Enrolment No.

/Seat No_______________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER–VII EXAMINATION – SUMMER 2025
Subject Code:3171923 Date:27-05-2025
Subject Name:Internal Combustion Engine
Time:02:30 PM TO 05:00 PM Total Marks:70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Simple and non-programmable scientific calculators are allowed.
MARKS
Q.1 (a) Compare S.I. and C.I. engine. 03
(b) Explain the emission of S.I. and C.I. engine. 04
(c) Compare properties of alternate fuels with Conventional I.C. engine 07
fuel.

Q.2 (a) Define Stoichiometric, Rich and Lean mixture. 03

(b) With neat sketch describe the simple carburetor. 04
(c) Explain the working of M.P.F.I. system. State its advantages over 07
carburetor.
OR
(c) Derive air fuel ratio through approximate analysis of simple carburetor. 07

Q.3 (a) How to control knocking tendency in S.I. engine? 03

(b) Explain knocking in S. I. engine. 04
(c) Explain stages of combustion in S. I. engine. 07
OR
Q.3 (a) How to control knocking tendency in C.I. engine? 03
(b) Explain Knocking in C. I. engine. 04
(c) Explain stages of combustion in C.I. engine. 07

Q.4 (a) Explain supercharger. 03

(b) Compare air cooling system with water cooling system. 04
(c) With neat sketch explain working of full pressure lubrication system. 07
OR
Q.4 (a) Explain turbocharger. 03
(b) Compare wet sump lubrication with dry sump lubrication system 04
(c) With neat sketch explain working of pressurized water cooling system. 07

Q.5 (a) Explain air box method to calculate the air consumption in I.C. Engine 03
(b) What are the requirements of a good fuel injection system for C.I. 04
Engine?
(c) In a test of 4 cylinder 4 stroke petrol engine having 80 mm bore and 110 07
mm stroke. The following results were obtained at full throttle at a
constant speed and with a fixed setting of the fuel supply of 0.09 kg/min.
B. P. with all cylinder working = 16.5 kW
B. P. with cylinder 1 cut off = 11. 35 kW
B. P. with cylinder 2 cut off = 10. 95 kW
B. P. with cylinder 3 cut off = 11. 45 kW
B. P. with cylinder 4 cut off = 11. 65 kW

1
 Calculate the indicated power, mechanical efficiency, Indicated thermal
efficiency and air standard efficiency of the engine. Take calorific value
of fuel is 44 MJ/kg. The clearance volume of engine is 120 cc.
OR
Q.5 (a) Explain Willan’s line method to find friction power of the engine. 03
(b) Explain C.R.D.I. system. 04
(c) The following observations were recorded in a test of 1 hour duration 07
on a single cylinder petrol engine working on four stroke cycle.
Bore: 300 mm
Stroke: 450 mm
Fuel used: 8.8 kg
C.V. of fuel: 41800 kJ/Kg
Speed: 200 rpm
M.E.P. : 5.8 bar
Brake friction load: 1860 N
Quantity of cooling water: 650 kg
Temperature rise of cooling water: 22o C
Cp of water:4.18 kJ/KgK
Diameter of the brake drum: 1.22 m
Calculate: (i) Mechanical efficiency (ii) Brake thermal efficiency and
(iii) Heat balance on Minute and Percentage basis.

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2
 Enrolment No./Seat No_______________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE- SEMESTER–VII (NEW) EXAMINATION – WINTER 2024
Subject Code:3171923 Date:16-12-2024
Subject Name: Internal Combustion Engine
Time:10:30 AM TO 01:00 PM Total Marks:70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Simple and non-programmable scientific calculators are allowed.

Marks
Q.1 (a) A 6-cylinder petrol engine operates on the four-stroke cycle. The bore of each 03
cylinder is 70mm and the stroke 100mm. The clearance volume per cylinder is
67cm3. At a speed of 3960 rpm the fuel consumption is 19.5 kg/h and the torque
developed is 140 Nm.
Calculate (a) the break power, (b) the break mean effective pressure (c) the break
thermal efficiency if the calorific value of the fuel is 44000 k J/kg, and (d) the relative
efficiency on a break power basis assuming the engine works on the constant volume
cycle. Assume r = 1.4, for air.
(b) In an ideal constant volume cycle the pressure and temperature at the beginning of 04
compression are 97 kN/ m2and 40 °C resply. The volume ratio of compression is 7:1.
The heat supplied during the cycle is 1200 K J/Kg of working fluid. Determine the
maximum temperature attained in the cycle, thermal efficiency of cycle and work
done during the cycle/ Kg of working fluid.

(c) Explain the following terms: Run on surface ignition, Run away surface ignition, 07
wild ping, Rumble, Pre ignition
temperature
Rating, Testing and Performance
Q.2 (a) A 10 cm X 12 cm four cylinder, 4 stroke engine running at 2000 rpm has a 03
carburetor venturi with a 3 cm throat. Determine the suction at the throat assuming
the volumetric efficiency of the engine to be 70 %. Assume density of air to be 1.2
Kg/ m2 and coefficient of air flow of 0.8.
(b) Explain basic requirements of a good combustion Chamber. 04
(c) Compare the performance characteristics of SI and CI engines. 07
OR
(c) What are the key operating variables that distinguish SI and CI engines, such as 07
compression ratio, air-fuel mixture preparation, and combustion timing?

Q.3 (a) How does a carburetor adjust the air-fuel mixture according to different loads and 03
speeds? What are the main factors affecting mixture requirements?
(b) Draw neat and labelled sketches of 04
(1) Bosch fuel Injection Pump
(2) Pintle Nozzle and Pintaux nozzle
(c) With neat sketch explain Stages of combustion in SI engines. 07

1
 OR
Q.3 (a) Explain the concept of detonation in CI engines. What factors contribute to the 03
occurrence of detonation
(b) Draw neat and labelled sketches of 04
(1) Solex carburetors (2) Cater Carburetor
(c) Compare different combustion chamber designs for SI engines. How do factors like 07
chamber shape, piston geometry, and valve arrangement influence combustion
efficiency and emissions?

Q.4 (a) List desirable properties of Engine Lubricants. 03

(b) Compare various Engine cooling systems. 04
(c) What is supercharging? Explain thermodynamic cycle of supercharged I.C engine. 07
OR
Q.4 (a) Explain S.A.E. rating of Lubricants. 03
(b) With neat sketch explain Engine Air cooling system. 04
(c) What is meant by pulse turbocharging? What are its advantages and disadvantages? 07

Q.5 (a) Explain working principle of Wankel engine. 03

(b) Explain suitability of Biofuels as alternative fuel in I.C engines. 04
(c) Discuss the role of catalytic converters in controlling exhaust emissions from SI 07
engines. How do they work, and what pollutants do they target?
OR
Q.5 (a) Explain working principle of stratified charge engine. 03
(b) Explain effect of following parameters on exhaust emission. 04
(1) Air fuel Ratio
(2) Surface to volume ratio
(3) Engine Speed
(c) What are the primary pollutants emitted from a spark-ignition engine, and how do 07
they contribute to air pollution?

***********

2
 Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER–VII (NEW) EXAMINATION – SUMMER 2024
Subject Code: 3171923 Date:01-06-2024
Subject Name: Internal Combustion Engine
Time:02:30 PM TO 05:00 PM Total Marks:70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Simple and non-programmable scientific calculators are allowed.

MARKS
Q.1 (a) Differentiate SI and CI engines. 03
(b) Compare the properties of petrol and diesel with unconventional fuels. 04
(c) A single cylinder, 4-stroke diesel engine having swept volume of 850 cm3 is tested at 07
300 rpm. When the braking torque of 50 Nm is applied, analysis of indicator diagram
gives a mean effective pressure of 10 bar. Find the brake power and mechanical
efficiency of the engine.

Q.2 (a) Explain the working principle of exhaust gas calorimeter. 03

(b) Explain the orifice-chamber method for air consumption measurement in IC engine 04
with neat sketch.
(c) A 4 cylinder 4-stroke SI engine of 60 mm bore and 90 mm stroke was tested at 07
constant speed. The fuel supply was fixed to 0.13 kg/min and plugs of 4-cylinder were
successively short-circuited without change of speed.
The power measurements were as follows:
BP with all cylinder working = 16.25 kW; BP with cylinder 1 cut-off = 11.55 kW; BP
with cylinder 2 cut-off = 11.65 kW; BP. with cylinder 3 cut-off = 11.70 kW; BP with
cylinder 4 cut-off = 11.50 kW. The calorific value of fuel is 42 MJ/kg. Find Indicated
thermal efficiency of the engine and compare it with air standard efficiency. The
clearance volume of one cylinder is taken as 50 cm3.
OR
(c) The following observations are made during a trail on an oil engine. (1) Motor power 07
to start the engine = 10 kW (2) R.P.M =1800 (3) Brake torque = 345 Nm (4) Fuel used
= 16 kg/hour (5) C.V. of fuel used = 42 MJ/kg (6) Air supplied = 4.85 kg/min (7)
Quantity of cooling water = 17 kg/min (8) Outlet temperature of cooling water = 68
0
C (9) Room temperature = 21 0C (10) Exhaust gas temperature = 400 0C. Take Cpw =
4.2 KJ/kg. K and Cpg = 1.25 KJ/kg.K.
Determine (a) B.P. (b) Mechanical efficiency (c) bsfc and (d) draw a heat balance
sheet on kW basis and percentage basis.

Q.3 (a) Define the following terms: (1) Ignition lag (2) Highest useful compression ratio 03
(HUCR) (3) Performance number
(b) Explain the effects of knocking in SI engines in details. 04
(c) Explain the stages of combustion in CI engine using P-Ɵ (pressure-crank angle) 07
diagram in details.
OR
Q.3 (a) Differentiate knocking in SI and CI engines. 03
(b) Explain the Lanova air-cell combustion chamber with neat sketch. 04
 (c) Enlist various design consideration parameters for good combustion chambers. Also 07
explain any one modern combustion chamber used in SI engine with neat sketch.

Q.4 (a) Enlist the functions of lubrication system. Designate the lubricating oil grade: SAE 03
20W/40.
(b) Differentiate air cooling and water-cooling system in details. 04
(c) Differentiate supercharging and turbocharging in details. 07
OR
Q.4 (a) Define EURO-III and EURO-IV emission norms. 03
(b) Explain the working principle of stratified charge engine with neat sketch. 04
(c) Explain pressure feed lubrication system with neat sketch. 07

Q.5 (a) Give the functions of following parts of simple carburetor. (1) Venturi (2) Float and 03
float chamber (3) chock valve
(b) Explain the compensating or double jet with neat sketch. 04
(c) Enlist various types of nozzles used in CI engine. Also explain the Individual pump 07
system with neat sketch.
OR
Q.5 (a) Enlist the requirements of ideal injection system. 03
(b) Write the chemically correct combustion equation for octane and define the practical 04
A:F (air-fuel ratio) limit for SI engine.
(c) Explain the following terms in details: 07
(1) Ice formation (2) Vapour lock (3) Back-firing
**********
 Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER–VII (NEW) EXAMINATION – WINTER 2023
Subject Code:3171923 Date:19-12-2023
Subject Name: Internal Combustion Engine
Time: 10:30 AM TO 01:00 PM Total Marks:70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Simple and non-programmable scientific calculators are allowed.

MARKS
Q.1 (a) Compare SI and CI engines based on initial and maintenance costs. 03
(b) Enlist and explain about different applications of SI and CI engine. 04

(c) Discuss about important qualities of IC engine fuels. 07

Q.2 (a) Explain in brief about necessity of engine cooling. 03

(b) Briefly discuss about types of lubricants and their properties. 04
(c) Explain pressurized water cooling system with neat sketch. 07
OR
(c) Explain splash lubrication system with neat sketch. 07

Q.3 (a) Enlist types of nozzles used in CI engine fuel injector. Explain any one of them 03
in brief.
(b) Explain carburetion mixture requirement for different loads and speeds in SI 04
engine.
(c) Explain working of MPFI system with neat sketch. 07
OR
Q.3 (a) Explain stoichiometric air fuel ratio in brief. 03
(b) Enlist different SI engine combustion chambers and explain any one of them 04
with neat sketch.
(c) Discuss in detail about various factors affecting engine knocking. 07

Q.4 (a) Explain in brief objectives of supercharging. 03

(b) Discuss about emission from SI engines in brief. 04
(c) Write short note on alternative fuels for I.C. engines. 07
OR

Q.4 (a) Explain diesel smoke and its control in brief. 03

(b) Discuss about trouble shooting and overhauling of engines in brief. 04
(c) A six cylinder, four-stroke gasoline engine having a bore of 90 mm and stroke 07
of 100 mm has a compression ratio 7. The relative efficiency is 55% when the
indicated specific fuel consumption is 300 gm/kWh.
Estimate: (i) the calorific value of the fuel and
(ii) corresponding fuel consumption, given that imep is 8.5 bar and speed is
2500 rpm.
Q.5 (a) Explain Willan’s line method to find friction power of the engine. 03
(b) Explain air box method to calculate the air consumption in an engine. 04

1
 (c) A gasoline engine working on four stroke develops a brake power of 20.9 kW. 07
A Morse Test was conducted on this engine and the brake power (kW)
obtained when each cylinder was made inoperative by short circuiting the
spark plug are 14.9, 14.3, 14.8 and 14.5 respectively. The test was conducted
at constant speed. Find:
(i) the indicated power,
(ii) mechanical efficiency and
(iii) bmep when all the cylinders are firing.
The bore of the engine is 75 mm and the stroke is 90 mm. The engine is running
at 3000 rpm.
OR
Q.5 (a) Explain in brief about working principle of stratified charge engines. 03
(b) A single-cylinder engine running at 1800 rpm develops a torque of 8 Nm. The 04
indicated power of the engine is 1.8 kW. Find the loss due to friction power as
the percentage of brake power.
(c) Write short note on Wankel engine. 07

*************

2
Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE – SEMESTER- VII EXAMINATION-SUMMER 2023
Subject Code: 3171923 Date: 19/06/2023
Subject Name: Internal Combustion Engine
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Simple and non-programmable scientific calculators are allowed.

Q.1 (a) Give classification of I.C.Engine in detail. 03

(b) Explain compression ratio and clearance volume. 04
(c) Explain working of a four-stroke petrol engine. 07

Q.2 (a) Explain ignition limit and stochiometric mixture. 03

(b) Explain factors affects the process of carburation. 04
(c) Explain the fuel supply system in petrol engine. 07
OR
(c) Explain the fuel supply system in diesel engine. 07

Q.3 (a) What do you mean by detonation? 03

(b) Briefly explain stages of combustion in S.I,Engine 04
(c) Compare supercharging and turbocharging. 07
OR
Q.3 (a) Explain supercharging of C.I.Engine. 03
(b) Briefly explain stages of combustion in C.I.Engine. 04
(c) State the different methods of supercharging & discuss 07
one of them.

Q.4 (a) Define A:F ratio and discuss its importance. 03

(b) What are the different parameters considered to control 04
knock?
(c) List different types of S.I.Engines combustion chamber. 07
OR
Q.4 (a) Explain induction swirl and compression swirl. 03
(b) Discuss heat balance sheet. 04
(c) Evaluate “Turbulence” is required in S.I.Engine and 07
“Swirl” is required in diesel engine.

Q.5 (a) Explain different types of emission from automobile. 03

(b) Explain MPFI engine. 04
(c) Carried out by mass analysis of carbon in case of complete 07
combustion.
OR
Q.5 (a) Briefly explain Bharat Stage. 03
(b) What do you mean by EGR (Exhaust Gas Recirculation. 04
(c) Carried out by mass analysis of carbon in case of 07
incomplete combustion.

*************

1
Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER–VII (NEW) EXAMINATION – WINTER 2022
Subject Code:3171923 Date:12-01-2023
Subject Name:Internal Combustion Engine
Time:10:30 AM TO 01:00 PM Total Marks:70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Simple and non-programmable scientific calculators are allowed.
MARKS
Q.1 (a) Compare Petrol and Diesel engine on the basis of: 03
I. Fuel Ignition
II. Thermal efficiency
III. Fuel supply
(b) What are the desirable properties of IC engine fuels? 04
(c) Compare the knocking in SI and CI engines. 07

Q.2 (a) Why rich mixture required during idling? 03

(b) What are the drawbacks of simple carburetor? 04
(c) Explain construction and working of Bosch fuel pump. 07
OR
(c) Explain the working of common rail fuel injection system with a line 07
diagram and also discuss about the advantages and disadvantages.

Q.3 (a) What is the importance of ignition lag in SI engine combustion? 03

(b) Explain the advantages of using hydrogen as a fuel in IC engines. 04
(c) Describe the various stages of combustion in CI engine with the help of 07
p-𝜃 diagram.
OR
Q.3 (a) Classify different types of combustion chambers in CI engine. 03
(b) Explain the term: 04
I. Vapor lock
II. Ice formation
(c) Explain the stages of combustion in SI engine with the help of p- 07
𝜃 diagram.

Q.4 (a) Give the classification of engine cooling system. 03

(b) Give comparison between wet sum and dry sump lubrication system. 04
(c) Derive an expression for air-fuel ratio for simple carburetor by using the 07
approximate analysis method.
OR
Q.4 (a) State the function of lubrication system in IC engine. 03
(b) Compare and differentiate the supercharging and turbocharging. 04
(c) Explain with neat sketch splash lubrication system. 07

Q.5 (a) Write a short note on SAE rating of lubricants. 03

(b) Give comparison between the catalytic convertor and thermal rector. 04
(c) A two stroke diesel engine was motored when energy meter reading was 07
1.5 KW. Then the test on the engine was carried out for one hour and
following observations were recorded:
Brake torque = 120Nm
1
 RPM = 600
Fuel used = 2.5 Kg/hr
C.V. of fuel = 40.3 MJ/Kg
Cooling water used = 818 Kg/hr
Rise in cooling water temperature = 100 𝐶
Cpw = 4.2 KJ/Kg-K
Exhaust gas temperature = 3450 𝐶
Room temperature = 250 𝐶
A:F ratio = 32:1
Cpg = 1.045 KJ/Kg-K

Draw heat balance sheet indicating units in KJ/min and also on

percentage basis.
OR
Q.5 (a) Explain the procedure of engine trouble shooting. 03
(b) Write a brief note on Wankel engine. 04
(c) In a test of four cylinder four stroke petrol engine of 75 mm bore & 07
100mm stroke. The following results were obtained at full throttle at a
constant speed and with a fixed setting of the fuel supply of 0.082
kg/min.
Brake power with all cylinder working = 15.24 KW
Brake power with cylinder 1 cut off = 10.45 KW
Brake power with cylinder 2 cut off = 10.38 KW
Brake power with cylinder 3 cut off = 10.23 KW
Brake power with cylinder 4 cut off = 10.45 KW
Estimate the indicated power of the engine under this conditions. If
calorific value of fuel is 44 MJ/Kg, find the thermal efficiency of the
engine and compare it with air standard efficiency. The clearance
volume is taken as 115 cc.

*************