Under idling conditions, the throttle valve of a petrol engine is more or less closed. That provides
Lean mixture
Rich mixture
Chemically correct air-fuel mixture
Only air flows
The automobile exhaust will have maximum of hydrocarbons when the vehicle is
Idling
Cruising
Accelerating
Running at high speeds
Petrol engines are adjusted to give minimum brakes specific fuel consumption at
No lead
25-50% of full load
Around 75% of full load
Near full load
Which unit is generally subjected to fuel lock in petrol engines?
Carburetor
Fuel pump
Suction manifold
Fuel lines
Pressure system is the most commonly used lubrication in automobile engines. In such a system the approximate oil pressure is
20-30 kPa
40-50 kPa
100-200 kPa
200-400 kPa
Control of maximum oil pressure in the lubrication system is effected by
Oil filter
Pressure switch
Pressure relief valve
Pump motor
Most commonly used lubricant in automobile engines is
Vegetable oil
Mineral oil
Animal oil
Synthetic oil
What technique is adopted for lubrication of the cylinder of a scooter engine?
Splash lubrication
Forced feed lubrication
Gravity feed lubrication
Petrol lubrication
What approximate percentage of heat of combustion is lost to the jacket cooling water?
5%
10%
15%
25%
In the automobiles water cooling system, the thermostat comes into operation at about
25oC
40oC
160oC
80oC
A fan is provided in the water cooling system to
Draw the air through the radiator
Provide drive to the water pump
Cool the engine by blowing air over it
Increase flow of coolant
Which is the antifreeze solution commonly used in automobiles?
Carbon disulphide
Alcohol
Ammonium chloride
Brine
The self starter for a car is
ac motor
dc shunt motor
dc series motor
dc 12 volt dynamo
Which part of the engine is directly driven by the starting motor?
Camshaft
Crankshaft
Flywheel
None of the above
The car batteries generally used in India are of the type
Dry battery
Lead-acid battery
Nickel-iron battery
Nickel-cadmium battery
The specific gravity of a fully charged 6 cell automotive battery on being tested by a hydrometer should give a reading of about
1.18
1.29
1.35
1.47
Small stroke-bore ratio (less than unity) in an I.C.engine is to be preferred because it gives
Better combustion
High power ratio
Better scavenging
Less friction
In a variable speed SI engine, the maximum torque occurs at the maximum
Speed
Brake power
Indicated power
Volumetric efficiency
Which of the following factors are responsible for the formation of NOx in spark ignition combustion engine?
incomplete combustion
high temperature
availability of oxygen
Select the correct answer
2 and 3
1 and 2
1 and 3
1, 2 and 3
The silencer of an I.C.engine
Reduce noise
Decreases brake specific fuel consumption
Increases brake specific fuel consumption
Has no effect on its efficiency