PERFORMANCES OF A SPARK IGNITION (SI) ENGINE

FUELLED WITH LIQUEFIED PETROLEUM GAS (LPG) USING

LIQUID SEQUENTIAL INJECTION (LSI) TECHNIQUE

MOHD MUSTAQIM BIN TUKIMAN

UNIVERSITI TUN HUSSEIN ONN MALAYSIA

PERFORMANCES OF A SPARK IGNITION (SI) ENGINE FUELLED WITH

LIQUEFIED PETROLEUM GAS (LPG) USING

LIQUID SEQUENTIAL INJECTION (LSI) TECHNIQUE

MOHD MUSTAQIM BIN TUKIMAN

A thesis report submitted in partial fulfillment of requirement for the award of the

Master of Engineering (Mechanical)

Faculty of Mechanical and Manufacturing Engineering

Universiti Tun Hussein Onn Malaysia

MAY 2017

iii

To my beloved parents, friend,

for their endless love, support and tolerance

iv

ACKNOWLEDGEMENT

In the name of Allah, the Most Merciful and the Most Compassionate. I thank

Allah for giving me the understanding and strength I needed to finish this study.

I would like to thank my supervisor Assoc. Professor Dr Mas Fawzi

Mohd Ali and my co-supervisor Dr Shahrul Azmir Osman, for their support,

impulse, tutoring and motivation along my research journey. My special thank to

my parent, Mr. Tukiman Nadi and Madam Siti Mariam Rahmat for the spiritual

support and their pray for my completion of this project.

I would like to record my thanks to the members of Automotive Research

Group (ARG-UTHM) (Assoc. Professor Dr Mas Fawzi Mohd Ali, Dr Shahrul

Azmir Osman, Dr Azwan Sapit, Dr Mohd Faisal Hushim and Mr. Muammar

Mukhsin Ismail) and my study comrade Mr. Norrizal Mustaffa, Mr. Rais

Hanizam, Mr. Khairul Ilman Sarwani, and Mr. Fathul Hakim Zulkifli for their

unequivocal support and advice for me throughout this research which has given

me confidence and strength to face any problems.

I also appreciate the cooperation from the Departments of Energy

Engineering and Thermofluids (JKT) and the Department of Manufacturing and

Industrial Engineering (JKPI), especially from Mr. Mzahar Abd Jalal and Mr.

Nizam Jamat for providing me the technical support to finish this research.

Without them this project is impossible to be complete. Lastly, I would like to

thank who have directly and indirectly contributed to the success of my study.

v

ABSTRACT

The increment of fuel cost and environmental pollutions from transportation sector has

created interest on alternative fuels particularly in spark ignition (SI) engines. One of the

seen potential of alternative fuel is Liquefied Petroleum Gas (LPG). LPG has a research

octane number higher than gasoline and low carbon to hydrogen ratio content, thus the

LPG has the potential to give more power in SI engines and to reduce exhaust

emissions. An experimental work was conducted on a 1.6 Liters, 4-cylinder engine from

a Proton Gen 2 (S4PH), equipped with gasoline Multi Point Port Injection (MPI)

system. The engine was retrofitted with LPG Liquid Sequential Injection (LSI) and a

piggy-back system emulated the stock Electronic Control Unit (ECU). The engine was

tested in steady state conditions, which are based on engine speed from 1500rpm to

4000rpm with increment of 500rpm. The Throttle Position (TP) was varied at four

different levels that were 25%, 50%, 75% and 100% for every engine speed tested. The

findings from the experiment showed that the liquid phase LPG increased brake power

(BP) and brake torque (BT) in the range of 3% to 7%. The brake specific fuel

consumption (BSFC) of LPG at low engine speed (1500rpm to 2500rpm) was reduced

in the range from 21% to 52%. Meanwhile, at higher engine speed (3000rpm to

4000rpm) the LPG BSFC increased in average between of 3% to 57%. The carbon

monoxide (CO) exhaust emission was reduced in the range of 2% to 19% when using

LPG. The carbon dioxide (CO2) is also lower than gasoline in average between 9% and

18%. The hydrocarbon (HC) emission from LPG was increased in the range of 40% to

70%, and concentration of NOx emission was increased in average of 60% in

comparison with gasoline. As a conclusion, the LPG LSI system used in S.I engine is

more effective than gasoline at low engine speed condition due to low fuel consumption

and emission.

vi

ABSTRAK

Peningkatan kos bahan api dan pencemaran alam sekitar yang terhasil daripada sektor

pengangkutan telah menarik minat terhadap penggunaan bahan api alternatif yang

digunakan pada sistem enjin pencucuhan percikan api (SI). Salah satu potensi yang di

lihat sebagai bahan api alternatif ialah gas petroleum cecair (LPG). LPG mempunyai

nombor penyelidikan oktana (RON) yang tinggi disamping kandungan nisbah karbon

yang rendah dibandingkan dengan hidrogen. Oleh itu LPG berpotensi untuk memberi

kuasa yang lebih pada enjin SI dan mengurangkan pencemaran pelepasan asap ekzos.

Pada kajian ini, eksperimen dijalankan pada enjin 1.6Liter, 4-silinder dari Proton Gen 2

(S4PH) dan sistem penghantaran bahan api dilengkapi oleh sistem multi suntikan (MPI).

Enjin ini telah dimodifikasi dengan suntikan turutan cecair (LSI) LPG dan sistem unit

kawalan eletronik (ECU) yang asal pula telah disambungkan kepada sistem LSI

tersebut. Enjin telah ditetapkan kepada mod keadaan kekal, di mana kelajuan putaran

enjin bermula dari 1500rpm hingga 4000rpm dengan peningkatan kelajuan putaran enjin

sebanyak 50rppm. Terdapat empat perbezaan kedudukan posisi injap pendikit (TP) iaitu

25%, 50%, 75% dan 100% untuk setiap ujikaji mod kekal dijalankan. Hasil dapatan

kajian menunjukkan pengunaan LPG pada fasa cecair telah meningkatkan kuasa brek

(BP) dan tork brek (BT) dalam lingkungan 3%-7%. Brek penggunaan bahan api khusus

(BSFC) bagi LPG telah berkurang sebanyak 21%-52% pada kelajuan rendah putaran

enjin (1500ppm-2500ppm). Manakala BSFC pada kelajuan tinggi putaran enjin

(3000rpm-4000rpm) menunjukkan peningkatan 3%-57%. Pencemaran CO telah

berkurang sebanyak 2%-19% dan CO2 juga berkurang dalam purata 9% dan18%

apabila LPG digunakan. Pencemaran HC mencatatkan peningkatan sebanyak 40%-70%

dan NOx juga meningkat kepada 60% apabila dibandingkan dengan gasoline.

Kesimpulannya, pengunaan sistem LPG LSI pada enjin S.I adalah lebih efektif

berbanding gasoline jika digunakan pada kelajuan rendah putaran enjin.

vii

CONTENTS

CHAPTER TITLE PAGE

TITLE

DECLARATION

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

ABSTRAK

CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF SYMBOLS AND ABBREVIATIONS

LIST OF APPENDIX

i

ii

iii

iv

v

vi

vii

xii

xiii

xvi

xix

CHAPTER 1 INTRODUCTION 1

1.1 Background of Study

1.1.1 Demands of Fuel

1.1.2 Asian Fuel Price

1.1.3 Emission from Vehicle in The

Transport Sector

1.2 Problem statement

1.3 Objectives

1.4 Scopes

1.5 Significance of Study

1

2

3

4

6

7

8

9

viii

CHAPTER 2 LITERATURE REVIEW 10

2.1 Introduction

2.2 The Internal Combustion Engine System

2.3 Exhaust Gas Pollution

2.3.1 Carbon Monoxide - CO

2.3.2 Carbon Dioxide - CO2

2.3.3 Hydrocarbon - HC

2.3.4 Oxide of Nitrogen - NOx

2.4 Liquefied Petroleum Gas (LPG) Processed

from Oil Refining

2.5 Liquefied Petroleum Gas (LPG)

Manufacturing

2.6 Liquefied Petroleum Gas (LPG) as an

Alternative Fuel

2.7 Liquid and Gaseous Injection for S.I

Engine

2.7.1 Injector system

2.7.2 Indirect Injection

2.8 Liquefied Petroleum Gas (LPG) Engine

Technology

2.8.1 Bi-fuel Engine Technology

2.8.2 Dual-fuel Engine Technology

2.9 Liquefied Petroleum Gas (LPG) Conversion

System

2.9.1 Mechanically Control LPG

Carburetion System (First

Generation)

2.9.2 Electronically Controlled LPG

Carburetion System (Second

Generation)

2.9.3 LPG Injection System Electronically

10

10

14

15

15

15

16

16

18

20

22

23

23

26

26

27

27

28

30

ix

Controlled (Third generation)

2.9.4 Sequential Gaseous Stage LPG

Injection (Fourth Generation)

2.9.5 Sequential Liquid Stage LPG

Injection (Fifth Generation)

2.10 Liquefied Petroleum Gas (LPG) Liquid

Sequential Injection (LSI) as a Latest

Generation

2.10.1 Properties of Liquefied Petroleum

Gas (LPG) in Liquid phase

2.11 Advantage of Liquefied Petroleum Gas

(LPG) for Latest Technology

2.12 Disadvantage of Liquefied Petroleum Gas

(LPG) for Latest Technology

2.13 Performance and Emissions of LPG Vehicle

2.14 LPG Refueling Systems

2.15 Summary

32

34

36

39

39

40

41

41

48

51

CHAPTER 3 METHODOLOGY 52

3.1 Overview

3.1.1 Process flow chart

3.2 Retrofit Kits for the Latest LPG Liquid

Sequential Injection (LSI)

3.2.1 Conversion of Gasoline to LSI LPG-

Spark Ignition Engine

3.2.2 Liquid Sequential Injection LPG

Conversion System

3.2.3 LPG Storage

3.2.4 LPG Refueling System

3.3 Experimental Apparatus

3.3.1 Test Engine

3.3.2 Chassis Dynamometer

52

53

54

55

56

58

60

64

64

65

x

3.3.3 Measurement of Fuel Consumption

3.3.4 Measurement of In-cylinder Pressure

3.3.5 Measurement of Air Fuel Ratio and

the Exhaust Gas Emissions

3.3.6 Bosch Scan Tool KTS 570 V1.2

Management Systems

3.4 Engine Test

3.4.1 Steady-state Test

3.4.2 Engine Test Parameters

3.5 Standard Experimental Procedures

3.5.1 Preparatory Experimental

3.5.2 Running the Engine

3.5.3 Steady-state Engine Speed Mode

3.6 Summary

66

67

69

70

71

72

72

73

73

74

75

76

CHAPTER 4 RESULT AND DISCUSSION 77

4.1 Introduction

4.2 The LPG Refueling process

4.3 Comparison of Gasoline and LPG

Effect on the Engine Performance and

Exhaust Emission

4.3.1 The Effects of Gasoline and LPG on

Brake Power (BP)

4.3.2 The Effect of Gasoline and LPG on

Brake Torque (BT)

4.3.3 Brake Specific Fuel Consumption

(BSFC) on Gasoline and LPG

4.3.4 Carbon Monoxide (CO) Emission

4.3.5 Carbon Dioxide (CO2) Emission

4.3.6 Hydrocarbon (HC) Emission

4.3.7 Nitrogen Oxide (NOx) Emission

77

77

79

79

81

83

85

87

89

91

xi

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 94

5.1 Conclusion

5.2 Future Recommendation

94

96

REFERENCES

APPENDIX

97

103

xii

LIST OF TABLES

TABLE TITLE PAGE

2.1 Classification of reciprocating engine by application

2.2 Effects of contaminants in LPG

2.3 Composition of LPG by country

2.4 Specification of LPG and gasoline in United Kindom

2.5 Reviews on characterizing on LPG engine

2.6 Reviews on characterizing on LPG engine (continued)

2.7 Reviews on characterizing on LPG engine (continued)

2.8 Reviews on characterizing on LPG engine (continued)

2.9 Reviews on characterizing on LPG engine (continued)

2.10 Reviews on characterizing on LPG engine (continued)

3.1 The specification of the LPG toroidal tank

3.2 Specification of LPG fuel pump

3.3 Specification of the LPG diaphragm pump

3.4 Specification of the test engine

3.5 The specification of dynamometer

3.6 Specification of the fuel flow meter display unit

3.7 The spec of the fuel flow meter

3.8 Specification of spark plug in-cylinder pressure sensor

3.9 Specification detail of the emission gas analyzer

3.10 The specification of Bosch scan tool KTS 570 V1.2

3.11 The steady-state set value

4.1 Air-fuel mixture from stock ECU mapping

13

20

21

22

42

43

44

45

46

47

59

60

62

65

66

67

67

69

70

71

72

91

xiii

LIST OF FIGURE

FIGURE TITLE PAGE

1.1 Total world demands of gasoline fuel

1.2 Price of fossil fuel from 2010 to 2016

1.3 Fuel price in Asia

1.4 Total vehicle registered in Malaysia from 2010 to

2014 according to type

1.5 Malaysia's total CO2 emission from consumption of

conventional fuel

2.1 Four stroke operating cycle in an internal

combustion engine

2.2 Block diagram of LPG manufacturing

2.3 Chart of the LPG Fuel system delivery

2.4 Method of LPG injection

2.5 Generations of LPG

2.6 Diagram of the LPG fuel delivery control in first

generation

2.7 Mechanically controlled LPG Carburetion system

2.8 Flow diagram for second generation of LPG

2.9 Electronically controlled LPG Carburetion system

for the second generation

2.10 Diagram of LPG delivery control system in third

generation

2.11 Electronically controlled LPG injection system

2

3

4

5

6

14

18

22

25

28

29

30

31

32

33

34

xiv

2.12 Diagram for function of sequential delivery system

fuel LPG

2.13 Diagram for fourth generation LPG gaseous

2.14 Schematic diagram for fifth generations

2.15 Diagram for fifth generation LPG-liquid phase

2.16 Configuration of liquid and gaseous phase LPG

2.17 Method for LPG refueling system

2.18 The LPG refueling station (BOB)

2.19 The LPG refueling station (FSS)

35

36

37

38

40

48

49

50

3.1 Research flow chart

3.2 Diagram of retrofit Kits for the latest LPG LSI

system

3.3 The process flow diagram for process assembly

3.4 The wiring diagram for the LSI LPG system

3.5 Schematic diagram for process conversion fuel

delivery LPG system

3.6 The parts of LPG storage systems

3.7 The process flow diagram for refueling

3.8 Schematic diagram of the LPG refueling station

3.9 Dish type nozzle for refueling process

3.10 Test engine for LPG

3.11 Dynapack chassis dynamometer

3.12 Diagram of pressure sensor placed in a cylinder

head

3.13 The schematic diagram of engine test conditions

4.1 Time duration for LPG refueling process

4.2 Comparison of brake power between gasoline and

LPG at various throttle valve positions

4.3 BP improvement % of LPG at 100% throttle valve

position

4.4 Comparison of brake torque between gasoline and

53

55

56

57

58

60

61

63

63

64

66

68

71

78

80

81

xv

LPG at several throttle valve positions

4.5 BT improvement % of LPG at 100% throttle valve

position

4.6 Comparison of BSFC between gasoline and LPG

at various engine speeds

4.7 BSFC improvement % of LPG at 100% throttle

valve position

4.8 Comparison of CO between gasoline and LPG at

various engine speeds

4.9 CO % of LPG at 100% throttle valve position

4.10 Comparison of CO2 between gasoline and LPG at

various engine speeds

4.11 CO2 % of LPG at 100% throttle valve position

4.12 Comparison of HC between gasoline and LPG at

various throttle positions

4.13 HC % of LPG increased than gasoline at 100%

throttle valve position

4.14 Comparison of NOx between gasoline and LPG at

various engine speeds

4.15 Comparison of NOx % of LPG and gasoline at

100% throttle valve position

82

83

84

85

86

87

88

88

90

90

92

93

xvi

LIST OF THE SYMBOLS AND ABBREVIATIONS

AFR

BP

BT

BDC

BOB

BSFC

BTDC

CEN

CI

CNG

CO

CO2

C3H8

C4H10

DI

ECU

EDU

EGR

EIA

FSS

GDI

GGE

HC

HCCI

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Air/fuel Ratio

Brake Power

Brake Torque

Bottom Dead Center

Bubbling on Board

Brake Specific Fuel Consumption

Before Top Dead Center

European Committee for Standardization

Compression Ignition

Compress Natural Gas

Carbon Monoxide

Carbon Dioxide

Propane

Butane

Direct Injection

Electronic Control Unit

Engine Driver Unit

Exhaust Gas Recirculation

Energy Information Administration

Fast Fill Station

Gasoline Direct Injection

Gasoline Gallon Equivalent

Hydrocarbon

Homogeneous Charge Compression Ignition

xvii

HP

H2O

H2S

ICE

LPG

LSI

MPI

MSDS

NA

NDIR

NOx

OBD

OEM

O2

PFI-G

RON

rpm

SAE

SI

TBI

TBI-G

TDC

TP

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Horsepower

Water Molecule

Hydrogen sulfide

Internal Combustion Engine

Liquefied Petroleum Gas

Liquid Sequential Injection

Multi Point Port Injection

Materials Safety Data Sheet

Naturally Aspirated

Non-disperse infrared

Oxide of Nitrogen

On-board Diagnostic

Original Equipment Manufacturer

Oxygen

Phase Port Injection - Gaseous

Research Octane Number

Rotation-Per-Minutes

Society Automotive Engineering

Spark Ignition

Throttle Body Injection

Throttle Body Injection - Gas

Top Dead Center

Throttle Position

xviii

LIST OF APPENDIX

APPENDIX TITLE PAGE

A Apparatus calibration procedures and certificates 103

B Experimental data 109

C List of publications 117

D Photographic of retrofitted LPG LSI engine 119

CHAPTER 1

INTRODUCTION

1.1 Background of Study

This ever-increasing consumption of fuel has led the world to face the twin challenge;

fuel scarcity and environment deterioration. The transportation sector has experienced

steady growth in the past 30 years, which almost entirely relies on fossil fuels, oil in

particular. This oil demand is projected to be increased around 60% of the growth and

expected to increase further in the future, where the current reserves-to-production ratios

are projected to stay in remaining 40 years (Leung, 2011). The numbers of demand is

directly proportional to the rate of production, which will affected the draining current

fossil fuel reserve levels at a faster rate. This has resulted in fluctuating oil prices and

supply disruptions. In form of the deterioration an environmental issues, the

transportation sector had also contributed to a huge and growing share of emissions that

affects global climate; namely Green House Gases (GHG) emissions. In additional, the

GHG emissions from the transportation sector were responsible for about 23% and keep

increasing from year to year (Khan et al., 2009). To overcome these limitations, the use

of an alternative fuel is the best option to be considered. Some of the promising

alternatives are Liquefied Petroleum Gas (LPG), Compressed Natural Gas (CNG), bio-

fuel, Hydrogen and others.

2

1.1.1 Demands of Fuel

Figure 1.1 shows the demands of conventional fuel increase every year. This is because

the automotive and transportation industry has grown tremendously worldwide.

According to the Energy Information Administration (EIA, 2016), from 2010 until 2016

demands of a gasoline increased in the range of 30% to 40%. Meanwhile, the demands

of Liquefied Petroleum Gas (LPG) are drastic decrease in the range 5% to 10% in every

year. To avoid the demand and supply to become unstable, the introduction of

alternative fuel technology for consumers may be an answer. Alternative fuel such as

Liquefied Petroleum Gas (LPG), Compress Natural Gas (CNG), Biofuel, Hydrogen,

Fuel cell, Electric vehicle, methanol and ethanol need to be highlighted, as the societal

understanding how important alternative fuel. Consequently, introduce the alternative

fuel will be stable the demands of fuel for spark ignition (SI) and Compression Ignition

(CI) on the future.

Figure 1.1: Total world demands of conventional fuel (reproduced from EIA, 2016)

3

1.1.2 Asian Fuel Price

Generally, the increasing demand of fossil fuel such as gasoline and diesel with respect

to fuel supply has created economy turmoil particularly in transportation sector. The

fluctuation of current fuel price depends on the demand of fuel in world wide. Figure 1.2

shows the trend of fuel price from 2010 to 2016. In sum, the fuel price increased from

2010 to 2011. The price for gasoline started at USD 2.75 to USD 3.48 per gasoline

gallon equivalent (GGE). Thus, fuel price for diesel increased from USD 2.67 to USD

3.42 per GGE, and for LPG increased from USD 4.02 to USD 4.28 per GGE. On 2012

until 2014, the gasoline shows a fluctuated trend which started from USD 3.65, USD

3.50 and USD 3.51 per GGE. Diesel fuel price was decrease from USD 3.56, USD 3.54

to USD 3.49 per GGE. The price of LPG declined steadily from USD 3.86 to USD 3.83

and increased to USD 4.34 per GGE. In 2015 to 2016, the fuel price for gasoline has

dropped from USD 2.47 to USD 2.10 per GGE. Meanwhile, diesel was dropped from

USD 2.64 to USD 2.03 per GGE and LPG fuel price has decreased from USD 4.00 to

USD 3.83.

2010 2011 2012 2013 2014 2015 20160.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

US

D/ G

aso

line

Ga

llon

Eq

uiv

ale

nt (G

GE

)

Years

GASOLINE

DIESEL

LPG

Figure 1.2: Price of fossil fuel from 2010 to 2016 (reproduced from EIA, 2016)

4

Due to an increased demand and fluctuated fuel price in the world, the Asian fuel

prices also effected, especially in Malaysia. Until March 6, 2017, the fuel price was

trading at USD 0.52 per liters for gasoline and USD 0.5 for the diesel as shown in

Figure 1.3. The fuel price of gasoline is lower than other country in Asia and the diesel

fuel is the second lower price after Brunei due to the government subsidy. The subsidy

is invalid for the industrial and commercial purpose. Consequently, this has created a

burden on economy development, especially in the transportation sector, where

companies need to bear the higher costs of operating due to fluctuation in fuel price.

Malaysia*

Thailand

Singapore

Indonesia

Brunei

Philippines

Veitnam

Japan

China

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

* Price updated March 2017

1

0.9

1.12

0.93

0.84 0.65

0.95

0.62

0.51 0.32

0.61

0.68

1.42

0.98

0.98 0.76

0.52 0.5

Current Oil Prices in Asia (USD/Liters)

Co

un

trie

s

GASOLINE

DIESEL

Figure 1.3: Fuel price in Asia (reproduced from MyTravelCost, 2017)

1.1.3 Emission from Vehicle in the Transport Sector

Until 2014, the total number of registered road vehicle in Malaysia increased in the

range of 4% to 5% annually. Figure 1.4 shows the total of transport registered between

2010 and 2014. The figure was reproduced from the Road Trasport Department of

Malaysia., (2016). The trend indicated a sharp growth in the use of motorcycle, from

2011 to 2014 the motorcyclists was recorded from 9.442 million to 11.629 million. The

trend also same with the motorcar, the number of registered vehicle is increased from

5

9.115 million to 11.028 million annually, followed by good vehicle, bus and taxi. The

increment of transportation industries and low price of vehicles have increased the

number of vehicles registered in Malaysia especially in the urban areas, has led to the

increment of environmental contamination.

The increasing the number of vehicles, contribute to the increasing overall

carbon dioxide (CO2) concentration emission in Malaysia. Figure 1.5 shows the trend of

the total CO2 emission from consumption of gasoline and diesel fuel. According to the

Natural Resources and Environment, (2014) the figure shows the increasing of CO2

emission from 1990 to 2010 annually. The CO2 emission from 1990 to 1995 was

recorded at an average of 102.6 million metric tons, meanwhile at 1995 to 2000 CO2

emission was increased by 116 million metric tons. Following from 2000 to 2005 the

increasing of total emission was at 127.4 million metric tons. Lastly, from 2005 to 2010

the CO2 emission reached at 130 million metric tons. The increase of CO2 is a very

critical problem because it affects the greenhouse gas and global warming. As an effort

to reduce the CO2 emission in Malaysia, alternative fuel, namely LPG in liquid phase

can be introduced. In addition, according to Myung et al., (2012) LPG produced more

power, less pollutant emitted and the demands still low compared to conventional fuel.

Motorcycle Motorcar Bus Taxi Goods Vehicle Others

0

2

4

6

8

10

12

0.8

82

0.8

63

0.5

40

0.5

16

0.5

161.1

60

1.1

16

1.0

32

0.9

98

0.9

66

0.1

06

0.1

00

0.0

93

0.0

90

0.0

85

0.0

65

0.0

63

0.0

74

0.0

72

0.0

69

11

.02

81

0.5

36

10

.35

59

.72

1

9.1

15

11

.62

9

11

.08

81

0.5

90

9.9

85

9.4

42

Nu

mb

er

of V

eh

icle

(M

illio

n)

Type of Vechicles

2010

2011

2012

2013

2014

Figure 1.4: Total registered vehicle in Malaysia from 2010 to 2014 according to type

(reproduced from Road Trasport Department of Malaysia, 2016)

6

1990 1995 2000 2005 2010

0

25

50

75

100

125

150

Gasoline and diesel emission

Mill

ion

Me

tric

To

ns o

f C

O2

Years

CO2

Figure 1.5: Malaysia's total CO2 emission from consumption of conventional fuel

(reproduced from Natural Resources and Environment, 2014)

1.2 Problem Statement

The CO2 pollution issue was elevated in this country, which caused from transportation

sector that has increased at an average of 118.6 million metric tons in every five years.

In addition, world crude oil demands and supplies are dwindling, this cause the cost of

gasoline becoming increasingly expensive. In this research, several steps were being

chosen wisely to resolve this problem, the vehicle was retrofitted with LPG liquid phase

system as a bi-fuel system. This is because the liquid phase LPG produced low emission

and lower fuel consumption than gasoline. The brake power (BP) and brake torque (BT)

are comparable with gasoline, but the modification leads to the discovery of several

technical problems was studies by Kang et al., (2001), Sobiesiak et al., (2003), Gumus,

(2011), Myung et al.,(2014) and Farrugia et al., (2014).

According to Kang et al.,(2001) in year 2000 more than 6 million uses LPG on

the vehicle in Korea. The LPG vehicle received a warm welcome in automotive

industry. The LPG conversion systems can be divided into five generations, where the

first to fourth generation used gas phase for the fuel delivery system, while the latest

7

technology system uses LPG in liquid phase. Based on the latest technologies of the

LPG conversion system; the Liquid Sequential Injection (LSI) technique offers various

advantages in comparison with the previous generation system. This implementation of

retrofitted LPG-LSI in SI engine is still limited and has substantial research gaps.

However, the implementing barriers need to be solved are:-

i. Retrofitting LPG LSI system for S.I engine

ii. The methodologies of fuel refuelling for the system

iii. The unknown characteristics of LPG LSI system in local vehicle in terms of for

S.I. engine; engine performances and exhaust gas emissions

iv. The trade-off fuel consumption analysis for both gasoline and retrofitted LPG-

LSI engine

Therefore, it is desired to have a spark ignition (SI) engine from local vehicle to

install LPG LSI system is functioning in bi-fuel system for running the both of fuel in

experiments. By installing an LPG LSI system in the local vehicle, it may open up

alternative solutions to solve the current issue.

1.3 Objectives

The objectives of this research are:

a) To identify the influence of liquid sequential injection (LSI) system liquified

petroleum gas (LPG) system of a Spark-ignition (SI) engine

b) To establish an LPG refueling system for an LPG tank designed for LSI

application

c) To analyze the engine performance and exhaust emission of gasoline fuel and

LPG

8

1.4 Scopes

The scopes of this study are:

a) The composition of LPG used in this study is; 60% butane and 40% propane,

according to the Materials Safety Data Sheet (MSDS, 2015) of LPG in Malaysia.

b) The research focused on the installation of the retrofitted kit liquid sequential

injection (LSI) liquefied petroleum gas (LPG) at large passenger car with a

capacity of 1.6 Liters (S4PH GEN2) multi point port injection (MPI) spark

ignition (SI) engine.

c) This experiment used unleaded gasoline (RON95) and LPG liquid phase. Where,

to compare the engine performance and exhaust emission on local vehicle.

d) The LPG refueling system should be able to perform:

i. A transfer from LPG industrial cylinder tank (50kg) to the toroidal

external tank (17 kg) in the test vehicle with using diaphragm pump,

which is the pump has specific features for the LPG transfer process.

e) Analysis in terms of:

i. Engine performance

Brake power (BP)

Brake torque (BT)

Brake Specific Fuel Consumption (BSFC)

ii. Exhaust emission

Carbon monoxide (CO)

Carbon dioxide (CO2)

Hydrocarbon (HC)

Oxides of nitrogen (NOx)

9

f) The experimental work was conducted via chassis dynamometer at these

conditions:

i. Steady-state conditions with specific engine speed; 1500rpm, 2000rpm,

2500rpm, 3000rpm, 3500rpm and the 4000rpm.

ii. Four different throttle valve positions; 25%, 50%, 75% and 100% throttle

valve positions.

f) Analyze the efficiency of energy consumed between gasoline and LPG in term

of brake specific fuel consumption (BSFC) at the specific engine speed and

throttle valve opening in order to compare the fuel economy

1.5 Significance of Study

Based on the experiment, the installation of LPG LSI system will produced new

knowledge in this study and the future studies. This research will also open a new

opportunity to introduce the LPG as a new alternative fuel in Malaysia. On the other

hand, this research also compared gasoline and LPG in term of performance, exhaust

emission and fuel economy in the 1.6 Liters (S4PH GEN2) engine. These results may

contribute as a reference to establish another alternative fuel in our country.

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

This chapter presents a review of literature on the efforts related to conversion and

evaluation of the LPG system into a spark ignition (SI) engine. It is an attempt to

establish the parameters, modification and technologies etc., which are required to make

this project successful. It began with the concept of an internal combustion engine

followed by the automotive trends from the findings of previous research experiments.

2.2 The Internal Combustion Engine System

The internal combustion engine (ICE) was producing the mechanical power, where the

chemical energy contained in the fuel (Heywood, 1988). There are two ignition type of

the internal combustion engine which is spark ignition (SI) and compression ignition

(CI).

11

Following to the standard of ICE engine, they were divided in some classified which

are:

1. Engine operating cycle

a. Four stroke cycles - Completed the sequence power stroke with two

revolutions of the crankshaft and has four piston movements.

b. Two stroke cycles - Completed the sequence power stroke with a single

revolution of the crankshaft and has two piston movements.

2. Types of ignition

a. Spark Ignition (SI) - Need spark plug as an igniter to initiate the air/fuel

mixture in the combustion chamber.

b. Compression Ignition (CI) - The combustion process starts when the

air/fuel mixture self-ignites due to high temperature in the combustion

chamber cause by high compression.

3. Air intake process

a. Naturally Aspirated (NA) - No forced air induction pressure system.

b. Supercharged - Forced air induction in the intake manifold to

combustion chamber and increased the air pressure with the compressor

driven by the engine crankshaft.

c. Turbocharged - Forced air induction in the intake manifold to the

combustion chamber and increased the air pressure with turbine-

compressor driven by engine exhaust gas.

4. Method of fuel delivery for (SI) engine

a. Carbureted

b. Multipoint Port Fuel Injection (MPI) - One or more fuel injector in the

each cylinder's intake.

c. Throttle Body Fuel Injection (TBI) - Fuel injector are mounted

upstream in the intake manifold.

d. Gasoline Direct Injection (GDI) - Fuel injector are mounted in the

combustion chamber with injected fuel directly into the cylinder.

12

5. Method of fuel delivery for (CI) engine

a. Direct Injection (DI) - The fuel will inject into the main combustion

chamber.

b. Indirect Injection - The fuel will inject into the secondary combustion

chamber.

c. Homogeneous Charge Compression Ignition (HCCI) - Some of fuel

will add during the intake stroke.

This classification is very important basic to understand internal combustion

engine. In addition, it helps to understand how the engine operates with a LPG LSI

system. According to Heywood (1988), the reciprocating engine from SI engine was

classified into four engine group as shown in Table 2.1 based on the power output; small

passenger cars, light commercial, large passenger cars and heavy engines commercial.

The small passenger car engine normally has the power output in the range of 15

kilowatts (kW) or 20 horsepower (HP) to 75kW or 100 HP. Followed by light

commercial engine has the power output in the range of 35 kW or 46 HP to 150 kW or

200HP. Meanwhile, for large passenger cars capable of producing power output in the

range of 75kW to 200kW and equivalent between 100HP to 268HP. Lastly, for the

heavy commercial has potential to generate power output in the range of 120kW or 160

HP to 400kW or 536 HP. These engines were categorized in the class road vehicle,

normally using for transportation sector.

13

Table 2.1: Classification of reciprocating engine by application (Heywood, 1988)

Class

Service

Approximate

engine power range

Predominant

type

Road

vehicle

Small

passenger cars

15 kW - 75 kW

20HP -100 HP

Spark Ignition

(SI)

Light

commercial

35 kW - 150 kW

46 HP - 200 HP

Large

passenger cars

75 kW-200 kW

100 HP - 268 HP

Heavy

commercial

120 kW - 400 kW

160 HP - 536 HP

Generally, the reciprocating SI and CI engine for four stroke cycle engine

requires four operating cycles, which are intake stroke, compression stroke, power

stroke and exhaust stroke. Figure 2.1 shows the four-stroke operating cycle for a

complete combustion.

Firstly, the intake stroke, which the piston starts from Top Dead Centre (TDC)

and the piston travel downward to Bottom Dead Centre (BDC). At the same time, the

intake valve is open to draw fresh mixture air into the cylinder and the exhaust valve is

closed. The traveling was produced a pressure differential, where the vacuum was

created in the cylinder.

Secondly, the compression stroke process, the piston upward from BDC to TDC

and the both of the valves are closed. Compression process produced higher pressure

and temperature in the cylinder. Meanwhile, the injector start to inject the fuel and

followed by the spark plug start ignite in the combustion chamber. These processes

happen at a certain degree Before Top Dead Centre (BTDC). For the CI engine the

combustion starts from evaporate of fuel mixture, higher pressure and temperature in the

cylinder this due the self ignite and producing combustion in the combustion chamber.

14

The next process is power stroke or expansion stroke, where the piston travels

downward from TDC to BDC. At this time, the high pressure and temperature forced the

piston downwards and rotate the crankshaft. Before the piston reach BDC the exhaust

valve starts to open and drop the cylinder pressure.

Lastly, exhaust stroke process, where piston starts to upwards from BDC to

TDC. Meanwhile, the exhaust valve opens until certain degree BTDC and the exhaust

valve fully closed at TDC. During exhaust valve open, the piston force out the burned

gases exit from the cylinder. The new operating cycle will be happening in the ICE.

Intake Compression Power Exhaust

Crankshaft

Connecting rod

Piston

Combustion

Chamber

Air-fuel

mixture

Intake valve

open

Spark plug

Exhaust

valve

closed

Valve closed Valve closed

Intake valve

closed

Exhaust valve

open

Exhaust gases

Spark

plug

firing

Figure 2.1: Four stroke operating cycle in an internal combustion engine (reproduced

from Britanicca, 2007)

2.3 Exhaust gas pollution

The automotive industry and transportation has grown tremendously in the world wide.

This gives challenges of environmental pollution, such as CO, CO2, HC and NOx

exhaust emissions produced from internal combustion engine. The effects of the

emission are contributing to global warming, acid rain, smog odors and other health

problem (Pulkrabek, 2004 ; Costa et al.,2012).

15

2.3.1 Carbon Monoxide - CO

Carbon monoxide is colorless, odorless and tasteless, but the high toxic. This gas is one

of the byproducts and produced from incomplete combustion when the fuel burned. The

production rate of CO in the engine depends on the value of the air/fuel ratio (AFR). If

the air/fuel ratio in richer conditions, the oxygen is insufficient to react with the entire

carbon bond and produce higher carbon monoxide (CO) (Toyota, 2012).

In the fact that CO emission has high toxic gas, direct exposures will cause

headache, dizziness, vomiting and nausea. Meanwhile, when the exposes over in a long

period of time also cause risks of heart disease and death (Pulkrabek, 2004).

2.3.2 Carbon Dioxide - CO2

Generally, carbon dioxide consists of greenhouse gas (GHG). However the combustion

of hydrocarbon (HC) in fuel produced water vapor H2O and carbon dioxide CO2. The

use of fuel in lower carbon content per unit energy its gives positive effect of reducing

the CO2 emission (Gumus, 2011).

The increased of CO2 gas emissions is a critical issue, because the GHG was

increased and the effect is higher thermal radiation. Thus, the average of earth

temperature also increased and bring the phenomenon of "global warming" (Pulkrabek,

2004; Heywood, 1988; Osman, 2014).

2.3.3 Hydrocarbon - HC

Hydrocarbon (HC) emission produced from raw unburned fuel and the increasing of HC

had showed incomplete combustion in the engine. Other than that, the engine was

affected towards misfire when the large amount of HC. The factor increased of HC

emission is the delay of ignition timing, fuel delivery system problem and air induction

problem. To avoid from this problem the air/fuel mixture need to control in the

stoichiometric range and the ignition timing need to set as to follow the ideal ignition

timing as follows engine requirement (Toyota, 2012).

16

2.3.4 Oxides of Nitrogen - NOx

Oxides of nitrogen (NOx) consists of nitric oxide (NO), with small amount of nitrogen

dioxide (NO2) and other nitrogen-oxygen combination (Pulkrabek, 2004).During the

combustion process the nitrogen was reacted with oxygen to form oxides of nitrogen

(NOx). According to Heywood (1988), the amount of NOx emission depends upon:

i. Temperature of the cylinder

ii. Pressure of cylinder

iii. Exhaust Gas Recirculation (EGR) system

iv. Injection timing

v. The properties of fuel

Effects NOx for the environments is acid rain, where the hazard to the ecosystem

by increasing irritation and effects of ozone. Meanwhile, the effects of human are

harmful to the lungs and other biological tissue (Pulkrabek, 2004; Heywood, 1988;

Osman, 2014).

2.4 Liquefied Petroleum Gas (LPG) Processed from Oil Refining

According to Bahadori (2014), LPG is produced from crude oil, where the LPG has

been produced by distillation process. LPG contains propane (C3H8), butane (C4H10) and

small amounts of propylene and butylenes. Mainly, the LPG gas is odorless, but for

safety precaution the LPG was added with pungent gas such as ethanethiol. This is

because to easy detect any leakage if it happen.

Production of the LPG gas from crude oil started from fractionation of natural

gas liquid by distillation, catalytic cracking, delays cookers and hydrocrackers process.

After all process done, the heated crude oil is pumped into the distillation tower and all

petroleum products are extracted a specific fraction including gasoline, naphtha,

kerosene, diesel, fuel oil oil and residue. In the extraction process for producing

petroleum products, the temperature of distillation tower was controlled as follows the

extraction point respectively. Therefore, the LPG gas product was flowing at the top of

17

the distillation tower to the lowest boiling point. In this stage the LPG gas still in raw

natural gas condition because has methane, ethane, propane, isobutane, buddiene,

pentane and pentene. To extract of these gases from raw natural gas to LPG gas, various

techniques are used to recover LPG from natural gas:

i. Recontacting-compression

The raw natural gas stream in the top distillation tower will be compressed,

combined, cooled and fed up to separator. From these processes, the

separator will isolate the liquid phase passed through the de-ethanizer and

the vapor phase is used as fuel gas.

ii. Refrigeration

This method is common for recovery of LPG from gas streams. Where,

the gas streams will be refrigerate to obtain LPG fractions and producing

LPG components.

iii. Adsorption

By using silica gel, activated carbon and alumina the molecules are

bonded to the surface and the natural gas will be separated as follows the

LPG molecules.

Therefore, the natural gas liquid and associated heavy hydrocarbon such as

ethane, propane and butane must be through the recovery process in order to separate

the heavy hydrocarbon from the raw natural gas and to control dew point of the natural

gas stream. The other reason, components of the product will be sold as high as the

demands of the industries.

18

2.5 Liquefied Petroleum Gas (LPG) Manufacturing

After LPG gas passed the recovery process, the LPG gas need to go through the

manufacturing process, to purify the LPG gas. The process manufacturing is shown in

Figure 2.2.

Raw natural gas stream

from distillation tower

Acid gas removal

Extraction unit

Fractionation unit

Product treatment unit

Finished product LPG

De-ethanizer section

Depropanizer section

Debutanizer section

Figure 2.2: Block diagram of LPG manufacturing

i. Acid gas removal

To remove gases contain corrosive acid such as carbon dioxide (CO2)

and hydrogen sulfide (H2S). The acid gas removal by using amine or

Benfield process. Removal acid gas is a compulsory process to produce

free natural gas.

ii. Extraction unit

The petroleum product stream was divided into two processes. The first

process has the liquid stream rich in propane, butane and gasoline will be

19

sent to the fractionation tower as producing LPG product. The second

stream will be sent to the product gas unit for further processing.

iii. Fractionation unit

In the liquid stream consisted of ethane, propane, butane and pentane.

This product will be separate in the fractionator train and LPG ready to

sold. Generally, the fractionation tower has three columns to produce

LPG gas. There are:

De-ethanizer section- This process separated out ethane from this

column. The ethane was condensed in the condenser by using

propane at -7 ̊C and the gas was collected in the reflex drum.

Next, the non-condensed vapors (pure ethane) are sent to the fuel

gas system.

Depropanizer section- The pressure bottom product of De-

ethanizer is reduced and the product was entered the depropanizer

column. This product was condensed in the condenser and

produce propane. The condensed product (pure propane) was

collected into the reflex drum and flow to the fuel gas system

Debutanizer section- The bottom product from depropanizer is

expanding the pressure and fed to top of the tower. The product

will be condensed in the condenser and produce butane.

iv. Product treatment unit

After producing propane and butane from the fractionation plant, the

products need to go through the treatment process unit. The purpose of

this process is to remove some impurities such as water, hydrogen

sulfide, carbon disulfide and sulfur compound. The reason for removing

these compounds is shown in Table 2.2.

20

Table 2.2: Effects of contaminants in LPG

Contaminates Reason for removal

Hydrogen sulfide Safety and environmental

Carbon dioxide Corrosion control

Carbon disulfide Avoid from freeze-out at

low temperature

Nitrogen Poisoning in downstream

facilities

Water Hydrate formation and

corrosion

LPG is considerable as flammable nontoxic gases. Therefore LPG was

commercial used for cooking in the common household. In the other hand, LPG also

used for aerosol propellant and hydrocarbon refrigerant. The advantage of LPG is it can

avoid from the damage ozone and uses of hydrocarbon refrigerant is more energy

efficient and cheaper than others chemicals. LPG also used as fuel, especially for

medium class vehicle such as a car. It is an advantage to use LPG as fuel, because it

burns cleaner than gasoline and diesel.

2.6 Liquefied Petroleum Gas (LPG) as an Alternative Fuel

Liquefied petroleum gas (LPG) is one of the clean alternative fuel and has low emission

of carbon dioxide (CO2) and high octane number. The uses of LPG in heavy duty engine

industries such as diesel, gasoline engine have potential to control the emission exhaust

(Khan & Watson, 2010 ; Oprešnik et al., 2012)

In year 2000, more than 6 million vehicle used LPG (Kang et al.,2001). It shows

that LPG is getting good acceptance in automotive industries. The composition of LPG

is mainly propane (C3H8) and butane (C4H10). This composition varies slightly by

season, country and the characteristics of supply crude oil, the refining process and cost

21

refined product. Therefore, there is no specific standard value for compositions of LPG.

Table 2.3 shows the composition of LPG fuel in several countries.

Table 2.3: Composition of LPG by country (Saleh, 2008; Mustafa & Gitano-Briggs,

2009; MSDS, 2015)

Country Propane (%) Butane (%)

Malaysia 40 60

Austria 50 50

Australia 70 30

Belgium 50 50

France 35 65

German 90 10

Italy 25 75

United Kingdom 100 0

Netherland 50 50

In previous studies, LPG as fuel also reduce exhaust emission of oxide of

nitrogen (NOx) by decreasing the peak combustion temperature, anti-knock properties,

increase the volumetric efficiency and increase torque output (Kang et al., 2001;

Pundkar et al.,2012; Genchi et al., 2013). As shown in Table 2.4, the LPG has the

higher Research Octane Number (RON) as comparable with gasoline, where the value

of RON is in the range 106-111. Besides that, in term of performance the energy content

produced from LPG is higher, thus the power output from LPG is higher than gasoline.

In terms of CO2 emission, the LPG more advantage as the content of CO2 is lower. Thus,

LPG was promoted as superiority fuel than gasoline as follow the advantages.

22

Table 2.4: Specification of LPG and gasoline in United Kingdom (Khan et al., 2006)

2.7 Liquid and Gaseous Injection for S.I Engine

The fuel delivery system is important for the engine, which is the process to supply fuel

in the combustion chamber and produce the combustion. Before the fuel through into the

combustion chamber the fuel has been mixed with air in the air intake manifold. Figure

2.3 shows the method for the fuel system delivery.

Injector System

Indirect Injection

Single Point Throttle

Body Injection (TBI)

Sequential Injection Banked Injection

Multi Point Port

Injection (MPI)

Figure 2.3: Chart of the LPG Fuel system delivery

Characteristics Liquified Petroleum Gas

(LPG) Gasoline

Chemical formula Butane C4H10 and

Propane C3H8 C8H18

Lower Heating Value (MJ/kg) 46.33 42.4

Research Octane Number (RON) 106-111 92-95

Relative Density at 25 ̊ C 0.51 0.74

Stoichiometries A/F ratio

(mass basic) 15.7 14.7

Relative CO2 per kJ 0.885 1

23

2.7.1 Injector system

The fuel injector should be capable to control the amount of fuel injection into a

cylinder depending on the engine condition such as load and engine speed (Phuong,

2006; Roberto Cipollone, 2000). Generally, the LPG injector was divided into two types

(LPG liquid injector and LPG gaseous injector). The practicality of injector type

depends from the fuel condition. The LPG liquid injector can inject fuel at high pressure

in the range of 12 to 20 bar compared with the LPG gaseous injector that has a lower

pressure range of 3 to 4 bar. Meanwhile, the size of liquid injector is smaller than

gaseous injector because the higher density of the liquid (Watson & Phuong, 2007;

Mitukiewicz et al, 2015)

On the contrary, the uses of LPG liquid are capable to increase the torque output,

higher volumetric efficiency, reduced the backfire and reduce the exhaust gas emission.

Theoretically, the LPG in liquid phase will be vaporized in the surrounding intake air

manifold. Consequently, the temperature will be reduced and give effect to cooler air

intake. As a result, the density and mass of the fuel/air mixture will be greater. Hence, it

contribute for performance engine (Lutz et al, 1998; Szpica, 2016).

2.7.2 Indirect Injection

Indirect injection as shown in Figure 2.4 is divided into two types:

i. Throttle Body Injection (TBI)

ii. Multi Point Port Injection (MPI)

The throttle body injection (TBI) system has one or two fuel injectors, which the

injectors were mounted on the upstream of the throttle. For this system the air and fuel

were mixed before the throttle body, the process is similar to the carburetor systems,

but this injector is capable control the air/fuel ratio and the system offer a better

volumetric efficiency of the internal combustion engine. TBI system can increase the

performance by setting the electronic fuel schedule. However, the port injection spray is

more precise and gives a faster response time than the gas mixer system. The TBI

24

system has weakness because the unequal division in terms of routes of travel during

air/fuel mixing induct in the intake manifold. According to Baker & Watson (2005) and

Masi (2012) the liquid phase LPG is not suitable for this system because the long

travelling process between the throttle body to the intake valve and the liquid phase

quickly vaporized to gas before the supply in the intake valve.

The multi port fuel injection (MPI) has many advantages over the TBI system

because the liquid phase LPG reduces the wettest in the intake air manifold wall and the

distance of travelling is near to the intake valve. The result is higher torque and power

output than the TBI system. The injector is mounted in every single air intake manifold

for the multi cylinder engine. The fuel injected in individual cylinder will follow the

firing order and the fuel injection quantity was controlled by the Electronic Control Unit

(ECU) depending on the engine speed and load. The injector for MPI has several types,

they are:

i. Bosch K-Jetronic; mechanical type and ability operate without the

Engine Driver Unit (EDU)

ii. Bosch L-Jetronic and LH-Jetronic; electronic type and the operation

depend on electronic controller

iii. Bosch KE-Jetronic; combine mechanical and electronic and operate

based on the mechanical MPI data acquisition

iv. Denso Disc type 297-2009; Welded seal construction and equipped with

fully electronic control. The finer fuel spray to reduce exhaust emission

v. Rochester ball type; These have excellent atomization and a wide spray

pattern. Mechanical and electronic controller with using EDU.

The MPI system was divided into two methods for injecting the fuel, firstly is

banked injection and second is sequential injection. Banked injection is one of the

method MPI systems to supply fuel in the engine. This system operates based on the

crank angle or cam angle sensor signal. In this system all injectors will spray with

simultaneously in a multi cylinder engine. Consequently, there has waste fuel when the

firing order still doesn't change for the next cycle duration. Secondly, the fuel delivery

MPI has optional system namely sequential injection. This system is more effective than

97

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