If the air-fuel mixture ignites before the spark takes place at spark plug, the condition is called
Detonation
Ignition
Pre-ignition
Rumble
Correct Answer :
C. Pre-ignition
Related Questions
Instead of valves, the ports are used in case of
Four stroke I.C. engines
Two stroke I.C. engines
V6 engines
None of these
The function of a proportioning control valve (PCV) in a brake system is to
Ensure that equal pressure is supplied to the front and rear brakes throughout every braking operation
Reduce the brake fluid pressure when the brakes approach their lockup point
Cause less brake fluid pressure to act on the front brakes than on the rear brakes when the fluid pressure exceeds a predetermined level
Cause less brake fluid pressure to act on the rear brakes than on the front brakes when the fluid pressure exceeds a predetermined level.
The basic function of the suspension is to
Absorbs vibration and impact forces from the road surface
Ensure that the steering wheel can deliver a suitable amount of steering force
Ensure that wheel alignment is not disturbed during driving
Automatically correct the effects of over steering
The purpose of adding pigment to the paint is that it
Optimises the viscosity of paint
Makes paint film hard
Gives colour and filling up effect to the paint
None of the above
The specific gravity of acid in a fully charged battery is generally
1.00
1.28
1.82
2.81
The specific gravity of petrol is about
0.75
0.85
0.95
1.25
Cushioning springs in clutch plate reduces
Vehicle speed
Torsional vibrations
Jerky starts
None of these
The ease with which petrol vaporizes is called its
Oxidation
Octane number
Volatility
Cetane number
The compression ratio in petrol engine is kept less than in Diesel engine because
It makes petrol engines lighter
Higher or equivalent compression ratio in petrol engines is not possible due to pre-ignition
Less compression ratio gives better performance
It is just customary to have less compression ratio in petrol engines
When the piston is at T.D.C, the volume above the piston in the combustion chamber is the
Clearance volume
Cylinder volume
Exhaust volume
None of these
The damper fluid leakage typically occur from
Upper damper mounting
Bottom of damper
Clearance between inner and outer tubes of damper
Coil spring mounting
The calorific value of petrol is about
36.5-38.5 MJ/kg
39.4-42.5 MJ/kg
42.7-43.5 MJ/kg
45.5-47 MJ/kg
What type of bearing is used for main bearings and connecting rod bearings?
Ball bearings
Plain bearings
Needle roller bearing
Taper roller bearing
In which of the following conditions, the idle CO percentage should be measured with the vehicle?
Headlights and other electrical devices are switched off
Headlights and other electrical devices are switched on
Headlights and other lights are switched off
Headlights are switched on
The Diesel engine works on
Otto cycle
Carnot cycle
Diesel cycle
Rankine cycle
A basic difference between the spark ignition engine and the Diesel engine is that the
Diesel engine compresses air alone instead of an air-fuel mixture
Air temperature ignites the fuel in the Diesel engine
Fuel is sprayed into the combustion chamber in the Diesel engine as the piston nears T.D.C. on the compression stroke
All of the above
When indicated power (I.P.) and frictional power (F.P.) are known, we can calculate
Brake power
Compression ratio
Specific air consumption
Mean effective pressure
In petrol engines, during suction stroke, ________ is drawn in the cylinder
Air and fuel
Only fuel
Only air
None of these
Which part of the automobile tyre is subjected to greatest flexing action?
Bead
Side wall
Shoulder
Tread
The temperature indicating instrument in vehicles indicates the temperature of
Engine piston
Engine cylinder
Lubricating oil
Jacket cooling water
The valve tappet clearance is measured by
Screw pitch gauge
Engineering scale
Feeler gauge
Vernier caliper
The petrol engines are also known as
Spark ignition (S.I.) engines
Compression ignition (C.I.) engines
Steam engines
None of these
The power source for a brake booster is
Exhaust manifold pressure
Electricity
The pressure difference between the atmospheric pressure and the vacuum pressure in the intake manifold
Hydraulic pump
For the same maximum pressure and temperature
Diesel cycle is more efficient than Otto cycle
Otto cycle is more efficient than Diesel cycle
Both Otto cycle and Diesel cycle are equally efficient
None of the above
When turning a corner
The front wheels are toeing out
The front wheels are turning on different angles
The inside front wheels has a greater angle than the outside wheel
All of the above
It is necessary to maintain the valve clearances as they
Reduce the resistance to sliding that occurs between the cam and the tappet
Allow for lengthening of the valves owing to the heat of combustion
Increase the speed at which the valves move up and down
Make the crankshaft turn smoothly
In bias ply tyres
All plies run parallel to one another
Belts of steel mesh are used in the tyres
One ply layer runs diagonally one way and another layer runs diagonally the other way
All of the above
The commonly used antifreeze solution in automobiles is
Carbon disulphide
Ethylene glycol
Ammonium chloride
Freon-12
In a four speed four stroke Diesel engine, the intake valve
Opens at T.D.C. and closes at B.D.C.
Opens at 20° before T.D.C. and closes at 35° after B.D.C.
Opens at 10° after T.D.C. and closes at 20° before B.D.C.
None of the above
The torque converter uses ________ to transfer torque.
Air
Automatic transmission fluid (ATF)
Gears
Steel belt