1. Maximum economy of engine, is obtained at the air fuel ratio of _________
a) 13.5:1 to 15:1
b) 15.5:1 to 18:1
c) 8:1 to 15:1
d) 7:1 to 10:1
Discussion
Explanation: Air-fuel ratio (AFR) is the ratio of mass of air to a solid or liquid or a gaseous fuel which is present during combustion. This combustion shall take place in a controller environment such as inside an IC engine or an industrial furnace. Maximum economy of engine, is obtained at the air fuel ratio is 13.5:1 to 15:1.
2. The lowest speed of engine at which the engine runs smoothly is called ________
a) at least speed
b) threshold speed
c) minimum speed
d) idling speed
Discussion
Explanation: Idle speed is the rotational speed of an engine when the engine is idling. An engine is said to be idle when the engine is not coupled from its drivetrain and the pedal for throttling is not in a depressed position. Idle speed is usually measured in RPM (revolutions per minute). At this speed, the engine will be generating enough power to run smoothly but it won’t be sufficient to perform any useful work.
3. Horse power of engines varies with ___________
a) air fuel ratio
b) amount of fuel in air fuel mixture
c) amount of air in air fuel mixture
d) engine speed
Discussion
Explanation: Air–fuel ratio (AFR) is the mass ratio of air to a solid, liquid, or gaseous fuel present in a combustion process. The horsepower of an engine is the power output of the engine, usually available at the crankshaft. So, if an engine is rated at 100 HP, it means that at the crankshaft of the engine, 100 horsepower of mechanical power is available when the engine is operating.
4. Preignition can be caused due to presence of ______
a) excess lubricants in cylinder
b) gum in fuel
c) over-heated spark plug
d) higher volume of air in air fuel mixture
Discussion
Explanation: Pre-ignition is a condition or situation in which the fuel and air mixture in spark plugin ignites before the timed spark and this can happen due to contact with hot surface. So, if the spark plug is over heated or its tip is too hot, it can result in pre-ignition.
5. In magnetic ignition system, the primary current is produced by __________
a) battery
b) magnet
c) electrical current
d) ice
Discussion
Explanation: A magnetic ignition system provides current primarily for the spark-ignition system of a petrol engine. This is achieved by producing pulses of high voltage for the spark plugs. In such systems, the primary current is produced by the use of a Magnet.
6. In spark ignited engines, the fuel tank is placed ___________
a) Above the level of carburettor
b) Below the cylinder
c) Below the level of carburettor
d) In the carburettor
Discussion
Explanation: In spark ignition engines, the fuel tank is placed above the level of the carburettor. The fuel flows from the fuel tank to the carburettor under the action.
7. The function of sediment bowl in fuel supply system is ___________
a) To hold the dust and dirt of the fuel
b) To maintain a good pressure
c) To hold the air in the cylinder
d) To clear the air entering into combustion chamber
Discussion
Explanation: This filter is mostly fitted on the fuel lift pump. It prevents dust and foreign materials from reaching inside the fuel line. It usually consists of a glass cap with gasket. Heavy dust particles settle at the bottom and clean full flows ahead.
8. The engine part in which carburation takes place is ___________
a) Radiator
b) Carburettor
c) Cylinder
d) Sediment bowling
Discussion
Explanation: Carburation is a process of preparing an air fuel mixture away from the cylinder of an engine on the device in which this process takes place is called carburettor.
9. In engines, the function of choke, is to ___________
a) Provide a rich air-fuel mixture
b) Heat the engine
c) Increase fuel in the cylinder
d) Remove the cylinder blockage
Discussion
Explanation: A choke is a butterfly value which is used to provide a richer mixture of air-fuel for the engine to start in cold condition.
10. In engine, the choke controls ___________
a) Volume of fuel
b) Heat of engine
c) Volume of air into venture
d) Speed of engine
Discussion
Explanation: A choke is a butterfly value which controls the volume of air entering into the venture. A venture is provided to produce low pressure in the throat of the carburettor.