Internal Combustion Engine Questions and Answers Part-10

1.What is the major loss in a C.I. engine?
a) direct heat loss
b) loss due to incomplete combustion
c) rubbing friction loss
d) pumping loss

Answer: b
Explanation: loss due to incomplete combustion

2. In an actual S.I engine the pumping loss with respect to speed ____________
a) increases
b) decreases
c) remains same
d) none of the mentioned

Answer: b
Explanation: In an actual S.I engine the pumping loss with respect to speed decreases

3. The volumetric efficiency is affected by ____________
a) the exhaust gas in the clearance volume
b) the design of intake and exhaust valve
c) valve timing
d) all of the mentioned

Answer: d
Explanation: all of the mentioned

4. In petrol engine the actual pressure developed compared to the predicted maximum pressure is?
a) 90%
b) 70%
c) 50%
d) 25%

Answer: c
Explanation: In petrol engine the actual pressure developed compared to the predicted maximum pressure is 50% while energy released in actual cycle is about 90% of the fuel input.

5. Energy released in actual cycle is about _____________ of the fuel input.
a) 90%
b) 70%
c) 50%
d) 25%

Answer: a
Explanation: 90%

6. The actual efficiency of a good engine is about _____________ of the estimated air fuel cycle efficiency.
a) 100%
b) 85%
c) 50%
d) 25%

Answer: b
Explanation: 85%

7. Fuel air efficiency is less than air standard efficiency by an amount equal to ____________
a) pumping loss
b) friction loss
c) loss due to specific heat and chemical equilibrium
d) exhaust blow down loss

Answer: c
Explanation: loss due to specific heat and chemical equilibrium

8. Fuel air ratio affects maximum power output of the engine due to ___________
a) higher specific heats
b) chemical equilibrium losses
c) all of the mentioned
d) none of the mentioned

Answer: c
Explanation: all of the mentioned

9. The ignition of charge by some hot surface in the engine cylinder before operation of spark plug is known as ____________
a) auto ignition
b) pre-ignition
c) detonation
d) none of the mentioned

Answer: b
Explanation: Pre-ignition is defined as the ignition of charge by some hot surface in the engine cylinder before operation of spark plug.

10. The brake mean effective pressure of an I.C. engine with an increase in speed will ____________
a) increase
b) decrease
c) remain same
d) none of the mentioned

Answer: c
Explanation: The brake mean effective pressure of an I.C. engine with an increase in speed will remain same