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MCQs

Total Questions : 1124 | Page 6 of 113 pages
Question 51. The knocking tendency in spark ignition engines may be decreased by
  1.    Controlling the air-fuel mixture
  2.    Controlling the ignition timing
  3.    Controlling the exhaust temperature
  4.    Reducing the compression ratio
 Discuss Question
Answer: Option D. -> Reducing the compression ratio
Question 52. The knocking in diesel engines may be prevented by
  1.    Reducing the delay period
  2.    Raising the compression ratio
  3.    Increasing the inlet pressure of air
  4.    All of these
 Discuss Question
Answer: Option D. -> All of these
Question 53. The two reference fuels used for cetane rating are
  1.    Cetane and iso-octane
  2.    Cetane and alpha-methyl naphthalene
  3.    Cetane and normal heptane
  4.    Cetane and tetra ethyl lead
 Discuss Question
Answer: Option B. -> Cetane and alpha-methyl naphthalene
Question 54. For the same power developed in I.C. engines, the cheaper system is
  1.    Naturally aspirated
  2.    Supercharged
  3.    Centrifugal pump
  4.    Turbo charger
 Discuss Question
Answer: Option B. -> Supercharged
Question 55. As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
  1.    Increase maximum pressure and maximum temperature
  2.    Reduce maximum pressure and maximum temperature
  3.    Increase maximum pressure and decrease maximum temperature
  4.    Decrease maximum pressure and increase maximum temperature
 Discuss Question
Answer: Option B. -> Reduce maximum pressure and maximum temperature
Question 56. The expansion of fuel in a four stroke cycle diesel engine
  1.    Starts at 15° before top dead center and ends at 30° after top dead center
  2.    Starts at top dead center and ends at 30° after top dead center
  3.    Starts at 15° after top dead center and ends at 30° before bottom dead center
  4.    May start and end anywhere
 Discuss Question
Answer: Option C. -> Starts at 15° after top dead center and ends at 30° before bottom dead center
Question 57. The fuel valve in a four stroke cycle diesel engine
  1.    Opens at 15° after top dead center and closes at 20° before bottom dead center
  2.    Opens at 15° before top dead center and closes at 20° after top dead center
  3.    Opens at top dead center and closes at bottom dead center
  4.    May open and close anywhere
 Discuss Question
Answer: Option B. -> Opens at 15° before top dead center and closes at 20° after top dead center
Question 58. In a typical medium speed, 4-stroke cycle diesel engine
  1.    Fuel injection starts at 10° before top dead center and ends at 20° after top dead center
  2.    Fuel injection starts at top dead center and ends at 20° after top dead center
  3.    Fuel injection starts at just before top dead center and ends just after top dead center
  4.    May start and end anywhere
 Discuss Question
Answer: Option A. -> Fuel injection starts at 10° before top dead center and ends at 20° after top dead center
Question 59. In a typical medium speed 4-stroke cycle diesel engine
  1.    Compression starts at 35° after bottom dead center and ends at top dead center
  2.    Compression starts at bottom dead center and ends at top dead center
  3.    Compression starts at 10° before bottom dead center and, ends just before top dead center
  4.    May start and end anywhere
 Discuss Question
Answer: Option A. -> Compression starts at 35° after bottom dead center and ends at top dead center
Question 60. The exhaust valve in a four stroke cycle petrol engine
  1.    Opens at 50° before bottom dead center and closes at 15° after top dead center
  2.    Opens at bottom dead center and closes at top dead center
  3.    Opens at 50° after bottom dead center and closes at 15° before top dead center
  4.    May open and close anywhere
 Discuss Question
Answer: Option A. -> Opens at 50° before bottom dead center and closes at 15° after top dead center

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