1995

Directions: The following sixteen items consist of two statements, one labelled the 'Assertion
A 'and the other labelled the 'Reason R'. You are to examine these two statements carefully
and decide if the Assertion A and the Reason R are individually true and if so, whether the
Reason is a correct explanation of the Assertion. Select your answer to these items using the
Codes given below and mark your answer sheet accordingly. 

Codes: (a) Both A and R are individually true and R is the correct explanation of A

(b) Both A and R are true but R is not a correct explanation of A

(c) A is true, but R is false

(d) A is false, but R is true. 

Assertion (A): A simple carburettor which is set to give a correct mixture at low air speeds
will give a progressively rich mixture as the air speed is increased.

Reason (R) : As the pressure difference over the jet of a simple carburettor increases the
weight of petrol discharge increases at a greater rate than does the air supply.

Explanation: (a) Both A and R are true and R provides correct explanation for A.

Match List I(Operating mode of SI engine) with List II (Appropriate Air-Fuel ratio) and
select the correct answer using the codes given below the lists:

List I List II

A. Idling 1. 12.5

B. Cold starting 2. 9.0

C. Cruising 3. 16.0

D. Maximum power 4. 22.0

5. 3.0

Codes:

A B C D

(a) 2 4 5 1

(b) 1 3 4 2
(c) 5 2 1 3

(d) 2 5 3 I

Sol. (d) Correct matching is A-2, B-5, C-3 D-I.

A gas engine has a swept volume of 300 cc and clearance volume of 25 cc. Its volumetric
efficiency is 0.88 and mechanical efficiency is 0.90. What is the volume of the mixture taken
in per stroke?

248 cc

252 cc

264 cc

286 cc

Sol. (c)

Match List I with List II, in respect of SI engines, and select the correct answer by using the
codes given below the lists: 
List I List II

A. Highest useful compression ratio  1. Ignitable mixture

B. Dopes  2. Knock rating of fuels
C. Limiting mixture strength 3. Detonation
D. Delay period  4. Chain of chemical reactions in
combustion chamber.

Codes:

A B C D

(a) 2 3 1 4

(b) 3 2 1 4

(c) 3 4 1 2

(d) 2 3 4 1

Codes: ABC D (a) 2 3 1 4 (e) 2 3 4 I Sol. (b) Correct matching is A-3, B-2, C-I, D-4. 

By higher octane number of 51 fuel, it is meant that the fuel has 

higher heating value
higher flash point
lower volatility
long ignition delay
Sol. (d) A fuel with higher octane number has longer ignition delay. 

Which of the following factors would increase the probability of knock in the CI engines? 
1. Long ignition delay of fuel
2. Self ignition temperature of fuel
3. Low volatility of fuel
Select the correct answer using the codes given below:
Codes: (a) 1,2 and 3
(b) I and 2
(c) I and 3
(d) 2 and 3.
Sol. (b) Long ignition delay and low self ignition temperature would increase the probability
of knock in c.I. engines. 

What does the Y-axis represent?

(a) Efficiency

(b) Specific fuel consumption

(c) Air-fuel ratio

(d) Total fuel consumption.

Sol. (d) Y-axis represents total fuel consumption.

Keeping other parameters constant brake power diesel engine can be increased by 
(a) decreasing the density of intake air
(b) increasing the temperature of intake air
(c) increasing the pressure of intake air
(d) decreasing the pressure of intake air.
Sol. (c) Brake power of diesel engine can be increased by increasing pressure of intake air. 

The method of determination of indicated power of multicylinder 51engine is by the use of 
(a) Morse test (b) Prony brake test (c) Motorint test (d) Heat balance test. Sol. (a) Morse test
is used to determine indicated power of multicylinder S.1.engine.

1996

Assertion (A): In SI engines, as the engine speed increases, spark is required to be advanced. 
Reason (R) : As the engine speed increases, flame velocity increases.
Sol. (c) A is true but R is false. 
Assertion (A): A very high compression ratio is favoured for a CI engine, in order to attain
high mechanical efficiency without knocking.
Reason (R): The delay period in CI combustion affects rate of pressure rise and hence
knocking.

Sol. (d) A is false but R is true.

61. Assertion (A): In a gas turbine, reheating is preferred over regeneration to yield a higher
thermal efficiency. 
Reason (R) The thermal efficiency given by the ratio of the difference of work done by
turbine (W,) and work required by compressor (We) to heat added (QA) is improved by
increasing the W, keeping We and QA constant in reheating, whereas in regeneration QA is
reduced keeping W, and We constant. 

Sol. (d) A is false but R is true.

83. Consider the following statements: 

Knock in the SI engine can be reduced by
1. supercharging
2. retarding the spark.
3. using a fuel of long straight chain structure.
4. increasing the engine speed.
Of these statement
(a) 1 and 2 are correct
(b) 2 and 3 are correct.
(c) 1,3 and 4 are correct
(d) 2 and 4 are correct.
Sol. (d) Knock in SI engine can be reduced by retarding spark and increasing the engine
speed. 

Compensating jet in a carburetter supplies almost constant amount of petrol at all speeds
because 
(a) the jet area is automatically varied depending on the suction.
(b) the flow from the main jet is diverted to the compensating jet with increase in speed.
(c) the diameter of the jet is constant and the discharge coefficient is invariant.
(d) the flow is produced due to the st~tic head in the float chamber.
Sol. (b) Statement at (b) is correct. 

In the context of performance evaluation of I.C. Engine, match List I with List II and select
the correct 
answer. 
List I (Parameter)

A. Brake power (B.H.P.)

B. Engine speed

C. Calorific value of fuel

D. Exhaust emissions

For maximum specific output of a constant volume cycle (Otto cycle) 

(a) the working fluid should be air
(b) the speed should be high
(c) suction temperature should be high
(d) temperature of the working fluid at the end of compression and expansion should be equal
Ans. (a) Working fluid should be air for maximum specific output of Otto cycle. 

A two-stroke engine has a speed of 750 rpm. A four-stroke engine having an identical
cylinder size runs at 1500 rpm. The theoretical output of the two-stroke engine will
(a) be twice that of the four-stroke engine
(b) be half that of the four-stroke engine
(c) be the same as that of the four-stroke
(d) depend upon whether it is a c.1. or S.1. engine
Ans. (c) In two-stroke engine there is one power stroke in 2 strokes, but in four-stroke engine
there is one power stroke in 4 strokes. 

For same power output and same co mpression ratio, as compared to two-stroke engines,
four-stroke S.1. engines have:
(a) higher fuel consumption

(b) lower thermal efficiency

(c) higher exhaust temperatures

(d) higher thermal efficiency

Ans. (d) Efficiency of 4 stroke engine is higher because of better utilisation compared to 2
stroke engine.

Consider the following statements:

Detonation in the S.1.engine can be suppressed by
1. retarding the spark timing.
2. increasing the engine speed.
3. using 10% rich mixture.
Of these statements
(a) 1 and 3 are correct.
(b) 2 and 3 are correct
(c) 1,2 and 3 are correct
(d) 1 and 2 are correct
Ans. (a) Decreasing the engine speed increases possibility of detonation.
Which one of the following figures correctly represents the variation of thermal efficiency (y-
axis)  with mixture strength (x-axis) ?

Ans. (a) For higher thermal efficiency, the mixture strength should be little leaner than
stoichiometric.

Assertion (A) : In practice, the efficiency of diesel engines is higher than that of petrol
engines. Reason (R) : For the same compression ratio, the efficiency of diesel cycle is higher
than that of Otto cycle.
Ans. (c) R is not correct because efficiency of otto cycle is higher than diesel cycle for same
compression ratio. 

Assertion (A) :One of the important requirements of a carburettor is to supply lean mixture at
starting. 
Reason (R) :A rather lean mixture is required at No-load and low-load operation of a SI
engine.
Ans (d) At starting rich mixture is required. 

1998

Assertion (A) : Cooling system in an IC engine must be such that there is no excessive
cooling.

Reason (R) : Overcooling would result in increased viscosity of the lubricant due to which
the overall efficiency of the engine will decrease.

Ans. (b) Both statements are true but cooling system in an IC engine is mainly to cool engine.
Thus R is not correct explanation of A.

Assertion (A) : In gas turbines, regenerative heating always improves the efficiency unlike
that in the case of reheating.

Reason (R) : Regenerative heating is isentropic.

Ans: c

1999

Velocity of flame propagation in the SI engine is maximum for a fuel-air mixture which is
(a) 10% richer than stoichiometric
(b) equal to stoichiometric
(c) more than 10% richer than stoichiometric
(d) 10% leaner than stoichiometric
Ans. (d) 

2000
Assertion (A) : The CI engine is basically more suitable for supercharging than the SI engine. 
Reason (R) : In the CI engine supercharging tends to prevent diesel knocking.
ADs. (b) 

2001

Match List-I with List-II and select the correct answer using the codes given below the lists: 
List-I
A. Supercharging
B. Morse test
C. Heterogeneous combustion
D. Ignition quality of petrol
List-II 
I. Multicylinder engine
2. C.I. engine
3. Calorific value
4. Aircraft engine
5. Octane number
6. Single cylinder S.l. engine 
Codes
A B C D
(a) 4 1 2 5
(B) 6 3 2 5
(c) 6 1 5 2
(D)  4 3 5 2

Ans. (a)

Assertion (A) : The air standard efficiency of the diesel cycle decreases as the load is
Int:reased 
Reason (R) : With increase of load, cut-off ratio inneases.
Ans. (d) 

Assertion (A) : Knocking in S.l. engine? is due to auto-ignition of the end t:harge while 
knocking, in c.l. engines is due to auto-ignition of the first t:harge.
Reason (R) : Spark ignition engines employ lower t:ompression ratio than diesel engines and
the fuel used has a calorific value lower than that of diesel oil.
ADS. (b) 

Assertion (A) : The c.I. engine is found to be more efficient than an S.l. engine. 
Reason (R) : Modern c.l. engines operate on a dual-cycle, which has an efficiency greater
than the Otto cycle.
AnS. (a) 
2002

44. In an air-standard Diesel cycle, r is the compression ratio, p is the fuel cut -off ratio and y
is the adiabatic.Its air standard efficiency is given by

46. Auto -ignition t[me for petrol- air mixture is minImum when the ratio of actual fuel-air
ratio and chemically correct fuel- air ratio is

(a) 0.8

(B) 1.0

(c) 1.2

(D) 1.5

 Consider the following statements regarding knock rating of 51 engine fuels : 

1. Iso-octane is assigned a rating of zero octane number.
2. Normal heptane is assigned a rating of hundred octane number.
3. Iso-octane is assigned a rating of hundred octane number.
4. Normal heptane is assigned a rating of zero octane number.
Which of the above statements are correct ?
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 4 and 1

In spark ignition engines knocking can be reduced by :

(a) increasing the compression ratio
(b) increasing the cooling water temperature
(c) retarding the spark advance
(d) increasing the inlet air temperature

The tendency of knocking in CI engine reduces by

(a) high self-ignition temperature of fuel
(b) decrease in jacket water temperature
(c) injection of fuel just before TDC
(d) decrease in injection pressure

2003
Assertion (A) : Octane number is used for rating of fuels in spark ignition engine.
Reason (R) : Octane number of a fuel is defined as percentage by volume, of iso- octane in a
mixture of iso-octane and α- methyl naphthalene.
a. Both A and R are individually true and R is the correct explanation of A
b. Both A and R are individually true but R is not the correct explanation of A
c. A is true but R is false
d. A is false but R is true

If the performance of diesel engines of different sizes, cylinder dimensions and power ratings
are to be compared, which of the following parameters can be used for such comparison ?
 a. Swept volume
b. Air fuel ratio
c. Specific brake fuel consumption
d. Volumetric efficiency

2004

Which of the following factor(s) increase(s) the ten- dency for knocking in the C.I. engine? 
(a) Increasing both the compression ratio and the coolant temperature
Increasing both the speed and the injection advance
Increasing the speed, injection advance and coolant temperature
(d) Increasing the compression ratio

The stoichiometric air/fuel ratio for petrol is 15 : 1. What is the air/fuel ratio required for
maximum power? 
(a) 16 : 1 - 18 : 1 (b) 15 : 1 (c) 12 : 1 - 18 : 1 (d) 9: 1 - 11 : 1

Assertion (A) A simple or elementary carburet- tor provides progressively rich

mixture with increasing air flow.
Reason (R) The density of the air tends to increase as the rate of air flow increases.

Match List I (5.1. Engine Operating Mode) with List II 

(Approximate AlF Ratio) and select the correct answer using the code given below the Lists : 

List I List II
A Cold Start 1. 10 : 1
B. Idling 2. 16 : 1
C. Cruising 3. 13 : 1
D. Maximum Power 4. 4 : 1 
5. 20: 1

A B C D

(a) 4 3 2 1

(b) 2 1 5 3

(c) 4 1 2 3

(d) 2 3 5 1

The knocking tendency in compression ignition engines increases with :

(a) Increase of coolant water temperature
(b) Increase of temperature of inlet air
(c) Decrease of compression ratio
(d) Increase of compression ratio

Which of the following cannot be caused by a hot spark plug?

1. Pre-ignition
2. Post-ignition
3. Detonation
4. Run-on-ignition.
Select the correct answer using the code given below:
(a) 1 and 4
(b) 2 only
(c) 2 and 3
(d) 3 only

Consider the following statements: 

1. Supercharging increases the power output and increases the volumetric efficiency.
2. Supercharging is more suitable for S.l, engines than C.I. engines.
3. The limit of supercharging for an S.I. engine is set by knock while that for a C.I.
engine is set by thermal loading.
Which of the statements given above are correct?
(a) 2 and 3
(b) 1,2and3
(c) 1 and 3
(d) 1 and 2

2006

Consider the following statements : 

In order to prevent detonation in a spark-ignition engine, the charge away from the
spark plug should have
1. low temperature
2. low density
3. long ignition delay
Which of the statements given above is/are correct?
(a) Only 1
(b) Only 2
(c) Only 3
(d) 1,2 and 3

Where does mixing of fuel and air take place in case of diesel engine?
(a) Injection pump
(b) Injector
(c) Engine cylinder
(d) Inlet manifold 

Consider the following statements : 

1. Supercharging increases the power output of an engine.
2. Supercharging increases the brake thermal efficiency considerably.
3. Supercharging helps scavenging of cylinders.
Which of the statements given above are correct?
(a) Only 1 and 2
(b) Only 2 and 3
(c) Only 1 and 3
(d) 1, 2 and 3

What is the purpose of employing supercharging for an engine?

(a) To provide forced cooling air
(b) To raise exhaust pressure
(c) To inject excess fuel for coping with higher load
(d) To supply an intake of air at a density greater than the density of the surrounding
atmosphere

2007

For a conventional S.I. engine, what is the value of fuel-air ratio in the normal operating
range?
a. 0.056 — 0.083
b. 0.083 — 0.56
c. 0.0056 — 0.83 

The delay period in CI engine depends upon which of the following?

a. Temperature and pressure in the cylinder at the time of injection
b. Nature of the fuel mixture strength
c. Relative velocity between the fuel injection and air turbulence pressure of residual gases
d. All of the above

Match List - I with List -II and select the correct answer using the code given below the lists
List I (SI Engine Operational Mode) List II (A/F Ratio Supplied by the Carburetor)
A Idling 1. 3:1
B. Cruising 2. 10 : 1
C. Maximum Power 3. 13 : 1
D. Cold Start 4. 16 : 1 
5. 20: 1
A B C D
(a) 2 4 5 1
(b) 4 5 3 2
(c) 2 4 3 1
(d) 4 5 3 1
What is the main objective of supercharging of the engine?
a. To reduce the mass of the engine per brake power
b. To reduce space occupied by engine
c. To increase the power output of engine
d. All of the above

Consider the following statements: 

Diesel knock can be reduced by
1. Increasing the compression ratio.
2. Increasing the engine speed.
3. Increasing the injection retard.
4. Decreasing the inlet air temperature.

Which of the statements given above are correct? 

 2 and 4 only
1, 2 and3, only
1 and 3 only
1, 2, 3 and 4

Made Easy Book ICGT practice set

The reduced knocking in SI engines is generally observed with

Increased exhaust pressure
Reduced atmospheric humidity
Increased cylinder carbon deposits
Increased atmospheric humidity

In scooter engine the cylinder valves are lubricated by

pressure lubrication
lubrication plug
oil mixed with fuel
cylinder does not require lubrication

 In a petrol engine by mistake diesel fuel is supplied

 the engine will not run
 the engine will run at lower RPM
 the engine will running reduce efficiency
 the Indian will give dense smoke and will consume more fuel as well as lubricating oil

 For the same maximum pressure and temperature

Otto cycle is more efficient than diesel cycle
diesel cycle is more efficient than Otto cycle
dual cycle is more efficient than otto and diesel cycle
dual cycle is less efficient than otto and diesel cycle

The function of piston rings in internal combustion engines is to

 to dissipate heat to cylinder walls
 seal the cylinder
 prevent piston from  wear
 all of the above

Increasing the compression ratio of a petrol engine from 5 to 6 changes the air standard
efficiency by
20%
8%
25%
17%

If the compression ratio in petrol engine is near that of diesel engine then
ignition of fuel will be delayed
pre-ignition of fuel will take place 
knocking will take place
destination will take place

The power to weight ratio of diesel engine compared to petrol engine is

High
Low
Same
high in some cases and low in  other cases

If the temperature of supply air to an IC engine increases, its efficiency

increases
decreases
does not change
may increase or decrease depending upon other factors

Reference fuels for knock rating of SI engine fuels would include

iso-octane and alpha-methyl naphthalene
normal octane and aniline
iso-octane and n-hexane
n-heptane and iso-octane

Which of the following quantity is assumed constant for an internal combustion engine while
estimating its friction power by extrapolation through Willan’s line
brake thermal efficiency
indicated thermal efficiency
mechanical efficiency
volumetric efficiency

The two reference fuels used for cetane ratings are

cetane and isooctane
cetane and tetraethyl lead
cetane and n heptane
cetane and alpha methyl naphthalene

By higher Octane number of SI fuel it is meant that fuel has

higher heating value
higher Flashpoint
lower volatility
longer ignition delay

Keeping other parameters constant brake power of a diesel engine can be increased by
decreasing the density of intake air
increasing the temperature of intake air
increasing the pressure of intake air
decreasing the pressure of intake air

The method of determination of indicated power of a multi cylinder SI engine is by the use of
Morse test
prony brake test
motoring test
heat balance  test 

In order to prevent knock the end gas should have

short ignition delay
high density
high temperature
a non reactive composition

Important factors which significantly affect the process of  carburetion  are
quality of fuels  supplied
inlet air temperature
time available for preparation of mixture
all of the above

Knock in a spark ignition engine

increases the work done during expansion
occurs during the early part of combustion
increased heat loss to the coolant
it is suppressed by advancing the spark timing

The area of P- V diagram can be measured by

Anemometer
Clinometer
Planimeter
Graphometer

If a SI engine is to be supercharged
compression ratio must be increased
compression ratio must be reduced
fuel of higher Octane value can be used
fuel of lower Octane value can be used

A smoky blue exhaust from a diesel engine indicates

excess air
rich mixture
incorrect valve timing
burning of lubrication oil in cylinder
Advantage of two stroke engine over a four stroke engine is
more uniform turning moment on crankshaft
reduced friction loss
more power for same cylinder dimensions
all of the above

Which cooling method is used for mopeds and motorcycles

water cooling system
evaporative cooling system
lub-cooling system
air cooling system

In an automobile choke is applied for

increasing speed
fuel economy 
starting in cold weather 
starting in hot weather

The curve shown in the figure given figure is characteristic of diesel engines. What does the y
axis represent?
efficiency
specific fuel consumption
air fuel ratio
total fuel consumption

For maximum specific output of a constant volume cycle (otto cycle )

the working fluid should be  air
the speed should be high
suction temperature should be high
temperature of the working fluid at the end of compression and expansion should be
equal

A two stroke engine has a speed of 750 RPM a four stroke engine having an identical
cylinder size runs at 1500 RPM the theoretical output of the two stroke engine will
be twice that of the two stroke engine
be half that of the four stroke engine
be the same as that of the four stroke engine
depends upon whether it is a CI or Si engine

For same power output and same compression ratio, as compared to two stroke engines, four
stroke SI engines have
Higher fuel consumption
Lower thermal efficiency
Higher exhaust temperatures
Higher thermal efficiency

A four stroke diesel engine does not have

cooling system
ignition coil
camshaft
piston rings

Which one of the following figures correctly represents the variation of thermal efficiency (y-
axis) with mixture strength (x-axis)

(c)

Stoichiometric air fuel ratio is 15:1.  What is the air fuel ratio required for maximum power
16:1- 18:1
15:1
12:1- 14:1
9:1- 11:1

Hypothetical pressure diagram for compression ignition engine is shown in the given figure
the diesel knock is generated during the period

 AB
 BC
 CD
 after D

Velocity of flame propagation in the SI engine is maximum for a fuel air mixture which is
10% richer than stoichiometric
equal to stoichiometric
more than 10%  richer than stoichiometric
10%  leaner than stoichiometric

In a variable speed Si engine the maximum torque occurs at the maximum

speed
brake power
indicated power
volumetric efficiency

The order of values of thermal efficiency of otto, diesel and dual cycle, when they have equal
compression ratio and heat rejection is given by
i. ηotto > ηdiesel > ηdual
ii. ηdiesel > ηdual > ηotto 
iii. ηdual > ηdiesel > ηotto 
iv. ηotto > ηdual > ηdiesel

In an air standard diesel cycle, r is the compression ratio,  is the fuel cut off ratio and Gamma
is the adiabatic index. Its air standard efficiency is given by
 1 ρ γ −1
η = 1− [ .
γr γ ρ−1 ]
1 ρ γ−1−1
η = 1− [ .
γrγ −1 ρ−1 ]
1 ρ γ−1
η = 1− [ .
γrγ −1 ρ−1 ]
1 ρ γ−1−1
η = 1− [ .
γrγ ρ−1 ]
In Spark ignition engine knocking can be reduced by:
increasing the compression ratio
increasing the cooling water temperature 
retarding the spark advance 
increasing the inlet air temperature

Besides meaning effective pressure, the data needed for determining the indicated power of
an engine would include
piston diameter, length of stroke and calorific value of fuel
Piston diameter, specific fuel consumption and calorific value of fuel
Piston diameter, length of stroke and speed of rotation
Specific fuel consumption, speed of rotation and torque

In a standard dual air cycle, for a fix amount of heat supplied and a fixed value of
compression ratio, the mean effective pressure
shall increase with increase in rp (pressure ratio of constant volume heating) and decrease in rc
(constant pressure cutoff ratio)
shall increase with decrease in rp and increase in rc
shall remain independent of rp
shall remain independent of rc

In the performance of diesel engines of different sizes cylinder dimensions and power ratings
are to be compared, which of the following parameters can be used for such comparison?
swept volume
air fuel ratio
specific brake fuel consumption
volumetric efficiency

Which of the following factors increases the tendency for knocking in CI engines
Increasing body compression ratio and the coolant temperature
Increasing both the speed and injection advance
Increasing the speed, injection advance and coolant temperature
Increasing the compression ratio

In an air standard otto cycle, r is the volume compression ratio and γ is an adiabatic index
(Cp/Cv) the air standard efficiency, η is given by
 1
η = 1− γ −1
r
1
η = 1− γ
r
1
1− γ −1
η=
r γ
1
η = 1− γ2−1γ
r

In a diesel engine, mixing of fuel and air occurs in

fuel pump
injector
inlet manifold
engine cylinder

Which of the following process is not a part of the dual cycle

Adiabatic compression
Constant volume expansion
Isothermal expansion
Constant pressure expansion

Supercharging of diesel engine is done primarily

To improve thermal efficiency
To reduce exhaust losses
To improve mechanical efficiency
To increase specific output

When an engine is idling, it requires

no fuel in the air
rich  fuel air mixture
lean  fuel air mixture
stoichiometric mixture

Stages of combustion in SI engine has been shown in crank angle-pressure diagram.

 the combustion rate in the stage 3 reduces because
 flame front  becoming smaller
 film front becoming larger
 reduction in turbulence
 reduction in turbulence and flame front becoming smaller 

Parameter which decreases the ignition lag in SI engine

turbulence 
speed 
advanced spark 
compression ratio
Swirl which is required in CI engines, is
an orderly movement of air with no general direction of flow
an orderly movement of air with particular direction of flow
disordered air movement of air with particular direction of flow
disordered air movement of air with no  general direction of flow

Which one of the following parameter when increased, increases the delay period in CI
engines
injection pressure
injection advance angle
compression
speed

Squish is related with

induction swirl
compression  swirl
combustion induced swirl
turbulence

supercharging is a process of
providing forced cooling air
injecting excess fuel for raising more load
supplying the intake of an engine with air at a density greater than the density of
surrounding atmosphere
supply compressed air to remove combustion products fully

The air requirement of a petrol engine during starting compared to theoretical air required for
complete combustion is
less
same
more
more or less depending on engine capacity

Air cooling can be not used in

aircraft engines
agricultural engines
cylinder and cylinder head
small engines

Engine has 4 cylinders of 68 mm bore and 75 mm stroke. the cubic capacity of the engine is
 1089.5 cm3
 128 9.5 cm3
 148 9.5 cm3
 168 9.5 cm3

Ans. (a)
Explanation: Capacity of the engine = 4 * Swept volume of each cylinder
= 4* (πd2/4) * L
 = 4* (π* 6.82/4)*7.5
= 1089.5 cm3

 A certain engine produces 10 kW indicated power and mechanical efficiency is 80%. The
friction power is
 12 kW
 8 kW
 4 kW
 2 kW

An engine at full load delivers 100 kilowatt power stop it requires 25 kilowatt to rotate it
without fuel at the same speed.  the mechanical efficiency at half load is
 25%
 50%
 66.7%
80%

 fuel consumption of an engine is 0.35 kg per kilowatt hour and heating value of fuel is 43000
Kilo joule per kg.The brake thermal efficiency is
 20.1 %
 23.9 %
 28.29%
 32.2 1%

A four Stroke Petrol engine delivers 35 kW full stop the fuel consumption of engine is 0.4
kg/kW-hr and air fuel ratio is 14.The air consumption per hour is
 121 kg/hr
 144 kg/hr
 169 kg/hr
 196 kg/hr

The full stop the ratio of competition is it the heat added during the constant volume process
is 1000 kJ/kg. CV is equal to  0.718 and γ is equal to 1.4.
 the maximum temperature of the cycle is
 1450 oC
 1781 oC
1890 oC
 2025 oC

air standard efficiency is

 46%
 49.5%
 56.5 %
 61%

 work done is equal to

 565 kilo joule per kg
 615 kilo joule per kg
 665 kilo joule per kg
 515 kilo joule per kg

 heat rejected in cycle is

 335 kilojoule per kg
 435 kilo joule per kg
 665 kilo joule per kg
 635 kilojoule per kg

 mean effective pressure is

 4.8 bar
 5.8 bar
 6.8 bar
 7.8 bar

Unit 4: Lubrication and cooling

1. In liquid cooling, the cylinder walls and heads are provided with jackets through which the
cooling liquid can circulate
a. True
b. False

2. Mist lubrication system is used for ____________ stroke cycle engines

a. Four
b. Two
c. Unpredictable
d. None of these

3. The following type of Lubrication system is used in two-stroke engine

a. Mist
b. Wet sump
c. Dry sump
d. All of the above

4. In full pressure system, oil from oil sump is pumped under pressure to the various parts
requiring lubrication
a. True
b. False

5. The following part(s) is(are) lubricated by splash system

a. Piston and piston rings
b. Tappets
c. Cams on camshaft
d. All of the above

6. The following part is not lubricated by Pressure feed system

a. Timing gears
b. Valve rods and Push rods
c. Rocker arms
d. Main bearings of crankshaft
7. The properties of lubricants are
a. Viscosity
b. flash point
c. fire point
d. all of the above

8. Full pressure sump lubrication system is generally adopted for high capacity engines
a. True
b. False

9. Lubricating oil
a. Minimizes wear in moving parts
b. Helps in keeping the parts cool
c. Washes away and carries away dirt
d. all of the above

10. In the following system, lubricating oil is carried in separate tanks from where it is fed to
the engine
a. Mist lubrication system
b. Wet Sump lubrication system
c. Dry Sump lubrication system
d. Splash lubrication system
 Unit 5: Engine testing and performance

1. An engine indicator is used to determine…….

a. Speed
b. Temperature
c. Volume of cylinder
d. B.H.P
e. m.e.p. and I.H.P.

2. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency
is called........
a. Net efficiency
b. Efficiency ratio
c. Relative efficiency
d. Overall efficiency

3. The power developed by the engine cylinder of an I.C. engine is known as.......
a. Indicated power
b. Break power
c. Actual power
d. None of the above

4. The break power of an engine is always......the indicated power

a. Equal to
b. Less than
c. Greater than
d. None of the above

5. If the speed of the engine is increased, the indicated power will.......

a. Increase
b. Decrease
c. Remain same
d. None of the above

6. Indicated power of a 4-stroke engine is equal to (p=effective pressure,L=stroke,A=area of

piston).....
a. pLAN/2
b. 2pLAN
c. pALN
d. pLAN/4

7. In case of gas turbines,the gaseous fuel consumption guarantees are based on......
a. High heat value
b. Low heat value
c. Net calorific value
d. Middle heat value

8. The mean effective pressure obtained from engine indicator indicates the
a. Maximum pressure developed
 b. Minimum pressure
c. Instantaneous pressure at any instant
d. Average pressure

10. The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in
newtons, l = Length of arm in meters, N  = Speed of engine in r.p.m., S =  Spring balance
reading in newtons, D = Dia. of brake drum in meters, and d = Dia. of rope in meters)
a. B.P = (Wl  × 2πN)/60 watts
b. B.P = [(W - S) πDN]/60 watts
c. B.P = [(W - S) π (D + d) N]/60 watts
d. All of these

11. The brake power of a diesel engine, keeping other parameters constant, can be increased
by
a. Decreasing the density of intake air
b. Increasing the temperature of intake air
c. Increasing the pressure of intake air
d. Decreasing the pressure of intake air

12. A gas engine has a swept volume of 300 cm 3 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
a. 248 cm3
b. 252 cm3
c. 264 cm3
d. 286 cm3

13. The ratio of the work obtained at the crankshaft in a given time to the energy supplied
during the same time is called
a. Mechanical efficiency
b. Overall efficiency
c. Indicated thermal efficiency
d. Volumetric efficiency

14. The frictional power (F.P.) is given by

a. F.P. = I.P. - B.P.
b. F.P. = B.P./I.P.
c. F.P. = I.P./B.P.
d. F.P. = B.P. - I.P.

15. The mechanical efficiency (ηm) of the engine is given by

a. ηm  = B.P/I.P
b. ηm = I.P/B.P
c. ηm = (B.P × I.P)/100
d. None of these

16. Morse test can be conducted for

a. Petrol engines
b. Diesel engines
c. Multi cylinder engines
 d. All of these

17. The brake power is the power available

a. In the engine cylinder
b. At the crank shaft
c. At the crank pin
d. None of these
 Unit 6: Gas Turbines

1. The gas turbine was invented by

a. John Barber
b. Brayton
c. Otto
d. Atkinson

2. The performance of a simple gas turbine depends on

a. Efficiency of the compressor
b. Efficiency of the turbine
c. Efficiency of the compressor and turbine
d. None of the above

3. The combustion in a gas turbine is at

a. Constant-pressure
b. Constant-volume
c. Partly constant-pressure and partly constant-volume
d. None of the above

4. A simple open-system gas turbine power plant consists of

a. Turbine, combustion chamber and heat exchanger
b. Turbine, combustion chamber and charge cooler
c. Turbine, combustion chamber and compressor
d. Turbine, compressor and heat exchanger

5. Reciprocating engines are preferred over gas turbines because of

a. High reliability
b. High power to weight ratio
c. All of the above
d. None of the above

6. A gas turbine cycle can be operated

a. Only as an open-cycle arrangement
b. Only as a close-cycle arrangement
c. Both as an open-cycle and close-cycle arrangement
d. None of the above

7. For the same pressure ratio and cycle peak temperature

a. Open-cycle is more efficient the closed-cycle
b. Closed-cycle is more efficient the open-cycle
c. Both open-cycle and closed-cycle will have same efficiency
d. None of the above

8. Adding heat exchanger to a simple ideal brayton cycle

a. Improves work output
b. Reduces work output
c. Improves efficiency
d. Improves both work output and efficiency
9. Major applications of gas turbine is for
a. Aircraft
b. Locomotive
c. Automotive
d. All of the above

10. The overall efficiency of a gas turbine engine compared to the reciprocating engine for
the same power output is
a. More
b. Less
c. Same
d. None of the above

11. Performance of an ideal cycle pertains to

a. Work output
b. Efficiency
c. Specific fuel consumption
d. All of the above

12. A simple ideal brayton cycle consists of

a. Two adiabatic and two isentropic
b. Two isentropic and two constant-pressure
c. Two adiabatic and two isothermal
d. Two isentropic, one constant-pressure and one constant volume

13. For maximum specific output, for any given value of temperature ratio (t), the optimum
pressure ratio is given by
a. c = √t
b. c = t
c. c = t2
d. c = 1/t

14. Power output of a simple gas turbine cycle is a function of

a. only pressure ratio
b. only temperature ratio
c. both the pressure ratio and temperature ratio
d. none of the above

15. The efficiency of the simple ideal gas turbine cycle is a function of
a. only the γ of the working fluid
b. only the pressure ratio
c. inlet temperature of the turbine
d. both the pressure ratio and γ
16. Maximum power output is achieved for a simple ideal cycle with respect to pressure ratio
when
a. outlet temperature of the compressor is equal to the outlet temperature of the
turbine
b. outlet temperature of the compressor is lower than the outlet temperature of the
turbine
c. outlet temperature of the compressor is higher than the outlet temperature of the
turbine
d. it has nothing to do with the outlet temperatures

17. When a heat exchanger is added to an ideal gas turbine cycle,

a. power output decreases but the efficiency increases
b. power output increases but the efficiency decreases
c. both remain the same
d. power output remains the same but the efficiency increases

18. For better performance, an ideal heat exchange cycle should be operated with
a. lower t and higher r
b. lower r and higher t
c. higher t and higher r
d. r and t should be same

19. An ideal cycle with reheat, intercooling and heat exchange will increase
a. efficiency
b. work output
c. both efficiency and work output
d. none of the above