4 stroke project

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ABSTRACT

This paper compares the manufacturing and refueling

costs of a 4 Stroke IC Engine in vehicles. 4 Stroke Engine

using an automobile model reecting the largest segment

of light-duty vehicles. e use results from !idely-cited

government studies to compare the manufacturing and

refueling costs of a 4 Stroke engine capable of delivering

"#$ horsepo!er and driving appro%imately #&& miles. 'ur

results sho! that performs far more favorably in terms of

cost( energy e)ciency( !eight( and volume. The

di*erences are particularly dramatic !hen !e assume that

energy is derived from rene!able resources.

+erhaps the invention of the engine( or even introducing

its concept( !as the most important scienti,c event in the

human history. The applications of the engines vary

according to its e)ciency( and the reuired !orking

conditions. or e%ample( certain applications reuire the

use of t!o stroke engines rather than four stroke engines.

'n the other side( some vehicles has diesel operated

engines/including passengers0 cars as !ell. Still( there

are other types of engines other than the above

"


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mentioned types( !hich !ere all invented a century or

more ago.

INTRODUCTION

1 four-stroke engine( also kno!n as four-cycle( is an

internal combustion engine in !hich the piston completes

four separate strokes/intake( compression( po!er( and

e%haust/during t!o separate revolutions of the engine2s

crankshaft( and one single thermodynamic cycle.

There are t!o common types of engines( !hich are closely

related to each other but have ma3or di*erences in their

design and behavior. The earliest of these to be developed

is the 'tto cycle engine !hich !as developed in "56 by

7ikolaus 1ugust 'tto in Cologne( 8ermany(9": after the

operation principle described by 1lphonse ;eau de


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di*erences bet!een the 'tto cycle engine and the four-

cycle diesel engine. The diesel engine is made in both a

t!o-cycle and a four-cycle version. Ironically 'tto2s

company =eut? 18 produces primarily diesel engines in

the modern era.

The 'tto cycle is named after the "56 engine of 7ikolaus

1. 'tto( !ho built a successful four-cycle engine !hich !as

based on the !ork of Aean Aoseph Etienne Benoir.9": It !as

the third engine type that 'tto developed. It used a sliding

ame gate!ay for ignition of its fuel !hich !as a mi%ture

of illuminating gas and air. 1fter "4 'tto also developed

the magneto allo!ing the use of an electrical spark for

ignition( !hich had been unreliable on the Benoir engine.

Today( the internal combustion engine ICED is used in

motorcycles( automobiles( boats( trucks( aircraft( ships(

heavy duty machinery( and in its original intended use as

stationary po!er both for kinetic and electrical po!er

generation. =iesel engines are found in virtually all heavy

duty applications such as trucks( ships( locomotives(

po!er generation( and stationary po!er. any of these

#

http://en.wikipedia.org/wiki/Two-stroke_enginehttp://en.wikipedia.org/wiki/Deutz_AGhttp://en.wikipedia.org/wiki/Etienne_Lenoirhttp://en.wikipedia.org/wiki/Four-stroke_engine#cite_note-esort-0http://en.wikipedia.org/wiki/Coal_gashttp://en.wikipedia.org/wiki/Motorcyclehttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Boathttp://en.wikipedia.org/wiki/Truckhttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Shiphttp://en.wikipedia.org/wiki/Two-stroke_enginehttp://en.wikipedia.org/wiki/Deutz_AGhttp://en.wikipedia.org/wiki/Etienne_Lenoirhttp://en.wikipedia.org/wiki/Four-stroke_engine#cite_note-esort-0http://en.wikipedia.org/wiki/Coal_gashttp://en.wikipedia.org/wiki/Motorcyclehttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Boathttp://en.wikipedia.org/wiki/Truckhttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Ship


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". I7T1FE StrokeG on the intake or induction stroke of

the piston( the piston descends from the top of the

cylinder to the bottom of the cylinder( reducing the

pressure inside the cylinder. 1 mi%ture of fuel and air(

or 3ust air in a diesel engine( is forced by atmospheric

or greaterD pressure into the cylinder through the

intake port. The intake valvesD then close. The

volume of airHfuel mi%ture that is dra!n into the

cylinder( relative to the volume of the cylinder is

called( the volumetric e)ciency of the engine.

@. C'+


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revolutionary ne! design( to completely transform the

conventional IC engine. The great advantage of this design

is that e%isting IC engines can be modi,ed to run as

Concept IC engines at minimum cost !hile at the same

time increasing e)ciency by as much as @&&M and also

reducing fuel emissions to ?ero. This may sound far

fetched but as you !ill see ( if you continue to read these

pages ( a detailed and !ell documented rationale is given

as to !hy this engine can and !ill !ork. In fact anyone

!ho can provide a logical and veri,able refutation of the

Concept IC engine shall receive from me a most ab3ect

and humble letter of apology. Studies have sho!n ( and

this may easily be veri,ed from The Colorado State

University Engine Web Site ( a link to !hich is provided (

that IC engines lose 4@M of their energy to e%haust and

@M of their energy to the cooling system. ith more than

$&& million cars !orld !ide not counting buses ( trains (

construction and military transport D and !ith this number

constantly increasing there is an urgent need for better (

cleaner ( more e)cient engines. The Concept IC engine

5

http://www.engr.colostate.edu/~allan/heat_trans/page2/page2.htmlhttp://www.engr.colostate.edu/~allan/heat_trans/page2/page2.htmlhttp://www.engr.colostate.edu/~allan/heat_trans/page2/page2.htmlhttp://www.engr.colostate.edu/~allan/heat_trans/page2/page2.html


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provides a lo! cost and highly e*ective solution to solving

all these problems.

Intro'ucing t%e Conce&t IC engine(

1utomotive engineering has seen a spate of innovations in

the past decade( N2s ultiple valve2sD( ='KC2s =ouble

overhead camsD( +I ulti-port fuel in3ectionD and =I

=irect fuel in3ectionD !hich ( !hen combined !ith

stronger and lighter carbon composites and metal alloys (

are rapidly bringing reciprocating internal combustion

engine technology( as !e kno! it ( to a point !here the

full potential of the engine has almost been realised.

E%tensive coverage in maga?ines and other media ( have

reported on almost every aspect of the !orking of these

innovations and the advantages their implementation has

resulted in ( such as better fuel economy ( more po!er

and a cleaner engine. hat is less !idely kno!n is the fact

that in spite of the huge amounts of money and man

hours spent on researching and implementing these

products the overall e)ciency of the


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e)cient as compared to an original e)ciency of less than

@&M.

Re#l contri$ution "#'e $y recent inno)#tions

The real contribution that innovations such as ='KC2s(

N2s ( +I and =I have made to


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through heat transfer. The loss incurred through ine)cient

use of energy is easily understood ( compressed fuel and

air is ignited and is then used to propel the piston do!n

the cylinder !ith e%plosive force for a distance of 3ust a

fe! inches after !hich all further energy developed by the

fuel is lost and in fact becomes a liability since the piston

has to reverse direction ( a process !hich is inhibited by

the pressure of trapped gases on the piston head. The

reason that energy loss to heat transfer has been

tolerated ( and even !elcomed by engineers ( is a little

more involved and !ill be referred to later on in the

article. 7ot!ithstanding the improvements made to the


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energy( the use of the engine( or by the cooling system

employed.

Engine con+gur#tions

Internal combustion engines can be classi,ed by their

con,guration.


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• Aet engine including turbo3et( turbofan( ram3et(


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and burns. The fuel produces po!er that is transmitted to

the crank shaft mechanism.

1 E2%#ust stroke( In the end of the po!er stroke( the

e%haust valve opens. =uring this stroke( the piston starts

its movement in the minimum volume position. The open

e%haust valve allo!s the e%haust gases to escape the

cylinder. 1t the end of this stroke( the e%haust valve

closes( the inlet valve opens( and the seuence repeats in

the ne%t cycle. our-stroke engines reuire t!o

revolutions.

any engines overlap these steps in timeO 3et engines do

all steps simultaneously at di*erent parts of the engines.

Ter"inology I

TDC( top dead center( piston position farthest from

crankshaft

BDC( bottom dead center( piston position nearest to

crankshaftDirect fuel in3ection( into main combustion chamber

In'irect fuel in3ection( into a secondary chamber

Bore( diameter of cylinder or piston face

Stroke( distance that piston moves clearance

)olu"e( volume in combustion chamber at T=C

=isplacement )olu"e( volume displaced by piston

Ignition 'el#y( Time bet!een start of ignition and start

of Combustion

"4


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Engine co"&onents

Kistory

'tto cycle

1n 'tto Engine from ">@&s LS anufacture 7ikolaus

1ugust 'tto as a young man !as a traveling salesman for

a grocery concern. In his travels he encountered the

internal combustion engine built in +aris by ;elgian

"$

http://en.wikipedia.org/wiki/Nikolaus_Ottohttp://en.wikipedia.org/wiki/Nikolaus_Ottohttp://en.wikipedia.org/wiki/Nikolaus_Ottohttp://en.wikipedia.org/wiki/Nikolaus_Otto


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$ngine position information is provided by engine position sensors

and a timing disks that are accurately attached to one or two of the

main engine shafts such as the camshaft. The firing se"uence and

variable spark advance is computed accurately from the pattern of

teeth or pegs on the timing disk. &f load mapping is re"uired this

can be achieved by adding a manifold pressure sensor or a throttle

angle potentiometer to the system. % variety of e'tra features are

available on such systems which can be accessed and adusted by

a C.

$lectronic &gnition systems provide e'tremely accurate spark

timings leading to improved combustion and emissions control. %s

there is no mechanical contact there is no wear therefore the

accuracy is maintained. These reasons are why electronic ignition is

used as standard throughout the industry.

&nductive ignition systems have e'isted since *+, developed by

Charles ettering who also developed the first practical engine

driven generator.

The design has been improved over the years but the most

significant recent development has been the introduction of

&nsulated /ate Bipolar Transistors (&/BT)0 these have allowed the

design of e'tremely accurate high spark energy inductive ignition

systems.

"5


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coil. !well time is decreased when there is more than enough spark

energy to combust the mi'ture this decrease will reduce spark plug

wear therefore increase spark plug life.

$lectronic capacitor discharge ignition (C!&) systems have been

common on large industrial engines because the technology has

been in use since the *+3,4s.

Capacitive discharge ignition systems work by storing energy in an

e'ternal capacitor which is then discharged into the ignition coil

primary winding when re"uired. This rate of discharge is much

higher than that found in inductive systems and causes a

corresponding increase in the rate of voltage rise in the secondary

coil winding. This faster voltage rise in the secondary winding

creates a spark that can allow combustion in an engine that has

e'cess oil or an over rich fuel air mi'ture in the combustion

chamber. The high initial spark voltage avoids leakage across the

spark plug insulator and electrodes caused by fouling but leaves

much less energy available for a sufficiently long spark duration0

this may not be sufficient for complete combustion in a lean burn

turbocharged engine resulting in misfiring and high e'haust

emissions.

">


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The high voltage power supply re"uired for a capacitor discharge

system can be a disadvantage as this supply provides the power for

all ignition firings and is liable to failure.

&gnition in lean fuel mi'tures by capacitor discharge systems can

sometimes only be accomplished by the use of multi-spark ignition

where the ignition system duplicates the prolonged spark of

inductive spark systems by sparking a number of times during the

cycle. This adds greater stress onto the high-tension leads and can

cause considerable spark plug wear and possible failure.

The term 4C!&4 is often incorrectly used to describe electronic

ignition systems. #ost modern ignition systems are actually

&nductive &gnition systems for good reason especially when using

lean burn fuel mi'tures. &nductive ignition systems can provide

prolonged spark duration0 resulting in more reliable and a cleaner

burn in modern lean burn engines.

Capacitive discharge systems may have advantage in older 5-stroke

engines an engine running beyond its service life or a cheap 6-

stroke engine. These engines will be running an oil rich 1 fuel rich

mi'ture which may cause fouling of the spark plug gap. The higher

initial discharge of a C!& system may be able to 4burn4 off these

deposits better than a comparative inductive ignition system.

@&


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combustion engine that compressed the fuel mi%ture prior

to combustion for far higher e)ciency than any engine

created to this time.

In "4( 'tto2s company( no! kno!n as 8asmotorenfabrik

=eut? 8=D developed electric ignition and the

carburetor.

In ">&( =aimler and aybach formed a company kno!n

as =aimler otoren 8esellschaft. Today that company is

kno!n as =aimler-;en?.

=iesel cycle

@@


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Au'i Diesel R,4 #t 5e !#ns

The diesel engine is a technical re,nement of the "56

'tto Cycle engine. here 'tto had reali?ed in "6" that

the e)ciency of the engine could be increased by ,rst

compressing the fuel mi%ture prior to its ignition(


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that fuel sprayed into the cylinder. =iesel used an air

spray combined !ith fuel in his ,rst engine.

=uring initial development( one of the engines burst

nearly killing =iesel. Ke persisted and ,nally created an

engine in ">#. The high compression engine !hich

ignites its fuel by the heat of compression is no! called

the =iesel engine !hether it is a four-stroke or a t!o-

stroke design.

The four-stroke diesel engine has been used in the

ma3ority of heavy duty applications for many decades.

Chief among the reasons for this is that it uses a heavy

fuel !hich contains more energy( reuires less re,nement(

and is cheaper to make although in some areas of the

!orld diesel fuel costs more than gasolineD. The most

e)cient 'tto Cycle engines run near #&M e)ciency. The

Nolks!agen Aetta T=I ".> liter engine achieves 46M. It

uses an advanced design !ith turbocharging and direct

fuel in3ection. Some ; ship =iesels !ith ceramic

insulation have e%ceeded 6&M e)ciency.

@4

http://en.wikipedia.org/wiki/Volkswagen_Jettahttp://en.wikipedia.org/wiki/Volkswagen_Jetta


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;oth 1udi and +eugeot compete in the endurance races of

the Be ans Series !ith race cars having diesel engines.

These are four-stroke( four-valve and high revving(

turbocharged diesels !hich dominate largely due to fuel

economy and having to make fe!er stops.

Thermodynamic 1nalysis

@$

http://en.wikipedia.org/wiki/Audihttp://en.wikipedia.org/wiki/Peugeothttp://en.wikipedia.org/wiki/Le_Mans_Serieshttp://en.wikipedia.org/wiki/Audihttp://en.wikipedia.org/wiki/Peugeothttp://en.wikipedia.org/wiki/Le_Mans_Series


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The thermodynamic analysis of the actual four-stroke or

t!o-stroke cycles is not a simple task. Ko!ever( the

analysis can be simpli,ed signi,cantly if air standard

assumptions are utili?ed. The resulting cycle( !hich closely

resembles the actual operating conditions( is the 'tto

cycle.

'ctane


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1


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product and is called a light fraction. 1s a light fraction it

has a relatively lo! ash point that is the temperature at

!hich it starts to burn !hen mi%ed !ith an o%idi?erD.

1 fuel !ith a lo! ash point may self ignite during

compression( and can also be ignited by carbon deposits

left in the cylinder or head of a dirty engine. In an internal

combustion engine self ignition can occur at une%pected

times. =uring the normal operation of the engine as the

fuel mi%ture is being compressed an electric arc is created

to ignite the fuel. 1t lo! rpm this occurs close to T=C Top

=ead CenterD. 1s engine rpm rises the spark point is

moved for!ard so that the fuel charge can be ignited at a

more e)cient point in fuel charge compression to allo!

the fuel to start burning even !hile it is still being

compressed. This produces more e*ective po!er based on

the rising molecular density of the !orking medium( since

this is the essence of e)ciency in the compressed charge

IE engine. 1 denser !orking medium the air fuel mi%tureD

!ill e%perience a greater heat( and therefore pressure( rise

on less fe! !hen its molecules are more densely packed

together.

@>


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e can see this in t!o of the designs of the 'tto engines.

The non-compression engine operated at "@M e)ciency.

The compressed charge engine had an operating

e)ciency of #&M. 1 =iesel engine can reach as high as

5&M =iesel2s lab engine tested at 5$.6M e)ciency( N

T=I is at 46MD.

The problem !ith compressed charge engines is that the

temperature rise of the compressed charge can cause pre-

ignition. If this occurs at the !rong time and is too

energetic( it can destroy the engine. ractions of

petroleum have !idely varying ash points the

temperatures at !hich the fuel may self igniteD. This must

be taken into account in engine and fuel design.

In engines( the spark is retarded !hen the engine is being

started( and progresses only to an appropriate amount

based on engine rpm. This is determined by laboratory

research. 1s the engine revolves faster it can accept

earlier ignition since the moving ame front !ill not have

time to be destructive.

#&


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In fuel( the tendency for the compressed fuel mi%ture to

ignite early is limited by the chemical composition of the

fuel. There are several grades of fuel to accommodate

di*ering performance levels of engines. The fuel is altered

to change its self ignition temperature. There are several

!ays to do this. 1s engines are designed !ith higher

compression ratios the result is that pre-ignition is much

more likely to occur since the fuel mi%ture !ill be

compressed to a higher temperature prior to deliberate

ignition. The higher temperature !ill more e*ectively

evaporate fuels such as gasoline and is factor in a higher

compression engine being higher e)ciency. Kigher

Compression ratios also mean that the distance that the

piston can push to produce po!er is greater !hich is

called the E%pansion ratioD.

#"

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;io =iesel

;iodiesel refers to a vegetable oil- or animal fat-based

diesel fuel consisting of long-chain alkyl methyl( propyl or

ethylD esters. ;iodiesel is typically made by chemically

reacting lipids e.g.( vegetable oil( animal fat tallo!DD !ith

an alcohol producing fatty acid esters.

;iodiesel is meant to be used in standard diesel engines

and is thus distinct from the vegetable and !aste oils used

to fuel converted diesel engines. ;iodiesel can be used

alone( or blended !ith petrodiesel. ;iodiesel can also be

used as a lo! carbon alternative to heating oil.

;lends

;lends of biodiesel and conventional hydrocarbon-based

diesel are products most commonly distributed for use in

the retail diesel fuel marketplace. uch of the !orld uses

a system kno!n as the P;P factor to state the amount of

biodiesel in any fuel mi%G9@:

• "&&M biodiesel is referred to as ;"&&( !hile

#@

http://en.wikipedia.org/wiki/Diesel_fuelhttp://en.wikipedia.org/wiki/Alkylhttp://en.wikipedia.org/wiki/Methylhttp://en.wikipedia.org/wiki/Propylhttp://en.wikipedia.org/wiki/Ethyl_grouphttp://en.wikipedia.org/wiki/Esterhttp://en.wikipedia.org/wiki/Lipidshttp://en.wikipedia.org/wiki/Vegetable_oilhttp://en.wikipedia.org/wiki/Tallowhttp://en.wikipedia.org/wiki/Alcoholhttp://en.wikipedia.org/wiki/Fatty_acid_esterhttp://en.wikipedia.org/wiki/Heating_oilhttp://en.wikipedia.org/wiki/Biodiesel#cite_note-1http://en.wikipedia.org/wiki/Diesel_fuelhttp://en.wikipedia.org/wiki/Alkylhttp://en.wikipedia.org/wiki/Methylhttp://en.wikipedia.org/wiki/Propylhttp://en.wikipedia.org/wiki/Ethyl_grouphttp://en.wikipedia.org/wiki/Esterhttp://en.wikipedia.org/wiki/Lipidshttp://en.wikipedia.org/wiki/Vegetable_oilhttp://en.wikipedia.org/wiki/Tallowhttp://en.wikipedia.org/wiki/Alcoholhttp://en.wikipedia.org/wiki/Fatty_acid_esterhttp://en.wikipedia.org/wiki/Heating_oilhttp://en.wikipedia.org/wiki/Biodiesel#cite_note-1


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• @&M biodiesel( &M petrodiesel is labeled ;@&

• $M biodiesel( >$M petrodiesel is labeled ;$

• @M biodiesel( >M petrodiesel is labeled ;@.

;lends of @&M biodiesel and lo!er can be used in diesel

euipment !ith no( or only minor modi,cations( although

certain manufacturers do not e%tend !arranty coverage if

euipment is damaged by these blends. The ;6 to ;@&

blends are covered by the 1ST =5465 speci,cation.94:

;iodiesel can also be used in its pure form ;"&&D( but

may reuire certain engine modi,cations to avoid

maintenance and performance problems. ;lending ;"&&

!ith petroleum diesel may be accomplished byG

• i%ing in tanks at manufacturing point prior to

delivery to tanker truck

• Splash mi%ing in the tanker truck adding speci,c

percentages of biodiesel and petroleum dieselD

• In-line mi%ing( t!o components arrive at tanker truck

simultaneously.

##

http://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/Biodiesel#cite_note-3http://en.wikipedia.org/wiki/ASTM_Internationalhttp://en.wikipedia.org/wiki/Biodiesel#cite_note-3


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• etered pump mi%ing( petroleum diesel and biodiesel

meters are set to J total volume( transfer pump pulls

from t!o points and mi% is complete on leaving

pump.

1pplications

;iodiesel can be used in pure form ;"&&D or may be

blended !ith petroleum diesel at any concentration in

most in3ection pump diesel engines. 7e! e%treme high-

pressure @>(&&& psiD common rail engines have strict

factory limits of ;$ or ;@&( depending on manufacturer.

;iodiesel has di*erent solvent properties than petrodiesel(

and !ill degrade natural rubber gaskets and hoses in

vehicles mostly vehicles manufactured before ">>@D(

although these tend to !ear out naturally and most likely

!ill have already been replaced !ith F( !hich is

nonreactive to biodiesel. ;iodiesel has been kno!n to

break do!n deposits of residue in the fuel lines !here

petrodiesel has been used. 1s a result( fuel ,lters may

#4

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become clogged !ith particulates if a uick transition to

pure biodiesel is made. Therefore( it is recommended to

change the fuel ,lters on engines and heaters shortly after

,rst s!itching to a biodiesel blend.

=istribution

Since the passage of the Energy +olicy 1ct of @&&$(

biodiesel use has been increasing in the Lnited States. In

the LF( the


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+roperties

;iodiesel has better lubricating properties and much

higher cetane ratings than today2s lo!er sulfur diesel

fuels. ;iodiesel addition reduces fuel system !ear( and in

lo! levels in high pressure systems increases the life of

the fuel in3ection euipment that relies on the fuel for its

lubrication. =epending on the engine( this might include

high pressure in3ection pumps( pump in3ectors also called

unit inectorsD and fuel in3ectors.

+roduction

;iodiesel is commonly produced by the transesteri,cation

of the vegetable oil or animal fat feedstock. There are

#5

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several methods for carrying out this transesteri,cation

reaction including the common batch process(

supercritical processes( ultrasonic methods( and even

micro!ave methods.

Chemically( transesteri,ed biodiesel comprises a mi% of

mono-alkyl esters of long chain fatty acids. The most

common form uses methanol converted to sodium

metho%ideD to produce methyl esters commonly referred

to as atty 1cid ethyl Ester - 1ED as it is the cheapest

alcohol available( though ethanol can be used to produce

an ethyl ester commonly referred to as atty 1cid Ethyl

Ester - 1EED biodiesel and higher alcohols such as

isopropanol and butanol have also been used. Lsing

alcohols of higher molecular !eights improves the cold

o! properties of the resulting ester( at the cost of a less

e)cient transesteri,cation reaction. 1 lipid

transesteri,cation production process is used to convert

the base oil to the desired esters. 1ny free fatty acids

1sD in the base oil are either converted to soap and

removed from the process( or they are esteri,ed yielding

more biodieselD using an acidic catalyst. 1fter this

#

http://en.wikipedia.org/wiki/Alkylhttp://en.wikipedia.org/wiki/Fatty_acidhttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Methylhttp://en.wikipedia.org/wiki/Fatty_acid_methyl_esterhttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Isopropanolhttp://en.wikipedia.org/wiki/N-Butanolhttp://en.wikipedia.org/wiki/Lipidhttp://en.wikipedia.org/wiki/Transesterificationhttp://en.wikipedia.org/wiki/Saponificationhttp://en.wikipedia.org/wiki/Alkylhttp://en.wikipedia.org/wiki/Fatty_acidhttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Methylhttp://en.wikipedia.org/wiki/Fatty_acid_methyl_esterhttp://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Isopropanolhttp://en.wikipedia.org/wiki/N-Butanolhttp://en.wikipedia.org/wiki/Lipidhttp://en.wikipedia.org/wiki/Transesterificationhttp://en.wikipedia.org/wiki/Saponification


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processing( unlike straight vegetable oil( biodiesel has

combustion properties very similar to those of petroleum

diesel( and can replace it in most current uses.

1 by-product of the transesteri,cation process is the

production of glycerol. or every " tonne of biodiesel that

is manufactured( "&& kg of glycerol are produced.

'riginally( there !as a valuable market for the glycerol(

!hich assisted the economics of the process as a !hole.

Ko!ever( !ith the increase in global biodiesel production(

the market price for this crude glycerol containing @&M

!ater and catalyst residuesD has crashed.

http://en.wikipedia.org/wiki/Straight_vegetable_oilhttp://en.wikipedia.org/wiki/Glycerolhttp://en.wikipedia.org/wiki/Straight_vegetable_oilhttp://en.wikipedia.org/wiki/Glycerol


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advancements in genetics( soil science( and horticultural

practices.

S8 ;iofuels( a San =iego-based Aatropha developer( has

used molecular breeding and biotechnology to produce

elite hybrid seeds of Aatropha that sho! signi,cant yield

improvements over ,rst generation varieties. S8 ;iofuels

also claims that additional bene,ts have arisen from such

strains( including improved o!ering synchronicity( higher

resistance to pests and disease( and increased cold

!eather tolerance.

+lant


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=iesel Engines

=iesel engines by their nature do not have concerns !ith

pre-ignition. They have a concern !ith !hether or not

combustion can be started. The description of ho! likely

=iesel fuel is to ignite is called the Cetane rating. ;ecause

=iesel fuels are of lo! volatility( they can be very hard to

start !hen cold. Narious techniues are used to start a

cold =iesel engine( the most common being the use of a

glo! plug.

In some applications( such as in burning used cooking oil(

the fuel itself is solid and must be heated to liuify prior to

use. 1 common complaint here is that the e%haust may

have the odor of rench ries.

=esign and engineering principles

+o!er output limitations

4@

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The four-stroke cycle

"QT=C

@Q;=C

A( Int#ke

B( Co"&ression

C( Po0er

D( E2%#ust

The ma%imum amount of po!er generated by an engine is

determined by the ma%imum amount of air ingested. The

amount of po!er generated by a piston engine is related

to its si?e cylinder volumeD( !hether it is a t!o-stroke or

four-stroke design( volumetric e)ciency( losses( air-to-fuel

ratio( the calori,c value of the fuel( o%ygen content of the

air and speed


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material strength and lubrication. Nalves( pistons and

connecting rods su*er severe acceleration forces. 1t high

engine speed( physical breakage and piston ring utter

can occur( resulting in po!er loss or even engine

destruction. +iston ring utter occurs !hen the rings

oscillate vertically !ithin the piston grooves they reside in.


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casting a!s( can be removed( and( !ith the aid of an air

o! bench( the radii of valve port turns and valve seat

con,guration can be modi,ed to reduce resistance. This

process is called porting( and it can be done by hand or

!ith a C7C machine.

Supercharging

'ne !ay to increase engine po!er is to force more air into

the cylinder so that more po!er can be produced from

each po!er stroke. This can be done using some type of

air compression device kno!n as a supercharger( !hich

can be po!ered by the engine crankshaft.

Supercharging increases the po!er output limits of an

internal combustion engine relative to its displacement.

ost commonly( the supercharger is al!ays running( but

there have been designs that allo! it to be cut out or run

at varying speeds relative to engine speedD. echanically

driven supercharging has the disadvantage that some of

the output po!er is used to drive the supercharger( !hile

po!er is !asted in the high pressure e%haust( as the air

has been compressed t!ice and then gains more potential

4$

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volume in the combustion but it is only e%panded in one

stage.

Turbocharging

1 turbocharger is a supercharger that is driven by the

engine2s e%haust gases( by means of a turbine. It consists

of a t!o piece( high-speed turbine assembly !ith one side

that compresses the intake air( and the other side that is

po!ered by the e%haust gas outo!.

46

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hen idling( and at lo!-to-moderate speeds( the turbine

produces little po!er from the small e%haust volume( the

turbocharger has little e*ect and the engine operates

nearly in a naturally aspirated manner. hen much more

po!er output is reuired( the engine speed and throttle

opening are increased until the e%haust gases are

su)cient to 2spin up2 the turbocharger2s turbine to start

compressing much more air than normal into the intake

manifold.

Turbocharging allo!s for more e)cient engine operation

because it is driven by e%haust pressure that !ould

other!ise be mostlyD !asted( but there is a design

limitation kno!n as turbo lag. The increased engine po!er

is not immediately available due to the need to sharply

increase engine


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e%haust gas to transfer more of its heat to the mechanical

parts of the engine.

In more recent times( turbochargers have become

advanced due to design improvements( and have little( to

no turbo lag. Turbocharged automobiles are very gas

e)cient due to lo! compression at lo!er engine speeds

Turbocharger not spooled upD.


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engine life. It also increases the cost and engine height

and !eight.

1 Psuare engineP is an engine !ith a bore diameter eual

to its stroke length. 1n engine !here the bore diameter is

larger than its stroke length is an oversuare engine(

conversely( an engine !ith a bore diameter that is smaller

than its stroke length is an undersuare engine.

Nalvetrain

The valves are typically operated by a camshaft rotating

at half the speed of the crankshaft. It has a series of cams

along its length( each designed to open a valve during the

appropriate part of an intake or e%haust stroke. 1 tappet

bet!een valve and cam is a contact surface on !hich the

cam slides to open the valve. any engines use one or

more camshafts Rabove a ro! or each ro!D of cylinders(

as in the illustration( in !hich each cam directly actuates a

valve through a at tappet. In other engine designs the

camshaft is in the crankcase( in !hich case each cam

contacts a push rod( !hich contacts a rocker arm !hich

opens a valve. The overhead cam design typically allo!s

4>

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higher engine speeds because it provides the most direct

path bet!een cam and valve.

$&


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Nalve clearance

Nalve clearance refers to the small gap bet!een a valve

lifter and a valve stem that ensures that the valve

completely closes. 'n engines !ith mechanical valve

ad3ustment e%cessive clearance !ill cause noise from the

valve train. Typically the clearance has to be read3usted

each @&(&&& miles #@(&&& kmD !ith a feeler gauge.

ost modern production engines use hydraulic lifters to

automatically compensate for valve train component !ear.

=irty engine oil may cause lifter failure.

$"

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Energy balance

'tto engines are about #&M e)cientO in other !ords( #&M

of the energy generated by combustion is converted into

useful rotational energy at the output shaft of the engine(

!hile the remainder being losses due to friction( engine

accessories( and !aste heat.9$: There are a number of

!ays to recover some of the energy lost to !aste heat.

The use of a Turbocharger in =iesel engines is very

e*ective by boosting incoming air pressure and in e*ect

$@

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provides the same increase in performance as having

more displacement. The ack Truck company decades ago

developed a turbine system !hich converted !aste heat

into kinetic energy !hich !as fed back into the engine2s

transmission. In @&&$( ; announced the development

of the turbosteamer( a t!o stage heat recovery system

similar to the ack system that recovers &M of the

energy in the e%haust gas and raised the e)ciency of the

'tto engines it is applied to by "$M.96:

;y contrast( a si%-stroke engine may convert more than

$&M of the energy of combustion into useful rotational

energy.

odern engines are often intentionally built to be slightly

less e)cient than they could other!ise be. This is

necessary for emission controls such as e%haust gas

recirculation and catalytic converters that reduce smog

and other atmospheric pollutants.


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In the Lnited States( the Corporate 1verage uel Economy

!ill mandate that vehicles must achieve an average of

#$.$ miles per gallon mpgD compared to the current

standard of @$ mpg. 1s automakers look to meet these

standards by @&"6( ne! !ays of engineering the

traditional internal combustion engine ICED could have to

be considered. Some potential solutions to increase fuel

e)ciency to meet ne! mandates include ,ring after the

piston is farthest from the crankshaft( kno!n as top dead

centre( and applying the iller cycle. Together( this

redesign could signi,cantly reduce fuel consumption and

7'% emissions.

Introduction to Inductive Ignition

$4

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&f the timing disk is attached to the crankshaft there is a need in

some engine configurations to have a sensor on the camshaft so

that the igniter knows which 7 of the four-stroke cycle the engine is

in.

% non-wasted spark system only provides a spark on the

compression cycle of each cylinder of a four-stroke engine. $ach

cylinder re"uires an ignition coil and the timing disk for the ignition

system needs to rotate at half engine speed (cam shaft speed).

CDI vs Inductive Ignition Systems

$6

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% wasted spark system produces a spark for the compression and

e'haust stroke of each cylinder in a four-stroke engine. The reason

this system is called wasted spark is that only the spark on the

compression cycle is useful the spark on the e'haust stroke is

wasted as there is no combustible mi'ture in the cylinder.

!epending on the engine configuration it may be possible to use

one dual-output ignition coil to operate two cylinders in wasted

spark mode. % benefit of wasted spark systems is that the timing

disk is attached to the crankshaft which is generally more

accessible.

2asted spark ignition systems are commonly found in motorcycles

but are not recommended for use in industrial or alternative fuelled

applications.

&gnition advance is the number of degrees before top-dead-centre

(T!C) that a spark occurs. The reason for ignition advance is that

the spark to combust the fuel1air mi'ture needs to be timed so that

the point of peak combustion pressure is when the piston is ust

beyond T!C. &f the point of peak combustion pressure is too early

and before T!C the pressure wave will slow down the speed of the

piston travelling up towards it and may cause detonation

(knocking) which is very damaging to the engine. &f the point of

peak combustion pressure is too late the pressure wave will chase

$5


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the piston as it travels back down the cylinder in the combustion

stroke and most of the energy will be lost.

Introduction to Ignition Coils

%s the speed of the engine rises the ignition advance angle needs

to increase. This is because the time to combust an unchanging

air1fuel mi'ture is appro'imately constant. &f the ignition advance

angle were kept the same the point of peak combustion pressure

would move further and further into the combustion stroke losing

more and more power. Therefore the ignition advance needs to be

increased to bring the point of peak combustion to ust beyond T!C.

Speed Mapping between Ignition Degree Vs rpm

$

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The optimum amount of ignition advance varies from engine to

engine and through different fuel types timing maps of different

engines using different fuels will be different. &t is not possible to

calculate the best map for your engine0 you need to test the engine

on appropriate test e"uipment to generate the engine maps.

$missions can be controlled via the use of ignition advance in

addition to controlling the air1fuel mi'ture. 8arge ignition advances

will promote the formation of o'ides in the e'haust gases and

increase engine power (to an e'tent) but will also decrease the

engines fuel consumption.

&f an engine is set up for ma'imum power the resultant carbon

mono'ide levels will be too high to meet current emissions

legislation so it is common practice to adust the ignition timing at

different load levels to suit (see 8oad #apping). /enerally the

$>


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ignition timing is retarded somewhat to reduce C9 and :9;

emissions.

% trade off between e'haust emissions fuel consumption and

engine power has to be taken by the application engineer during

testing.

The amount if time taken for a fuel1air mi'ture to combust mainly

depends on the richness of the fuel mi'ture. 2hen the engine is

under low load with a lean air1fuel mi'ture the degree of ignition

advance will need to be large to allow for the slow combustion of

this mi'ture. Conversely when the engine is under load a richer

air1fuel mi'ture is used to provide more power. This richer mi'ture

has a faster combustion time so the degree of ignition advance

needs to be reduced to keep the peak combustion pressure ust

beyond T!C.

To achieve this variation of ignition advance in modern engines load

mapping is used. &nformation is sent from either a throttle

potentiometer or a manifold pressure sensor to indicate how much

load the engine is under. Therefore load mapping varies the

amount of ignition advance in relation to engine speed and load.

The picture below is a simulation our & software. The /


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performance. 2e will assume the load mapping is being carried out

by a throttle potentiometer.

Ignition Timing

&gnition coils are used to step up the voltage of the engines primary

circuit of the *6 - 65 volt range to 6,,,, to 5,,,, volt range. The

increased voltage is re"uired for the current to ump the spark gap

in spark plugs producing the ignition of the air1fuel mi'ture. The

increase of the voltage is matched by a proportionate decrease in

current.

%t its most basic an ignition coil is made up of a primary winding a

secondary winding and a laminated core.

6"

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Wasted Spar and !on"Wasted Spar Ignition

The secondary winding is wound with considerably more turns than

the primary winding. The resulting difference in number of turns is

proportional to the step up in voltage. %n inductive ignition system

swill charge the primary winding with generally *6 volts when the

current is removed a large $#A is generated in the secondary

winding of up to 5,,,, olts more than enough to ump across a

spark gap.

&n practice ignition coils will have some e'tra components but are in

operation practically the same.

6@

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#oad Map $ene%its

The above is the cycle of operation of one cylinder of a 5-stroke

engine. /enerally engines have 6 or more cylinders acting in

concert with each other to produce the engine power.

&t is interesting to note that one complete engine cycle takes two

revolutions but that individual valves and spark plugs only operate

once in this time. Hence their timing needs to be taken from a half

engine speed signal which is the camshafts speed.

%ll ignition systems need to know at what position the engine is in

its cycle to be able to perform accurate spark timing calculations.

This information is generally provided by a timing disc attached

either to the crankshaft (engine speed) or camshaft (half engine

speed) and an electronic sensor mounted close by. Timing discs

either have teeth or magnets arrayed around the circumference

which the electronic sensor can see. To enable the igniter to know

when the first cylinder is at top dead centre the timing disk either

has an additional tooth or magnet or one missing.

6#

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&f the timing disk is attached to the crankshaft there is a need in

some engine configurations to have a sensor on the camshaft so

that the igniter knows which 7 of the four-stroke cycle the engine is

in.

Ignition Diagnostics

% non-wasted spark system only provides a spark on the

compression cycle of each cylinder of a four-stroke engine. $ach

cylinder re"uires an ignition coil and the timing disk for the ignition

system needs to rotate at half engine speed (cam shaft speed).

64

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% wasted spark system produces a spark for the compression and

e'haust stroke of each cylinder in a four-stroke engine. The reason

this system is called wasted spark is that only the spark on the

compression cycle is useful the spark on the e'haust stroke is

wasted as there is no combustible mi'ture in the cylinder.

!epending on the engine configuration it may be possible to use

one dual-output ignition coil to operate two cylinders in wasted

spark mode. % benefit of wasted spark systems is that the timing

disk is attached to the crankshaft which is generally more

accessible.

6$


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Woring &rinciple

&nternal combustion engine design has been dominated by two

primary types the 6 stroke and the 5 stroke.

2hile the 6 stroke has dominated the market for small bikes

(mopeds scooters and commuter bikes) the 5 stroke has been

favored by manufacturers for their large capacity machines--6?, cc

and above.

2ith more stringent emission control standards being enforced

throughout the world the 5 stroke is the power unit of choice for

most manufacturers. This power unit offers reliability with good fuel

consumption and low emissions.

6

http://classicmotorcycles.about.com/od/historicaldevelopment/ss/2Strokeengines.htmhttp://classicmotorcycles.about.com/od/collectingoldbikes/ig/Small-Classic-Motorcycles/http://classicmotorcycles.about.com/od/historicaldevelopment/a/Uk-Sports-Mopeds.htmhttp://classicmotorcycles.about.com/od/collectingoldbikes/a/Vespa.htmhttp://classicmotorcycles.about.com/od/buyingandsellingadvice/ss/Classic-Motorcycles-For-Commuters.htmhttp://classicmotorcycles.about.com/od/historicaldevelopment/ss/2Strokeengines.htmhttp://classicmotorcycles.about.com/od/collectingoldbikes/ig/Small-Classic-Motorcycles/http://classicmotorcycles.about.com/od/historicaldevelopment/a/Uk-Sports-Mopeds.htmhttp://classicmotorcycles.about.com/od/collectingoldbikes/a/Vespa.htmhttp://classicmotorcycles.about.com/od/buyingandsellingadvice/ss/Classic-Motorcycles-For-Commuters.htm


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The 5 stroke engine powers most of the classic motorcycles over

6?, cc. There are three designs of valve layout available for 5

stroke engines over head valves (9H) operated by push-rods (/)

overhead camshaft (9HC) either gear or chain driven (A) and side

valves (


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SV


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• Connecting God (!)

• Crankshaft ($)

• Camshaft (A)

• ushrod (/)

• $'haust alve (H)


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The first stroke is the inlet or induction stroke. %s the piston moves

down inside the cylinder the inlet valve opens allowing a fresh

change of mi'ed gasoline and air to enter the cylinder.

5@


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Arr#nge"ent of Cylin'ers

Fuel in3ection

ultipoint port fuel in3ectionG one or more in3ectors at each

cylinder intake Throttle body fuel in3ectionG in3ectors

upstream of intake manifold.

I

C#r$uretor

54


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ord origin

The !ord carburetor comes from the

rench carbure meaning PcarbideP.

Carburer means tocombine !ith carbon. In fuel chemistry( the term has the

more speci,c meaning of increasing the carbonand

therefore energyD content of a fuel by mi%ing it !ith a

volatile hydrocarbon

+rinciples

The carburetor !orks on ;ernoulli2s principleG the faster air

moves( the lo!er its static pressure( and the higher

its dynamic pressure. The throttle acceleratorD linkage

does not directly control the o! of liuid fuel. Instead( it

actuates carburetor mechanisms !hich meter the o! of

air being pulled into the engine. The speed of this o!(and therefore its pressure( determines the amount of fuel

dra!n into the airstream.

hen carburetors are used in aircraft !ith piston engines(

special designs and features are needed to prevent fuel

starvation during inverted ight. Bater engines used an

early form of fuel in3ection kno!n as a pressure

carburetor.

ost production c#r$urete' as opposed to fuel-in3ectedD

engines have a single carburetor and a matching intake

manifold that divides and transports the air fuel mi%ture to

the intake valves( though some engines like motorcycleenginesD use multiple carburetors on split heads. ultiple

5$

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carburetor engines !ere also common enhancements for

modifying engines in the LS1 from the ">$&s to mid-

">6&s( as !ell as during the follo!ing decade of high-

performance muscle cars fueling di*erent chambers of the

engine2s intake manifold.

'lder engines used updraft carburetors( !here the air

enters from belo! the carburetor and e%its through the

top. This had the advantage of never PoodingP the

engine( as any liuid fuel droplets !ould fall out of thecarburetor instead of into the intake manifoldO it also lent

itself to use of an oil bath air cleaner( !here a pool of oil

belo! a mesh element belo! the carburetor is sucked up

into the mesh and the air is dra!n through the oil-covered

meshO this !as an e*ective system in a time !hen

paper air ,lters did not e%ist.

;eginning in the late ">#&s( do!ndraft carburetors !ere

the most popular type for automotive use in the Lnited

States. In Europe( the sidedraft carburetors replaced

do!ndraft as free space in the engine bay decreased and

the use of the SL-type carburetor and similar units from

other manufacturersD increased. Some small propeller-

driven aircraft engines still use the updraft carburetor

design.

'utboard motor carburetors are typically sidedraft(

because they must be stacked one on top of the other in

order to feed the cylinders in a vertically oriented cylinder

block.

56

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">5> Evinrude Type I marine sidedraft carburetor

'peration

Fi2e'-)enturi( in !hich the varying air velocity in

the venturi alters the fuel o!O this architecture is

employed in most carburetors found on cars.

6#ri#$le-)enturi( in !hich the fuel 3et opening is

varied by the slide !hich simultaneously alters air

o!D. In Pconstant depressionP carburetors( this is done

by a vacuum operated piston connected to a tapered

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needle !hich slides inside the fuel 3et. 1 simpler version

e%ists( most commonly found on small motorcycles and

dirt bikes( !here the slide and needle is directly

controlled by the throttle position. The most common

variable venturi constant depressionD type carburetor

is the sidedraft SL carburetor and similar models from

Kitachi( enith-Stromberg and other makers. The LF

location of the SL and enith-Stromberg companies

helped these carburetors rise to a position of

domination in the LF car market( though such

carburetors !ere also very !idely used on Nolvos and

other non-LF makes. 'ther similar designs have been

used on some European and a fe! Aapanese

automobiles. These carburetors are also referred to as

Pconstant velocityP or Pconstant vacuumP carburetors.

1n interesting variation !as ord2s NN Nariable NenturiD

carburetor( !hich !as essentially a ,%ed venturi

carburetor !ith one side of the venturi hinged and

movable to give a narro! throat at lo! rpm and a !ider

throat at high rpm. This !as designed to provide good

mi%ing and airo! over a range of engine speeds(

though the NN carburetor proved problematic in

service.

Dis#')#nt#ges of t%e C#r$uretor

The main disadvantage of basing a carburetor2s operation

on ;ernoulli2s principle is that( being a uid dynamic

device( the pressure reduction in a venturi tends to be

5

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proportional to the suare of the intake air speed. The fuel

3ets are much smaller and limited mainly by viscosity( so

that the fuel o! tends to be proportional to the pressure

di*erence. So 3ets si?ed for full po!er tend to starve the

engine at lo!er speed and part throttle. ost commonly

this has been corrected by using multiple 3ets. In SL and

other movable 3et carburetors( it !as corrected by varying

the 3et si?e. or cold starting( a di*erent principle !as

used( in multi-3et carburetors. 1 o! resisting valve called

a choke( similar to the throttle valve( !as placed upstream

of the main 3et to reduce the intake pressure and suck

additional fuel out of the 3ets

Lnder all engine operating conditions( the carburetor

mustG

easure the airo! of the engine

=eliver the correct amount of fuel to keep the fuelHair

mi%ture in the proper range ad3usting for factors such

as temperatureD

i% the t!o ,nely and evenly

This 3ob !ould be simple if air and gasoline petrolD !ere

ideal uidsO in practice( ho!ever( their deviations from

5>

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ideal behavior due to viscosity( uid drag( inertia( etc.

reuire a great deal of comple%ity to compensate for

e%ceptionally high or lo! engine speeds. 1 carburetor

must provide the proper fuelHair mi%ture across a !ide

range of ambient temperatures( atmospheric pressures(

engine speeds and loads( and centrifugal forcesG

Cold start

Kot start

Idling or slo!-running

1cceleration

Kigh speed H high po!er at full throttle

Cruising at part throttle light loadD

In addition( modern carburetors are reuired to do this

!hile maintaining lo! rates of e%haust emissions.

To function correctly under all these conditions( most

carburetors contain a comple% set of mechanisms to

support several di*erent operating modes( called circuits.

Ty&es of C#r$uretors(

". Sole% Carburetor

&

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@. Carter carburetor

#. S.L. Carburetor

C#r$uretor E*ciency

1 carburetor is the part of an internal combustion engine

that blends air and fuel in a tiny e%plosion. The kinetic

energy from that e%plosion is used to push the pistons of

the engine.

1 basic understanding of ho! an internal combustion

engine !orks is as follo!sG

The fuel in3ectors in3ect the gasoline.

The spark plugs ignite the gasoline.

The gasoline e%plosion moves the pistons. Sort of like

a potato cannon.D

The pistons turn the crankshaft.

The crankshaft turns the rest of the car.

There is alternatives to an internal combustion engine.

E%ternal Combustion Q Bess efficient.

8as Turbine Q ore E%pensive( but very efficient.

Electrical Q Currently difficult to refuel.

Kybrid Internal CombustionHElectrical Q ore efficient(

slightly more e%pensive.

"


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Kydrogen uel Cell Q Nery efficient( currently more

e%pensive.

Back of E)ciency

The primary problem

!ith carburetors is

the fact that most of

the energy it makes

is !asted as heat

and isn2t converted

into kinetic energy.

The standard

Carburetor that !e2ve been seeing for the last 5& years is

only >M e)cient. It gets an average of @$ milesHgallon of

gasoline( depending on the !eight of the car. hile thishas gone up since then usually by making more e)cient

@


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use of the other parts of the car and by making cars out of

light!eight materialsD( carburetors today are still only

about "@M e)cient.

hich means the other M is basically !asted energy in

the form of heat.

#


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Co"$ustion

1ll intern#l co"$ustion engines depend on the

combustion of a chemical fuel( typically !ith o%ygen from

the air though it is possible to in3ect nitrous o%ide in order

to do more of the same thing and gain a po!er boostD. The

combustion process typically results in the production of a

great uantity of heat( as !ell as the production of steam

and carbon dio%ide and other chemicals at very high

temperatureO the temperature reached is determined by

the chemical makeup of the fuel and o%idisers see

stoichiometryD( as !ell as by the compression and other

factors.

The most common modern fuels are made up of

hydrocarbons and are derived mostly from fossil fuels

petroleumD. ossil fuels include diesel fuel( gasoline and

petroleum gas( and the rarer use of propane. E%cept for

the fuel delivery components( most internal combustion

engines that are designed for gasoline use can run on

natural gas or liue,ed petroleum gases !ithout ma3or

modi,cations. Barge diesels can run !ith air mi%ed !ith

gases and a pilot diesel fuel ignition in3ection. Biuid and

4

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gaseous biofuels( such as ethanol and biodiesel a form of

diesel fuel that is produced from crops that yield

triglycerides such as soybean oilD( can also be used.

Engines !ith appropriate modi,cations can also run on

hydrogen gas( !ood gas( or charcoal gas( as !ell as from

so-called producer gas made from other convenient

biomass.


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such as an alternator or generator driven by the engine.

8asoline engines take in a mi%ture of air and gasoline and

compress it to not more than "@. bar ".@ +aD( then

use a spark plug to ignite the mi%ture !hen it is

compressed by the piston head in each cylinder.

Diesel Ignition Process

6

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=iesel engines and KCCI Komogeneous charge

compression ignitionD engines( rely solely on heat and

pressure created by the engine in its compression process

for ignition. The compression level that occurs is usually

t!ice or more than a gasoline engine. =iesel engines !ill

take in air only( and shortly before peak compression( a

small uantity of diesel fuel is sprayed into the cylinder via

a fuel in3ector that allo!s the fuel to instantly ignite. KCCI

type engines !ill take in both air and fuel but continue to

rely on an unaided auto-combustion process( due to

higher pressures and heat. This is also !hy diesel and

KCCI engines are more susceptible to cold-starting issues(

although they !ill run 3ust as !ell in cold !eather once

started. Bight duty diesel engines !ith indirect in3ection in

automobiles and light trucks employ glo!plugs that pre-

heat the combustion chamber 3ust before starting to

reduce no-start conditions in cold !eather. ost diesels

also have a battery and charging systemO nevertheless(

this system is secondary and is added by manufacturers

as a lu%ury for the ease of starting( turning fuel on and o*

!hich can also be done via a s!itch or mechanical

5

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apparatusD( and for running au%iliary electrical

components and accessories. ost ne! engines rely on

electrical and electronic engine control units ECLD that

also ad3ust the combustion process to increase e)ciency

and reduce emissions.

T0o-stroke con+gur#tion

Engines based on the t!o-stroke cycle use t!o strokes

one up( one do!nD for every po!er stroke. Since there are

no dedicated intake or e%haust strokes( alternative

methods must be used to scavenge the cylinders. The

most common method in spark-ignition t!o-strokes is to

use the do!n!ard motion of the piston to pressuri?e fresh

charge in the crankcase( !hich is then blo!n through the

cylinder through ports in the cylinder !alls.

Spark-ignition t!o-strokes are small and light for their

po!er output and mechanically very simpleO ho!ever(

they are also generally less e)cient and more polluting

than their four-stroke counterparts. In terms of po!er per

cmU( a t!o-stroke engine produces comparable po!er to

an euivalent four-stroke engine. The advantage of having

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one po!er stroke for every #6&V of crankshaft rotation

compared to 5@&V in a 4-stroke motorD is balanced by the

less complete intake and e%haust and the shorter e*ective

compression and po!er strokes. It may be possible for a

t!o-stroke to produce more po!er than an euivalent

four-stroke( over a narro! range of engine speeds( at the

e%pense of less po!er at other speeds.

Small displacement( crankcase-scavenged t!o-stroke

engines have been less fuel-e)cient than other types of

engines !hen the fuel is mi%ed !ith the air prior to

scavenging allo!ing some of it to escape out of the

e%haust port. odern designs Sarich and +aggioD use air-

assisted fuel in3ection !hich avoids this loss( and are more

e)cient than comparably si?ed four-stroke engines. uel

in3ection is essential for a modern t!o-stroke engine in

order to meet ever more stringent emission standards. ;ut

the problem of total loss oil consumption still remains a

cause of high hydro carbon emissions.

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are much cleaner burning than their traditional

counterparts. T!o-stroke engines are !idely used in

sno!mobiles( la!nmo!ers( string trimmers( chain sa!s(

3et skis( mopeds( outboard motors( and many motorcycles.

T!o-stroke engines have the advantage of an increased

speci,c po!er ratio i.e. po!er to volu"e ratioD( typically

around ".$ times that of a typical four-stroke engine.

The largest internal combustion engines in the !orld are

t!o-stroke diesels( used in some locomotives and large

ships. They use forced induction similar to super-

charging( or turbochargingD to scavenge the cylindersO an

e%ample of this type of motor is the artsila-Sul?er

turbocharged t!o-stroke diesel as used in large container

ships. It is the most e)cient and po!erful internal

combustion engine in the !orld !ith over $&M thermal

e)ciency. or comparison( the most e)cient small four-

stroke motors are around 4#M thermal e)ciency S1E

>&&64DO si?e is an advantage for e)ciency due to the

increase in the ratio of volume to surface area.

Common cylinder con,gurations include the straight or

inline con,guration( the more compact N con,guration(

>&

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and the !ider but smoother at or bo%er con,guration.

1ircraft engines can also adopt a radial con,guration

!hich allo!s more e*ective cooling. ore unusual

con,gurations such as the K( L( J( and have also been

used.

ultiple crankshaft con,gurations do not necessarily need

a cylinder head at all because they can instead have a

piston at each end of the cylinder called an opposed

piston design. ;ecause here gas in- and outlets are

positioned at opposed ends of the cylinder( one can

achieve unio! scavenging( !hich( as in the four-stroke

engine( is e)cient over a !ide range of engine speeds.

1lso the thermal e)ciency is improved because of lack of

cylinder heads. This design !as used in the Aunkers Aumo

@&$ diesel aircraft engine( using t!o crankshafts at either

end of a single bank of cylinders( and most remarkably in

the 7apier =eltic diesel engines. These used three

crankshafts to serve three banks of double-ended

cylinders arranged in an euilateral triangle !ith the

crankshafts at the corners. It !as also used in single-bank

>"

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locomotive engines( and continues to be used for marine

engines( both for propulsion and for au%iliary generators.

T0o-stroke

This system manages to pack one po!er stroke into every

t!o strokes of the piston up-do!nD. This is achieved by

e%hausting and recharging the cylinder simultaneously.

The cylinder of the four strokes engine di*ers from the t!o

strokes engine. The ma3or di*erence bet!een both

engines is the valves that are located on the top of the

cylinder. These t!o valves open and close alternatively to

allo! either airHfuel mi%ture to enter or e%haust gases to

come out. 1s it !as previously mentioned( the motion of

the t!o valves happen through the camshaft system. The

spark plug is the one that ignites the compressed fuel-air

mi%ture at a time !hen both valves are closed.

1ccordingly( the piston is pushed do!n!ard( transmitting

po!er to the crankshaft. +o!er is then transferred to the

>@

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!heel through other mechanisms.

The steps involved here areG

Suction IntakeD strokeG =uring this stroke( the piston

starts its motion from the top do!n!ard of the cylinder.

Synchronously( the intake valve is opened based on the

camshaft mechanismD( allo!ing airHvapori?ed fuel mi%ture

to enter to the combustion chamber.

>#


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Compression strokeG In this one( both valves should be

closed. The piston starts to move up!ard to compress the

fuel( until it reaches the top dead center. ;y compressing

the fuel( the fuel temperature and pressure increases.

>4


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+o!er StrokeG 1s the piston reaches the top dead center(

the spark plug ignites a spark( allo!ing the fuel to burn.

The combustion yields a high po!er that is transmited

through the crankshaft mechanism. It should be noted

that in order for combustion energy to be consumed

e)ciently in moving the piston( both valves should be

closed.

>$


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E%haust StrokeG 1fter reaching to the ma%imum

displacement of the piston( most of the energy liberated is

transferred. 1ccordingly( the pistons starts it back up!ard

motion to get rid of the e%haust gases that result from

combustion. 1t that moment( the e%haust valve is opened

to allo! it to go outside the cylinder.

>6


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T0o Stroke Srk Ignition 7SI8 engine(

In a t!o-stroke SI engine a cycle is completed in t!o

strokes of a piston or one complete revolution #6&VD of a

crankshaft. In this engine the intake and e%haust strokes

are eliminated and ports are used instead of valves. In this

cycle( the petrol is mi%ed !ith lubricant oil( resulting in a

simpler( but more environmentally damaging system( as

the e%cess oils do not burn and are left as a residue. 1s

the piston proceeds do!n!ard another port is opened( the

fuelHair intake port. 1irHfuelHoil mi%tures come from the

carburetor( !here it !as mi%ed( to rest in an ad3acent fuel

chamber. hen the piston moves further do!n and the

cylinder doesn2t have anymore gases( fuel mi%ture starts

to o! to the combustion chamber and the second

process of fuel compression starts. The design carefully

considers the point that the fuel-air mi%ture should not

mi% !ith the e%haust( therefore the processes of fuel

in3ection and e%hausting are synchroni?ed to avoid that

concern. It should be noted that the piston has three

functions in its operationG

>5


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• The piston acts as the combustion chamber !ith the

cylinder and compresses the airHfuel mi%ture(

receives back the liberated energy( and transfers it to

the crankshaft.

• The piston motion creates a vacuum that sucks the

fuelHair mi%ture from the carburetor and pushes it

from the crankcase ad3acent chamberD to the

combustion chamber.

• The sides of the piston act like the valves( covering

and uncovering the intake and e%haust ports drilled

into the side of the cylinder !all.

The ma3or components of a t!o-stroke spark ignition

engine are theG

• CylinderG 1 cylindrical vessel in !hich a piston makes

an up and do!n motion.

• +istonG 1 cylindrical component making an up and

do!n movement in the cylinder.

>

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• Combustion chamberG 1 portion above the cylinder in

!hich the combustion of the fuel-air mi%ture takes

place.

• Intake and e%haust portsG 1n intake port allo!s the

fresh fuel-air mi%ture to enter the combustion

chamber and an e%haust port discharges the

products of combustion.

• CrankshaftG 1 shaft !hich converts the reciprocating

motion of the piston into a rotary motion.

• Connecting rodG 1 rod !hich connects the piston !ith

the crankshaft.

• Spark plugG 1n ignition-source located at the cylinder

head that is used to initiate the combustion process.

O&er#tion

>>

http://en.wikipedia.org/wiki/Combusti

4 stroke project

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