Valve+timing+diagram 326521

L.J. Institute of Engineering & Technology, Ahmedabad Mechanical engineering department SUB: I.C.ENGINE

SEM: VI

PRACTICAL : 1

AIM : To draw the valve timing diagram of 4- stroke single cylinder Diesel engine.

INTRODUCTION: Valve timing diagram stands for all types of heat engine. In this practical we only study about 4-stroke single cylinder diesel engine. Heat engine: A heat engine is a device which converts the chemical energy of fuel in to heat energy and subsequently in to mechanical energy. Types of Heat engine:

It has two types

1. External combustion engines (EC) 2. Internal combustion engines (IC) 1. External combustion engine: The combustion takes place outside of the cylinder. 2. Internal combustion engine: The combustion takes place inside of the cylinder. It has two types A. Spark ignition engine (SI) B. Compression ignition engine (CI) A. Spark ignition engine: Ignition takes place inside the engine with the help of spark. B. Compression ignition engine: Ignition takes place inside the engine by compressed fuel. 4-Stroke single cylinder diesel engine: Working:

The working of a 4- stroke single cylinder Diesel engine is based on using very high compression ratio. It is based on Diesel cycle. The compression ratio used for diesel engine is 14:1 to 20:1. Liquid fuel is injected in to the cylinder in the form of spray by an injector. The working cycle is completed in the four stroke named suction stroke, compression stroke, power or expansion stroke and exhaust stroke. 1

4-Stroke single cylinder petrol engine: Working:

The working of a 4- stroke single cylinder Petrol engine is based on using low compression ratio. It is based on Otto cycle. The compression ratio used for petrol engine is 5:1 to 10:1. Air fuel mixture is injected and ignited with the help of spark plug placed at the top of the cylinder. The working cycle is completed in the four strokes named suction stroke, compression stroke, power or expansion stroke and exhaust stroke.

2-Stroke single cylinder diesel engine: Working:

port is used instead of valve. Mechanism is quite simpler. Cam mechanism is not used. Injector is used to spray the fuel.

2-Stroke single cylinder petrol engine: Working:

port is used instead of valve. Mechanism is quite simpler. Cam mechanism is not used. Spark plug is to ignite the fuel.

Valve timing diagram of 4- stroke single cylinder diesel engine. IVO - 250 before TDC IVC - 300 after BDC EVO - 450 before BDC EVC - 150 after TDC FVO - 150 before TDC FVC - 250 after TD

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Valve timing diagram of 4- stroke single cylinder petrol engine.(low speed) IVO - 100 before TDC IVC - 200 after BDC EVO - 250 before BDC EVC - 50 after TDC Valve timing diagram of 4- stroke single cylinder petrol engine.(high speed) IVO - 100 before TDC IVC - 500 after BDC EVO - 450 before BDC EVC - 200 after TDC Port timing diagram of 4- stroke single cylinder petrol engine EPO - 450 before TDC EPC - 450 after BDC TPO - 350 before BDC TPC - 350 after TDC

CONCLUSION: As per valve timing diagram total process is done before the timing which we assume theoretically. This timing is very helpful for practical studies and actual efficiencies.

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L.J. Institute of Engineering & Technology, Ahmedabad Mechanical engineering department SUB: I.C.ENGINE

SEM: VI

PRACTICAL : 3

AIM : to study different types of combustion chamber of S.I. engine. INTRODUCTION: Combustion is defined as the rapid and high temperature oxidation of fuel with liberation of heat energy. The requirement for initiating a combustion processare the presence of a combustible mixture of air and fuel, a means for initiating the combustion, the formation of a flame and its propagation across the combustion chamber. The combustion reaction depends upon: 1. Rate of formation of chain carriers. 2. Rate of destruction of chain carriers. 3. Temperature, pressure and density of the explosive mixtures. Combustion stages in S.I. Engines: In case of spark ignition engines, the combustion mixture and air is supplied in a desired ratio with the help of carburetor and combustion process is initiated with the help of a very high intensity spark provided by a spark plug few degrees before the end of compression stroke. Various stages of combustion: Based on the experimental result the combustion in S.I. engines takes place in three stages as follows: 1. Period of ignition lag or preparation phase ignition lag represents the period of flame preflame reaction in which the chain carries are formed. the ignition lag depends upon the molecular structure of fuel, temperature, pressure, density, air-fuel ratio and the proportion of residual gasesin the mixture. 2. Flame propagation phase as the combustion proceeds the pressure and temperature keeps on rising with heat energy release which is transferred from burned to unburned charge, the flame propagates across the combustion chamber at high speeds in the range of 15 – 35 m/s 4

3. After burning or flame termination phase. burning continues due to left over fuel and the reassociation of disassociated gases existing in the combustion chamber. Effect of engine variables on ignition lag: The various variables which affect the ignition lag are as follows: 1. Pressure and temperature at high pressure the molecules are nearer and their rate of collisions increases. It helps in forming the chain carriers and reduces the ignition lag. 2. Compression ratio higher compression ratio increases the pressure and the temperature of the working substance. 3. 4. 5. 6. 7.

Mixture strength Residual gases Nature of fuel Speed Electrode gap

Different types of combustion chamber for S.I.engine 1. T-head combustion chamber 2. L-head or side valve combustion chamber 3. Recardo turbulent combustion chamber Modern S.I. engine combustion chambers: 1. 2. 3. 4. 5.

Bath tub combustion chamber Rover head combustion chamber Wedge head combustion chamber F-head combustion chamber Combustion chamber for jaguar engine

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TUTORIAL 1. 2. 3. 4. 5. 6.

Explain detonation and factors affecting it. Explain flame propagation and ignition lag and also explain factors affecting it. Explain of engine variables on ignition lag. Explain detonation and knock in S.I.Engine. Explain different types of combustion chamber if S.I.Engine with diagram. Explain morden S.I. engine combustion with neat sketch.

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L.J. Institute of Engineering & Technology, Ahmedabad Mechanical engineering department SUB: I.C.ENGINE

SEM: VI

PRACTICAL : 4

AIM : To study different types of combustion chamber of C.I. engine. INTRODUCTION: Stages of combustion in C.I. engine are: 1. 2. 3. 4.

Delay period having physical and chemical delay Period of uncontrolled combustion Period of controlled combustion After burning

Physical delay period is reduced by increasing the injection pressure. Delay period is reduced due to increased C.R. inlet pressure and temperature, decreased engine speed, increased load and jacket water temperature. Factors which tends to increase the detonation tendency in S.I. engine, same will reduce the knocking tendency in C.I. engine. OBJECTIVES OF COMBUSTION CHAMBER: 1. 2. 3. 4. 5.

To provide proper mixing of fuel and air. Required turbulence. Burning of fuel to obtain peak pressures. Low surface to volume ratio. Short delay period.

AIR SWIRL: Air swirl is provided in combustion chambers C.I. engine for proper mixing of fuel air. Methods: 1. Induction swirl 2. Compression swirl 3. Combustion induced swirl

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Combustion chambers for C.I. engine are classified as: 1. Non turbulent or open or direct injection combustion chambers 2. Turbulent or indirect injection combustion chambers These are classified as:   

Swirl combustion chambers Precombustion chambers Air cell chambers

M.A.N COMBUSTION CHAMBER: M.A.N combustion chamber was developed in which is suitable for small, high speed engines. It has spherical cavity in the piston on which fuel spray impinges. It ensures high performance, low smoke levels in exhaust with low weight to power ratio of the engine.

TUTORIAL

1. What are the requirements of a good combustion chamber for C.I.Engine. 2. Compare advantages and disadvantages of induction swirl with compression swirl. 3. What is swirl? Why swirl is required for C.I. engine combustion chambers? Explain method of creating swirl. 4. Explain methods of turbulence in combustion chambers. 5. What are the criteria for a good combustion chamber? Explain with neat sketch the pre combustion chamber used in C.I. engine what are its advantages and disadvantages. 6. Explain open type combustion chamber. 7. Explain different types of combustion chamber with neat sketch.

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L.J. Institute of Engineering & Technology, Ahmedabad

Mechanical engineering department SUB: I.C.ENGINE

SEM: VI

PRACTICAL : 5

AIM : To study Fuel pump and Injector. INTRODUCTION: FUEL PUMP: The function of fuel pump is to draw fuel from tank through pipe line and supply to carburetor. Types of fuel pump: 1. Mechanical fuel pump 2. Electrical fuel pump FUEL INJECTION SYSTEM: The function system is to provide atomized fuel in the form of spray according to the load and speed of the engine and to distribute it uniformly throughout the combustion chamber of a C.I. engine. Modern engines use fuel injection system in S.I. engine also. It is due to inherent drawbacks of the carburetor like non-supply of A.F. ratio at all loads and speeds, unequal distribution of A.F. ratio in multi cylinder engines, high s.f.c, back firing, low volumetric efficiency and high exhaust emissions. Types of gasoline injection system in S.I. engine: 1. Continuous port and intake manifold injection system: a pump under the pressure of 1 to 1.5 bar injects fuel through a nozzle continuously into air supply. 2. Timed fuel injection system: obsolete today due to high fuel consumption and high exhaust emission 3. Gasoline direct injection in to cylinder. Advantages of continuous injection system: 1. It increases atomization of fuel 2. It provides uniform A.F. ratio 9

3. It improves volumetric efficiency M.P.F.I. system for S.I. engine: M.P.F.I. system involves the injection of fuel under low pressure into each cylinder by separate injectors. 1. It’s main components are computer(U), sensors and solenoid injector. 2. It is classified as: (a) D-M.P.F.I. system in which fuel is injected in the intake manifolds by sensing vacuum, density of air and speed of engine. (b)L-M.P.F.I. system regulates the fuel injection by sensing speed. It is a port fuel injection system. M.P.F.I. system components are fuel injection control, idle air control and ignition time control. Advantages of M.P.F.I. system over conventional system: 1. 2. 3. 4. 5. 6. 7. 8.

More uniform A.F. ratio. High volumetric efficiency More power Less s.f.c. Provision for sudden acceleration/ deceleration Low exhaust emissions Better mileage No need to crank the engine in case of cold starting

Fuel injection system types: 1. Solid or airless injection system 2. Air injection  In solid injection system air is first compressed to a high pressure and temperature and used for injecting the fuel at 70 bar and higher pressures. 

These are of tree types: (a) common rail system (b) individual pump system (c)distributor system

NOZZLE: Nozzle is a part of an injector through which fuel is injected to combustion chamber, these are pintle, single hole, multiple hole and pintaux types. The use of pintle nozzle avoid the dribbling of fuel in the combustion chambers. Single hole nozzles are suitable for open combustion chambers, since these give small spray cone angle with inadequate mixing of fuel air.

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TUTORIAL 1. Discuss the reason for adopting fuel injection system for S.I. engine. What are various types of petrol injection system? 2. Why M.P.F.I. system is used in modern automobiles in S.I. engines? 3. How the M.P.F.I. system is classified? Explain the working principle any of them. 4. Explain different types of pumps and nozzles with neat sketches. 5. Explain (i) injection pressure, (ii) maximum pressure, (iii) mean effective pressure. 6. Give the name of injection system and explain any two.

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L.J. Institute of Engineering & Technology, Ahmedabad Mechanical engineering department SUB: I.C.ENGINE

SEM: VI

PRACTICAL : 6

AIM : To study different types of Ignition system of I.C.Engine.

INTRODUCTION:

the ignition system carries the critical current to the spark plug where the spark carries sufficient energy to increase the temperature of surrounding charge to the ignition point at which combustion becomes self sustaining. The spark appears at the plug gap in S.I engine just as the piston approaches the TDC of the compression stroke, when the engine is idling. at higher speed or during increased throttle operation of the engine the spark is advanced. To produce the necessary high voltage required to jump a set gap of the spark plug to produce spark in the combustion chamber for the ignition of the combustible charge at the correct time.

The ignition systems are classified as follows: 1. Battery - ignition system 2. Magneto - ignition system 3. Electronic - ignition system| 1) Battery – ignition system:The components of battery ignition system area battery, an ignition switch, an ignition coil with or without an added ballast resistor, a distributor which houses the breaker points, the cam , the condenser, the rotor and the advanced mechanism, a spark plug, and low & high tension wirings. There are two circuits of the ignition system; the primary circuit and the secondary circuit. The primary circuit consists of the battery, the ignition switch, the ballast resistor, the primary coil winding, the condenser and the breaker point. The secondary circuit consists of the secondary coil winding, the distributor and the spark plug.

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Battery:

electronic energy is provided by the storage battery. The six plate – 12 volt battery supplies a steady current for ignition, starter motor, lighting, and other electric circuits, and provides a reserve of electricity when the current consumed by the electronic equipment exceeds that being produced by the dynamo.

Ignition switch: The ignition switch is placed between the battery and the primary winding of the ignition coil. It has extra set of s that are used when the switch is turned past ON to START. Ballast resistor: It may be placed in a series with the primary winding of the ignition coil to regulate the primary current. At low engine speed the average current is high due to longer closer of the break point. It is heated up and produces more resistance with cuts down the current. Ignition coil:

It is used to step up 12-volts battery to a very high voltage of 10,000 to 20,000 volts to induce an electric spark across the electrodes of the spark plug. The typical ignition coil of metal clad type consists of a primary winding of 200 to 300 turns of thick wire to provide resistance of about 1.5Ώ and the secondary winding is made of a large no of turns about 21,000 of fine enameled wire sufficiently insulated to with stand high voltages. These winding are wound upon a cylindrical soft core , and enclosed by a soft iron shell. The secondary coil is closed to the core and the primary winding is located at outside of the secondary coil.

breaker points: It is a mechanical device for making and breaking the primary circuit of the ignition system. it consist of a fixed metal point which is ground and another metal point attached to a movable, spring loaded insulated breaker arm. The metal used is invariably one of the hardest metals, usually tungsten and each point has a circular face of about 3mm diameter. Condenser:

As the breaker points open, the current from the battery through the primary winding of the coil is stopped. The magnetic field is therefore collapse. The collapsing magnetic field induced current which continuous to flow in the same direction in the primary circuit and thus charges the condenser plate. This absorbs current surges back out of the condenser and towards the ignition coil, thus helping to bring about the complete collapse of the magnetic field in the coil which in turn induces a high voltage of necessary magnitude in the secondary winding.

Distributor:

It consist of a housing a drive shaft with breaker cam, an advance mechanism, a breaker plate with points and a condenser, a rotor, and a cap. The shaft is driven by the camshaft of the engine through spiral gears. It rotates at one-half of the speed of crank shaft. This shaft is usually coupled to another shaft which drives the oil pump of 13

lubrication. The distributor has several functions; it closes and opens the points to complete and interrupt the primary circuit between the battery and the ignition coil. When the primary circuit is completed through the closed points, the current flows in the ignition coil and builds up a magnetic field. When the points open by the cam rotation, the primary circuit is opened and the current stops flowing. The magnetic field collapses and this produces a high voltage in the secondary winding of the ignition coil. It distributes each high voltage surge to the correct spark plug at the correct instant. It does this with the distributor rotor. The rotor rotates with the breaker cam and connects the central terminal of the cap with each outside terminal in turn. 2) Magneto ignition system: The Magneto ignition system is extensively used in mopeds, three wheelers, motor cycles, sports and racing cars and reciprocating air craft engines. It is similar to the battery ignition system in the principle except that the magnetic field in the core of the primary and secondary winding is produced by a rotating permanent magnet. The magneto has got its own current generating unit without making the use of battery and ignition coil. It consist of a fixed armature having primary and secondary winding and a rotating assembly of magnets driven from the engine.it is called high tension magneto. A magneto having no separate secondary winding on its armature is called a lowtension magneto. For the spark to occur, the required voltage is produced on stepping up the low tension supply by means of an ignition coil. This system is cheap, reliable and requires little maintenance. The starting of engine is difficult as the magneto does furnish enough voltage for ignition at low speeds. The efficiency of the system improves with the increasing speed. Advantages: 1) Less maintenance 2) Light in weight and occupies less space 3) Provides high intensity spark at high speeds 4) System is reliable Disadvantages: 1) Since wirings carry high voltage current, there is a strong possibility of leakage which may cause misfiring of engine 2) The system requires extensive shielding to prevent leakage of high voltage current 3) At low speeds it develops poor quality of spark at the spark of starting

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Comparison between battery and magneto ignition system:

Sr. Battery- coil ignition No. 1 It provides high intensity spark at low speeds and low intensity spark at high speed of engine 2 It needs excessive maintenance of battery system 3 System is less reliable compared to magneto system 4 Cost of system is low 5 System is heavier due to battery weight 6 Variation of ignition timing can be achieved easily without affecting the spark intensity 7

It occupies more space

Magneto ignition It provides low intensity spark at low speeds and high intensity spark at high speeds It does not need maintenance since the battery is eliminated System is more reliable compared to Battery- coil system Cost of system is high System is lighter in weight Variation of ignition timing cannot be achieved easily without affecting the spark intensity It occupies less space

Electronic ignition system: It has two types 1) Transistorized coil ignition system (TCI) 2) Capacity discharge ignition system (CDI)

1) Transistorized coil ignition system (TCI): This system has been found to offer decided advantages in handling the increasing voltage required for high performance of the engines, longer spark plug life, reduced wear, maintenance of the ignition system and high reliability.

Advantages: 1) 2) 3) 4)

Higher ignition voltage and a longer duration of spark Reduced wear of C.B. points Consistency of spark voltage over the entire speed range Increased dwell and less bounce

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Disadvantages: 1) System requires breaker points of the conventional system for timing the spark 2) The maximum speed of engine is governed by the limitation of breaker machanism

2) Capacity discharge ignition system (CDI): A battery of 6 volt usually connected to a transistorized DC to DC converter which is designed to give high voltage in the range of 250-300 V from battery Advantages: 1) Avoids break points and their frequent maintenance 2) Gives better cold starting since the system draws high current at low speed and low current at high speed 3) It provides constant voltage to spark plug at all speeds 4) Improves the efficiency of the engine

Spark plug: Its function is to receive high voltage ignition current from secondary coil of ignition system and to supply spark to combustion chamber of engine cylinder which jumps across the electrodes It consists of a central porceline insulator through which an electrode es It has external at the top to wire from ignition coil

Types of spark plug: Spark plugs are classified as hot spark plug and cold spark plug The operating temperature of the plug depends upon the area of insulation and electrode exposed to the hot gases and the length of the path from electrode points and insulation back to the cooled parts of the cylinder wall in to which the plug is screwed. The plug with a short center electrode is known as cold plug and the plug with the long centre electrode is known as hot plug.

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Factors affecting spark advance: 1) Mixture strength: for weaker mixture the rate of flame propagation is lower, so the complete combustion period will be greater. In order to obtain the maximum power from weak mixture the spark should therefore be advanced. 2) Compression ratio: with the increase in compression ratio the charge density will be increased, which will increase the rate of propagation. The spark advance must therefore be reduced as the compression ratio is increased. 3) Engine speed: as the engine speed increases the combustion duration in of degrees crank-angle also increases. Therefore the angle of spark advanced must increase as the speed increases. 4) Turbulence: as the degree of turbulence is increased, more quality of mixture es the ignition point in a certain time, so the effect is similar to that of increased flame speed. Increasing the turbulence should therefore require a retardation of the ignition timing. 5) Engine load: at light loads a partial vacuum is generated in the intake manifold, resulting in less quantity of mixture during the compression stroke. There is a large gain in efficiency at light loads by advancing the ignition timing. 6) Types of fuels: a fuel having lower flame speed will need a greater spark advance for maximum power and economy.

Spark advance mechanism: When engine is idling the spark is timed to occur just before the piston reaches the TDC on the compression stroke. At higher speeds it is necessary to deliver the spark to the combustion chamber earlier. This gives ample time for mixture to burn and deliver its power to the piston There are two types 1) Centrifugal advanced mechanism 2) Vacuum advance mechanism

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Centrifugal advance mechanism: It consist of advance cam integral with the ignition cam, a pair of governors or advance weights and a plate attached to the distributor shaft. All are located beneath the ignition cam and breaker plate. As the engine speed increases the advance weights are thrown out against spring tension. they are pivoted on their pins. As they swing out they push the advance cam so that it rotates the breaker cam ahead of the distributor shaft. This advance cause the cam open. The timing of spark to the cylinder thus varies at high speeds. This advance timing is as much as 28 degrees of crank angle.

Vacuum advance mechanism: The vacuum advance is obtained by attaching the movable breaker plate to a diaphragm which is held in full retard position by a spring. The breaker point is ed in bearings so that it can turn with respect to distributor housing. The spring loaded side of a diaphragm is connected through a vacuum line to the intake manifold through the carburetor. There is no vacuum advance in the idling position. As the throttle valve opens it swings past the opening of vacuum age the intake manifold the vacuum can then draw air from the vacuum line and the air tight chamber in the vacuum advance mechanism. This cause the diaphragm to move against the spring. The linkage of the breaker plate then rotates the breaker plate. This movement carries the points around so the cam, as it rotates, closes and opens the points earlier in the cycle and supplies spark at the spark plug earlier at the compression stroke. TUTORIAL:

1. What are the disadvantages of battery ignition system? How can these be overcome? 2. Give merits and demerits of electronic system over conventional system. 3. Compare the battery and magneto ignition system. Why battery system is used in cars? 4. Draw diagrams of battery, magneto and electronic systems and explain in brief.

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L.J. Institute of Engineering & Technology, Ahmedabad Mechanical engineering department SUB: I.C.ENGINE

SEM: VI

PRACTICAL : 8

AIM : To carry out heat balance sheet of single cylinder diesel engine. The aim of testing of engines is to confirm the engine performance as per design specification and justify the rating of engine. INDICATED POWER(I.P.): I.P. of engine represents power developed within the cylinder and can be determined by engine indicator, Farnborough balanced engine indicator and electrical indicator.

BREAK POWER(B.P.): B.P. represents the useful power available at the crankshaft. Methods of its measurement by various dynamometers are: 1. 2. 3. 4. 5. 6.

Prony break Rope break Hydraulic dynamometer Swinging field dynamometer Eddy current dynamometer Transmission dynamometers

MECHANICAL EFFICIENCY: It is a ratio of B.P and I.P. FRICTION POWER: It represents the mechanical friction losses and the pumping losses of the engine. F.P. = I.P. – B.P.

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It can be measured by; 1. 2. 3. 4.

By measurement of I.P & B.P. Willan’s line method Morse test for multi-cylinder engines Motoring test

Heat balance sheet represents the of energy supplied in fuel and its corresponding expenditure. It is drawn either on KJ/min basis or on percentages basis.

TUTORIAL

1. A two stroke diesel engine was motored when the meter reading was 1.5 KW then the test on the engine was carried out for one hour and the following observations were recorded,(i) break torque= 125Nm,(ii)speed = 600 Rpm,(iii)fuel used = 2.5Kg, (iv)C.V. of fuel= 40.3MJ/Kg,(v) cooling water used = 818Kg,(vi)rise in temperature of cooling water = 100 C,(vii) exhaust gas temperature = 3450C,(viii) room temperature = 250 C and(ix) A:F = 32:1. Determine (a)B.P. (b)I.P. (c)mechanical efficiency,(d)indicated thermal efficiency, (e) draw heat balance sheet on minute bases and also in percentage

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L.J. Institute of Engineering & Technology, Ahmedabad Mechanical engineering department SUB: I.C.ENGINE

SEM: VI

PRACTICAL : 9

AIM : To study simple carburetor and other types of modern carburetor. INTRODUCTION: The process of preparation if mixture of atomized fuel and air is called carburetion. The device which supplies the metered spray of fuel mixed with correct amount of aim for efficient combustion in cylinder at all operating condition is called carburettor. Fuel feeding system for S.I. engine consists of fuel tank, carburettor, throttle valve and intake manifolds. Main components of a simple carburetor are float chamber with float, main fuel jet, venture and the choke tube. Drawback of this carburetor is that it supplies rich mixtures with the increase in air speed. Starting choke when closed, provides rich mixture at the time of cold starting of the engine. Idling system consist of an idle port located just below of throttle valve. During Idling, the low pressure existing in intake manifolds helps in providing the rich mixture through idle jet. Acceleration system consists of an accelerating pump whose plunger is controlled by spring force and supplies excess fuel through metering orifice. Various compensating devices are used to maintain constant A.F. ratio with variation in speed since a simple carburettor tends the supply the richer mixture with increase in speed. Modern carburetor use the following compensating devices: 1. 2. 3. 4. 5. 6.

Compensating jet Emulsion tube or air bleed Auxiliary air valve Auxiliary air part Metering pin method for part load running Quality control by back suction

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Various modern automobile carburettors used are: 1. Solex carburettor 2. Cater carburettor 3. S.U. carburettor Problems associated with carburetion are: 1. Ice formation may take place in case temperature of mixture at venture becomes less than dew point of water vapour associated with air. 2. Vapour lock, may be caused due to vaporisation of fuel in pipes or float chamber in carburettor

TUTORIAL

1. Explain function of carburetor. 2. Various mixture requirements of S.I. engine for different conditions. 3. What are A.F. ratio requirements of a spark ignition engine under varying operating conditions? Why? 4. Find mass flow rate , air fuel ratio and jet dia. With and without compressibility

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