EPA-460/3-74-011-C
October 1975
A STUDY OF STRATIFIED CHARGE
FOR LIGHT DUTY POWER PLANTS:
VOLUME 3. EXECUTIVE SUMMARY
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
-------
EPA-460/3-74-011-C
A STUDY OF STRATIFIED CHARGE
FOR LIGHT DUTY POWER PLANTS:
VOLUME 3. EXECUTIVE SUMMARY
by
Ricardo and Company Engineers (1927) LTD
Bridge Works
Shoreham-by-Sea, Sussex, BN4 5FG
Contract No. 68-03-0375
EPA Project Officers: T.C. Austin and J.J. McFadden
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Mobile Source Air Pollution Control
Emission Control Technology Division
Ann Arbor, Michigan 48105
October 1975
-------
This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the
Air Pollution Technical Information Center, Environmental Protection
Agency, Research Triangle Park, North Carolina 27711; or, for a fee,
from the National Technical Information Service, 5285 Port Royal Road,
Springfield, Virginia 22161.
This report was furnished to the Environmental Protection Agency by
Ricardo and Company Engineers (1927) LTD, Bridge Works, Shoreham-
by-Sea, Sussex, BN4 5FG, in fulfillment of Contract No. 68-03-0375.
The contents of this report are reproduced herein as received from
Ricardo and Company Engineers (1927) LTD, Bridge Works. The opinions,
findings, and conclusions expressed are those of the author and not
necessarily those of the Environmental Protection Agency. Mention of
company or product names is not to be considered as an endorsement
by the Environmental Protection Agency.
Publication No. EPA-460/3-74-011-C
11
-------
PREFACE
This report Is the outcome of a stratified charge engine study carried out
under a contract awarded by the Environmental Protection Agency. The report is
divided Into three parts, the first of which is an Executive Sunmary
containing a brief description of the tests and methods used in the study and a
presentation of the findings and recommendations. Volume I presents the results
and conclusions of the literature survey section of the report while Volume II
presents the configuration study, rating report and the specific discussions and
conclusions of the complete project.
In an earlier work 'A Study of the Diesel as a Light-Duty Power Plant1
(EPA-J*60/3 ~ 7^-011) Rlcardo and Company drew heavily on the expertise of their
engineers In the dlesel department, and the design phases of the exercise used
engine designers with particular experience in diesel engines. In order to ensure
balanced conclusions, however, the rating and discussion sections of the study were
a joint effort Involving engineers from both the gasoline and diesel departments.
In this study, although the targets, brief and overall programme were similar,
the team of engineers and designers was changed to include engineers from the
gasoline department and designers with gasoline (and stratified charge) design
experience. During the rating exercise, however, the panel was essentially the
same balanced panel as was used In the earlier study - this ensured that con
sistent and balanced decisions were made In this phase.
The team involved In the performance of the project would like to thank those
members of the automotive and oil industries who commented on the interim reports
produced during the study and were so helpful as to permit the publication of some
of their latest Information. The team also wish to express their appreciation of
the action of the Environmental Protection Agency in arranging the Interim exchanges
of Information and reports.
iii
-------
ABSTRACT
The objectives of this project were to determine the acceptability of various
types of stratified charge engines as potential power plants for lighl duty
vehicles and motorcycles in America. The light duty vehicle considered was a k/S
seat compact sedan with good acceleration capabilities and exhaust emissions below
a primary tarqet of O.^l g/mile HC, l.k g/mile CO, 1.5 g/mile NOX. A secondary
target of Q.k\ g/mile HC, 3-1* g/mile CO and 0.4 g/mile NO was also considered.
A literature survey was undertaken, comparing stratified charge engines with
examples of good conventional gasoline and diesel engines. While some stratified
charge engines had exhaust emission or fuel economy advantages, there were always
sacrifices in other areas.
Eleven engines were configured, four of which were specifically directed to-
wards the secondary emission targets. A method of rating the engines was derived,
and che design concepts were compared with two gasoline engines by a jury panel.
The overall result was that the Ford PROCO and Honda CVCC combustion processes
were serious contenders to the gasoline engine at the primary emission target, and
that both of these systems, together with the VW combustion process, might be
suitable at the secondary targets.
iv
-------
Table of Contents
Page No,
Introduction I
Conclusions 2
Recommendations 3
Organisation of Study and Baseline Data
-------
INTRODUCTION
The combination of the provisions of the Clean Air Act and the steadily
Increasing cost of fuel has begun to Influence the possible modes of transportation
In America to such an extent that engines other than the conventional gasoline
engine are now being actively considered and developed for passenger cars. Of the
many forms of prime mover proposed for future passenger cars the stratified charqo
engine apparently offers the possibility of a low emissions cnqlnc with the ability
to use gasoline fuel or even a variety of fuels while at the same time offering
the Increasingly Important promise of good fuel economy associated with many
engines of this type.
The object of this study was to determine the feasibility of the various types
of stratified charge engine for light duty use. To achieve this aim a careful
survey of current experience with all types of stratified charge engines was
required and then, by the consideration of a target vehicle and an emissions
environment, the design, performance and problem areas of the most promising types
could be studied In detail.
For the purposes of this study the term 'light duty1 was regarded as embracing
passenger cars although consideration was also given to the motorcycle as a light
duty vehicle.
The emissions targets proposed were such as to provide an interim target for
a passenger car, I.e. Primary Emissions level
HC .41 g/mlle
CO 3.4 g/mile
NO 1.5 g/mile
X
when tested by the CVS-CH procedure.
A longer term target for the passenger car was the provisions of the Clean
Air Act, I.e. Secondary Emissions level
HC .1*1 g/mile
CO 3.k g/mlle
N0x 0.4 g/mlle
For the motorcycle the emissions targets were those currently proposed as an
interim phase for this class of vehicle, I.e. Proposed Motorcycle Emissions level
HC a siIdlng scale
50-170 cc 8 g/mile
170-750 cc 8-22,4 g/mile
Above 750 cc 22.4 g/mile
CO fixed level 27 g/mlle
N0x fixed level 1.92 g/mile
In order to provide a specific reference for the detailed sections of the
study a 'target' vehicle was defined. This was a 4/5 seat sedan with a loaded
weight of about 1600 kg (3500 Ib), capable of 0-97 km/h (0-60 mph) in 13.5 s
and 40-113 km/h (25*70 mph) In 15 s, I.e. a compact size sedan but with standard
I
-------
performance capabilities. For motorcycle applications no specific target vehicle
was defined due to the varied nature and use of these vehicles.
The first phase of the study required that a survey of all past and current
experience with stratified charge engines be carried out. Because of the world-
wide Interest In these engines existing literature from published sources in America,
Europe and Japan was to be Included. Since It was recognised that many of the
engines surveyed would be at an early stage of development it was decided to
restrict this phase of the study to what was essentially published information so
that future studies and resources would be concentrated on new developments with
potentially viable engines.
The second phase of the study required that design schemes be made of all
engines which the literature survey Indicated as being feasible power plants for
the passenger car target vehicle. During this process detailed calculations would
be carried out to determine the likely performance and emissions levels of vehicles
propelled by these engines.
In the next phase the various powerplants were to be compared on a numerical
basis so that their potential performance, emissions or problem areas could be
considered objectively.
In the final phase of the study the results of all the previous phases were
to be considered so that overall conclusions could be drawn on the viability and
likely potential of all the stratified charge engines considered. A further
requirement of the fourth phase was the statement of recommendations for further
action and study In order to achieve the most desirable light duty vehicle for an
environment Involving both emissions and fuel consumption constraints.
CONCLUSIONS
At the completion of all the phases of the study the following broad con-
clusions were drawn:-
1. Unthrottled stratified charge engines always give high hydrocarbon emissions.
Reduction of these can usually be achieved by throttling but they usually
remain greater than those of conventional spark Ignition engines. Acceptable
levels can only be obtained by burning extra fuel to achieve hydrocarbon
oxidation In the exhaust or by placing great reliance on catalytic reactors.
2. Existing methods of hydrocarbon control are unsatisfactory and a new method
of Initiating and propagating combustion, other than spark or compression
ignition, Is required to permit satisfactory oxidation of lean air fuel
mixtures.
3. Although carbon monoxide emissions from stratified charge engines are usually
low they generally give more than J.k g/mlle (the target level) In CVS tests
unless some form of after treatment Is used,
k. NO emissions are always lower than those from conventional gasoline engines.
The pre-chamber type of stratified charge engine with fuel Injection Into
the prechamber Is capable of giving the lowest NO emission of all the variants
surveyed.
5. Although unthrottled operation with power controlled by fuel flow should yield
the best possible fuel economy, the results obtained by the engines studied
were disappointing. Only the direct Injection type of stratified charge engine
-------
showed any real Improvement over a good conventional gasoline engine.
6. The specific output of naturally aspirated stratified charge engines is
lower than that of conventional gasoline engines at the primary emissions
target.
7. The only stratified charge engines to display any significant multi-fuel
capability are those engines operating on principles similar to the MAN-^M
and the TCCS systems.
8. Stratified charge engines are generally more complex and costly than
conventional engines. Cost penalties range from a few nor cent lo over 100
per cent depending upon the system,
9. Stratified charge engines are generally larger and heavier than conventional
engines. Only the CurtIss-WrIght rotary system shows any advantage in this
respect.
10. The drive-by noise of stratified charge engines depends upon the combustion
system but no engine is significantly quieter than the conventional engine
and most are more noisy.
II. Unthrottled engines give higher noise levels at Idle and light load conditions
than either throttled stratified charge engines or conventional engines.
12. None of the stratified charge engines showed any major starting problems.
13- At the primary emissions level the rating study Indicated that the PROCO
and CVCC systems were very close to the conventional gasoline engine when
considering all aspects of operation. The PROCO system, however, places
great reliance on catalyst durability.
H». At the secondary emissions level the CVCC and PROCO systems were the most
viable power plants. The CVCC system, however, sacrifices fuel consumption
to meet the secondary targets while the PROCO system relies even more
heavily on catalyst durability.
15- At the emissions targets considered stratified charge engines are not
attractive for motorcycle engines; mainly for economic reasons.
RECOMMENDATIONS
1 The scavenged prechamber engine (e.g. Honda CVCC) should continue to receive
study as an Interim measure to achieve the primary emission target. Although
It has demonstrated the ability to meet the secondary target, It may not
prove to be a satisfactory powerplant in the long term, due to poor fuel
economy and drIveablI Ity.
2. The Ford PROCO emerged high in the rating study and although catalyst
durability, first cost and noise problems exist, It has some attractive
features. Notably the secondary emission targets have been demonstrated
with virtually no loss In fuel economy compared with existing gasoline
engines. Continuity of production could be achieved as the emission levels
were reduced.
-------
3. As the engine with the lowest exhaust emissions and best test bed fuel
consumption of any reviewed In this survey, the MAN-.FM should be applied
to an automotive vehicle, so that a direct comparison can be made with other
stratified charge engines. The multi-fuel capability of this engine may also
prove useful In other applications.
J». The Porsche and VW engines should receive further study as configurations
most likely to achieve the secondary emission targets without sacrifice in
durability or engine performance.
5. Research groups should be encouraged to study alternative methods for
Initiating and controlling combustion, besides compression and spark ignition.
The basic premise that unthrottled engines, operating at moderate compression
ratios could give better utilisation of energy than existing internal com*
bustlon engines, Is sound. The exhaust emission limitations associated with
existing stratified charge engines are related to the method of combustion,
I.e. Initiating the combustion with a spark and relying on flame propagation
to oxidise al1 the fuel.
6. Our understanding of combustion and heat transfer In stratified charge
engines Is rather limited. Further experimental studies by combustion
photography and Instantaneous heat transfer measurements would establish
empirical relationships, and help in the formulation of complex mathematical
models. Existing models are of limited use, due to outmoded and non-
applicable empirical relationships.
7. The next phase of emission levels proposed for motorcycles (the L.D.V.
figures of .M HC, 3-^CO, .!» NOj will be very difficult to achieve with
existing engines. It Is therefore recommended that work be carried out to
Investigate the application of a CVCC variant to the larger motorcycles.
Although very restricted In configuration the Kushul engine offers the
possibility of achieving the lower levels without the cost, economy and
Installation penalties of the CVCC system and thus the potential of this
engine for larger motorcycles should also be Investigated.
ORGANISATION OF STUDY AND BASELINE DATA
Stratified charge engines can take many forms and may vary the degree of
stratification throughout the load and speed range, A result of this great
variety of concepts and mode of operation Is that the definition of a 'stratified
charge1 can be a subject for considerable discussion, For the purposes of this
study the following definition of stratified charge engines was determineds-
DefInition
A stratified charge engine Is an engine with Intermittent combustion
Initiated by a spark plug, where the element of mixture Ignited by the spark plug
Is not typical of the mixture In the remainder of the working gas, over some
portion of the engine operating regime. Before ignition, the remainder of the
working gas will correspond to one of two cases;
(a) A mixture of air and fuel where the average mixture strength is leaner
than that Ignited by the spark. In addition there may be exhaust residuals
from a previous working cycle distributed throughout the working gas.
-------
(b) A mixture composed of the same ratio of air and fuel as that nt the spark
plug, but with considerable dilution by exhaust residuals from n pervious
working cycle.
Classlfication
Within the above definition there are many engines lying between the general
classes of throttled conventional gasoline engines and unthrottled diesel engines
and these stratified charge engines can differ widely in their characteristics.
To simplify analysis and comparison, therefore, the general class of
stratified engines was divided Into different categories, each category being chosen
so that It embraced all those engines with a similar combustion chamber config-
uration and nature of combustion,
Category 1 : Single combustion chamber with fuel Injection before tdc, mixture
formation by fuel Injection and/or air movement,
Category 2 : Single combustion chamber with fuel Injection during combustion and
combustion controlled by Injection.
Category 3 : Single combustion chamber with fuel Injection onto the piston.
Combustion controlled by fuel evaporation from the piston.
Category I* : Split combustion chambers with fuel injection into a pre-chamber.
Fuel can also be added to the Inducted air.
Category 5 : Split combustion chambers with a separate Inlet valve for the
prechamber.
Category 6 : Other weak mixture spark Ignition engines based on carburettors.
Category 7 : Two strokes, exhaust diluent engines and miscellaneous.
The table below shows how this classification was achieved and qlves examples
of some of the engines In each category.
-------
STRATIFIED CHARGE ENGINE CATEGORIES
1
f. t 1 MP 1 F PHA
• n in luirr
Early Injection
Into moving
air
EXAMPLES
Ford Proco
FCP
Mitsubishi
Hesse 1 man
Witsky
i
2
T i nM
Late Injection
1 n to mov 1 ng
air
Texaco TCCS
Curtiss-Wright
3
Combustion
Control led
by wa 1 1
evaporation
Man F-M
k
, ... i
1
Fuel Injection
into prechamber
also
fuel addition
to mai n chamber
Newhall
VW
Huber
5
tr ADDiiDrTTnnc _— ^
Mixture suppl ied
by carburettor (s)
separate
prechamber
inlet valve
Honda CVCC
Nllov
Heintz
6
(•SINGLE CHAM
V
1 .F.P.
7
Two strokes
exhaust
diluent
engines
Mi seel laneous
Ricardo
Jessel
Kushul
-------
Baseline Data
Because the stratified charge engines which were studied varied so much in
their application, performance and emissions characteristics, it was necessary to
derive baseline data to give a reliable basis for comparison and it was felt that
the best results which could be achieved by existing gasoline and diesel passenger
cars should be used. To derive these data a study was made of published gasoline
and diesel CVS-CH results so that 'good1 fuel consumption figures could be obtained
for the two target emission levels. These data points were used throughout the
study to provide constant reference lines!
Many of the engines studied had not been developed to the point where they
could be Installed In a vehicle, indeed much of the published information only
covered single cylinder test bed results, and thus some means of predicting the
performance of a light duty engine of appropriate power for the vehicle under
consideration was required. Calculations had Indicated that a 96 kW (128 BMP)
engine was required to power the target passenger car and so all test bed results
were modified to give values applicable to an engine of this output. This could
usually be achieved by a simple scaling exercise.
In a previous study the test bed emissions and fuel consumption of a diesel
engine specifically configured to power the target vehicle was presented and it
was considered that these figures represented the best basis for comparison. This
was because the diesel emissions figures were very much lower than those which
conventional gasoline engines could achieve and the diesel figures were obtained
without any exhaust treatment. The fuel consumption of the diesel was also lower
than that of gasoline engines. As a result of the above all the stratified charge
engine results relating to test bed figures were compared with those which could be
achieved by the 96 kW (128 BMP) diesel engine.
Because no specific motorcycle was defined the results from the passenger car
performance comparison-; were used to predict the likely motorcycle performance.
LITERATURE SURVEY
Stratified charge literature Is available from sources throughout the world
and dates almost from the original conception of the Internal combustion enqine.
Since the primary objective «f the literature survey was to provide a preliminary
assessment of the feasibility of the various stratified charge engines as power
plants for the target vehicles emissions levels considered, the period covered by
the survey was from 1920 to the present day. It was felt that earlier publications
would be unlikely to contain sufficient emissions, fuel consumption and durability
Information for the necessary predictions. In all, some 200 items of literature
were studied and these emanated from sources throughout the world including
America, Europe, U.S.S.R. and Japan.
All the literature surveyed was studied under a 'topic1 system and the engines
covered in the literature were, of course, classified according to the seven
categories described above. Combining the 'topic1 sub-classification with the
seven engine categories allowed general conclusions to be formed on each category
as well as permitting specific conclusions on Individual engines' It also allowed
a ready comparison to be made of the specific characteristics of engines In
different categories. The topic areas used to review each category were as
fo11ows:
Hi story
Combustion chamber and stratification technique
-------
Combustion characteristics and heat rejection
Performance
Fuel consumption
Emi ss ions
Multi-fuel capability
Engine Components and Manufacturabi1ity
Cost
Mathematical Models
Engine size and weight
No!se and Vibrat ion
Durability and Starting
OriveabiIi ty
Patents
The general conclusions drawn from the literature survey were-
1. Unthrottled stratified charge engines have demonstrated large potential
improvements In fuel economy but the lack of throttling usually leads to
high hydrocarbon emissions.
2. Throttled stratified charge engines can be shown to achieve satisfactory
hydrocarbon levels but usually at the expense of fuel economy.
3. The nitrogen oxide emissions of all the stratified charge engines studied
were lower than those of conventional gasoline engines and perhaps the most
attractive feature of stratified charge engines is their ability to meet the
secondary nitrogen oxide target of O.1* g/mlle.
k. The Ford Proco engines can be made to meet the secondary targets with little
sacrifice In fuel economy but a larger, heavier engine is required to permit
control of emissions during the CVS-CH tests.
5. The divided chamber category IV engines (e.g. VW and Porsche) have con-
siderable practical and theoretical advantages and should be able to
achieve the secondary emissions target with less performance and driveability
sacrifices than any other Internal combustion engine while still retaining
an acceptable fuel consumption.
6. The following engines were considered as feasible power plants for the
primary emissions targets:
PROCO
TCCS
Curtiss Wright Rotary
MAN-FM
VW Prechamber
CVCC
-------
7. The following engines were considered as feasible power plants for the
secondary emissions targets*
PROCO
TCCS
VW Prechamber
CVCC
Category 1 Literature Survey
(Single combustion chamber with fuel Injection before tdc, mixture formation
by fuel Injection and/or air movement)
The engines covered within this category were:
1. Ford PROCO
2. Windsor-Smith
3- Hesselman
1*. Starr
5. Wltsky
6. Mitsubishi (MCP)
In general the engines in this category rely on the characteristics of the
fuel injection to achieve stratification within a swirling air stream. Injector
position, Injection riming, spark plug position and spark timing are all critical
factors In the operation of any of the systems but they all feature fuel injection
direct Into a more or less open type chamber with air swirl within the chamber.
The conclusions from the literature covering the above engines were
I. Stratification within direct injection engines can only be achieved with
difficulty and requires the combination of suitable air movement and a
tailored Injection system,
2. The unthrottled stratified charge engines In this category can give a fuel
economy approaching that of the dlesel, but all have high hydrocarbon emissions,
Meeting the emissions targets with this principle requires what are currently
Impossible conversion efficiencies from oxidation catalysts.
3. By throttling these stratified charge engines the hydrocarbon levels can be
reduced with some sacrifice In fuel economy.
k. A PROCO engine fitted with an oxidation catalyst and using some exhaust gas
recirculation would be able to achieve the primary target with fuel economy
similar to that of a conventional engine at a NO level of 2*1* g/mile.
X
5. By using high levels of exhaust gas reelrculation at part load and by using
an engine approximately 25% greater In swept volume to restrict load during
the CVS-CH test procedure, a PROCO engine would achieve the secondary target
-------
with little sacrifice In fuel economy. The high hydrocarbon levels with this
quantity of exhaust gas reelrculation, however, make It highly likely (hat
catalyst durability will be a major problem.
6. The cost of the fuel Injection equipment would be very high relative to the
base cost of motorcycle engines and the application of the category 1
combustion process to small cylinders Is likely to be difficult.
7. The performance penalties associated with these types of combustion system
also make them unattractive for motorcycles.
Category 2 Literature Survey
(Single combustion chamber with fuel Injection during combustion : mixture
formed by fuel Injection and/or air movement)
In this category, which Is almost a sub-section of the category I classification
the TCCS and Oeutz systems were studied as reciprocating engines while the
application of the principle to a rotary engine by Curtiss-Wright was also studied.
The mode of combustion is similar to that of category 1 engines except that
the fuel is Injected Into the swirling air during combustion and the heat release
rate Is partially controlled by the Injection rate.
The conclusions deduced from the literature survey were<
1. The combustion process In all these systems is extremely complex and depends
on many other parameters besides fuel Injection rate,
2. The output of all the engines In this category is limited by smoke emissions
and air utilisation is relatively poor, although the rotary engine is not so
limited by this consideration.
3. Hydrocarbon emissions from all the engines In this category are high
particularly from the rotary engine.
'i. In the absence of emission controls the fuel consumption of the reciprocating
engines would be low.
5. The reciprocating engines have demonstrated multi-fuel capability with
acceptable fuel economy.
6. The TCCS engine is potentially viable for the primary emissions target but
great reliance Is placed on catalyst conversion efficiency with a low
temperature exhaust.
7. The TCCS engine Is also viable for the secondary emission target where large
quantities of EGR will be required and reliance on catalyst efficiency will
still be required due to the high hydrocarbon emissions,
8. At the secondary target the fuel consumption of a TCCS englned passenger car
wl11 be poor.
9. The Curt Iss-WrIght Rotary Combustion engine could be made viable for the
primary emissions target although It Is likely to give a poor fuel consumption
and place great reliance on catalyst conversion efficiency1.
10
-------
10. The complexity and cost of all the systems In this category makes them
unsuitable for motorcycle use. There are doubts as to the effectiveness
of these combustion processes In small cylinders and the intrinsically high
hydrocarbon levels and performance penalties make the use of category 2
engines for this application extremely unattractive.
Category 3 Literature Survey
(Single combustion chamber with fuel injection onto the piston. Combustion
controlled by fuel evaporation from the piston).
Only the 'FM1 (Fremdzundung) system developed from the MAN-M system diesel
engine fitted this category. In the 'FM1 system high levels of air swirl are
generated bv a helical Inlet port and a spherical combustion cavity In the piston.
During the compression stroke fuel Is sprayed Into the cavity when evaporation
from the piston surface or from within the swirling charge air causes mixing and
carries the fuel to the spark plug or flame front.
The literature survey Indicated that;
I. Such a system could give extremely good fuel consumption.
2. The MAN-FM system will burn a wide range of fuels with consistently good
fuel consumption.
3. This type of combustion system limits the power output of the engine due to
smoke emissions. This and breathing penalties limit the specific output
to that of diesel engines.
*». The base-line hydrocarbon levels of this system are low.
5. An engine operating on the MAN-FM s/stem could be made viable for the
primary emissions target when It would only require a single oxidation
catalyst.
6. The MAN-FM system Is rather complex for motorcycle use and the performance
limitations make It unattractive for this application,
Category fr Literature Survey
(Divided combustion chamber with fuel Injection Into a prechamber)
.n this category the prechamber may vary from a small prechamber acting
almost as an Ignition source to a large prechamber In which extensive charge
stratification Is used.
For convenience the engines within this category were divided into three
classes Identified by the size of the prechamber.
(a) Prechambers less than 2Q% of combustion chamber
The engines In this class Include the Freeman, the Porsche and the Clawson
systems. The engines all resemble the conventional gasoline engine in that
load Is controlled by throttling the Intake air and the mixture strength is
not varied over a wide range. The prechamber Is enriched by a separate fuel
Injection system and combustion Is Initiated In the prechamber. The 'torch1
II
-------
Issuing Into the main chamber thus Initiates combustion ,11 >i lunntvi ol
points and this gives more reliable combustion which permits operation
at leaner overall mixture strengths than can be achieved in the conventional
gasolIne engIne.
(b) Prechambers between 20 and kQ% of the combustion chamber
These engines, which Include the VW, Broderson and Schlamann systems, are
generally a compromise between the very large and small pre-chambers and
can thus usually operate In two modes, In the first mode the engine is
unthrottled, the prechamber acts as in the class fa) engines but extra fuel
Is supplied to the main chamber for high load operation. In the second mode
the engine Is throttled so that approximately constant overall air fuel
ratios are maintained In the two chambers at all loads.
(c) Prechambers greater than ^0% of the combustion chamber
Engines In this class are usually unthrottled and load Is controlled by the
prechamber fuelling. At low loads the prechamber mixture is stratified to
ensure combustion while at high loads the prechamber mixture strength is
greater than stolchlometrIc and the rich mixture is finally burnt as it is
expelled Into the main chamber. The Huber and Newhall systems fall within
this classification.
Careful study of the published Information on the nine engine types yielded
the following conclusions*
I. The results obtained from the VW and Porsche- systems (throttled, usinq a
small pre-chamber as an Ignition cell) were quite good.
2. The good fuel consumptions from test bed results were not repeated in
vehicle tests.
3. The hydrocarbon emissions are similar to those from conventional gasoline
eng Ines.
J*. Nitrogen oxide emission levels are exceptionally low and levels below 1 g/mi le
can be achieved without EGR.
5. A VW prechamber engine would be able to meet the primary emissions targets
using only an oxidation catalyst but fuel economy would be little better than
a conventional gasoline engine.
6. By the use of EGR and a further catalyst the same engine should be capable
of meeting the secondary emissions target with only a slight fuel economy
sacrifice.
7. All of the engines examined could be designed to fit into a motorcycle
application but their great complexity and reduced specific output make
them all unattractive.
Some recent results from Porsche, referring to a six cylinder engine
installed In a car indicate good specific output and low emissions. Taken with
the good test bed fuel consumptions the system appears to be extremely attractive.
12
-------
Category 5 Literature Survey
(Divided combustion chamber with a separate inlet valve foi the pi e-ch.nubor)
Probably the best known system within this category is the Honda CVCC although
many recently developed scavenged pre-chamber engines were reviewed. These were the
Ford, G.M., VW. Eaton and Helntz scavenged prechambers. Several Russian engines in
this category Including the Nllov, GAZ and Z1L engines were examined. In addition
many early publications describing engines falling into this category were studied
Including the results from recent retrofit approaches such as those of Morghan,
Philips, Teledyne and Walker.
The general principle of operation Is that the engine induces a lean mixture
through the main Intake valve while a very rich mixture Is Induced into the pre-
chamber via the third valve. The compression process gives some dilution of the
prechamber mixture so that at Ignition an air/fuel ratio of 9 to I2tl exists at the
spark plug In the prechamber. After Ignition the hot gas in the prechamber is
expelled as a 'torch1 Into the main chamber so Initiating combustion in the
leaner mixture.
The large quantity of publications studied In this category gave the
following general conclusions:
1. The specific output of this class of engine can be similar to that of
conventional gasoline engines if stratification is sacrificed at full load.
If stratification Is maintained then a loss of some 10% in specific output
results.
2. The fuel economy of a car equipped with a scavenged pre-chamber engine
should only be slightly Inferior to a conventionally powered vehicle.
3. If stratification Is maintained at full load the emissions should be
within the prii
-------
plug. The weaker mixture flowed Into the cylinder In the normal manner.
The main conclusions reached after studying the literature on this engine
were:
I. Insufficient data were available to predict the likely emissions performance
under transient conditions.
2. The maximum output would be the same as for a conventional gasoline engine
since at full load the system operates as a homogeneous charge system.
3. Test bed results Indicated that the low load fuel consumption might be better
than obtained from a conventional gasoline engine although no vehicle fuel
consumptions are available to confirm this.
5. The test bed results did Indicate the ability to maintain the minimum levels
of hydrocarbons and carbon monoxide over a wider range of mixture strengths
than a conventional engine, although the absolute levels were no lower.
6. Because a weak mixture carburetted system can be applied easily to existing
engines It may present a means of reducing the hydrocarbon and carbon
monoxide emissions from existing four-stroke motorcycle engines and improve
the fuel economy at the same time. The use of some variation of the IFP
system In this application may provide a worthwhile palliative approach in
view of the proposed emission levels and the operating range of motorcycle
engines.
Category 7 Literature Survey
(Two stroke, exhaust diluent and miscellaneous engines)
Many different types of engine were covered in this category, The first of
these the Nippon Clean Engine - NICE is a modified two-stroke engine relyinq on air
motion produced by three transfer ports. The positioning of the third transfer
port, a wedge shaped combustion chamber and the design of the transfer passages
are essential for the controlled scavenging process. An exhaust control valve is
disc required In the exhaust port to prevent over-rapid blow down and in fact both
inlet and exhaust are throttled throughout the speed range.
The YOCP engine (Yuo and Ohnlshl Combustion Process) Is a Schnurle scavenged
two-stroke with In-cyllnder Injection of the fuel and throttling Is only required
at light load.
The Fairbanks Morse engine Is an opposed piston design utilising two very
small pre-chambers for each cylinder and Is only used as a gas engine. Gas Is
Injected into the pre-chambers where Ignition occurs and torch ignition is used.
Both the Kataoka and Hlrako (K and H) and the Clawson two-stroke systems
apply an unscavenged pre-chamber to a loop scavenged two stroke with fuel addition
to both the main and pre chambers and are unthrottled engines at the present state
of development.
The Helntz Ram Stratlcharge system was a scavenged pre-chamber two stroke
with pre-chamber scavenge supplied from the second stage of a two stage Roots
blower and the main chamber scavenge from the first stage.
-------
The Rlcardo two strokes were sleeve valve two strokes with fuel Injection
Into a bulb shaped pre-chamber.
In the Jessel engine, stratification was achieved by the control of exhaust
dilution by exhaust reelrculatIon through an additional valve.
In the Kushul engine two separate cylinders were connected by a transfer
port and one cylinder, the mixture cylinder containing the fuel and air and where
Ignition occurs leads the air cylinder by 20 - 30° crank. Complete combustion
and wide burning ranges were claimed due to the intense air and gas motion during
combust Ion.
Early Ricardo work was also carried out on a 4 stroke sleeve valve achieving
charge stratification by means of a second row of Intake air ports low down in the
cylinder.
The general conclusions from the survey of published Information on these
engines were;
1. Al1 of the two stroke systems reviewed added expense and complexity to
the basic engines without overcoming the fallings.
2. The fuel consumption of all the two stroke engines was poor. The Kushul
engine, however, would seem to be capable of giving fuel economies com-
parable with that of an I.D.I, dlesel.
3. As far as could be determined from the published results all the engines
were likely to give high levels of hydrocarbons and carbon monoxide while
giving low levels of oxides of nitrogen.
I*. The only engine to achieve the primary target (and the secondary target)
was the NICE equipped with a very complex afterburner system.
5. None of the engines was considered viable for the target passenger car.
6. The NICE might be suitable for the two-stroke motorcycles but the degree
of after treatment required for the various emissions levels cannot be
predIcted easily.
ENGINE CONFIGURATION STUDY
The literature study indicated that some stratified charge engines could
provide viable power plants for a passenger car and thus the study required
that all potentially viable variants be designed In sufficient detail to allow
their likely performance to be assessed realistically. The vehicle to be
powered by any of the candidate power plants was a V5 seat sedan weighing less
than 1600 kg (3500 1b) and capable of meeting the EPA standard car performance
specifications, I.e. 0.97 km/h CO-60 mph) In less than 13.5 s, 1*0-113 km/h
(25-70 mph) In less than 15 s and capable of overtaking a 80 km/h (50 mph) truck
in less than 15 s. The emission targets were:
15
-------
Primary (or short term)
HC 0.1«1 g/mlle
CO J.k g/mlle
NO 1.5 g/mlle
Secondary (or long term)
HC 0.<<1 g/mlle
CO 3.<« g/mlle
wn
x 0.<» g/mlle
and were to be obtained when the vehicle was tested according to the CVS'CH
procedure. Computer calculations Indicated that a 3-speed automatic gear box
would require an Installed power of approximately 97 kw (130 bhp) for engines
with normal torque characteristics, and thus all the power plants were designed
with this In mind.
In order to provide a firm basis for comparison in the rating section of the
study typical gasoline engines were specified briefly at the commencement of the
configuration study phase. Two engines, a V-8 following current good American
practice and an IL-6 more representative of European designs were specified.
The stratified charge engines selected as potentially viable were all schemed
out In some detail so that the true potential of each system could be realised
and also so that design problem areas and restrictions on configuration,
Installation or performance could be foreseen. As far as possible the V-8 and
IL-6 designs followed current American gasoline engine practice while the emissions
control gear on all of tho power plants was specified to permit operation for
50,000 miles or at least 25,000 miles with little maintenance.
To provide a further basis for comparison and to maintain continuity with the
earlier diosel study the naturally aspirated V-8 indirect injection diesel from
that study was also included In this phase.
A brief description of the 2 gasoline engines, 12 stratified charge engines
and the diesel engine is given below while salient engine dimensions, performance
and emissions control gear are all compared In the Summary Table at the end of this
sect ion.
1. V-8 Gasoline Engine
8 cylinder 97 nrn x 76 mm (3.82" x 3.00") - <«.5 litre (275 CID)
96 kW (128 BHP) at 66.7 rev/s
285 N m (210 Ib.ft) at M.6 rev/s
2*«5 kg (5<<0 Ib) estimated weight!
For the primary emission target (1.5 g/mile NO ) the engine would require
modulated exhaust gas reelrculation, sophisticated close tolerance carburettors,
air Injection into the exhaust manifold and an oxidation catalyst In the exhaust
system.
16
-------
The 'good performance1 target gasllne engine for this study will have a fuel
consumption of approximately 1*1.6 1/100 km (16.0 mlle/U.S. gallon) over the C\/S-CH
-ycle In the primary emissions build.
Driveabillty noise level would be 71 dBA under U.S. Federal Test conditions.
2. In-line Gasoline Engine
6 cylinder 88 mm x 82 mm (3.46" x 3.22")
3 litre (183 CID)
96 kW (128 BHP) at 83.3 rev/s
232 N m (171 Ib.ft) at 50 rev/s
204 kg (450 Ib) estimated weight.
The engine would be equipped with similar emissions control qear to the V-8
engine.
Fuel consumption In primary emissions build would be approximately 13.5 1/100
krr (17.4 mMes/U.S. gallon) over the CVS-CH cycle.
Drive-by noise level will be 73 dBA.
3. \/-8 PROCO Engine Primary Target
8 cylinder 87 mm x 87 mm (3.43" x 3.43")
4.15 litre (254 CID)
96 kW (128 BHP) at 66.7 rev/s
292 N m (215 Ib.ft) at 38 rev/s
250 kq (550 Ib) estimated weight
To meet the primary emissions target, some exhaust qas must be recirculated.
A large oxidation catalyst will also be required.
Predicted fuel consumption Is 12.5 1/100 km 08.7 mlle/U.S. gallon) over the
CVS-CH cycle.
Drive-by noise level will be 71 dBA.
4. In-line 6 PROCO Engine - Primary Target
6 cylinder 96 mm x 96 mm (3.78" x 3,78")
4.15 litre (25^ CID)
96 kW (128 BHP) at 66.7 rev/s
293 N m (216 Ib.ft) at 37 rev/s
263 kg (580 Ib) estimated weight
The same emissions control will be required as on the V 8.
Predicted fuel consumption Is 12.7 1/100 km (18.4 mile/U.S. gallon) over the
CVS-CH cycle.
17
-------
Drive-by noise level wl11 be 75 dBA.
5. V-8 PROCO Engine - Secondary Target
8 cylinder <)k m x 3k m (3.7" x 3.7")
5.22 litre (320 CIO)
122 kW H63 BMP) at 66.7 rev/s
365 N m (270 Ib.ft) at *»0 rev/s
259 k9 (570 Ib) estimated weight
For the secondary emissions target It will be necessary to employ higher
exhaust qas reelrculatIon rates than for the primary targets with modulation of this
rate with load. The resulting Increase In HC emissions will require a larqc
volume of oxidation calalyst to give satisfactory durability.
Predicted fuel consumption is Hi.2 1/100 km (16.5 mlles/U.S. gallon).
Drive-by noise will be 72.5 dBA.
6. V-8 TCCS Engine - Primary Target
8 cylinder 95 mm x 95 mm (3.7V x 3.7^")
5.^ litre (330 CID)
96 kW (128 BHP) at 66.7 rev/s
280 N m (206 lb.lt) ai 29 rcv/s
273 kg (600 Ib) estimated weight.
Modulated exhaust gas reelrculation together with two catalysts for HC and
CO control will be required.
Predicted fuel consumption Is 13.8 1/100 km (17 miles/US gallon).
Drive-by noise will be 70.5 dBA.
7. In-Llne 6 Turbocharged TCCS Engine - Primary Target
6 cylinder 96 mm x 96 mm (3.78" x 3-78")
*»-l& litres (25^ CID)
96 kW (128 BHP) at 66.7 rev/s
298 N m (210 Ib.ft) at l«2 rev/s
260 kg (572 Ib) estimated weight
Similar emission control gear will be required to that fitted to the V-8
TCCS engine.
Drive-by noise will be 71 dBA.
Predicted fuel consumption is 13.8 1/100 km (17 mlles/U.S. gallon)
18
-------
8. Roiary, 2 Biink Engine - Primary Target
2 rotors 5-5 litre (336 CID)
97 kW (130 BMP) at 83 rev/s
214 N m (158 Ib.ft) at 56 rev/s
150 kg (330 Ib) estimated weight
Due to the high Inherent HC emissions from rotary engines, two oxidation
catalysts will be required.
Predicted fuel consumption Is 16.7't 1/100 km (14 mlles/tJ.S. gallon)
Drive.by noise Is estimated at 71 dBA,
9. V-8 Turbocharged TCCS Engine _ Secondary Target
101 mm x 92 mm (3-96" x 3.64")
5.87 litres (358 CID)
135 kW (181 BMP) at 66.7 rev/s
423 N m (312 Ib.ft) at 41 rev/s
286 kg (630 Ib) estimated welqht.
For emissions control, Ignition retard and modulated exhaust gas recirculation
are required together with two oxidation catalysts, It might be possible to replace
one of the catalysts by a thermal reactor.
Predicted fuel consumption Is 16.7^ 1/100 km (14 miles/U.S. qallon)
Drive-by noise will be 72.5 dBA.
10. V-8 HAN-FM Engine - Primary Target
93 mm x 93 mm (3.66" x 3.66")
5.05 litre (309 CID)
96 kW (128 BMP) at 66.7 rev/s
298 N m (219 Ib.ft) at 33 rev/s
300 kg (660 Ib) estimated weight
This engine has inherently low NO emissions but will require an oxidising
catalyst for HC and CO control.
Predicted fuel consumption Is 12.3 1/100 km (19 miles/US qallon)
Drive-by noise will be 72 dBA.
11. V-8 VW Engine - Primary Target
86 mm x 79 mm (3.39" x 3.H")
3.67 litre (224 CID)
96.5 kW (129 BMP) at 75 rev/s
19
-------
228 N m (168 Ib.ft) at 66 rev/s
250 kg (550 Ib) estimated weight
This engine has Inherently low NO emissions but will require an oxldisinq
catalyst for HC and CO control.
Predicted fuel consumption Is l*».2 1/10D kw (16.5 mi le/U .S. gallon)
Drive-by noise will be 73 dBA.
12. V-8 VW Engine - Secondary Target
Engine specification Identical to VW for Primary Target,
Modulated exhaust gas reelrculatlon and two oxidising catalysts will be
required for emissions control.
Predicted fuel consumption Is 15.1 1/100 km (15.5 miles/U.S. qallon)
Drive-by noise will be 73 dBA.
13. V-8 CVCC Engine - Primary Target
88 mm x 88 mm (3.'«611 x 3.*»6")
k.28 litres (260 CID)
97.5 kW (130.5 BMP) at 73-5 rev/s
268 N m (197 Ib.ft.) at 35 rev/s
250 kg (550 Ib) estimated weight.
A thermal reactor will be required for emissions control.
Predicted fuel consumption Is 13.95 1/100 km (16,8 mile/U.5. gallon)
Ifr. V-8 CVCC Engine - Secondary Target
96 mm x 96 mm (3.78" x 3.78")
5.56 litres (3'«0 CID)
121 kW (162 BMP) at 66.7 rev/s
350 N m (258 Ib.ft.) at 33.5 rev/s
273 (600 Ib) estimated weight,
Modulated exhaust gas reelrculation and a thermal reactor will be required for
emissions control. (An additional oxidising catalyst may be found to be necessary
for HC and CO control).
Predicted fuel consumption is 15.6 1/100 km (15 miles U.S. gallon)
Drive-by noise will be 73 dBA.
20
-------
15. V-8 Diesel - Primary Target
While no dlesel engine has been configured, It is convenient, for comparison
purposes to repeat the specification produced in the previous study.
88 mm x 98 mm (3.W x 3.86")
*».78 litre (292 CIO)
96 kW (128 BMP) at 66.7 rev/s
290 N m (210 Ib.ft.) at 33.3 rev/s
320 kg (700 Ib) estimated wight
Apart from retardation of Injection timing, no add-on devices are required for
emIssion control.
Predicted fuel consumption on diesel fuel Is 11 1/100 km (21 miles/U.S.qalIon)
Drive-by noise will be 7** dBA.
21
-------
SUMMARY TABLE
CASOIIK Vt
CASOLIHE IL6
noco vs
»OCO IL6
MOCO Vt
1CCS Vt
TCCS IU
CM »OTWT
TCCS Vt
HAN tH VB
VU Vt
VW VS
CVCC V8
CKC Vt
DIESEL Vt
CATECOIT
CASOIIK
CASOLIM
I
I
I
II
II
II
II
III
IV
rv
v
V
Eitissia
TAAUT
FIIIMIY
ruivuiT
»IM>V
nil MAY
SECOHOA1Y
MWM,
„«.,
niiKMf
UCOHOAKY
«,«,,
-IIIVUT
SECOMAIT
PIIHAIY
KUWAIT
MINIM
CKIHC SPECIFICATION
•ME
17
81
87
16
It
11
16
101
11
16
86
on
££
STiioa
76
11
17
9*
It
IS
16
11
11
71
71
H
cwric-
UMTIOH
HA
Vt
HA
IL6
HA
Vt
HA
IL6
HA
V8
HA
Vt
TC
IL6
1 lAM
lOTAir
TC
Vt
MA
VI
HCkT I
t.S
2.99
t 15
t.15
S.1S
S.t
t 16
S S
S 87
505
1
vt j J"
HA
Vt
,10
11 0
II 0
10 0
1 0
8.5
9.0
15 0
8 5
1 67 its
"» ! t 28 79
vt ! *•" 7 »
VI ( S
7 9
M >8 £ t7l 20
1
FACUGC
lEHcnt 'HEIGHT
WIDTH! 101
•• IVDLM n1
HOT COHFIUMO
HOT COBFICUIEO
770
115
800
111
111
511
its
7t5
761
76]
76,
517
6)8
601
658
610
660
6*5
6*1
6,0
610
660
715 J675
600
S28
622
622
578
615
630
6tO
610
610
6tl
.175
.1)5
.10]
.117
3*6
.It
It,
.107
.21*
I8t
121
M2
7S8 itOt 651 110
• I
«t
2tS
tot
150
26)
251
27)
260
150
186
100
150
250
COST
S
SIS
518
7tl
66*
127
811
827
667
185
756
it'l 76*1
Itt
(EFl 811)
111
ISO | 600
271
670
320 ' 701
tUF.nwcE
row' Ml
•t r«v/»
16
66 7
16
81.0
16
66 7
96 5
66 7
III
66.7
16
66.7
16
66.7
17
11
115
66 7
16
66.7
96.5
75
16 5
75
97 5
7) 5
11'
66 7
66*7
TOKQUI •»
•t r«v/t
It5
1)1
so
IT
111
17
MS
to
100
19
19t
56
tl
118
11
III
66
128
268
35
ISO
Jl 5
286
1) t
man
IS
10
19
16
1)
11
.s.*
17 t
19 0
Ik. I
9 8
9.8
26 t
21.5
2t 0
VEHICLE rEiraHMKI
ECOMMY
•/USgil
16
17 t
18.7
18 t
16. S
17 0
17.0
It 0
It.O
11.0
16.5
IS S
16.8
15.0
21 0
:O»SU»TIOH
L/IOO k»
It 6
l].5
12.5
12.75
It.l
D.8
M 1
16.7*
,6.,t
12.1
It.l
15 1)
13 95
IS 6
II 0
HC CORTtOl
«C IASE
0 1
1 8
0 2
1 8
0.15
1 0
0 IS
1.0
0.2S
2.S
0 1
2.5
0 22
1 0
0 )
1 0
0.2S
t.5
0.1
0 t
0 21
1 8
0 28
2 5
0.2
0.37
0 *6
CO COHTtOL
CO BASE
1.0
10 0
1.0
30.0
1 0
8 0
0 8
8 0
0 8
12
ID"
I 5
10
08
•5
1 0
11.0
o.n
8 0
O.I
t.o
Hfl »OISE
dIA
I.J 71
1 ) 7)
I
' * , "
I.J 75
0.)7 72 5
1
0 8 70. S
0 8 ' 71
1 0 71
EKISSIW COHTHOL
CATALYST mrjifjfim 'CH
1
A,«"u. ' "
. tlH. 1
All IU. 1
1
1 »
j
1 i '
i i i
i i
2 1
2 . I
2
;
0 Jl 72.5 ' 2 | «
1 0 72
i •
1 0 . 73 '
, t
,iS OJ5 73 ' i
'.' ..3 -J
!
J.° 0 )? '3 ' '
20 i :
-------
COST ANALYSIS
The literature survey yielded virtually no information on the likely pro-
duction costs of many of the stratified charge engines considered in the con-
figuration study. It was felt that the aspect of production cost was so important
to the overall alms of the study that a separate task should be made of this one
aspect. As a result a detailed cost estimate was made for each of the engines
schemed In the configuration study. For the cost estimates information was taken
mainly from 'In-house1unpublI shed sources and from surveys carried out by NAS into
engine production costs. An allowance was made for inflation when information
from previous surveys was used and the bar chart below gives the estimated
production costs (1975 U,S, dollars) for each power plant Involved In the con-
figuration study.
The production costs obtained In this task were used as input for the rating
phase of the study.
23
-------
STRATIFIED CHARGE ENGINE - FEA SIBILITT STU D Y
BAB CHART SHOWING ESTIMATED MANUFACTURING COST BREAKDOWN FOR THE VARIOUS POWER PLANTS - U.S. DOLLARS
POVER PLANT-
I. CYLINDEB BLOCK
2. CON-RODS, CRANKSHAFT, VALVE
GEAR, FLYW HEEL, ETC.
3. PISTONS
4. CYLINDER HEAD(S)
S. CONTROL GEAR BETWEEN EGR,
THROTTLE, DISTRIBUTOR AND
IN.IKCTlnN PI'MP
6. MANIFOI OS R HEATING PIPEWORK EFE.
7. EXHAUST REACTOR AND/OR CATALYST
8. IGNITION DISTRIBUTOR, COIL, PLUGS
<>. EGR VALVE A,NT, PIPEWORK
ID. OTHER EMISSION CONTROL GEAR: EVAP
CONTROL, P.C.V. INTAKE HEATER,
TRANSMISSION CONTROLLED SPARK,
SPARK ADVANCE CONTROL. ANTI
DIESEL1NG SOLENOID, ETC. ETC.
11. AIR PUMP
12. STARTER MOTOR, ALTERXA7CJ
VACUUM PUMP, HYDSACUC FVV.?
13. TURBOCHARGER
14. CARBURETTOR AND/OR INJECTION
PUMP, PRIMARY INJECTORS.
SECONDARY INJECTORS
V-« GASOLINE
IL6 GASOLINE
PROCO V-«
PROCO 1U6
PSOCO V-8
TCCS V-«
TCCS IL-6 T/C
CURTIS WRIGHT ROTARY
TCCS V-» t/C
M. A.N. K. M. V-B
V.W. V ft
v.w. v-a
CVCC V-B
CVCC V-8
DIESEL V-»
I 1 2 1 3 1 * l6l< 7 lal 9 1 10 1 II 1 12 1 U 1
-f 1 } 1 3 1 i 1 61 1 1 4 1 9
1 . ' -5
1 i r
1 ! "-T— ' 1 l~J—L]
— i — n — igi
* ' — 3 'B'
16 1 *t 1 12 1 U 1
~1 1 — 9 — TaTi
5-7—12 — r
1-1 ! 1 3 1 1 1 5 161 7 | 8 191HJI Ml 1* 1
!
! 1 — ' 1 r-1
• '
— i — i — i — ? —
. * ' —
1 . 1 3 1 t 1 5 ]
.
TI 1 1
• — i — s — rrirr
12 1 '
6l 7 1 • 19 1101 12 1
— i I 2 • I 3 1 i 1 5 |6| 7 1 8 111 10
1
T.I.I.*
1 1
, 0— r-J
^ ^
J : 1
!
i '. '. 1 '• ,
=— »-, *—
|L L.
i * i * — L
1 J ' 4 — I
1 ill
1 ' .
1 I J 1 '
1
L, LI ^
51 7 I 8 I 10 1
u • • 1
12 1 U 1
- 1
J 1
• 1
J 1 * 1 a 1 ° I !__
— — 5 1 z — m 1 r«-r
a l°l '
— E — nn — '• 7
> 1*1 '-
— Z IKI
* I fl lift 1 TJ — r-
la! a he,
12 1 ~
T — n 1
7 — : 1 s 1 IP — i — n — i — n —
' 1
— rnn — ri — i —
1 _
— R '
I i 161 7 1 6 1 9 1 10 1 U 1 U i
1 ' ' '
: isi « i1 u
u
—\
3
• r -- IT — !
• f — ^
1^
RSOUCEO
ELECTRO
u
'COST FOR
NIC F.I.E. .
1 1
100
200
300
UJO
SCO
600
700
SCO
900
1000
-------
POWER PLANT RATING
In order to provide a quantitative assessment of the relative merits of the
various power plants selected, a major aim of the study was to rate the per-
formance aspects of each power plant. The methodology already developed for the
light duty dlesel engine study was considered suitable for this application. By
the use of the existing methodology a direct comparison between the assessment of
the existing power plants and those rated in the earlier survey was possible and
those aspects which render a particular power plant viable or not for a light duty
application Identified and quantified, Furthermore, the methodology allows an
assessment of changes 'In a particular area as well as highlighting areas worthy of
effort to make a particular configuration more suitable for use in a qiven environ-
ment
The fitness of any power plant for a given duty is a combination of the
excellence with which It meets various performance aspects or requirements and the
relative Importance of those Individual aspects.
The methodology employed in the light duty diesel engine study established
twenty-six performance aspects by which a power plant was rated. Each of these
performance aspects was also Individually weighted as a measure of its relative
Importance. For the current study the same performance aspects were employed.
The performance aspects are listed In the following table together with the
weighting factors.
Aspect Weighting
1 Smoke ^.'18
2 Partlculates 2.1*4
3 Odour I*.1*8
I* NO 3 92
X
5 HC 3.99
6 CO 3.61
7 S02 3.^8
8 HC reactivity 1.83
9 Evaporative Emissions 1.60
10 Miscellaneous Emissions 0.98
II Noise (Drive-by) 6.32
12 Package volume 2.61
13 Package weight 2.59
Ht Fuel economy 12.20
15 Fuel cost 5.*»0
16 Vehicle first cost li.65
17 Maintenance cost '«.35
18 Startabillty ^.85
19 Hot driveabillty '•.W
20 Cold drlveabllIty 3.52
25
-------
Aspect Weighting
71 Torque back-up 1.98
22 Durability
-------
experienced members of Rlcardo staff and great care was taken to ensure that the
committee had no bias to Hiesel, gasoline or any of the stratified charge
configurations considered In this study, The power plants considered were those
described In the 'engine configuration1 section of this report with the addition
of the two gasoline engines and the IDI dlesel engine described briefly in that
section. The engines considered are listed below, together with the categories
in which they are divided and their respective emission targetst-
Category Emission Target
1. V-8 'American1 Gasoline - primary
2. IL6 'European* Gasoline - primary
3. PROCO V-8 1 primary
ft. PROCO IL6 I primary
5. PROCO V-8 I secondary
6. TCCS V-8 I I primary
7. TCCS IL6 T/C II primary
8. Curtiss Wright Rotary II primary
9. TCCS V-8 T/C I I primary
10. MAN FM V-8 III primary
II. VW V-8 IV primary
12. VW V-8 IV secondary
13- CVCC V-8 V primary
1ft. CVCC V-8 V secondary
15. IDI Diesel V-8 - primary
Each of the power plants above were considered for the emission targets shown
and where a secondary target Is not included It indicates that the particular power
plant was not considered viable for such an emission level. The quantity of exhaust
pollutants for the two target levels are shown below measured according to the
CVS-CH test procedure*
Primary Targets
HC O.ftl g/mlle
CO 3.ft g/mlle
NO 1.5 g/mlle
Secondary Targets
HC O.ftl g/mlle
CO 3.ft g/mlle
NO O.ft g/mlle
A table, showing the ratings awarded for each aspect may be found at the end
of this section.
27
-------
The product of the rating and the weighting for each performance aspect was
summed for each power plant and the results are shown in the table below-
Englne Final Score
(to nearest Primary Tarqet Secondary Tarnet
whole number) Position Position
V-8 Gasoline 616 2
11-6 Gasoline 627 1
PROCO V-8 615 3
PROCO IL-6 599 5
PROCO V-8 576 2
TCCS V-8 566 9
TCCS IL-6 T/C 5^7 11
Curtlss Wright Rotary 552 10
TCCS V-8 T/C 517 ^
MAN-FM V-8 57*» 8
VW V-8 586 6
VW V-8 561 3
CVCC V-8 613 4
CVCC V-8 583 1
Diesel V-8 581 7
These results are revealing In that they Indicate how small the relative
differences are between the power plants, With the rating methodology employed
a power plant rated as acceptable In each of the performance aspects would achieve
a score of 500 but If a zero were to occur In any score, that power plant must be
rejected whatever Irs final total. As none of the candidates rate zero in any of
the performance aspects and all achieved a total score In excess of 500, all must
be considered as viable alternatives,
The highest scoring power plant, the IL-6 gasoline engine scored approximately
202; more points than the lowest, the TCCS secondary emissions engine. Of particular
Interest Is the score attained by the PROCO primary emissions engine which attained
a similar rating to the conventional V-8 gasoline engine, mainly on the grounds of
improved fuel economy. With a slightly lower total score than the PROCO V-8 engine
came the CVCC primary engine followed by the PROCO IL-6. The conventional I.D.I.
diesel rated 7th in the listing, but since Its fuel economy was taken using diesel
Fuel whereas all the other power plants used gasoline, there may be some error in
the relative position of this engine.
This application of the rating method Indicated that none of the candidate
power plants was better than existing gasoline engines for the primary emissions
target but that both the PROCO and CVCC systems were almost as good,
At the secondary emissions target (0.4 g/mlle NO ) the CVCC and PROCO engines
achieved the highest score with the CVCC system having an almost Insignificant
numerical advantage. The scores achieved by all the secondary engines considered
however Indicate that none of the combustion systems can be regarded as completely
non-viable.
28
-------
^ »SA
/; //
1
2
3
4
5
6
7
9
10
11
12
13
14
15
16
17
1 Q
IB
19
21
22
24
25
26
Smoke
Participates
Odour
NO
HC
CO
SO
Evap Emissions
Misc Emissions
Noise (Drive-by)
Package Volume
Package Weight
Fuel Economy
Fuel Cost
Vehicle First Cost
Maintenance Cost
Stortribihty
Hot Drive-ability
Cold Driveabihty
Torque Back-up
Durability
LJ — j., 1 _««,
neat LOSS
Fire Risk
Idling Noise
Torque Recoil
j
9
7
6
5
5
5
5
5
5
7
7
6
65
5
6
5
8
7
5
5
8
8
>N
9
7
6
5
5
5
5
55
5
65
7
7
7
5
6
5
8
65
5
5
8
75
V
85
65
6
5
5
5
5
55
5
7
7
6
75
5
45
45
8
65
45
5
55
66
^
85
65
6
5
5
5
5
55
5
5
5
6
65
5
55
45
8
7
45
5
5
6
^
85
65
6
5
5
5
5
55
5
65
6
6
7
5
4
3
8
5
3
5
5
6.6
•9 >
'&
6
3
45
6
5
5
5
55
5
75
5
56
7
5
4
3
B
7
3
5
5
6
'
-------
TECHNICAL MEPOHT DATA
i an nutl /NU/i/r limn mi ill, rriirir Injun iiitiii'li
HLfOHl NU
EPA-460/3-74-011-C
4 rnLL ANUbuunILL
A STUDy OF STRATIFIED CHARGE FOR LIGHT
DUTY POWE.R, PLANTS.' -VOLUME' -3. 'EXECUTIVE
SUMMARY " -
AUIMOH(t>)
RICAROO f. CO.
It HtHhOHMINli OHl, •XNI/AIION NAML AND AUUHLSS
RICARUO t CO. ENGINEERS (192?) LTD.,
BRIDGE WORKS. SHOHEHAM-BY-SEA, SUSSEX, BN^ 5FG.
ENGLAND.
\J SPUNbOMINCi AlilNlY NAMt ANU ADDHL^S
ENVIRONMENTAL PROTECTION AGENCY, OFFICE OR AIR
WATER PROGRAMS, OFFICE OF MOBILE SOURCE AIR
POLLUTION CONTROL, EMISSION CONTROL TECHNOLOGY
DIVISION, ANN ARBOR, MICHIGAN <»8l05
.1 lUCIPIbNT'b ACCtbSlOI»NO
b HEPOHT DATt
_. _OCIOJ£fi_ia75
b HLHFORMING ORGANIZATION COOt
0 PIHHOHMING ORGANISATION HtPOM I NO
DP 210137
10 PHOCiRAM iLtMhNT NO
l"T CO NT H ACT/C R ANT~NO ~'
68-03-0375
13 T YHL Of RLPOH1 >«NO HtHlUD COVLHLD
F I NA.L..REPORT
14 SfONSORING ACLNCV CODE
B SUPCL bMLN I AMY NOT I i.
Pick up from Volume 1
6 ABSTRACT
Thn objectives of this project were to determine the acceptability of various
types of stratified charge engines at potential power plants for light duly
vehicle:, jnd motorcycles In America. The light duty vehicle considered WH» a W5
seat co pact seiMn with good acceleration capcibllltles and exhaust emissions below
a prlmaiy target of U M g/ml le HC, }.'i g/ml le CO, 1.5 rj/inl le NO . A secondary
target of 0 fiMi|>
H DISTHIUUriON STA ILMLNT
RELEASE UNLIMITED
19 StCURITY CLASS (Ihit Kcp,,rl)
lJNCj-A§§IF.LEf)
10 SfcCUHITV~CLASb"(//iij"/ijjfr;
UNCLASSIFIED
21 NO OF PACES
35
22 PRICE
CPA Form 2220 1 (I-7J)
30
------- |