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
Correct Answer :
C. Less than stroke volume
Related Questions
The following volume of air is required for consuming 1 litre of fuel by a four stroke engine
1 m3
5 m3
56 m3
910 m3
The inlet valve of a four stroke cycle internal combustion engine remains open for
130°
180°
230°
270°
The air-fuel ratio in petrol engines is controlled by
Controlling valve opening/closing
Governing
Injection
Carburetion
Compression loss in I.C engines occurs due to
Leaking piston rings
Use of thick head gasket
Clogged air inlet slots
All of the above
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
A supercharged engine as compared to an ordinary engine
Requires smaller foundation
Is lighter
Consumes less lubricating oil
All of these
As a result of detonation in an I.C. engine, following parameter attains very high value
Peak pressure
Rate of rise of pressure
Rate of rise of temperature
Peak temperature
The increase of efficiency of a compression ignition engine, as the load decreases, is due to
Higher maximum temperature
Qualitative governing
Quantitative governing
Hit and miss governing
Stoichiometric ratio is
Chemically correct air-fuel ratio by weight
Chemically correct air-fuel ratio by volume
Actual air-fuel ratio for maximum efficiency
None of the above
In a naturally aspirated diesel engine, the air is supplied by
A supercharger
A centrifugal blower
A vacuum chamber
An injection tube
The cetane number of diesel oil, generally available, is
20 to 25
25 to 30
30 to 40
40 to 55
The pressure at the end of compression, in diesel engines, is approximately
10 bar
20 bar
25 bar
35 bar
A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of
75% iso-octane and 25% normal heptane
75% normal heptane and 25% iso-octane
75% petrol and 25% diesel
75% diesel and 25% petrol
Detonation is harmful due to
Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine
Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls
High intensity of knock causes crankshaft vibration and the engine runs rough
None of the above
The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be
25 %
50 %
70 %
100 %
Which of the following statement is wrong?
A four stroke cycle engine develops twice the power as that of a two stroke cycle engine
For the same power developed, a four stroke cycle engine is lighter, less bulky and occupies less floor area
The petrol engines are costly than diesel engines
All of the above
The knocking in diesel engines may be prevented by
Reducing the delay period
Raising the compression ratio
Increasing the inlet pressure of air
All of these
It the temperature of intake air in IC engines is lowered, then its efficiency will
Increase
Decrease
Remain same
Increase up to certain limit and then decrease
A stoichiometric air-fuel ratio is
Chemically correct mixture
Lean mixture
Rich mixture for idling
Rich mixture for over loads
The knocking tendency in spark ignition engines may be decreased by
Controlling the air-fuel mixture
Controlling the ignition timing
Controlling the exhaust temperature
Reducing the compression ratio
The cetane (C16H34) which is a straight chain paraffin, is assigned a cetane number of
0
50
100
120
A diesel engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
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
A diesel engine is _________ as compared to petrol engine, both running at rated load.
Equally efficient
Less efficient
More efficient
None of these
The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
Net efficiency
Efficiency ratio
Relative efficiency
Overall efficiency
Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle
A higher compression ratio causes
Pre-ignition
Increase in detonation
Acceleration in the rate of combustion
Any one of these
The firing order in an I.C. engine depends upon
Arrangement of the cylinders
Design of crankshaft
Number of cylinders
All of these
In a cycle, the spark lasts roughly for
1 sec
0.1 sec
0.01 sec
0.001 sec
The frictional power (F.P.) is given by
F.P. = B.P. - I.P.
F.P. = I.P. - B.P.
F.P. = B.P./I.P.
F.P. = I.P./B.P.