Question 51 : The maximum propulsive efficiency of a turbo-jet engine is at a speed of
1. 3000 km/h
2. 1000 km/h
3. 2000 km/h
4. 2400 km/h
View Answer   Discuss with Members

Question 52 : Which of the following statement is wrong ?
1. In compression ignition engines, detonation occurs near the beginning of combustion.
2. Since the fuel, in compression ignition engines, is injected at the end of compression stroke, therefore, there will be no pre-ignition.
3. To eliminate knock in compression ignition engines, we want to achieve auto-ignition not early and desire a long delay period.
4. In compression ignition engines, because of hetrogeneous mixture, the rate of pressure rise is comparatively lower
View Answer   Discuss with Members

Question 53 : In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then __________ is employed.
1. carburettor
2. fuel pump
3. injector
4. none of these
View Answer   Discuss with Members

Question 54 : The colour of exhaust from diesel engine is generally.
1. bluish
2. A. white
3. black
4. violent
View Answer   Discuss with Members

Question 55 : A mixture containing 65% of iso-octane and 35% of normal heptane will have
1. cetane number 65
2. octane number 65
3. octane number 35
4. qetane number 35
View Answer   Discuss with Members

Question 56 : Supercharging __________ the power developed by the engine.
1. all of these
2. increases
3. decreases
4. has no effect on
View Answer   Discuss with Members

Question 57 : In compression ignition engines, swirl denotes a
1. rotary motion of the gases in the chamber
2. radial motion of the gases in the chamber
3. haphazard motion of the gases in the chamber
4. none of the above
View Answer   Discuss with Members

Question 58 : Which of the following statement is correct regarding petrol engines?
1. all of the above
2. The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug.
3. The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition.
4. A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure.
View Answer   Discuss with Members

Question 59 : The knocking in spark ignition engines can be reduced by
1. none of these
2. increasing the engine speed
3. both (a) and (b)
4. retarding the spark
View Answer   Discuss with Members

Question 60 : A higher compression ratio causes
1. increase in detonation
2. an acceleration in the rate of combustion
3. pre-ignition
4. any one of these
View Answer   Discuss with Members