The exhaust valve in a four stroke cycle petrol engine
Opens at 50° before bottom dead centre and closes at 15° after top dead centre
Opens at bottom dead centre and closes at top dead centre
Opens at 50° after bottom dead centre and closes at 15° before top dead centre
May open and close anywhere
Correct Answer :
A. Opens at 50° before bottom dead centre and closes at 15° after top dead centre
Related Questions
A fuel of cetane number 40 has the same ignition quality as a mixture of
40% cetane and 60% alpha methyl naphthalene
40% alpha methyl naphthalene and 60% cetane
40% petrol and 60% diesel
40% diesel and 60% petrol
In a four stroke cycle diesel engine, the inlet valve
Opens at 20° before top dead centre and closes at 40° after bottom dead centre
Opens at 20° after top dead centre and closes at 20° before bottom dead centre
Opens at top dead centre and closes at bottom dead centre
May open and close anywhere
A petrol engine, during suction stroke draws
Air only
Petrol only
A mixture of petrol and air
None of these
Fuel oil consumption guarantees for I .C. engine are usually based on
Low heat value of oil
High heat value of oil
Net calorific value of oil
Calorific value of fuel
The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will
Increase
Decrease
Be independent
May increase or decrease depending on other factors
In a typical medium speed 4-stroke cycle diesel engine the inlet valve
Opens at 20° before top dead center and closes at 35° after the bottom dead center
Opens at top dead center and closes at bottom dead center
Opens at 10° after top dead center and closes 20° before the bottom dead center
May open or close anywhere
If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the percentage increase in efficiency will be
2 %
4 %
8 %
14 %
If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the
Exhaust will be smoky
Piston rings would stick into piston grooves
Engine starts overheating
Scavenging occurs
The increase of cooling water temperature in petrol engine will __________ the knocking tendency.
Not effect
Decrease
Increase
None of these
In a typical medium speed 4-stroke cycle diesel engine
Compression starts at 35° after bottom dead center and ends at top dead center
Compression starts at bottom dead center and ends at top dead center
Compression starts at 10° before bottom dead center and, ends just before top dead center
May start and end anywhere
Supercharging is essential in
Diesel engines
Gas turbines
Petrol engines
Aircraft engines
If the speed of the engine is increased, the indicated power will
Increase
Decrease
Remain same
None of these
In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a
Fuel pump
Fuel injector
Spark plug
None of these
A gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is
248 cm3
252 cm3
264 cm3
286 cm3
If the compression ratio in I.C. engine increases, then its thermal efficiency will
Decrease
Increase
Remain same
None of these
In a petrol engine, if diesel is used, then the engine will
Not run
Run more efficiently
Run at high speed
Explode
In a four stroke cycle engine, the sequence of operations is
Suction, compression, expansion and exhaust
Suction, expansion, compression and exhaust
Expansion, compression, suction and exhaust
Compression, expansion, suction and exhaust
The actual volume of fresh charge admitted in 4-stroke petrol engine is
Equal to stroke volume
Equal to stroke volume and clearance volume
Less than stroke volume
More than stroke volume
Scavenging is usually done to increase
Thermal efficiency
Speed
Power output
Fuel consumption
Which of the following statement is correct regarding petrol engines?
A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure
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
The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition
All of the above
An engine indicator is used to determine the following
Speed
Temperature
Volume of cylinder
m.e.p. and I.H.P.
In the opposed piston diesel engine, the combustion chamber is located
Above the piston
Below the piston
Between the pistons
There is no such criterion
High speed compression engines operate on
Otto cycle
Diesel cycle
Dual combustion cycle
All of these
The knock in diesel engine occurs due to
Instantaneous and rapid burning of the first part of the charge
Instantaneous auto ignition of last part of charge
Delayed burning of the first part of the charge
Reduction of delay period
Which of the following statement is wrong?
In compression ignition engines, detonation occurs near the beginning of combustion.
Since the fuel, in compression ignition engines, is injected at the end of compression stroke, therefore, there will be no pre-ignition.
To eliminate knock in compression ignition engines, we want to achieve auto-ignition not early and desire a long delay period.
In compression ignition engines, because of heterogeneous mixture, the rate of pressure rise is comparatively lower.
The air-fuel ratio in petrol engines is controlled by
Controlling valve opening/closing
Governing
Injection
Carburetion
Which of the following does not relate to a compression ignition engine?
Fuel pump
Fuel injector
Governor
Carburettor
In case of gas turbines, the gaseous fuel consumption guarantees are based on
High heat value
Low heat value
Net calorific value
Calorific value
The expansion of fuel in a four stroke cycle diesel engine
Starts at 15° before top dead centre and ends at 30° after top dead centre
Starts at top dead centre and ends at 30° after top dead centre
Starts at 15° after top dead centre and ends at 30° before bottom dead centre
May start and end anywhere
The mean effective pressure obtained from engine indicator indicates the
Maximum pressure developed
Minimum pressure
Instantaneous pressure at any instant
Average pressure