2578
C. 0.3898
D. 0.3696

488. what would be the compression ratio of the engine if the clearnce volume is 0.065lit and the engine bore is of 70mm and the stroke is of 100mm
A. 5.632
B. 7
C. 6.923
D. 8

489. what would be the mean effective pressure of the engine if the area of the indicator diagram is 13 cm2 , length of the indicator diagram is of 6cm and spring constant 2.9 bar/cm
A. 6.5bar
B. 5.8bar
C. 3.5bar
D. 7.8bar

490. what would be the mass flow rate of gasoline in kg/s, if the engine consumes 8lit/hr, taking the specific gravity of the gasoline is 0.8
A. 0.00178
B. 0.00168
C. 0.1234
D. 0.4321

491. what would be the mass flow rate of the gasoline in kg/s, the engine sonsumes 8lit/hr of gasoline, taking density of gasoline is 800 kg/cubic meter
A. 0.00125
B. 0.00178
C. 0.2345
D. 0.0123

492. a single cylinder engine operating at 2000 rpm develops a torqu of 8 N-m and the indicated power of the engine is 2.0KW. What would be the frictional power
A. 0.234 kw
B. 0.1324kw
C. 0.3253kw
D. 0.0012kw

493. for four cylinder four stroke petrol engien the bore is 11cm and stroke is 13cm, running at speed of 2250 rpm. What is the swept volume of the engine
A. 0.18 cubic meter per second
B. 0.25 cubic meter per second
C. 0.37 cubic meter per second
D. none of the above

Answer: C 0.37 cubic meter per second

494. a single cylinder four stroke engine having bore 18 cm and stroke 36cm, revolving at 285 rpm and having mean effective pressure 7.2 bar. The indicated power is
A. 7.85kw
B. 31.4kw
C. 15.7kw
D. none of the above

495. what would be the mean effective pressure of the engine if the area of the positive loop of the indicator diagram is of 5.75 squr cm, area of negative loop of the indicator diagram 0.25 squre cm and the length of the indicator diagrma is of 5.5cm
A. 4bar
B. 3bar
C. 7bar
D. 2bar

496. what would be the heat supplied to the engine in KJ/s, if the engine consumes 8 lit of gasoline per second. Take caloric value and specific gravity of fuel is 44000 kj/kg and 0.8 resp.
A. 9.78
B. 8.48
C. 7.35
D. 4.35

497. what would be the heat supplied to the engine in KJ/s, if the engine consumes 8 lit of gasoline per second. Take caloric value and density of fuel is 44000 kj/kg and 800 kg per cubic meter resp.
A. 8.48
B. 9.78
C. 7.35
D. 4.35

498. if the brake thermal efficiecny and indicated thermal efficiecny of the engine is 28% and 35%. What would be the mechanical efficiency of the engien
A. 0.75
B. 0.8
C. 0.85
D. 0.78

499. what is the density of the fuel whose specific gravity is 0.8
A. 800 kg/ cubic meter
B. 780 cubic meter
C. 850 cubic meter
D. 810 cubic meter

Answer: A 800 kg/ cubic meter

500. what would be the air fuel ratio ot the engine if the air consumtion time for 0.1 cubic meter as 16.3 sec and whose density is 1.175kg per cubic meter and fuel consumtion time for 10 cc as 20.sec whos specific gravity is 0.7…….
A. 17.6
B. 19.6
C. 18.6
D. 20.6

501. what would be the mass flow rate of the air, if the air consumption time for 0.1 cubic meter as 16.3 sec whose density is 1.175 kg per cubic meter
A. 0.00821 kg/sec
B. 0.00531 kg/sec
C. 0.00231 kg/se
D. 0.00721 kg/se