McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Uncategorized topics .
| 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 |
| Answer» A. higher | |
| 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 |
| Answer» B. petrol engine | |
| 107. |
A spark plug should be located at the |
| A. | center of cylinder head |
| B. | near the inlet valve |
| C. | near the exhaust valve |
| D. | none of the above |
| Answer» A. center of cylinder head | |
| 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 |
| Answer» B. reduce | |
| 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 |
| Answer» A. increase | |
| 111. |
SI engines are |
| A. | always over loaded |
| B. | never over loaded |
| C. | both a and b |
| D. | it does not matter |
| Answer» B. never over loaded | |
| 112. |
Which of the following factor decreases detonation in SI engines |
| A. | increased cr |
| B. | advancing the spark timing |
| 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 |
| Answer» B. to avoid preignition | |
| 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 |
| Answer» A. increase | |
| 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 |
| Answer» B. decrease | |
| 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 |
| Answer» A. long flame travel | |
| 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 |
| D. | provides cooler cylinder head |
| 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 |
| Answer» B. 70 | |
| 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 |
| Answer» A. reduces auto-ignition | |
| 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 |
| Answer» 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 |
| Answer» C. 70 to 80 | |
| 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 |
| Answer» A. octane rating | |
| 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 |
| Answer» C. toluene rating | |
| 138. |
Performance number of iso-octane is |
| A. | 1 |
| B. | 100 |
| C. | zero |
| D. | 50 |
| Answer» B. 100 | |
| 139. |
The maximum compression ratio which can be used without knocking is |
| A. | hcr |
| B. | hucr |
| C. | pn |
| D. | on |
| Answer» B. hucr | |
| 140. |
Ideal fuel for SI engine should have |
| A. | low sit |
| B. | high sit |
| C. | low cv |
| D. | less volatility |
| Answer» B. high sit | |
| 141. |
Which is not true about L-head combution chamber? |
| 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 |
| Answer» C. near exhaust valve | |
| 144. |
Which is not true about I-head combution chamber? |
| A. | higher volumetric efficiency |
| B. | non-uniform pressure rise |
| C. | permits higher compression ratio |
| D. | less flame travel |
| Answer» B. non-uniform pressure rise | |
| 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 |
| Answer» 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 |
| Answer» C. quantity governing | |
| 147. |
Economizer is used to provide enriched mixture during |
| A. | starting |
| B. | idling |
| C. | cruising |
| D. | full throttle opening |
| Answer» 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 |
| Answer» B. lean | |
| 149. |
The choke in automobile carburettor system is meant for supplying |
| A. | lean mixture |
| B. | rich mixture |
| C. | stoichiometric mixture |
| D. | weak mixture |
| Answer» B. rich mixture | |
| 150. |
Modern carburettor provide the correct qaulity of air-fuel mixture during |
| A. | starting |
| B. | idling |
| C. | cruising |
| D. | all conditions |
| Answer» D. all conditions | |
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