List Of 100 Objective Questions On Ic Engines
1.The pressure at the end of compression in the case of diesel engine is of the order of
6 kg/cm
12kg/cmz
20 kg/cmz
27.5 kg/cmz
35 kg/cm
ANSWER : : 35 kg/cm
2.The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
net efficiency
efficiency ratio
relative efficiency
overall efficiency
cycle efficiency.
ANSWER : : relative efficiency
3.Compression ratio of LC. engines is
the ratio of volumes of air in cylinder before compression stroke and after compression stroke
volume displaced by piston per stroke and clearance volume in cylinder
ratio of pressure after compression and before compression
swept volume/cylinder volume
cylinder volume/swept volume.
ANSWER : : the ratio of volumes of air in cylinder before compression stroke and after compression stroke
4.Supercharging is the process of
supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere
providing forced cooling air
injecting excess fuel for raising more load
supplying compressed air to remove combustion products fully
raising exhaust pressure.
ANSWER : : supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere
5.The specific fuel consumption per BHP hour for diesel engine is approximately
0.15 kg
0.2 kg
0.25 kg
0.3 kg
0.35 kg.
ANSWER : : 0.2 kg
6.The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed
80�C
120�C
180�C
240�C
320�C.
ANSWER : : 180�C
7.In a diesel engine, the fuel is ignited by
spark
injected fuel
heat resulting from compressing air that is supplied for combustion
ignitor
combustion chamber.
ANSWER : : heat resulting from compressing air that is supplied for combustion
8.The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is
same
less
more
more or less depending on power rating
unpredictable.
ANSWER : : more
9.If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the %age increase in efficiency will be
2%
4%
8%
14%
27%.
ANSWER : : 14%
10.All heat engines utilize
low heat value of oil
high heat value of oil
net claorific value of oil
calorific value of fuel
all of the above.
ANSWER : : low heat value of oil
11.The maximum temperature in the I.C. engine cylinder is of the order of
500- 1000�C
1000- 1500�C
1500-2000�C
2000-2500�C
2500-3000�C
ANSWER : : 2000-2500�C
12.The calorific value of gaseous fuels is expressed in terms of
kcal
kcal/kg
kcal/m2
kcal/n?
all of the above.
ANSWER : : kcal/n?
13.Pick up the wrong statement
2-stroke engine can run in any direction
In 4-stroke engine, a power stroke is obtained in 4-strokes
thermal efficiency of 4-strokc engine is more due to positive scavenging
petrol engines work on to cycle
petrol engines occupy more space than diesel engines for same power output.
ANSWER : : petrol engines occupy more space than diesel engines for same power output.
14.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
none of the above.
ANSWER : : decrease
15.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
remains open for 200�.
ANSWER : : opens at 20� before top dead center and closes at 35� after the bottom dead center
16.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
all of the above.
ANSWER : : high heat value of oil
17.The fuel in diesel engine is normally injected at pressure of
5-10 kg/cm2
20-25 kg/cm2
60-80 kg/cm2
90-130 kg/cm2
150-250 kg/cm2
ANSWER : : 90-130 kg/cm2
18.Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged ?
yes
no
to some extent
unpredictable
depends on other factors.
ANSWER : : no
19.In case of gas turbines, the gaseous fuel consumption guarantees are based on
high heat value
low heat value
net calorific value
middle heat value
calorific value.
ANSWER : : low heat value
20.The pressure and temperature at the end of compression stroke in a petrol engine are of the order of
4 – 6 kg/cm2 and 200 – 250�C
6 – 12 kg/cm2 and 250 – 350�C
12 – 20 kg/cm2 and 350 – 450�C
20 – 30 kg/cm2 and 450 – 500�C
30 – 40 kg/cm2 and 500 – 700�C.
ANSWER : : 6 – 12 kg/cm2 and 250 – 350�C
21.An engine indicator is used to determine the following
speed
temperature
volume of cylinder
m.e.p. and I.H.P.
BHP.
ANSWER : : m.e.p. and I.H.P.
22.If the intake air temperature of I.C. engine increases, its efficiency will
increase
decrease
remain same
unpredictable
depend on other factors.
ANSWER : : decrease
23.Scavenging air in diesel engine means
air used for combustion sent under pres-sure
forced air for cooling cylinder
burnt air containing products of com-bastion
air used for forcing burnt gases out of engine’s cylinder during the exhaust period
air fuel mixture.
ANSWER : : air used for forcing burnt gases out of engine’s cylinder during the exhaust period
24.Combustion in compression ignition engines is
homogeneous
heterogeneous
both (a) and (b)
laminar
turbulent.
ANSWER : : heterogeneous
25.The output of a diesel engine can be increased without increasing the engine revolution or size in following way
feeding more fuel
increasing flywheel size
heating incoming air
scavenging
supercharging.
ANSWER : : supercharging.
26.The air-fuel ratio of the petrol engine is controlled by
fuel pump
governor
injector
carburettor
scavenging.
ANSWER : : carburettor
27.A 75 cc engine has following parameter as 75 cc
fuel tank capacity
lub oil capacity
swept volume
cylinder volume
clearance volume.
ANSWER : : swept volume
28.Which of the following is not an interna combustion engine
2-stroke petrol engine
4-stroke petrol engine
diesel engine
gas turbine
steams turbine.
ANSWER : : steams turbine.
29.The accunmulation of carbon in a cylinder results in increase of
clearance volume
volumetric efficiency
ignition time
effective compression ratio
valve travel time.
ANSWER : : effective compression ratio
30.The specific fuel consumption per BH hour for a petrol engine is approximately
0.15 kg
0.2 kg
0.25 kg
0.3kg
0.35 kg.
ANSWER : : 0.25 kg
31.In diesel engine the diesel fuel injected intc cylinder would burn instantly at about compressed air temperature of
250�C
500�C
1000�C
150CPC
2000�C.
ANSWER : : 1000�C
32.It the temperature of intake air in IC engines is lowered, then its efficiency will
increase
decrease
remain same
increase upto certain limit and then decrease
decrease upto certain limit and then in-crease.
ANSWER : : increase
33.Pick up the false statement
Thermal efficiency of diesel engine i about 34%
Theoretically correct mixture of air am petrol is approximately 15 : 1
High speed compression engines operate on dual combustion cycle
Diesel engines are compression ignition engines
S.I. engines are quality-governed engines.
ANSWER : : S.I. engines are quality-governed engines.
34.The air requirement of a petrol engine during starting compared to theoretical required for complete combustion is
more
loss
same
may be more or less depending on engine capacity
unpredictable.
ANSWER : : loss
35.The rating of a diesel engine, with increase in air-intlet temperature, will
increase linearly
decrease linearly
increase parabolically
decrease parabolically
first decrease linearly and then increase parabolically.
ANSWER : : decrease linearly
36.In a typical medium speed, 4-stroke cycle diesel engine
fuel injection starts at 10� before to dead center and ends at 20� after tor dead center
fuel injection starts at top dead center and ends at 20� after top dead center
fuel injection starts at just before top dead center and ends just after top dead center
may start and end anywhere
none of the above.
ANSWER : : fuel injection starts at 10� before to dead center and ends at 20� after tor dead center
37.Compression loss in I.C engines occurs duto
leaking piston rings
use of thick head gasket
clogged air-inlet slots
increase in clearance volume caused b bearing-bushing wear
all of the above.
ANSWER : : all of the above.
38.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
none of the above.
ANSWER : : compression starts at 35� after bottom dead center and ends at top dead center
39.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
exhaust temperature will be high
engine starts overheating
scavenging occurs.
ANSWER : : scavenging occurs.
40.Diesel fuel, compared to petrol is
less difficult to ignite
just about the same difficult to ignite
more difficult to ignite
highly ignitable
none of the above.
ANSWER : : more difficult to ignite
41.Which of the following medium is compressed in a Diesel engine cylinder
air aione
air and fuel
air and lub oil
fuel alone
air, fuel and lub oil.
ANSWER : : air aione
42.For the same compression ratio
Otto cycle is more efficient than the Diesel
Diesel cycle is more efficient’than Otto
both Otto and Diesel cycles are, equally efficient
compression ratio has nothing to do with efficiency
which is more efficient would depend on engine capacity.
ANSWER : : Otto cycle is more efficient than the Diesel
43.When crude oil is heated, then which of the following hydrocarbon is given off first.
kerosene
gasoline
paraffin
diesel
natural gas.
ANSWER : : natural gas.
44.Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle
Carnot cycle.
ANSWER : : Dual combustion cycle
45.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
rate of rise of horse-power.
ANSWER : : rate of rise of pressure
46.The inlet value of a four stroke cycle I.C engine remains open for nearly
180�
125�
235�
200�
275�.
ANSWER : : 235�
47.The precess of breaking up or a liquid into fine droplets by spraying is called
vaporisation
carburetion
ionisation
injection
atomisation.
ANSWER : : atomisation.
48.Which of the following statements is cor�rect?
All the irreversible engines have same efficiency
All the reversible engines have same efficiency
Both Rankine and Caront cycles have same efficiency between same tempera�ture limits
All reversible engines working between same temperature limits have same-ef-ficiency
Between same temperature limits, both petrol and diesel engines have same ef-ficiency.
ANSWER : : All reversible engines working between same temperature limits have same-ef-ficiency
49.Pick up the wrong statement about supercharging
supercharging reduces knocking in diesel engines
there can be limited supercharging in petrol engines because of detonation
supercharging at high altitudes is essential
supercharging results in fuel economy
supercharging is essential in aircraft engines.
ANSWER : : supercharging results in fuel economy
50.Engine pistons ‘are usually made of aluminum alloy because it
is lighter
wears less
absorbs shocks
is stronger
does not react with fuel and lub oil.
ANSWER : : is lighter
51.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
more than cylinder volume.
ANSWER : : less than stroke volume
52.In diesel engine, the compression ratio in comparison to expansion ratio is
same
less
more
variable
more/less depending on engine capacity.
ANSWER : : more
53.Which of the following is false statement. Some of the methods used to reduce diesel smoke are as follows
using additives in the fuel
engine derating i.e. reducing the maxi-mum flow of fuel
increasing the compression ratio
adherence to proper fuel specification
avoidance of overloading.
ANSWER : : increasing the compression ratio
54.The term scavenging is generally associated with
2-stroke cycle engines
4-stroke cycle engines
aeroplane engines
diesel engines
high efficiency engines.
ANSWER : : high efficiency engines.
55.The size of inlet valve of.an engine in comparison to exhaust valve is
more
less
same
more/less depending on capacity of engine
varies from design to design.
ANSWER : : less
56.A diesel engine as compared to petrol engine (both running ar rated load) is
more efficient
less efficient
equally efficient
unpredictable
other factors will decide it.
ANSWER : : more efficient
57.Flash point of fuel oil is
minimum temperature to which1 oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
temperature at which it solidifies or congeals
temperature at which it catches fire without external aid
indicated by 90% distillation temperature, i.e. when 90% of sample oil has distilled off
none of the above.
ANSWER : : minimum temperature to which1 oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
58.In a typical medium speed 4 stroke cycle diesel engine
exhaust valve opens at 35� before bot-tom dead center and closes at 20� after top dead center
exhaust valve opens at bottom dead center and closes at top dead center
exhaust valve opens just after bottom dead center and closes just before top dead center
may open and close anywhere
none of the above is true.
ANSWER : : exhaust valve opens at 35� before bot-tom dead center and closes at 20� after top dead center
59.Gaseous-fuel guarantees are based on
calorific value of oil
low heat value of oil
high heat value of oil
mean heat value of oil
all of the above.
ANSWER : : low heat value of oil
60.The cam shaft of a four stroke I.C. engine running at 1500 rmp will run at
1500 rpm
750 rpm
3000 rpm
any value independent of engine speed
none of the above.
ANSWER : : 750 rpm
61.Polymerisation is a chemical process in which molecules of a compound become
larger
slowed down
smaller
liquid
gaseous.
ANSWER : : larger
62.The fuel air ratio in a petrol engine fitted with suction carburetor, operating with dirty air filter as compared to clean filter will be
higher
lower
remain unaffected
unpredictable
none of the above.
ANSWER : : higher
63.Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads
the friction is high
the friction is unpredictable
the small difference in cooling water temperature or in internal friction has a disproportionate effect
the engine is rarely operated
none of the above.
ANSWER : : the small difference in cooling water temperature or in internal friction has a disproportionate effect
64.The operation of forcing additional air under pressure in the engine cylinder is known as
scavenging
turbulence
supercharging
pre-ignition
dissociation and carburretion of fuel.
ANSWER : : supercharging
65.Which of the following is false statement : Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following
piston ring and cylinder wear
formation of hard coating on piston skirts
oil sludge in the engine crank case
detonation
forms corrosive acids.
ANSWER : : detonation
66.The reason for supercharging in any engine is to
increase efficiency
increase power
reduce weight and bulk for a given out-put
effect fuel economy
none of the above.
ANSWER : : reduce weight and bulk for a given out-put
67.Supercharging is essential in
diesel engines
gas turbines
petrol engines
aircraft engines
marine engines.
ANSWER : : aircraft engines
68.In a cycle, the spark lasts roughly for
1 sec
0.1 sec
0.01 sec
0.001 sec
0.0001 sec.
ANSWER : : 0.001 sec
69.The minimum cranking speed in case of petrol engine is about
half the operating speed
one-fourth of operating speed
250-300 rpm
60-80 rpm
10-20 rpm
ANSWER : : 60-80 rpm
70.The magneto in an automobile is basically
transformer
d.c. generator
capacitor
magnetic circuit
a.c. generator.
ANSWER : : d.c. generator
71.The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is
same
more
less
less or more depending on operating conditions
unpredictable.
ANSWER : : more
72.Most high speed compression engines operate on
Otto cycle
Diesel cycle
Dual cycle
Carnot cycle
Two stroke cycle.
ANSWER : : Dual cycle
73.Air fuel ratio for idling speed of a petrol engine is approximately
1 : 1
5 : 1
10:1
15 : 1
20 : 1.
ANSWER : : 10:1
74.In the opposed piston diesel engine, the combustion chamber is located
above the piston (/;) below the piston
between the pistons
any when
there is no such criterion.
opt 5
ANSWER : : between the pistons
75.In the crankcase method of scavenging, the air pressure is produced by
supercharger
centrifugal pump
natural aspirator
movement of engine piston
reciprocating pump.
ANSWER : : movement of engine piston
76.In loop scavenging, the top of the piston is
flat
contoured
slanted
depressed
convex shaped.
ANSWER : : contoured
77.Scavenging is usually done to increase
thermal efficiency
speed
power output
fuel consumption
all of the above.
ANSWER : : power output
78.For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of
9 : 1
12 : 1
15 : 1
18 : 1
20: 1.
ANSWER : : 12 : 1
79.Air fuel ratio at which a petrol engine can not work is
8 : 1
10 : 1
15 : 1
20 : 1 and less
will work at all ratios.
ANSWER : : 20 : 1 and less
80.Which of the following is the lightest and most volatile liquid fuel
diesel
kerosene
fuel oil
gasoline
lub oil.
ANSWER : : gasoline
81.A stoichiometric air-fuel ratio is
chemically correct mixture
lean mixture
rich mixture for idling
rich mixture for over loads
the ratio used at full rated parameters.
ANSWER : : chemically correct mixture
82.Pour point of fuel oil is the
minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
temperature at which it solidifies or congeals
it catches fire without external aid
indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off
temperature at which it flows easily.
ANSWER : : temperature at which it solidifies or congeals
83.Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power
upto 25%
upto 35%
upto 50%
upto 75%
upto 100%.
ANSWER : : upto 100%.
84.A hmh flame speed is obtained in diesel engine when air fuel ratio is
uniform throughout the mixture
chemically correct mixture
about 3-5% rich mixture
about 10% rich mixture
about 10% lean mixture.
ANSWER : : about 10% rich mixture
85.The following volume of air is required for consuming 1 liter of fuel by a four stroke engine
1 m3
5 m3
5-6 m3
9-10 m3
15-18 m3.
ANSWER : : 9-10 m3
86.The air-fuel ratio in petrol engines-is controlled by
controlling valve opening/closing
governing
injection
carburettion
scavenging and supercharging.
ANSWER : : carburettion
87.A 5 BHP engine running at full load would consume diesel of the order of
0.3 kg/hr
1 kg/hr
3 kg/hr
5 kg/hr
10 kg/hr.
ANSWER : : 1 kg/hr
88.The theoretically correct air fuel ratio for petrol engine is of the order of
6 : 1
9 : 1
12 : 1
15 : 1
20 : 1.
ANSWER : : 15 : 1
89.In a naturally aspirated diesel engine, the air is supplied by
a supercharger
a centrifugal blower
a vacuum chamber
an injection tube
forced chamber
ANSWER : : a vacuum chamber
90.For the same power developed in I.C. engines, the cheaper system is
naturally aspirated
supercharged
centrifugal pump
turbo charger
none of the above.
ANSWER : : supercharged
91.Diesel engine can work on very lean air fuel ratio of the order of 30 : 1. A petrol engine can also work on such a lean ratio provided
it is properly designed
best quality fuel is used
can not work as it is impossible
flywheel size is proper
engine cooling is stopped.
ANSWER : : can not work as it is impossible
92.A diesel engine has
1 valve
2 valves
3 valves
4 valves
no valve.
ANSWER : : 3 valves
92.The knock in diesel engine occurs due to
instantaneous and rapid burning of the first part of the charge
instantaneous atuo iginition of last part of charge
delayed burning of the first part of the charge
reduction of delay period
all of the above.
ANSWER : : instantaneous and rapid burning of the first part of the charge
93.Volatility of diesel fuel oil is
minimum temperature to which oil is heated in order to give off inflam�mable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
temperature at which it solidifies or congeals
it catches fire without external aid
indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off
temperature at which it flows easily.
ANSWER : : indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off
94.Which is more viscous lib oil
SEA 30
SAE 40
SAE 50
SAE 70
SAE 80.
ANSWER : : SAE 80.