KATHMANDU UNIVERSITY

SCHOOL OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

A PROGRESS REPORT ON

COMPARATIVE ANALYSIS OF CARBURETOR AND FUEL INJECTION SYSTEM

(a case study of Apache 160)

Submitted To

Suman Aryal

Project Supervisor

Mechanical Engineering

Submitted By

Netra Jung Karki (41066)

Prabesh Poudel (41075)

Prajwol Shrestha (41086)

November 23, 2010

CERTIFICATION

FOURTH YEAR PROJECT PROGRESS REPORT

On

COMPARATIVE ANALYSIS OF CARBURETOR AND FUEL INJECTION

SYSTEM

(a case study of Apache 160)

Submitted By:

Netra Jung Karki (41066)

Prabesh Poudel (41075)

Prajwol Shrestha (41086)

Approved by:

Project supervisor

Dr. Bivek Baral

---------------------- -------------------------- ------------------

(Signature) (Name) (Date)

Abbreviation

US United States

DTS-Fi Digital Twin Spark Fuel Injection

Mm millimeter

WFO

DFI Digital Fuel Injection

L liters

GM General Motors

EFI Electronic Fuel Injection

ECU Electronic Control Unit

TBI Throttle Body Injection

CO2 Carbon Dioxide

EPA Environmental Protection Agency

LCD Liquid Crystal Display

Hp Horse Power

Table of ContentsCERTIFICATION.....................................................................................................................................2

Abbreviation................................................................................................................................................3

Abstract.......................................................................................................................................................6

1. Rationale..............................................................................................................................................1

2. Introduction.........................................................................................................................................1

3. Objectives............................................................................................................................................2

4. Benefits and feasibility........................................................................................................................3

5. Literature Review................................................................................................................................4

5.1 Carburetor.........................................................................................................................................4

5.1.1 Carburetor basics........................................................................................................................4

5.1.2 Parts of carburetor.....................................................................................................................6

5.1.3 How carburetors work................................................................................................................6

5.1.4 Carburetor adjustment...............................................................................................................9

5.1.5 Factors influencing carburetion................................................................................................10

5.1.6 Types of Carburetors................................................................................................................10

5.1.7 Basic forms of Carburetor.........................................................................................................11

5.2 Fuel injection...................................................................................................................................12

5.2.1 History of fuel injection............................................................................................................13

5.2.2 Operation Cycle of Electronic Fuel Injection (EFI).....................................................................16

5.2.3 Functions of fuel Injection........................................................................................................16

5.2.4 Objectives of Fuel Injection.......................................................................................................17

5.2.5 Benefits.....................................................................................................................................17

5.2.6 Advantages of Fuel Injection.....................................................................................................18

5.2.7 Types of Fuel Injections............................................................................................................19

5.2.8 Risks of Fuel Injection...............................................................................................................20

6. Materials and Methods.....................................................................................................................21

7. Timeline.............................................................................................................................................22

8. Costs, resources required..................................................................................................................23

9. Conclusion.........................................................................................................................................24

Reference..................................................................................................................................................25

Abstract

This project figures out the differences between fuel injection system and carburetor in terms of emission,

economy, power and operation. The earliest form of fuel supply mechanism for modern automobile is

carburetor. The primary function of carburetor is to provide the air-fuel mixture to the engine in the

required proportion. Fuel injection systems have a fuel injector for each cylinder, usually located so that

they spray right at the intake valve.

Emission Analysis will be done by gas analyzer. Economical and Power calculation can be done by the

company standards and the local rates for the initial cost of the machine, operational and maintenance

cost and resale value.

As a result of this project, we will find out the suitable system whether carburetor or fuel injection in the

context of bikes in Nepal.

1. Rationale

We have done this project as a part of our undergraduate final year course. The major

purpose behind choosing this project is to study on the field of our interest i.e. Air-fuel supply to

the engine cylinder. Low income of Nepalese people and the high demand of bikes for daily

purpose, a long term vision on reducing the operational and initial cost of bikes, reducing

pollution and selection of suitable air-fuel supply system in bikes for Nepal is the major

motivation to carry out this project.

2. Introduction

Carburetor is the earliest form of fuel supply mechanism of automobile. The primary

function of carburetor is to provide the air-fuel mixture to the engine in the required proportion.

The goal of a carburetor is to mix just the right amount of gasoline with air so that the engine

runs properly.

Fuel injection technology is used to eliminate the need for carburetors. The technology helps

the engine to supply fuel directly to the cylinder in the intake manifold, eliminating the use of

carburetor to much extent. Overall, the fuel injection is required to supply fuel directly to the

engine. It is one wherein the fuel is directly supplied to the cylinder in the intake chamber.

Sensors located in such engines will regulate the flow of fuel injected and maintains it to

appropriate levels. This system is developed so as to improve fuel efficiency.

Replacing the carburetor, an old fuel system, fuel injection system has been developed for

reliable and efficient fuel supply to the combustion process in automobiles. Advances made with

this system have dramatically improved since their invention. In modern vehicles, fuel injection

supplies the engine with its needed fuel in a constant feed accurately and with a great deal of

precision. Using this design ensures greater fuel efficiency because there is little waste in terms

of unnecessary fuel consumption.

This project aims to carry out the analysis of different parameters of the both fuel systems.

Fuel injection has been recently introduced in motorbikes of Nepal.

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3. Objectives

Emission analysis between carburetor and fuel injection system of two models

Analysis of sound level, pick-up, power, efficiency and economy between the two

systems

Selection of best alternative

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4. Benefits and feasibility

The main aim besides doing this project is to identify whether fuel injection system is

required in the motorbikes running in Nepal. As most of the motorbikes are based on

carburetor fuel supply system, it is seen that this is quite comfortable economically and in

terms of power for Nepali riders and roads till the date. Is there the need of fuel injectors in

the motorbikes of Nepal? The solution of this major question in terms of different aspects is

what we are trying to find from this project. The major outcome will be the recommendation

for using carburetor or fuel injection in the motorbike for Nepal.

All we need to carry out this project is a gas analyzer, environmental standards for

emission, maintenance and setup cost, operating cost, mileage data and fuel cost. The test

will be performed on the bikes of showroom workshop according to their permission which

can be obtained with co-ordination with the Department of Mechanical Engineering,

Kathmandu University. So, the project is feasible.

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5. Literature Review

Fuel is the major source of an automobile engine for operation and power generation. The project

is totally based on the comparative analysis of fuel supply to engine of carburetors and fuel

injection system in motorbike. Carburetors are the traditional form of fuel supply mechanism in

Europe and US, but still in use in almost all motorbikes here in Nepal. Some of the motorbikes

like Bajaj Pulsar 220 DTS-Fi, Hero Honda Karizma ZMR, Apache RTR 160 Fi, Yamaha FZ16,

Yamaha YZF R15 have introduced fuel injection system. The project is a case study of

comparative analysis between overall performance of carburetor and fuel injection system in an

identical motorbike engine. We have chosen Apache 160 model bike for the purpose.

We have planned to analysis different aspects of fuel supply systems. Power, economy,

environment, emission, sound level, speed, pick-up and efficiency are the major topics for the

comparative analysis between carburetor and fuel injection system.

5.1 Carburetor

Engine works on fuel. The earliest form of fuel supply mechanism for modern automobile is

carburetor. The primary function of carburetor is to provide the air-fuel mixture to the engine in

the required proportion. The goal of a carburetor is to mix just the right amount of gasoline with

air so that the engine runs properly. If there is not enough fuel mixed with the air, the engine

"runs lean" and either will not run or potentially damages the engine. If there is too much fuel

mixed with the air, the engine runs rich and either will not run (it floods), runs very smoky, runs

poorly (bogs down, stalls easily), or at the very least wastes fuel. The carburetor is in charge of

getting the mixture just right.

5.1.1 Carburetor basics

A carburetor basically consists of an open pipe through which the air passes into the inlet

manifold of the engine. The pipe is in the form of a venturi: it narrows in section and then widens

again, causing the airflow to increase in speed in the narrowest part. Below the venturi is a

butterfly valve called the throttle valve - a rotating disc that can be turned end-on to the airflow,

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so as to hardly restrict the flow at all, or can be rotated so that it almost completely blocks the

flow of air. This valve controls the flow of air through the carburetor throat and thus the quantity

of air/fuel mixture the system will deliver, thereby regulating engine power and speed. The

throttle is connected, usually through a cable or a mechanical linkage of rods and joints or rarely

by pneumatic link, to the accelerator on a motorbike or the equivalent control on other vehicles

or equipment.

Fuel is introduced into the air stream through small holes at the narrowest part of the venturi and

at other places where pressure will be lowered when not running on full throttle. Fuel flow is

adjusted by means of precisely-calibrated orifices, referred to as jets, in the fuel path.

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Figure 1: Carburetor Basics

5.1.2 Parts of carburetor A carburetor is essentially a tube.

There is an adjustable plate across the tube called the throttle plate that controls how

much air can flow through the tube.

At some point in the tube there is a narrowing, called the venturi, and in this narrowing a

vacuum is created.

In this narrowing there is a hole called as jet, that lets the vacuum draw in fuel.

Figure 2: Schematic Diagram of a simple or elementary carburetor

5.1.3 How carburetors work

All carburetors work on "the Bernoulli Principle. Bernoulli principle states that as the velocity

of an ideal gas increases, the pressure drops. Within a certain range of velocity and pressure, the

change in pressure is pretty much linear with velocity-if the velocity doubles the pressure halves.

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However, this linear relationship only holds within a certain range. Carburetor has to accelerate

from rest, to some speed. How fast depends upon the air flow demanded by the engine speed and

the throttle butterfly setting. According to Bernoulli, this air flowing through the throat of the

carburetor will be at a pressure less than atmospheric pressure, and related to the velocity (and

hence to how much air is being fed into the engine).

If a small port is drilled into the carburetor throat in this low pressure region, there will be a

pressure difference between the throat side of the port, and the side that is exposed to the

atmosphere. If a reservoir of gasoline, the float bowl, is between the inside of the port, and the

atmosphere, the pressure difference will pull gasoline through the port, into the air stream. At

this point, the port gets the name of a jet in the concept of a carburetor. The more air that the

engine pulls through the carburetor throat, the greater the pressure drop across the jet, and the

more fuel that gets pulled in. As noted above, within a range of airflow in the throat, and fuel

flow in the jet, the ratio of fuel to air that flows will stay constant. And if the jet is the right size,

that ratio will be what the engine wants for best performance

A venturi/jet arrangement can only meter fuel accurately over a certain range of flow rates and

pressures. As flow rates increase, either the venturi or the jet, or both, will begin to choke, that is

they reach a point where the flow rate will not increase, no matter how hard the engine tries to

pull air through. At the other extreme, when the velocity of the air in the venturi is very low-like

at idle or during startup, the pressure drop across the jet becomes vanishingly small. It is this

extreme that concerns us with respect to starting, idle and low-speed throttle response.

At idle, the pressure drop in a 32 mm venturi is so small that essentially no fuel will be pulled

through the main jets. But the pressure difference across the throttle butterfly (which is almost

completely closed) can be as high as 25+ mm Hg. Carb designers take advantage of this situation

by placing an extra jet, the "idle jet" natch, just downstream of the throttle butterfly. Because of

the very high pressure difference at idle, and the very small amount of fuel required, this jet is

tiny. When the throttle is open any significant amount, the amount of fuel that flows through this

jet is small, and for all intents and purposes, constant. So its effect on the midrange and up

mixture is easily compensated for.

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During startup, the amount of air flowing through the carburetor is smaller still. At least till the

engine begins to run on its own. But when it is being turned by the starter or the kicker, rpm is in

the sub 100 range sometimes. So the pressure difference across the jets is again in the

insignificant range. If the engine is cold, it wants the mixture extra- rich to compensate for the

fact that a lot of the fuel that does get mixed with air in the carb precipitates out on the cold walls

of the intake port. All this really is another port or jet from the float bowl to just downstream of

the throttle butterfly. Except that the fuel flow to this jet is regulated by a valve that is built into

the carb body. At startup, when the lever is in the full on position, the valve is wide open, and the

fuel supply to the cold start jet is more or less unlimited. In this condition, the amount of fuel that

flows through the cold start jet is regulated just like the idle jet is. When the throttle is closed, the

pressure drop across the jet is high, and lots of fuel flows, resulting in a very rich mixture, just

perfect for ignition of a cold motor. If the throttle butterfly is opened, the pressure difference is

less, and less fuel flows. However, the mixture quickly gets too rich, and opening the throttle a

tad will make things better. Just like the idle jet, the cold start jet is small enough that even when

the circuit is wide open, the amount of fuel that can flow is small enough that at large throttle

openings, it has little impact on the mixture. This is why you can ride off with the starting circuit

on full, and the bike will run pretty well-until you close the throttle for the first time, and the

mixture gets so rich the engine stalls. The valve that controls fuel supply to the cold start jet

allows the rider to cut the fuel available through that jet down from full during startup, to none or

almost none once the engine is warm. In most cases, at the intermediate setting, fuel to the cold

start jet is cut to the point where the engine will still idle when warm, although very poorly since

it is way too rich.

True "chokes" are different. A choke is simply a plate that can be maneuvered so that it

completely (or very nearly) blocks off the carburetor throat at its entrance. That means the main,

idle, intermediate, etc. jets are all downstream of the choke plate. Then, when the engine tries to

pull air through the carb, it can't. The only place that anything at all can come in to the carb

venturi is through the various jets. Since there is little or no air coming in, this results in an

extremely rich mixture. The effect is maximized if the throttle butterfly (which is downstream of

the big main jets and the choke plate) is wide open, not impeding things in any way. If the

throttle butterfly is completely closed, the engine does not really know that the choke is there-all

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the engine "sees" is a closed throttle, so there is little enrichening effect. The engine will pull as

much fuel as possible through the idle jet, but that is so small it won't have much effect. So a

carb with a choke behaves in exactly the opposite manner as one with an enrichener. During the

cranking phase, it is best to have the throttle pegged at WFO so that the most fuel gets pulled in,

resulting in a nice rich mixture. But as soon as the motor starts, you want to close the throttle to

cut down the effect of the choke. Even that is not enough, and most chokes are designed so that

as soon as there is any significant airflow, they automatically open part way. Otherwise the

engine would flood. Even "manual" chokes have this feature most of the time.

Figure 3: A motorcycle carburetor

5.1.4 Carburetor adjustment

Too much fuel in the fuel-air mixture is referred to as too rich, and not enough fuel is too lean.

The mixture is normally adjusted by one or more needle valves on an automotive carburetor, or a

pilot-operated lever on piston-engined aircraft (since mixture is air density (altitude) dependent).

The stoichiometric air to gasoline ratio is 14.7:1; meaning that for each weight unit of gasoline,

14.7 units of air will be consumed. Stoichiometric mixture is different for various fuels other

than gasoline.

Ways to check carburetor mixture adjustment include: measuring the carbon monoxide,

hydrocarbon, and oxygen content of the exhaust using a gas analyzer, or directly viewing the

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colour of the flame in the combustion chamber through a special glass-bodied spark plug. The

flame colour of stoichiometric burning is described as a bunsen blue, turning to yellow if the

mixture is rich and whitish-blue if too lean.

The mixture can also be judged after engine running by the state and color of the spark plugs:

black, dry sooty plugs indicate too rich mixture, white to light gray deposits on the plugs indicate

a lean mixture. The correct color should be a brownish gray.

In the early 1980s, many American-market vehicles used special "feedback" carburetors that

could change the base mixture in response to signals from an exhaust gas oxygen sensor. These

were mainly used to save, but eventually disappeared as falling hardware prices and tighter

emissions standards made fuel injection a standard item.

Where multiple carburetors are used the mechanical linkage of their throttles must be

synchronized for smooth engine running.

5.1.5 Factors influencing carburetion

1. The engine speed; the time available for the preparation of the mixture.

2. The vaporization characteristics of fuel.

3. The temperature of the incoming air

4. The design of the carburetor.

5.1.6 Types of Carburetors

1. Open choke type

Here, the main orifice known as the choke tube or venturi is of fixed dimensions, and

metering is affected by varying the pressure drop across it.

2. Constant vacuum type

In this type of carburetor the area of the air passage is varied automatically while the

pressure drop is kept approximately constant.

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5.1.7 Basic forms of Carburetor

i. Updraught

ii. Downdraught

iii. Horizontal

Figure4: Basic forms of Carburetor

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5.2 Fuel injection

Fuel Injection is a technology that is being used in bikes and cars these days. The technology is

used to eliminate the need for carburetors. The technology helps the engine to supply fuel

directly to the cylinder in the intake manifold, eliminating the use of carburetor to much extent.

Overall, the fuel injection is required to supply fuel directly to the engine.

Fuel injection technology is one where the fuel is directly supplied to the cylinder in the intake

chamber. Sensors located in such engines will regulate the flow of fuel injected and maintains it

to appropriate levels.

As long as the sensors (usually electronic) are working properly, the possibilities of breakdown

and chock are immensely reduced. One can even find different amounts of fuel injecting systems

like throttle body fuel injection systems and single point fuel injection systems. The throttle body

system supplies the fuel located on throttle body directly to the intake chamber whereas the

single point systems will supply the fuel from a single injector.

Whatever might be the type of fuel injection used, we are sure that they will result in better

riding and control of the machine.  Fuel injection systems are developed so as to improve fuel

efficiency and also to eliminate the use of carburetor.

The Electronic Fuel Injection system can be divided into three basic sub-systems. These are the

fuel delivery system, air induction system, and the electronic control system.

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Figure5: Electronic Fuel Injector

Figure6: Schematic Diagram of simple EFI system

5.2.1 History of fuel injection

It began as early as 1883 with Edward Butler, Duetz and other pioneers. It wasn't until World

War II when Germany pursued it further by bringing the Robert Bosch Company into developing

fuel injection for the aviation field. During that time, however, United Kingdom and United

States combined efforts to build a system to use in the Patton tank.

Electronic fuel injection had its beginnings in Italy by an engineer named Ottavio Fuscaldo

incorporated an electrical solenoid as a means to control fuel flow, this was a modern electronic

fuel injection development.

After the World War II, most aircraft industries turned away from further development and

towards jet engines, fuel injection was basically put on the back burner. Even the automotive

manufacturers were content to make minor progressive developments to the inexpensive

carburetor.

Then in 1949 an Indy race featured a fuel injected Offenhauser. The system was developed by

Stuart Hillborn and featured an indirect injection system.

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Later Chevrolet introduced the Rochester

Ramjet in 1957. It was also used in the

1957 Pontiac Bonneville; it used a lot of

systems designed by Hillborn. The system

was not popular with the general public

and it was dropped after 1959, except for

the Corvette which used it as an option

until 1965. Across in Europe, some

manufacturers, including Bosch pursued fuel

injection on Volkswagen, Mercedes Benz in the 60's and 70's.

GM then in 1975 introduced the first mass produced domestic fuel injection system on the 1976

model Cadillac Seville. It was a system

consisting of a throttle body, 8 fuel injectors

mounted on a fuel rail directing fuel into the

intake, a crude analog computer and various

sensors. It had been developed between

Bendix, Bosch and General Motors. It was at

that time that it was necessary for the

industry to developed specialized

troubleshooting techniques and flow charts which

are now taken for granted.

Later in 1980 the first digital computerized control was introduced for Cadillac called Digital

Fuel injection (DFI), originally conceptualized as a multipoint injection, cost constraints again

limited it as a throttle body system with two fuel injectors. The introduction of a digitally

controlled system made it possible for a finer refinement of fuel control via various sensors, and

to make minor adjustments on the fly and to be able to store trouble codes indicating

malfunctions that can be recalled by a technician in troubleshooting.

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Figure7: Rochester Ramjet

Figure8: Cardillac Seville

In 1982, Pontiac introduced the single injector throttle body system on its 2.5L 4 cylinder "iron

duke" engine. Chevrolet and other divisions introduced it on its "A" and "X" body designs

including Citation, Celebrity, Skylark, Omega, Phoenix and even on the Camaro.

1983 saw the introduction of the cross fire injection on the 5.0L Camaro/Firebird and the 5.7L

Corvette. This system had two single throttle bodies mounted on opposite ends of a special

manifold and allowed for better fuel atomization and velocity. It was good for a 20 hp gain over

a carbureted 5.0L Camaro. The system was not perfect,

and suffered from some of the same problems as its

carbureted cousin such as manifold wetting and poor

fuel distribution, and special problems such as icing of

the throttle body bores under certain conditions, and a

leaky air intake seal. Fortunately, the system was short

lived as GM's engineers worked overtime on their next

project and they would be greatly rewarded for.

A technological milestone was reached in 1985 with the introduction of the Multiport Fuel

Injection on its 2.8L V6 used in the Celebrity, Camaro, Cavalier, Citation and a multitude of

other GM division vehicles. Also in the same year Chevrolet introduced the Tuned Port Fuel

Injection on the 5.0L Camaro and the 5.7L Corvette. Compared to the cross fire, with various

valve train improvements was good for a 40 hp gain on the 5.7L engine! The system with its

specially designed intake, elegant long runners and tightly controlled fuel management was good

for powerful low end torque and mid range power.

In 1989, the cold start injector was eliminated. In 1990, the mass air flow was eliminated and

speed density control was introduced. It required a different harness and computer. This system

was used all the way up 1992, where it was replaced by the shorter runner designed LT1 and

LT4 power plants.

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Figure9: Camaro

5.2.2 Operation Cycle of Electronic Fuel Injection (EFI)

Air enters the engine through the air induction system where it is measured by the air

flow meter. As the air flows into the cylinder, fuel is mixed into the air by the fuel

injector.

Fuel injectors are arranged in the intake manifold behind each intake valve. The injectors

are electrical solenoids which are operated by the ECU.

The ECU pulses the injector by switching the injector ground circuit on and off.

When the injector is turned on, it opens, spraying atomized fuel at the back side of the

intake valve.

As fuel is sprayed into the intake airstream, it mixes with the incoming air and vaporizes

due to the low pressures in the intake manifold. The ECU signals the injector to deliver

just enough fuel to achieve an ideal air/fuel ratio of 14.7:1, often referred to as

stoichiometric.

The precise amount of fuel delivered to the engine is a function of ECU control.

The ECU determines the basic injection quantity based upon measured intake air volume

and engine rpm.

Depending on engine operating conditions, injection quantity will vary. The ECU

monitors variables such as coolant temperature, engine speed, throttle angle, and exhaust

oxygen content and makes injection corrections which determine final injection quantity

5.2.3 Functions of fuel Injection

- Filter the fuel

- Meter or measure the correct quantity of fuel to be injected

- Time of fuel injection

- Control the rate of fuel injection

- Atomize or break up the fuel to fine particles

- Properly distribute the fuel in the combustion chamber

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5.2.4 Objectives of Fuel Injection

Though the functional objectives for different types of fuel injections vary, the main task is to

supply fuel to the combustion process. The objectives of a fuel injection are

Fuel Efficiency

Reliability

Emission performance

Output power

To accommodate alternative fuels

Smooth Operation

Basic cost

Maintenance cost

Diagnostic Capability

Environmental operation

It is practically impossible for a single system to have all these objectives as certain

combinations are conflicting. But all the systems try to supply most of these objectives.

5.2.5 Benefits

Many benefits of fuel injection include:

Smoother and dependable engine response during quick transitions.

Easier and faster engine starting.

Better operation at a high or low ambient temperature.

Increased fuel efficiency and

Increased maintenance intervals.

Modern electronic fuel injections help in maintaining accurate fuel metering and help in

producing less air pollutants.

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5.2.6 Advantages of Fuel Injection1. Uniform Air/Fuel Mixture Distribution

Each cylinder has its own injector which delivers fuel directly to the intake valve. This

eliminates the need for fuel to travel through the intake manifold, improving cylinder

to cylinder distribution.

2. Highly Accurate Air/Fuel Ratio Control

Throughout All Engine Operating Conditions EFI supplies a continuously accurate

air/fuel ratio to the engine no matter what operating conditions are encountered. This

provides better drive ability, fuel economy, and emissions control.

3. Superior Throttle Response and Power

By delivering fuel directly at the back of the intake valve, the intake manifold design

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can be optimized to improve air velocity at the intake valve. This improves torque and

throttle response.

4. Excellent Fuel Economy With Improved Emissions Control

Cold engine and wide open throttle enrichment can be reduced with an EFI engine

because fuel puddling in the intake manifold is not a problem. This results in better

overall fuel economy and improved emissions control.

5. Improved Cold Engine Startability and Operation

The combination of better fuel atomization and injection directly at the intake valve

improves ability to start and run a cold engine.

6. Simpler Mechanics, Reduced Adjustment Sensitivity

The EFI system does not rely on any major adjustments for cold enrichment or fuel

metering. Because the system is mechanically simple, maintenance requirements are

reduced.

5.2.7 Types of Fuel Injections

Throttle-body injection: Commonly known as TBI, this system injects fuel at the throttle

body.

Continuous injection: In this system, the fuel sprays continuously from injector rather

than getting pulsed every time a stroke is given to the engine.

Multi-point fuel injection: In this system, the fuel is injected into the intake port along the

side of cylinder’s intake valve rather than a central point.

Central port injection: In this system, tubes along with valves are used to spray fuel at

each intake rather than full throttle body.

Direct Injection: It is the most used fuel injection. In this system, the nozzle used for

injection is placed in the combustion chamber and the piston causes a depression when an

initial combustion takes place.

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5.2.8 Risks of Fuel Injection

Every system has it’s own share of benefits and risks. So does the fuel injection system, though

the risks are very minimal. Due to the high pressure developed in the engine, a fuel injection

system causes some potential hazards.

A residual pressure may remain in the engine even after the engine is turned off and it may cause

an injury to the operator.

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6. Materials and Methods

The method of comparative analysis in emission between carburetor and fuel injection

will be done with the help of a gas analyzer. There are different types of gas analyzers used

in emissions tests. However, all of these analyzers are used to measure the levels of emission

gases in a vehicle. 

The Four Gas Analyzer is equipment used to monitor the four gases that are needed to be

monitored according to the EPA emissions standards. These gases are Carbon Monoxide

(CO), Hydrocarbons (HC), Carbon Dioxide (CO2), and Oxygen (O2). The Gas Analyzer is

inserted in the tail pipe of the vehicle to measure the levels of emission of these gases. The

Four Gas Analyzer uses a sampling probe that tests a tiny part of the exhaust gases.

The Five Gas Analyzer is capable of measuring the five different gases that are

considered dangerous by EPA. Just like the Four Gas Analyzer, it can measure the levels of

emission gas of the four gases plus Nitrogen Oxides.

Almost all of the Gas Analyzers have LCD screen and computer system to display the

data gathered from the test.

Sound Level testing is done with Digital Sound Level Meter 8928.

Economic analysis can be done by comparing the initial cost and calculating the average

mileage of both systems.

Other Analysis can be performed from the engine specification and company manual.

Power, pick up, sound, efficiency analysis will also be performed.

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7. Gantt Chart

No. Activity

September

October

November

December

Estimated No. of hours

1 Literature Review         40

2 Detail study of Carburetor & Fuel Injection         25

3 Detail study about Emission standards         25

4 Progress report and Presentation         10

  Total Time (Hours) 100

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8. Costs, resources required

The estimated cost of our project is around six thousand Nepali rupees.

Gas Analyzer for emission analysis, sound level detector and the costs for buying,

operation of bike are the major resources required for the completion of the project.

The company manual is also a major resource for performing different analysis.

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9. Conclusion

From the above facts we are pretty sure that the project will be completed with the

desired results in the allocated time. As, fuel injection system bikes has been recently

introduced in Nepal, we will find out the importance of it in present context. This project

will provide a good reason for the choice between fuel injection and carburetor system

for those who want to buy a motorbike. Also it provides the comparative data between

power, economy, efficiency which can be used for different class of people for the bike

selection.

This project can be a milestone in present context as the generation is changing from

carburetor to fuel injection. Finally, it may or may not support the change in different

aspects. So, providing the best alternative in the present scenario will be our main aim.

Hence, this project will have a concrete output.

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Reference

R.K.Rajput : “A Textbook of Automobile Engineering”, Laxmi Publications (P) LTD, New

Delhi, India, 2007

http://www.carcraft.com/techarticles/carburetor_vs_injection/index.html

http://hemrickperformance.com/Carb.aspx

http://auto.howstuffworks.com/fuel-injection1.htm

http://autoforums.carjunky.com/Automotive_World_C11/

Gasoline,_Motor_Oils,_Concept_Cars_and_Engines_F24/

Fuel_Injector_vs_carburetor_P339/

http://www.brighthub.com/diy/automotive/articles/51709.aspx

http://www.articlesbase.com/cars-articles/fuel-injection-vs-carburetors-1125454.html

http://www.tuning.wanadoo.co.uk/carburettor-or-fuel-injection.htm

http://www.moddedmustangs.com/forums/5-0-mustangs/119761-carb-vs-fuel-

injection.html

http://www.quickcashauto.com/Car-Facts/Fuel-Injection-Vs-Carburetors.html

http://bikeadvice.in/fuel-injection/

http://bikeadvice.in/tvs-apache-rtr-fi-review/

http://www.tvsapache.com/

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