Questions set 57

Engine Cycle

1.      In an automobile engine the temperature of the piston will be more at
a) The crown of the piston
b) The skirt of the piston
c) The piston walls
d) The piston rings
Answer: a
Explanation: The crown of the engine experiences the highest temperature.

2.      The firing order in case of four cylinder inline engines is usually
a) 1-2-4-3
b) 1-3-4-2
c) 1-4-3-2
d) Either 1-3-4-2 or 1-4-3-2
Answer: d
Explanation: The firing order of these engines can be either 1-3-4-2 or 1-4-3-2.

3.      In case of four cylinder opposed cylinder engines the firing order is
a) 1-4-3-2
b) 1-3-4-2
c) 1-2-3-4
d) 1-2-4-3
Answer: a
Explanation: The firing order in these engines is 1-4-3-2.

4.      In case of four cylinder inline engine the number of firing strokes in one revolution of crank is
a) 1
b) 2
c) 3
d) 4
Answer: b
Explanation: In a four cylinder engine the number of firing strokes for one revolution of crank is two.

5.      In four cylinder engines the ignition advance depends on
a) Quality of fuel
b) Engine speed
c) Cylinder dimensions
d) Quality of fuel and engine speed
Answer: d
Explanation: Ignition advance depends on both quality of fuel and engine speed.

6.      Ignition advance is expressed in terms of
a) Crank angle
b) Millimetres of piston travel before TDC
c) Time in milli seconds
d) All of the mentioned
Answer: d
Explanation: Ignition advance can be expressed in terms of any of the following.

7.      In internal combustion engine the approximate percentage of the combustion heat that passes to the cylinder walls is
a) 5%
b) 10%
c) 30%
d) 60%
Answer: c
Explanation: Approximately 30% of heat passes to the cylinder walls.

8.      In a four stroke S.I engine the exhaust valve usually opens
a) At BDC
b) 35 degree to 60 degree before BDC
c) 35 degree to 60 degree after BDC
d) 10 degree to 20 degree before BDC
Answer: b
Explanation: Exhaust valve opens at 35 degree to 60 degree before BDC.

9.      In S.I engine the intake valve closes
a) At BDC
b) At TDC
c) 25 degree to 84 degree after BDC
d) 10 degree to 20 degree before TDC
Answer: c
Explanation: The intake valve closes at 25 degree to 84 degree after BDC.

10.  In a diesel engine the pressure during combustion may increase to a range at
a) 10-15 atm
b) 15-20 atm
c) 20-30 atm
d) 55-75 atm
Answer: d
Explanation: Pressure can increase as high as 55 to 75 atm during combustion in diesel engine.

11.  In a diesel engine the temperature of gases under full load may be of the order of
a) 550-650 degree Celsius
b) 200-300 degree Celsius
c) 150-200 degree Celsius
d) 100 degree Celsius
Answer: a
Explanation: Temperature under full load may be as high as 550 to 650 degree Celsius.

12.  The fuel is injected into the cylinder in diesel engine when the piston is
a) Exactly at TDC after compression stroke
b) Exactly at the BDC before compression stroke
c) Approaching TDC during compression stroke
d) Approaching TDC during exhaust stroke
Answer: c
Explanation: Fuel is injected when piston is approaching TDC during compression stroke.

13.  A single cylinder four stroke engine is rotating at 2000 rpm. The number of power strokes occuring in one minute is
a) 500
b) 1000
c) 2000
d) 4000
Answer: b
Explanation: For every two revolutions one cylse is completed in a four stroke engine. If speed is 2000 rpm then number of complete cycles per minute is 1000.

14.  The pressure in an engine cylinder is less than atmospheric pressure when the engine is performing which stroke
a) Suction
b) Compression
c) Power
d) Exhaust
Answer: a
Explanation: During suction stroke the inside pressure is less than atmospheric pressure.

15.  The angle in degrees moved by the crankshaft of a four cylinder engine between firing impulses is
a) 90
b) 180
c) 360
d) 720
Answer: b
Explanation: As engines are alternately fired so the angle moved by crankshaft decreases to 180 between firing impulses.