STUDY ON ADVANCE TECHNOLOGIES IN IMPROVING PERFORMANCE AND EFFICIENCY FOR INTERNAL COMBUSTION ENGINE 0942909480

HO CHI MINH UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING GRADUATION PROJECT STUDY ON ADVANCE TECHNOLOGIES IN IMPROVING PERFORMANCE AND EFFICIENCY FOR INTERNAL COMBUSTION ENGINE PHAN NGOC VINH HIEN (16145013) TRUONG HOANG LONG (16145030) Major AUTOMOTIVE ENGINEERING Advisor LY VINH DAT, PhD Ho Chi Minh City, August 2020 HO CHI MINH UNIVERSITY OF TECHNOLOGY AND EDUCATION FACULTY FOR HIGH QUALITY TRAINING GRADUATION PROJECT STUDY ON ADVANCE TECHNOLOGIES IN IMPROVING.

HO CHI MINH UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

Major: AUTOMOTIVE ENGINEERING

Advisor: LY VINH DAT, PhD.

Ho Chi Minh City, August 2020

HO CHI MINH UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

Major: AUTOMOTIVE ENGINEERING

Advisor: LY VINH DAT, PhD.

Ho Chi Minh City, August 2020

THE SOCIALIST REPUBLIC OF VIETNAM

Independence – Freedom– Happiness

-Ho Chi Minh City, August 14, 2020

GRADUATION PROJECT ASSIGNMENT

Student name: PHAN NGOC VINH HIEN Student ID: 16145013

Student name: TRUONG HOANG LONG Student ID: 16145030

Major: Automotive Engineering Class: 16145CLA

Date of assignment: February, 2020 Date of submission: August, 2020

1 Project title: STUDY ON ADVANCE TECHNOLOGIES IN IMPROVING PERFORMANCE

AND EFFICIENCY IN INTERNAL COMBUSTION ENGINE

2 Initial materials provided by the advisor: Ph.D LY VINH DAT

3 Content of the project: Research on commen advance technologies applied on vehicles

4 Final product:

CHAIR OF THE PROGRAM

(Sign with full name)

ADVISOR

(Sign with full name)

THE SOCIALIST REPUBLIC OF VIETNAM

Independence – Freedom– Happiness

-Ho Chi Minh City, August 14, 2020

ADVISOR’S EVALUATION SHEET

Student name: PHAN NGOC VINH HIEN Student ID: 16145013

Student name: TRUONG HOANG LONGStudent ID: 16145030

Student name: Student ID:

Major: AUTOMOTIVE ENGINEERING

Project title: STYDY ON ADVANCE TECHNOLOGIES IN IMPROVING PERFORMANCE

AND EFFICIENCY IN INTERNAL COMBUSTION ENGINE

Advisor: Ph.D LY VINH DAT

1.1 EVALUATION

1 Content of the project:

2 Strengths:

3 Weaknesses:

4 Approval for oral defense? (Approved or denied)

(Sign with full name)

THE SOCIALIST REPUBLIC OF VIETNAM

Independence – Freedom– Happiness

-Ho Chi Minh City, August 14, 2020 PRE-DEFENSE EVALUATION SHEET Student name: PHAN NGOC VINH HIEN Student ID: 16145013 Student name: TRUONG HOANG LONG Student ID: 16145030 Student name: Student ID:

Major: AUTOMOTIVE ENGINEERING Project title: STUDY ON ADVANCE TECHNOLOGIES IN IMPROVING PERFORMANCE AND EFFICIENCY IN INTERNAL COMBUSTION ENGINE Name of Reviewer:

1.1 EVALUATION 1 Content and workload of the project

2 Strengths:

3 Weaknesses:

4 Approval for oral defense? (Approved or denied)

5 Overall evaluation: (Excellent, Good, Fair, Poor)

6 Mark:……….(in words: )

Ho Chi Minh City, August 14, 2020

REVIEWER

(Sign with full name)

THE SOCIALIST REPUBLIC OF VIETNAM

Independence – Freedom– Happiness

-EVALUATION SHEET OF DEFENSE COMMITTEE MEMBER Student name: PHAN NGOC VINH HIEN Student ID: 16145013 Student name: TRUONG HOANG LONG Student ID: 16145030 Student name: Student ID:

Major: AUTOMOTIVE ENGINEERING Project title: STUDY ON ADVANCE TECHNOLOGIES IN IMPROVING ENGINE PERFORMANCE AND EFFICIENCY IN INTERNAL COMBUSTION ENGINE Name of Defense Committee Member: Ph.D Nuyen Van Trang, M.Sc Duong Tuan Tung, Ph.D Ly Vinh Dat, Ph.D Nguyen Manh Cuong, K.S Huynh Tan Thuyet, K.S Grigoryan Narek 1.1 EVALUATION 1 Content and workload of the project

2 Strengths:

3 Weaknesses:

4 Overall evaluation: (Excellent, Good, Fair, Poor)

5 Mark:……….(in words: )

Ho Chi Minh City, August 14, 2020

COMMITTEE MEMBER

(Sign with full name)

To complete the project on time and achieve the results not only the effort of theperson who made the topic, but also the help and advice of the Faculty of Vehicle andEnergy Engineering and Faculty of High Quality Training and the motivation andexperience of classmates, the project team completed the graduation project on time.Our group would like to sincerely thank to:

- The guidance and enthusiastic help of Mr Ly Vinh Dat for instructing, providingneccesary documents and supporting to check and correct inaccurate information

- The classmates who shared useful information and documents

- Our team would like to thank the Ho Chi Minh City University of Technology andEducation lecturers, Faculty of Vehicle and Energy Engineering, and Faculty ofHigh Quality Training for their dedication to instruction, imparting experienceand knowledge in the learning and training process so that we could have todaysuccess

In the process of implementing this project, although we have tried our best, there will

be inevitable shortcomings We hope to receive the comments and criticism of lecturersand students

Once again, thank you lecturers and students

Ho Chi Minh City, August 14th, 2020

Phan Ngoc Vinh Hien

Truong Hoang Long

Ph.D Ly Vinh Dat

1

LIST OF FIGURES

Figure 2.1: Comparison in efficiency of original engine and technology applied engine 7

2

Figure 3.43: Continuously Variable Valve Lift Mechanism 40

Figure 3.63: Deactivation diagram showing the combustion intervals during deactivation

Figure 3.78: Schematic of Ford Duratec 3.5L V6 PFI engine combustion system with

Figure 3.79: Typical combustion system for a DISI engine with side-mounted swirl

Figure 3.81: Relationship between combustion chamber, injector and spark plug 74

3

Figure 3.86: Spray-guided combustion flow movement diagram 78Figure 3.87: Layout of the position off injector and spark plug of Spray-Guided 78

Figure 3.93: Toyota stratified-charge combustion system with side-mounted fan (slit)

Figure 3.94: Operational modes of direct-injection SI engine within speed–load map 83Figure 3.95: Mini-map points and associated optimization targets for a naturally aspirated

Figure 3.96: (a) Injection timing effect on volumetric efficiency, and (b) vaporized fuelfrom cylinder wall, at 3000 rpm full-load conditions with multi-hole (MH) and slit (fan)

Figure 3.107: Alfred J Büchi (1879–1959), an automotive engineer employed by the

4

Figure 3.127: Inside supercharger component 115

Figure 3.138: Difference of Turbocharger and Supercharge and speed of turbine 125

Figure 4.20: Torque performance in Porsche Carrera engine with Vonnen Shadow Drive

151Figure 4.21: Horsepower performance in Porsche Carrera engine with Vonnen Shadow

5

Figure 4.33: Full Kit E-Turbocharger installed in vehicle 163

6

LIST OF TABLES

7

i - VTEC : intelligent - Variable Valve Timing and Lift Electronic Control

MIVEC: Mitsubishi Innovative Valve timing Electronic Control

Variable Lift and Timing System (English)

8

HCCI : Homogeneous Charge Combustion Ignition

9

10

CHAPTER 2: IMPROVING ENGINE PERFORMANCE AND EFFICIENCY

CHAPTER 3: ADVANCE TECHNOLOGIES IN INTERNAL COMBUSTION

3.1.2.2 History 58

12

4.4.1 Introduction 147

4.5.1.5 ECO Assist allows intelligent operating strategy in all vehicles with

13

With the major concern to increase the efficiency of internal combustion (IC)engines, various technologies and innovations have been implemented to improveefficiency and reduction of emissions This thesis gives a detailed description ofadvanced IC engine concepts The thesis is divided into advanced technology for ICengines (Introduction, History, Structure and Operation and Advantages andDisadvantages), the combination and applied between those advance technologies andsome future technologies that could be appeared soon Toward the end of this thesis, aconclusion and some recommendation has been presented for the next generation whocontinue working and researching this topic The latest research topics are included inthis thesis which will be very useful to students, research scholars as well as industriesworking in IC engine

14

CHAPTER 1:INTRODUCTION 1.1 Overview

Car engines have come a long way since their early days Although the basicprinciples of the very first cars are still used today, modern and older car engines differfrom each other

As with any technology, there has been a gradual improvement in efficiency andcomplexity, as you'd expect As it turns out quite a lot

Despite the basic concept remaining relatively unchanged, modern cars haveundergone a series of many little improvements over time In the following article, we'llfocus on 4 interesting examples

The basic principles of the very first cars are still used today One of the maindifferences is that modern cars are the result of a pressure to improve the power ofengines and ultimately fuel efficiency In part, this has been market pressure fromconsumers as well as larger market forces

An internal combustion engine takes a fuel source, like gasoline, mixes it with air,compresses it and ignites it This causes a series of small explosions that, in turn, driveset of pistons up and down These pistons are attached to a crankshaft that translatesthe reciprocating linear motion of the pistons into rotational movement by turning the

1

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

crankshaft The crankshaft, in turn, transfers this motion through the transmission,which transmits the power to the wheels of the car.

a Modern engines are more efficient

Burning fuel, like gasoline, isn't particularly efficient Of all the potential chemicalenergy in it, around 14-30% is converted into energy that actual moves the car The rest

is lost to idling, parasitic losses, heat, and friction

Modern engines have moved a long way to tease out as much energy as possiblefrom the fuel Direct injection technology, for example, does not pre-mix the fuel and airbefore reaching the cylinder, like older engines Rather, fuel is directly injected into thecylinders This gives about a 1% improvement

Turbochargers use exhaust gas to power a turbine that pushes extra air (meaningmore oxygen) into the cylinders to further increase efficiency by up to 8% Variablevalve timing and cylinder deactivation further improve efficiency by only allowing theengine to use as much fuel as it needs

b Ultimate Power

As Jeremy Clarkson once said, "It's all about MPG than MPH nowadays" or maybe itwasn't him

Modern cars better fuel efficiency, they are also a lot more powerful

For instance, A 1983 Chevrolet Malibu had a 3.8-liter V-6 engine could spew out 110horsepower By comparison, the 2005 version had a 2.2-liter inline four cylindergenerating 144 horsepower Not too shabby

2

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

c Size of the engines

This drive, no pun intended, for better efficiency in engines has also shrunk their sizeover time This is not a coincidence Car manufacturers have learned that you don'tneed to make something bigger to make it more powerful

All you need to do is make the object work smarter The same technology that hasmade engines more efficient has had the side effect of making them smaller

Ford F-series trucks are a great example The F-150 had two versions in 2011 A liter V-6 engine that generates 365 horsepower and a 5.0-liter V-8 that generates 360horsepower

3.5-d Out with the old

Modern engines are also the result of a gradual replacement of the mechanical partswith electronic ones This is because electrical parts tend to be less prone to wear andtear like mechanical ones, for one

They also require less frequent tune-ups, per se Parts like pumps have increasinglybecome replaced with electronically controlled ones rather than their analog ancestors.Carburetors have been replaced with throttle bodies and electronic fuel injectionsystems Distributors and caps have been replaced with independent ignition coilscontrolled by the ECU Also, sensors monitor everything

3

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

Although on basic level modern and old car engines work via the same principle,modern engines have undergone a lot of gradual improvements over time The maindrive has been the race for efficiency over power A nice set of side effects have resulted

in modern engines becoming relatively more powerful and generally smaller An increasing reliance on electronic control and monitoring systems has slowly beenreplacing analog ones, for better or worse

ever-All in all, modern car engines are more efficient, smaller, relatively more powerful,smarter and less prone to inevitable mechanical failure On the other hand, repairs andservicing are now a more highly skilled and time-consuming undertaking

1.2 The object and scope of research

1.2.1 Object of research

- Weaknesses of old internal combustion engines

- Advance technologies:

+ Intake improvement methods

+ Gasoline Direct Injection

+ Reducing fuel consumption

+ Reducing pumping loss

- Combined and applied technologies in vehicles:

4

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

+ Mazda SkyActiv – G

+ Ford EcoBoost

- Future technologies will be appeared soon:

+ Mazda HCCI engines

+ Porsche Vonnen

+ Mercedes – Benz EQ Boost and Electric Turbo

1.2.2 Scope of the research

The thesis is focused on advance technologies that improved performance andefficiency of internal combustion engine such as: Variable Valve Timing,Turbocharger, Supercharger…, not only those methods, but also the combination

of technologies by automotive manufactures, for instance, Sky-Activ by Mazda,Ecoboost by Ford Moreover, there are some future technologies which is inresearch and nearly available in automotive industry: Mazda HCCI, PorscheVonnen,…

- Overview of each technology

- Development history

- Structure and operation

- Performance and Efficiency

- Advantages and Disadvantages

The content of this thesis revolves around the history of formation anddevelopment of each technology through different milestones of the autoindustry In addition, the thesis mentions about the structure and operation ofcurrent and future technologies, and how its performance and efficiency ininternal combustion engine Besides We also point out the benefit and drawback

of those technologies

5

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

1.3 Research methodology

Research methods are scientific principles and ways of working to achieve objectivetruth on the basis of scientific evidence By this definition, it is necessary to have specificprinciples and based on which problems are solved

- Method of document research

- Method of synthesis and analysis

- Method of expert reference

- Refer to textual sources: books, textbooks, reference materials, articles fromtrusted sources on the Internet, research works, public videos from carmanufacturers, to determine development history, operating principles andcollect results in improving engine performance and fuel efficiency

1.4 Outline of thesis

- Chapter 1: Introduction

A brief introduction and overview about this graduation thesis Bringing out andmaking clear infomation about the object, scope and method of the research andwhat we are focusing on the current and future technologies that applied invehicles

- Chapter 2: Improving engine performance and efficiency internal combustionengine

6

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

We would like to show out the reasons for improving engine performance andsome methods that become popular all over the world in many recent years.

- Chapter 3: Advance technologies in internal combustion engine

In this chapter, three commen methods such as: Intake process improvement,Gasoline Direct Injection and Forced Induction are taken out to discuss, researchand given out the conclusion of advantages and disadvantages through numbers,graphs, tables, and expert comments

- Chapter 4: Applied technologies on vehicle

Mazda SkyActiv-G and Ford Ecoboost systems are two famous examples for thecombination of three methods above and achieve excellent results Moreover,Mazda HCCI, Porsche Vonnen, Mercedes-Benz EQ Boost are three technologieswhich can get good comments from customers and experts in the near future

- Chapter 5: Conclusion and recommmendation

Giving out the main conclusion for the whole thesis and some recommendationfor the next generation students who could continue and research about thistopic

7

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

CHAPTER 2:IMPROVING ENGINE PERFORMANCE AND EFFICIENCY INTERAL COMBUSTION ENGINE.2.1 Reason for improving engine

2.1.1 The mixture does not burn completely

- The engine burns onto the cylinder during the movement of the car fuel (gasoline,oil), but there is no quantity of oxygen supplied to the cylinder to clean up the fuel,

to form toxic gasses, such as CO, HC, PM, and particularly soot, to the cylinderburn

- The fuel will not burn out to produce carbon soot that binds to motor details, due

to petroleum fuel mixed with impurities when fuel burns

- Those reasons lead to:

+ Carbon black creates a fine particle with a high hardness in high temperature andpressure cylinders, clings to the cylinder, the piston head and cylinder wall, thefunnel plug The engine loading, compression, explosion and unloadingoperation, the piston rises and falls into the cylinder, pulls the carbon particles.+ As high-hardness carbon particles scratch the cylinders and thicker soot thatchanges the engine compression ratio, it is also possible This is why the engine

is weaker, idle, weak, noise-causing The acceleration and deceleration will then

be unpleasant, causing the car to run uniformly and increasing fuel consumption infuel burning

8

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

2.1.2 Friction of internal combustion engine

When the engine is working, it created many friction between the metal part inthe engine when the piston move from top dead center (TDC) to bottom dead center(BDC) of the block the such as: piston, cylinder block, camshaft…by the temperatureinside the block at the combustion stroke, carbon black.…That is one of reasons whythe internal combustion engine just get 30% performance which it can achievethough the fuel consumption The longer time the engine works, the moreweaknesses of performance of the engine it paid

2.1.3 General reasons make the engine works inefficiency 100%

Due to the Second Law of Thermodynamics, there is no engine which is efficiency100% power After research, we believed that your car could loses energy through:

- Heat flows from the motor and cylinders The combustion is not capable ofdriving the car all of the energy

- Friction between moving parts makes heat dissipate some of the energy to theenvironment If your motor is well lubricated, this loss will be reduced

- Motor pumping fuel Your car needs to use energy to move into the engine,since your gas tank is beneath your engine

- Unfinished burning During your cycle, your engine can't fully burn the wholefuel Some fuel has not been burnt and wasted

- Braking Thanks to friction, energy is dissipated by heat

- Robust wind The air in the atmosphere must push your car through Thiscreates drag and increases the motor's energy consumption

9

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

- Resistance to rolling Friction exists between the tires and the road thatdischarges heat energy Conducting along paved roads with properly inflatedtires helps to reduce rolling strength.

- Losses drive train Energy is never transmitted between parts of your car 100percent efficiently so your motor must burn more fuel to compensate for that

2.2 General methods to upgrade the power and performance.

● CO2 reduction in petrol engine emissions

Three approaches in the development of a variety of technology to improvemotor efficiency:

- Efficient (higher cycle efficiency) combustion

- Low intake and resistance to exhaust (less loss of pumping)

- Lower friction and easier rotation

The VVEL is significantly further developed for reducing pumping loss.Improvements in combustion methods leading to HCCI are especially important

in achieving high efficiency in cycles

10

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

Figure 2.1: Comparison in efficiency of original engine and technology applied engine

● Measures to improve cycle effectiveness

In order to increase cycle efficiency, given how vital it is to determine theprogress of combustion, each combustion stage must be simulated To this day,automobile manufacture has developed different techniques of simulation Thefirm developed a high speed, 3D, HCCI combustion simulation system to producehigh-specific representation of chemical reactions in the HCCI combustionprocess for the development of HCCI, the ultimate combustion system with bothgreater fuel efficiency and cleaner exhaust

12

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

Figure 2.2: Development of engine’s efficiency

13

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

In this thesis, we mentioned some upgrade advanced technologies applying inAutomobile industry.

- Variable Valve Timing and Cylinder Deactivation

- Gasoline Direct Injection

- Forced Induction

- Hybrid Vehicle

- Electric Vehicle

- Upgrade Exhaust System

- Upgrade Mechanical Components

- ECU Modification

CHAPTER 3:ADVANCE TECHNOLOGIES IN INTERNAL

COMBUSTION ENGINES3.1 Some improvements for intake process

3.1.1 Variable Valve Timing

3.1.1.1 History

It was first apparent in the 1920s that the duration of the opening of the valve couldvary according to the rotary speed of the motor had been increased by the maximumallowable RPM limits Up to this level, the idle RPM and running RPM of an enginewere quite close and the variable valve length was therefore not required

14

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

A few days before 1919, Vauxhall's chiefs of designer, Lawrence Pomeroy, haddesigned a 4.4-liter motor to replace the existing 30-98 model by calling the H-Type Theone overhead camshaft of this motor had to be moved longitudinally to allow themovement of various camshaft lobes.

Alfa Romeo is the first automobile manufacturer to apply variable valve timing totheir products it's the mechanical VVT system developed on the 2000 Alfa RomeoSpider in 1980 and since 1983 all their models have been equipped with this VVTsystem

After the technology era of European automakers, Japanese automakers also launchedtheir VVT system One example is the introduction of Honda's VTEC in 1989 andMitsubishi's MIVEC, both based on the principle of Cam Switching at high speed andachieving maximum power In 1991, Toyota jumped into the race with the firstgeneration of VVT and later Mazda with the Cam Phasing principle

As technology has become more and more applied in cars, with stringent regulations

in European countries and the United States on emissions, it has become a seeminglyimpossible thing to remove camshafts and replace them it is the control on / off, lift andtiming of electric valve lift We can take examples of BMW's Valvetronic, MultiAir ofFiat or higher is Koenigsegg's FreeValve

Car manufacturers rely on the common principles of variable valve types of threetypes: Cam Phasing, Cam Switching, Mechanical Valvetrain and Cam Less And eachmanufacturer has a unique name for the technology they have created:

15

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

Table 3.1: VVT 's names from different brands

Volvo

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

VVT-i Variable Valve Timing intelligent Toyota

Kia

Electronic Control

Honda,Acura

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm

3.1.1.2 Cam Phasing

a Introduction

Cam phasing VVT is the simplest, cheapest and most widely employed process But

it also shows the least and very equal benefit in performance

Cam phasing is a form of VVT, in which there are appropriate means of changingthe relative phase difference between the crank shaft and the camshaft Cam phasingdoes not adjust the length of the valve lift or valve duration in its separate shape.Therefore, it is only associated with the valve opening time advancing or delaying andtherefore valve closing time There are many ways to incorporate the phase gapbetween the pitcher shaft and the camshaft and between several camshafts Nearly allforms of cam phasing include a camshaft which can rotate as long as the timing drive(project, squirrel or gear) is concerned

Essentially, by changing the phase angle of camshafts it shifts the timing of thevalve At high speed, for instance, the inlet camshaft is rotated by 30 degrees inadvance to make earlier intake possible This movement is regulated and operated

by hydraulic valve gages by the motor management system as necessary The length

of the valve opening cannot be adjusted by cam phasing VVT It only permits theopening of the valve before or later Of note, earlier opening outcomes were better

b Structure and operation

18

Effect

Stable idle Reduced fuel consumption

Stable idle Reduced fuel consumption

Reduced fuel consumption Reduced emissions

Increased torque at low and medium rpm