EPA/AA/CTAB-91-01
                       Technical Report
            Conversion of Methanol-Fueled 16-Valve,
           4-Cylinder  Engine to Operation On Gaseous
               2H2/CO Fuel - Interim Report  III
                              by
                      Ronald M. Schaefer
                     Gregory K.  Piotrowski
                        James C.  Martin
                          April  1991
                            NOTICE

     Technical Reports  do not  necessarily represent  final  EPA
decisions or positions.   They are intended  to  present technical
analysis  of  issues using  data which  are  currently  available.
The purpose in the release of such reports  is  to  facilitate  the
exchange  of  technical  information and  to inform the  public  of
technical developments which may form the basis for  a final  EPA
decision, position or regulatory action.

             U. S. Environmental Protection Agency
                  Office of Air and Radiation
                   Office  of Mobile  Sources
              Emission Control Technology  Division
           Control Technology and Applications  Branch
                      2565 Plymouth  Road
                   Ann Arbor, Michigan   48105

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       UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                    ANN ARBOR. MICHIGAN 48105
                                                       OFFICE OF
                                                     AIR AND RADIATION
MEMORANDUM .
SUBJECT:   Exemption  From  Peer  and  Administrative  Review
FROM:
TO:
Karl H. Hellman, Chief
Control Technology and Applications Branch

Charles L. Gray, Jr., Director
Emission Control Technology Division
     The attached report entitled,  "Conversion  of  Methanol-
Fueled  16-Valve,  4-Cylinder  Engine  to  Operation  On  Gaseous
2H2/CO   Fuel   -  Interim   Report   III,"   (EPA/AA/CTAB/91-01)
describes  progress  to  date on  a  project  to  convert  a  Nissan
CA18DE  engine previously  modified  for  operation  on  M100  neat
methanol   to   operation    on   dissociated   methanol   (2H2/CO)
gaseous  fuel.   This  engine  has  been operated  on  both MlOO  and
simulated  dissociated  methanol  (hydrogen and  carbon  monoxide)
gaseous  fuels.   This  report describes modifications made  to  the
engine  and  summarizes  the  results  of  recent testing.   Further
work on  this project  will  be  described  in  a  future  technical
report.

     Since this  report  is  concerned  only with  the presentation
of data  and  its  analysis  and does not involve matters  of  policy
or   regulations,  your   concurrence  is  requested   to  waive
administrative  review  according  to  the  policy  outlined in  your
directive of April 22, 1982.
   Concurrence:
                                    Date
                                           ECTD
Nonconcurrence:
                                    Date:
               Charles L. Gray, Jr., Dir., ECTD

cc:  E. Burger, ECTD

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                       Table of Contents


                                                          Page
                                                         Number

I.    Summary	   1

II.  Introduction  	   2

III. Description of Test Engine	3

IV.  Exhaust Analysis  	   3

V.    Recent Engine/Fuel System Modifications 	   4

VI.  Discussion of Test Results	   6

VII. Highlights From Current Testing 	   9
                                                x

VIII.Future Effort 	  10

IX.  Acknowledgments	11

X.    References	12
APPENDIX A - Test Engine Specifications -	A-i
             2H2/CO Fuel Operation

APPENDIX B - Previous Engine/Fuel System   	 B-l
             Modifications For 2H2/CO Fuel Operation

APPENDIX C - Air/Fuel Ratio Calculation   	 C-l
             For 2H2/CO Fuel Operation

APPENDIX D - Exhaust Mass Emission Calculation 	 D-l
             For 2H2/CO Fuel Operation

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I.    Summary

     A  16-valve,  4-cylinder  light-duty  automotive  engine  has
been converted to operation  on a mixture of hydrogen  (H2)  and
carbon  monoxide  (CO) gaseous  fuel  in a  2:1  molar ratio  of  H2
to CO.   This engine has been used to  investigate  the  difference
in  emission  levels   and   lean  limit  operation  between  two
different fuels:  M100  neat  methanol  and  simulated  dissociated
methanol gaseous fuel (2H2/CO).

     The  work  described  in   this  report  contains  results  of
recent  emission testing  begun  in  July  1990  with  the  engine
equipped  with  stock  and  modified  intake  camshafts.   These
results  are  compared  to  results   obtained  during  previous
testing  with the  modified camshaft.   This  previous  work  was
completed in March 1989 and is described in EPA/AA/CTAB-89-02.
[1]   The  present  report  also  contains  a  summary  of  fuel
system/engine experiments  conducted  to more  accurately measure
gaseous  fuel  flow to  the test engine and increase  the  power
output of the engine.

     Table 1 is a summary of our test  results.  The  first entry
refers  to testing  conducted  in March  1989.  Previously,  the
test engine  was  operated  at  lean  conditions  with  the  2H2/CO
fuel.  Under  load, the maximum output torque achieved using the
gaseous  fuel was  26.6  ft-lbs  at 2,000 rpm  and an A/F  ratio of
11.9:1.   (The  stoichiometric  A/F  ratio  for  operation  on  the
gaseous  fuel is the same as it  is for M100 operation,  6.4:1.)

     Recent  testing  consisted of  the engine  operating  under
load at wide-open throttle  (WOT),  fueled  with gaseous 2H2/CO,
and  with a spark timing  of  0° before top dead  center (BTDC) .
Spark  timing was  limited to  near  BTDC  because  severe  engine
backfire  or  knock  resulted  when  spark  timing  was   advanced.
Separate  tests  were  performed  with  the engine  equipped with
both modified  and stock intake camshafts.   Fuel  flowrate here
was  calculated from  the  change in  weight  of the  gas  bottle
during  each  test,   the density  of  the  fuel,  and   the  time
duration  of  each  test.   A meter which measured the remainder of
the gas  bottle contents in standard cubic feet was also used.

     During  testing  with  the  modified  camshaft,  an  output
torque  of 60 ft-lbs at an A/F of 7.89:1,  under  2,000 rpm,  WOT
conditions was  measured.   This^ torque was more  than  twice  the
highest  value  measured during  the  previous  testing  performed
under both WOT/throttled and lean operating conditions.

     Output  torque  increased   during  engine  warmup.   When  the
engine  was  cold  started,  the output   torque  was  usually 15
ft-lbs  below the maximum  value  recorded  later.   The  torque
reached  its  maximum value after  approximately 5 minutes  into
each  test.   It  remained  constant   at   that  value  for  the
remainder of the test until the engine was  shut off.

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                               -2-
                            Table  l

                     Summary of Test  Results
               Nissan CA18DE Engine,  2H2/CO  Fuel
Test
Number
1
2
3
4
5
6
7
8
Date
03/01/89
10/30/90
12/04/90
01/28/91
01/30/91
02/20/91
02/21/91
02/25/91
Camshaft
Modified
Modified
Modified
Stock
Stock
Stock
Stock
Stock
RPM
2,
2,
2,
2,
2,
1,
1,
2,
000
000
000
000
000
750
750
000
Torque
ft-lbs BHP
27
55
60
65
65
67
66
70
10
20
22
24
24
22
21
26
.30
.94
.85
.75
.75
.32
.99
.28
Air/Fuel
11.90
8.33
7.89
N/A
N/A
6.07
7.36
N/A
N/A  Not available.

Note:  All tests at WOT; torque values are maximum.

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                              -3-
     Approximately  13  percent  of the  fuel  was  unburned  and
passed  through the  exhaust with the  modified camshaft.   The
stock  intake  camshaft was  then  placed  in the  test engine  to
enhance mixing  of the air/fuel  charge  in the  chamber  prior  to
combustion.  The  result  was the  highest  torque  measured on  a
single test (70 ft-lbs)  under  the same 2,000  rpm,  WOT operating
conditions.   The  engine  ran  much  smoother  with  the  stock
camshaft  at  these  same  conditions,  with  no  fluctuation  in
torque  during  each  entire test.   Higher amounts  of  unburned
fuel  at  1,750  rpm  (41.7 percent  was  not burned)  under richer
conditions were noted.

     The 70 ft-lbs  torque  value obtained  here  is  approximately
38  percent below the maximum  value  (110  ft-lbs)   obtained  by
Nissan  with  an  MIOO-fueled,   12.0  compression  ratio  CA18DE
engine.  However, with recent  engine/fuel system modifications,
the power  output  has been  increased 160  percent when  compared
to results obtained from previous testing  with 2H2/CO fuel.[l]

     A  direct   comparison  of  emissions   test  results  from  the
engine  when it   is  alternately  fueled   with  M100  and  2H2/CO
fuels  is  not  possible at this  time.  The previous  testing with
the M100  fuel  utilized  a  catalytic converter  in  the  exhaust
stream  while  2H2/CO  fuel  results  are  engine-out  emissions.
Also,   the  limited  amount  of   gaseous  fuel   in the  T-cylinder
storage  bottles  did  not  permit  starting and  warming  to  true
steady-state conditions prior to emission  testing.

     Higher emissions  of CO and  NOx were measured  during this
testing.   High CO  emissions  may result from  the  substantial
amount  of  unburned  fuel passing  out  of the  exhaust.   H2  in
the exhaust was  also  measured  and was consistently twice the CO
levels,  this   proportion   being   the   same   as  that   of  the
components in the gaseous fuel.

     Future efforts  will utilize  a  recently  acquired mass flow
controller  to  accurately  control and measure  fuel  flow.   The
large   amounts   of   unburned   fuel  in   the   exhaust  will  be
investigated.   An in-cylinder pressure sensor will  also be used
to investigate the combustion event.

II.  Introduction

     Methanol  may  be catalytically decomposed to  H2  and  CO
gases according to the reaction:

     CH3OH(1) 	  2H2(g) + C0(g)

     The decomposition of methanol to  this gaseous  fuel mixture
has  been  postulated  as  a  more   efficient  method  of  using
methanol  as  a   light-duty  motor  vehicle   fuel.    The  major
attraction  of  methanol   decomposition is that the  resulting
gases  have  a  higher heating value per pound than  the  original
liquid   methanol.    A  discussion   of   the   application   of
dissociated  methanol  as   a  light-duty   automotive  fuel  was
presented  in previous papers.[1,2]

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                              -4-
     In order  to  evaluate this concept,  EPA modified a  Nissan
CA18DE  multi-valve  engine to  better  utilize  the  combustion
characteristics of  dissociated  methanol fuel.   This engine,  a
stock model  modified by Nissan Motor  Corporation for use  with
liquid  methanol,   was   loaned  to  EPA  by  Nissan  for   use  in
alternative  fuels   research.   This report  summarizes the  most
recent  EPA  efforts  to  investigate dissociated  methanol as  an
automotive fuel with this engine.

Ill.  Description of Test Engine

     The base  engine used for this project was  a Nissan CA18DE
engine.  The stock  engine  is  an in-line,  4-cylinder,  1.8-liter
capacity powerplant.   The valve  arrangement  is  a  4-valve  per
cylinder  configuration,  consisting  of   two   intake  and   two
exhaust valves per  cylinder.   The valves  are operated  by two
overhead camshafts, one each for the intake and exhaust  sides.

     The test  engine was modified  by  Nissan to  better  utilize
the  qualities  of  M100  neat  methanol  over unleaded gasoline.
These  modifications were  discussed  in detail   in  an  earlier
paper. [1]    A  summary  of  them is  included in  this report  in
Appendix A.

     EPA also  modified  the engine  to use  simulated dissociated
methanol  fuel   (66  volume percent  H2  and 33   volume  percent
CO).    The  most  significant  modification  made  here  was   the
replacement  of the  intake  camshaft with  a  specialty camshaft.
The  specialty  cam  admits air  only through one intake valve and
gaseous  fuel   only  through  the  second  valve.    These   EPA
modifications  were  also discussed  in  a previous  report  [1]  and
are detailed here in Appendix B.

     EPA installed,  at Nissan's request,  a  thicker head gasket
for  the testing mentioned  in this report.   This  thicker  head
gasket  raised  the  clearance  between   the  valve  face   and  the
piston  crown;   this  modification  was made   to  improve   the
durability  of  the   engine.  The effect  of  this modification was
to lower the compression ratio from 11.0 to 10.5.   The current
testing   referred   to   in  this   report   made   use  of  this
modification.

IV.  Exhaust Analysis

     Engine  exhaust passes from  the  exhaust  pipe  to   a 2-1/2
inch  diameter  flexible  metal  tube.   This  tube  passes  the
exhaust  overhead  to a  6-inch  rigid  tube  hung  from  ceiling
supports.   The rigid tube delivers the exhaust to a Philco Ford
350  cfm constant  volume sampler  (CVS).   Total  length  of  the
flexible and rigid  tube  sections is 40  feet.

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                              -5-
     A  gaseous  sample  line  and  electronic  ties  have  been
extended through  the cell  ceiling and  connect the  mechanical
CVS with an electronic display  panel  in the cell control  room.
A  fitting  in the  sample  line at  the  control room enables  bag
sampling  at   this  point.    Analysis   of  bag   samples   is
accomplished  at  a  bank  of  analyzers   located  in  another  test
cell.  Emissions measured as  hydrocarbons  (HC)  are measured on
Beckman model  400 flame ionization detector (FID).  NOx level
determination   is   conducted   on   a   Beckman   model   951
chemiluminescent NO/NOx  analyzer.   CO  is measured by  infrared
technique  using  a  Horiba   model  A1A23   infrared   analyzer.
Hydrogen gas  in  the  exhaust was measured using  a  Gow-Mac model
550  gas  chromatograph calibrated  with  a  40  percent  hydrogen
span gas.

V.   Recent Engine/Fuel System Modifications

     A significant period  of time,  in  excess of  one year,  had
elapsed from  the  date of the last report  [1]  to  the  start of
the testing commented on here.   It was necessary,  therefore, to
first  perform leak  checks   on  the  entire  fuel  system  and  a
leakdown  check  on  the  engine cylinders  to  determine  their
integrity.   No  leaks were  detected when  the  fuel  system  was
pressurized,  and  the greatest  loss of  pressure in  a  cylinder
was  only  2 percent,  indicating that  the  compression  had  not
significantly deteriorated.

     Next,   the fuel  valve  lifters  were removed  and  the  fuel
system was  pressurized  to 60 psi  using bottled  nitrogen.   The
engine was  then motored  by  the  dynamometer.  No  flow  in  the
flowmeter  was  observed,  indicating  no  leakage  in  the  fuel
delivery system.

     When the modified intake camshaft  was  installed, gaps were
noted  in the  gasket  that  mates  the swirl control  valve housing
to  the engine head.   These  gaps  made possible  the transfer of
fuel and air between the separated fuel and  air  intakes in each
runner.   These  gaps  were   plugged to   limit  inaccuracies  in
air/fuel flowrate measurement.

     Air flowrates through  the  engine  at WOT conditions  over  a
range  of  engine  speeds  were  determined  and  are  plotted in
Figure  1.   Air  flowrates  over the  same  conditions  with  the
engine as  modified by Nissan for  M85  liquid fuel  use  are also
plotted  for   comparison.     (The   air   intake   passages  were
significantly modified when  the special intake  cam was added to
restrict  air  flow  to  one  of   the   intake  valves  in  each
cylinder.)    The   objective  of   these  measurements   was  to
determine the effect of the restriction on air flow.

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                              -6-


                            Figure 1
                          Air Flow Rate
    4000
         Air Flow (liter/min.)
                                       CA18DE (M85) WOT
    3000 -
    2000
    1000 -
CA18DE (H2/CO) WOT
TWO RUNS
         0      800    1600   2400   3200   4000   4800   5600
                         Engine Speed (rpm)
     The two  sets  of data follow a  roughly similar trace until
approximately 3,000  rpm,  where restriction  of air  flow  to only
one  runner  may  have  significantly  affected  the  volumetric
efficiency.  However, for the  engine speed  range  800-2,500 rpm
the  air  flowrates  are  similar.    In  this  range,  volumetric
efficiency values are approximately 80 percent.

     The  Dwyer  10  cfm  rotameter  used  during  the  previous
testing may have provided inaccurate fuel flowrate measurements
as it  was  not calibrated  for  the gaseous  fuel.   With  varying
engine   speeds   at  constant   air  flowrates,   the  rotameter
indicated  only  slight  differences  in  fuel  flowrates.   During
one  test,   an audible  leak of  the  gaseous  fuel  through  the
rotameter control valve  was  detected.   A less-audible  leak may
not have been detected  as  the result of background noise from
the ventilation system in the test cell.

     Other  fuel   flowrate   measurement  devices   were   tried,
however, none of these methods provided consistently accurate
measurements.    To   date,   three  different   fuel  measurement
devices have  been used  when operating the engine on the gaseous
fuel (rotameter, electronic/calibrated orifice  metering  system,
and  a  dry  gas  meter).   Each  should   have been capable  of
measuring fuel flow into the engine.  However,  in  each case the
methods  provided  conflicting  flowrate  information  when  the
engine was operated under steady-state conditions.

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                              -7-
     One  indirect  check of  fuel consumption  for this  gaseous
fuel  system  is to  use the  change in  mass of  the  cylindrical
fuel  tank  as  a measure  of  fuel  flowrate.   The  fuel tank  was
weighed immediately  prior  to and following an  engine test;  the
change  in  fuel  tank mass  indicates  fuel consumed.   The  engine
was  brought  to  test  conditions  immediately  after   start,  and
these conditions remain unchanged during testing.  This  is  not
quite steady-state testing due  to  the warmup of the  engine that
occurs  after  start.   The  time  duration  of   the   test  was
recorded,   and  the  mass  of fuel  consumed  was  converted  to
standard cubic feet  of gas.   This method,  used  in the  testing
discussed  below,  provide  accurate,  consistent  measurements  of
gaseous fuel flowrate.

     A  scaled  pressure gauge which  correlates  bottle pressure
with  standard  cubic feet  of gas  present  in  the cylinder  was
also used as a check on the weighing method referred  to above.

     Finally,  it  was  necessary to vent the  crankcase   to  the
test  cell ventilation system.   This  action was taken  as  the
result  of a  severe   oil  leak  at  the  oil  filter   caused  by
overpressure  in  the crankcase.   This  situation  was   alleviated
by this rerouting of the PCV system.

VI.  Discussion of Test Results

     All  of  the  testing  described   here was  performed  using
2H2/CO  bottled  gas,   simulating  dissociated  methanol  fuel.
Table  2 is  a  summary  of  the  emission results.  Test  numbers
here  correspond  to the same test  numbers  in  Table  1.  In test
numbers 5  and 7,  two  bag samples  were  taken  during one test
run, hence the a and b distinctions.

     The  first entry  in  Table 2 refers to  testing conducted
during  March   1989.    Air/fuel  ratios  at   that   time  were
calculated  to be  11.9:1,  very lean  of  stoichiometric.   This
value may be high; subsequent experiments at  similar   conditions
have  suggested  that  the rotameter supplied fuel flowrates were
too  low.   Only  27 ft-lbs  of brake  torque were  generated under
these conditions.

     The  remainder  of  the  tests  described  in  Table   2 were
conducted  as part  of the recently completed testing.   The head
gasket, which  reduced the compression  ratio to 10.5, from 11,0
previously, was in place for this testing.   The rotameter which
previously  measured fuel  flowrate was  also  removed from  the
fuel  circuit;  any backpressure therefore  caused by  the meter
was  removed.   Test  numbers  2   and  3  were conducted with  the
modified  intake camshaft in  place, as in test  number   l.   At WOT
conditions,  torque increased to 55 ft-lbs,  a  considerable gain
over  the  value  noted previously.   Fuel  flowrate was   calculated
by running at a single set  of  conditions and  noting   the  change
in the  mass  of  the   fuel  bottle  and the  duration  of  the
experiment.    H2    and   CO   emission   concentrations   were
measured.   Because  intake  and  dilution air  was  also metered,
the  rate  of  unburned  fuel  could  be  calculated.  The  rate of
unburned  fuel was calculated to be approximately  13 percent.

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                              -8-
                            Table 2

                     Emission Test Results
               Nissan CA18DE Engine,  2H2/CO Fuel
Test
Number
1
2
3
4
5a
5b
6
7a
7b
8
Torque
(ft-lbs)
27
55
60
65
65
65
67
66
66
70
UBF
(%)
N/A
13.4
13.8
N/A
N/A
N/A
24.8
41.7
41.7
N/A
Brake
A/F
11.90
8.33
7.89
N/A
N/A
N/A
6.07
7.36
7.36
N/A

0
0
0
0
0
0
0
0
0
0
HC
.130
.011
.008
.004
.007
.006
.004
.006
.005
.015
Specific Emissions
(q/BHP-hr)
CO
2.
29
33
79
57
78
76
125
119
11

27
.23
.62
.66
.25
.09
.37
.40
.20
1.90
C02
426
349
349
455
376
355
261
256
239
452
NOx
8.
0.
6.
10.
9.
6.
4 .
2.
2.
7.
57
79
69
87
33
96
09
35
24
64
N/A  Not available.

a,b  Two bag samples for one test run.

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                              _g	
     Several  other  experiments  were  conducted  in  order  to
accurately  determine  the  fuel  flowrate.   Only   H2   and  CO
emissions were  measured  during these  experiments;  the  values
measured during that  work were  similar  to those  given to  the
second and third tests in Table 2.

     Spark  ignition  was  timed  at  0  degrees  before  top  dead
center  (BTDC).   Advancing the spark  even slightly caused  an
audible  knocking  condition.   At  2,000  rpm,  part  throttle  also
caused  an  audible knock.   It  was  not  possible  to vary  fuel
flowrate with a  high degree  of accuracy using  the current  fuel
system.

     The modified  intake cam was then  replaced with  the  stock
camshaft  and hydraulic  lifter  system.   This  camshaft  would
enable  fuel  and  air  to  mix  in the  cylinder  earlier,  as  the
stock  camshaft permits  the introduction of fuel  earlier  in the
combustion  cycle.   The  stock  control  slide  housing,  however,
did  not replace  the housing  modified to  separate the  valves
into  fuel  and air  admission  passages.   Fuel  continued to  be
admitted  through  a  single valve  while air  only was  admitted
through the other valve.

     Tests 4 through 5b in Table 2 were conducted  at 2,000  rpm,
WOT  conditions  with the  stock intake camshaft.   The  admission
of  fuel was  accomplished in  the same  manner  as  in  previous
experiments, and was not closely controlled.

     The  higher   cam profile   and  extended  valve  open  period
caused  a richer  mixture,  richer than  stoichiometric.   Torque
increased  to  65-70  ft-lbs   at  the  richer   condition.   This
maximum  value  was   still   below  the   value  of   110  ft-lbs
experienced  by   Nissan   with  an  MIOO-fueled,   12.0  compression
ratio  CA18DE  engine.  No backfire was experienced at  WOT.   The
amount  of  fuel  unburned was  unknown because  of  a  calibration
problem with the engine air sensor.

     NOx emission  levels  were  similar in magnitude  between the
testing  conducted  with  the   modified  camshaft  and  the  stock
camshaft.   CO emissions,  a  component  of  unburned  fuel,  more
than   doubled  to  approximately  75   g/BHP-hr,  with the  stock
camshaft.

     Engine  speed  was  then   reduced  to  1,750   rpm  at   WOT
conditions.    Brake  torque  was  measured  at   approximately  67
ft-lbs,  similar to  the  values  recorded at 2,000  rpm.   Air/fuel
ratio  went  slightly  lean during this testing  to approximately
7.3:1.   Fuel efficiency decreased  significantly,  however,  as
unburned  fuel  rose   sharply   to  a  calculated  value  of  40
percent.  CO  levels,  representing unburned  fuel, rose sharply
as  engine  speed  was  reduced.  H2 was  measured  at  roughly
twice  the volumetric concentration of CO during this testing.

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                             -10-
     A pressure  sensor  was  installed in the spark plug  well  of
the number 1 cylinder  in  the test engine.   An attempt was  made
to monitor  cylinder pressure  during the  combustion event  and
use this  in  an attempt to  relate the  pressure  pattern  to  the
onset  of  lean  misfire.  It  was hoped that the  shape  of  the
pressure  versus  crank  angle  curve  would  provide  information
concerning   abnormal   combustion  occurrences.   The  pressure
sensor  ultimately  failed,   however,   due  to  pressure   wave
resonation in the cavity which housed the sensor.

     It  is  not  yet  possible  to  determine  to   what   extent
air/fuel mixing  within the  cylinder  is a  problem  and  whether
the lower torque values are associated with mixing.   At  WOT,  in
all cases,  when fuel  flowrate  was  reduced,  output torque  at
constant engine speed  was  also reduced.  For air/fuel ratios in
excess  of  6.4:1,   enough  air  should  have  been  present  to
complete the combustion of the fuel present.

VII.  Highlights From Current Testing

     1.    Restricting  the  air  flow  to  the engine  to one of the
two intake  valves  per  cylinder  did  not appreciably affect the
maximum  air   flowrate  possible  in  the   engine   speed  range
800-2,500 rpm at WOT conditions.

     2.    The  rotameter   used  to  measure fuel  flowrate  was
eliminated from  the fuel system, and the  compression ratio was
reduced to  10.5  through the installation of a new  head  gasket.
At  2,000  rpm  engine  speed,  WOT  conditions  brake  torque  was
measured  at  55-60  ft-lbs.    This  was  a considerable  increase
above the levels measured previously at these conditions.

     3.    The testing mentioned in 2.  above,  was  conducted at
an   air/fuel   ratio   of    approximately    8.0:1    (lean   of
stoichiometric).   Thirteen  percent  of  the  gaseous  2H2/CO fuel
was  passed  through  the exhaust  as  unburned  fuel   during  this
testing.    CO   emissions,   an  indicator   of   unburned  fuel,
increased  sharply  during  this  testing,   to  approximately  30
g/BHP-hr.

     4.    Testing  was  also  conducted with  the  stock  intake
camshaft in place of the specialty camshaft.   At 2,000  rpm, WOT
conditions,  brake  torque increased  slightly to  65  ft-lbs.  The
amount  of CO  in the  exhaust  more  than  doubled,   from  levels
measured with the specialty  camshaft.

     When  the  engine   speed  was reduced  and held  constant  at
1,750 rpm the percentage of  unburned fuel  rose sharply to about
40 percent.   Brake torque  rose  only slightly  to 67 ft-lbs.  CO
(unburned fuel) increased to  levels exceeding 100 g/BHP-hr.

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                             -11-
VI11.Future Efforts

     This  engine  conversion  project  was  begun  to  develop  a
suitable   test   bed   for   a   practical,   onboard   methanol
dissociation   system.    Further   development  of   this   engine
concept will be structured to accommodate  this  goal.   Immediate
plans concern development of two measures of engine performance:

     1.    Emissions/fuel economy; and

     2.    Engine performance at lean operating conditions.

     Further  emissions  testing   at  various  engine  speed/load
operating  conditions   will  be  conducted  to  characterize  the
emissions profile  of this engine  when operated on both M100 and
dissociated methanol.  A/F  ratio at  these various test  points
will also  be  determined.  A/F ratios will  now  be controlled by
varying  fuel  flowrate  to the  engine with the  use of a  Tylan
General  Corporation mass flow controller.   This equipment  will
enable accurate metering and control of the gaseous fuel.

     Previous  testing  with  M100  liquid  methanol  was  conducted
with a catalytic  converter  in  the exhaust stream.  Testing will
be conducted  with the catalytic  converter removed in  order to
provide engine-out emissions data with M100 fuel.

     Spark  timing was limited  to  near  TDC  in these  tests by
knock.    Spark  timing  will continue  to  be  adjusted ""as  air/fuel
conditions  are  changed with  the  new fuel controller in order to
better utilize this operating parameter.

     One  way  to  determine  the proximity  to  the  lean  misfire
limit  at  various engine operating conditions  is to  obtain  a
quantifiable  measure  of increasing engine  roughness  as  the
air/fuel mixture  is  leaned  out.   A measure of proximity to  lean
misfire  limit  may be  obtained  directly,  through measurement of
changes  in cylinder  pressure during the combustion effort.  An
indirect   method  might  involve   the    measurement   of   the
variability  in  successive  crank  rotation  times as  leanness
increases.   The  test  engine  is not  equipped   with  a  knock
sensor;   it   should   therefore   be  possible   to   obtain   a
quantifiable measure of  engine  performance as  the lean misfire
limit  is approached  when the engine  is  fueled  with the gaseous
2H2/CO blend.

     EPA  has  obtained  a  cylinder  pressure  transducer   less
susceptible  to  the  resonation  problem  experienced  with  the
earlier  generation  sensor   used   in the  present  work.     This
sensor  will be  used   in an effort  to  optimize  the  combustion
event.

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                             -12-
IX.  Acknowledgments

     The  CA18DE  test  engine  described  in  this  report  was
modified for use with M100  neat methanol  and loaned to  EPA by
the  Nissan  Motor  Corporation  as  support   for   an  effort  to
investigate  the  potential  of  neat  methanol  as  an  alternative
motor  vehicle  fuel.    The  authors  appreciate  the  efforts  of
Jennifer  A.  Criss  and  Leslie  A.   Cribbins  of   CTAB/ECTD  for
typing, formatting, and editing this report.

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                             -13-
X.References

     1.    "Conversion  of  Methanol-Fueled  16-Valve,  4-Cylinder
Engine  to  Operation  on Gaseous  2H2/CO  Fuel  -  Interim  Report
II," Piotrowski,  Gregory  K.,  James Martin,  EPA/AA/CTAB-89-02,
March 1989.

     2.    "Resistively  Heated  Methanol  Dissociator  for  Engine
Cold Start  Assist -  Interim Report,"  Piotrowski, Gregory  K. ,
EPA/AA/CTAB/88-02, March 1988.

     3.    "Internal  Combustion  Engines  and  Air  Pollution,"
Obert,  E. F., Harper and Row, New York, NY, 1973.

     4.    "Standards for  Emissions From  Methanol-Fueled Motor
Vehicles  and  Motor  Vehicle  Engines:   Final  Rule,"  Federal
Register, U.S. Environmental Protection Agency, April 11,  1989.

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                             A-l
                           APPENDIX A

        TEST ENGINE SPECIFICATIONS, M100 FUEL OPERATION
              CONDITION AS LOANED BY NISSAN TO EPA
Manufacturer

Basic engine designator

Displacement

Cylinder arrangement

Valvetrain

Combustion chamber

Bore x Stroke

Compression ratio

Compression pressure


Fuel control system


EGR

Valve clearance

Idle speed

Engine oil



Fuel

Air/fuel control



Spark advance control
Nissan Motor Co., LTD.

CA18DE

1809 cc

4-cylinder, in-line

Dual-overhead camshaft

Pentroof design

83 mm x 83.6 mm

11.0, 10.5*

16.5 kg/square cm (350 rpm,
80 degrees Celsius)

Electronically controlled fuel
injection

EGR not used

0 mm (automatically adjusting)

750 rpm

Special formulation supplied by
Nissan for methanol engine
operation

Ml00 neat methanol

Excess air ratio may be varied
from 0.5 to 2.0 by means of an
external control

Ignition timing can be varied
from  0   degrees   BTDC   to   54
degrees  BTDC  by  means  of  an
external control
     Reduced to 10.5 for testing referred to in this paper.

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                              B-l
                          APPENDIX B

           PREVIOUS ENGINE/FUEL SYSTEM MODIFICATIONS
                   FOR 2H2/CO FUEL OPERATION


     The  simulated  dissociated  methanol  product  gas  used  in
this work  is  a mixture of  H2  and CO  gases  in the molar  ratio
2H2/CO.   EPA  did  not  possess  a  methanol dissociation  system
capable of generating  the necessary  quantities of  gaseous  fuel
at  the time work  on this  project was  started;  the engine  was
therefore tested on a bottled gas  mixture of  2H2/CO.

     The Nissan  CA18DE engine utilizes  a  4-valve  per  cylinder
valvetrain  configuration;   both   the  stock  gasoline  and  M100
methanol modified  versions  utilize two  intake  and two  exhaust
valves  per  cylinder.  This  arrangement was  modified  to  allow
for admission  of  air to the  cylinder  through one  intake  valve
only;   the  second intake valve supplied  the  gaseous fuel.   The
exhaust-side valve scheme was not  modified  (Figure 1).


                           Figure 1

                         Valve Scheme
                     2H2/CO Fuel Conversion
                     Nissan CA18DE Engine
                              AIR    EXH. \
                             FUEL.  , EXH. i
                           VALVE SCHEME

                      2H2/CO FUEL CONVERSION

                       NISSAN CA18DE ENGINE

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                             B-2
                      APPENDIX B (CONT'D)

           PREVIOUS ENGINE/FUEL SYSTEM MODIFICATIONS
                   FOR 2H2/CO FUEL OPERATION


     The  advantages  of structuring  the  intake process this way
are  threefold.   First,  air  flow  into  the  engine may  be less
restricted  if  the  fuel,  already  in  the   gaseous   state,  is
introduced into only  one of  the intake  runners.   Second,  there
may  be  less  chance  of  flashback  and  a   resulting manifold
ignition  if  fuel  exclusively,  and  not  a combustible fuel/air
mixture,  is  introduced at an  intake valve.    Finally,  fuel may
enter  the  combustion  chamber  at   the  designer's  discretion,
rather  than  at the same  time  the  air needed for combustion is
admitted.

     It was necessary  to alter the  fuel and  air  intake system
in  order  to   allow  for  the  admission  of   gaseous   fuel  only
through  one  of   the   intake  valves.   An  intake  air  control
assembly  encloses the  swirl  control  valves  and is situated
between the intake manifold  and  the combustion chambers  on the
liquid-fueled  engine.   This assembly  controls the air  flow so
that it is through one intake runner  and/or  through both intake
runners  as  necessary.    This  is to  control   in-cylinder  charge
motion  on the liquid-fueled  engine.  The control valve  slide
and  actuator  were  disassembled and the  swirl  control  valves
removed.  The runners through the valve  assembly  that contained
wells   for   fuel   injectors  were   welded  shut   approximately
1/2-inch upstream from the well holes.   These seals prevent the
admission of  air to  the ports through  which the  gaseous  fuel
passes.

     The hole in the assembly left  by the  power valve slide was
sealed  to prevent leakage of fuel  and air  between runners.   A
metal impregnation technique was  used to  seal the holes.   The
sealed holes were then coated with  a layer of epoxy.

     Fuel  injectors  are  not used  to  feed   the  gaseous  state
fuel.   The  rail  and the  individual  injectors were removed  and
3/8-inch  inside   diameter stainless  steel  pipe  fittings  were
used  in  their  place.   The  stainless   steel   fittings   were
threaded  and  the insides of the  aluminum injector  wells  were
then threaded to  accept the fittings.

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                            B-3
                      APPENDIX B  (CONT'D)

           PREVIOUS ENGINE/FUEL SYSTEM MODIFICATIONS
                   FOR 2H2/CO FUEL OPERATION


     The  2H2/CO  fuel is  a  gaseous blend  with a composition of
67  and 33  volume percent  H2  and  CO respectively.   This fuel
is  stored in compressed  gas cylinders  (T-sized)  at 2,000 psig.
A  fuel  supply  cylinder  is  located  outside  the  test  cell,
approximately  5  feet  from  the  cell  wall  during  testing.  The
bottle, fitted  with a regulator  and  pressure  gauge,  is  opened
by  a  hand  valve  prior   to  testing.    The fuel  line  from  the
bottle  is  1/4-inch  stainless  steel  tubing,   approximately  22
feet in length from bottle to cell wall.

     The  stainless  steel fuel  line  enters the cell  through a
hole drilled  through the concrete  wall.   A  Gould  electrically
controlled  solenoid  valve  is  located  in  the  line immediately
after  the wall.   An  electrical  signal  from  the   control room
controls the opening of the valve.

     The  fuel  line  from  the cell wall to  a fuel  flow regulator
measures  approximately 54-1/2  feet.  This  regulator  is  a Twin
Bay  Model   TB-100.    Gas   flow  through  this   regulator   is
controlled  by  a  flexible diaphragm.   The diaphragm  is  opened
proportionally  to  the  pressure  exerted  by  a stream  of  air
provided by a  tank  of compressed  air;  the pressure  exerted  by
this airstream  is controlled  by a  valve  located  in  the cell
control room.

     The  final  stage  of   the  fuel  system  supplies the  gaseous
fuel to  the combustion  chamber  ports.   The  fuel  passes to  a
cylindrical plenum,  this plenum  serving  as  a header  to  four
flexible  fuel  lines.   Inserted in  each  of the four  fuel lines
approximately  17  inches  from  each cylinder  is  a 2-stage  H2
flame  arrester.    The fuel  lines  are  connected  to  threaded
fittings which are screwed into the fuel injection  ports  in  the
valve  control  assembly.    The  2H2/CO  fuel is  supplied  to  the
combustion chambers by the opening of  the fuel valves.

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                               C-l
                           APPENDIX C
                   AIR/FUEL RATIO CALCULATION
                        WITH 2H2/CO FUEL
Given:
Air  flowrate,  29  standard  cubic  feet/minute  (scfm)
Change  in weight  of gas bottle,  4.5  Ibs
Density of fuel,  0.02969 Ibs/cubic feet
Time of test,  10.0 minutes  (min)
 Fuel flowrate =  (4.5  lbs)/(0.02969  Ibs/cubic  feet)(10.0 min)
 Fuel flowrate =  15.16 scfm
Air/fuel ratio is defined  [3] as:
     Mass flowrate of  air, dimensionless                      (1)
     Mass flowrate of  fuel
     Molecular weight  of air, 28.89, approximately
Calculate molecular weight of fuel,  2H2/CO:
     2/3 (molecular weight of H2, 2)  =  1.333
     1/3 (molecular weight of CO, 28) =  9.333
     Molecular weight of fuel, approx.  10.666
At standard conditions for gases:
    PV  =   nRT                                               (2)
Where:
     P  =   pressure (atmosphere)
     V  =   volume (cubic feet)
     n  =   pound moles
     R  =   gas constant (0.7302 atm-cubic feet/lb mol-degrees R)
     T  =   Temperature (degrees R)
At standard conditions:
     T  =   492 degrees R
     P  =   1 atmosphere

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                             C-2
                      APPENDIX C  (CONT'D)
                   AIR/FUEL RATIO CALCULATION
                        WITH 2H2/CO FUEL
Mass flowrate may then be defined as:
     (PVt/RT)(molecular weight) = nt(molecular weight)        (3)
Where:
     vt =  cubic feet/minute
     nt =  Ib moles/minute
Calculate A/F ratio:
Mass flowrate of air from (3)
     (1 atm)(29 scfm)(28.89 Ib/lb mol)/(0.7302)(492 degrees R)
     = 2.332 Ib/minute of air
Mass flowrate of fuel using (3)
     (1 atm)(15.16  scfm)(10.67 Ib/lb  mol)/(0.7302)(492 degrees
     R)
     = 0.4501 Ib/minute of fuel
From (1):
     A/F = (2.332 Ib/minute air)/(0.4501 Ib/minute fuel)
     A/F =5.18

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                           APPENDIX D

               EXHAUST MASS EMISSION CALCULATION
                        WITH 2H2/CO FUEL


     The   procedure   for   calculating   mass   emissions   for
methanol-fueled  light-duty engines  is  defined in  the  Federal
Register,[4] and that same method was utilized in this report.

     From exhaust  gas  bag analysis, you  are  given the following
dilute  concentrations:   HCe,  COe,  C02e,  and NOxe.   It   is  now
necessary   to   correct   for   background   concentrations.    All
concentrations are in parts  per million (ppm)  except  for  C02
concentrations which are  in  a percentage   (percent).   This is
done with the use of the following formula,

     Yconc = Yex - Yb(l - 1/DF)                               (4)

Where:

     Yconc =     emission concentrations corrected for background

     Yex   =     dilute concentrations measured in bag samples

     Yb    =     background concentrations

     DF    =     dilution factor.

The  values  used  for  the  background  concentrations   of   each
emission were:

     HCb   =     1.0 ppm

     COb   =     0.0 ppm

     C02b  =     0.04 percent

     NOxb  =     0.0 ppm

     The dilution  factor is calculated by:

      DF   =     100[x+y/2+3.76(x+y/4-z/2]/C02ex+(HCex+COex)0.0001
                                                              (5)

     This formula  is provided  for methanol-fueled vehicles where
fuel composition is CxHyOz.  Therefore, for our fuel  (2H2/CO),
x=l, y=4, z=l.

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                             D-2
                      APPENDIX D  (CONT'D)

               EXHAUST MASS EMISSION CALCULATION
                        WITH 2HZ/CO FUEL
     Once    each    emission   is   corrected   for   background
concentrations,  it  is  now possible to  calculate the  mass of
each  emission contained  in the bag  sample with  the following
formula:

     Ymass =     Vmix x Dy  x (Yconc/1,000,000)                (6)

Where:

     Ymass =     mass value of each emission, grams

      Vmix =     total dilute exhaust volume, cubic feet

        Dy =     density of each emission, grams/cubic feet

     Yconc =     corrected  concentration of each emission, ppm.

     The  densities  of  each  emission  are  also  listed   in  the
Federal Register.   When  finding the correct mass  of  NOx, there
is  an  additional  NOx factor  (Kh)  that must  also  be  applied to
equation 6.  This value was calculated as follows:

        Kh =     1/[1 - 0.0047(H - 75)]                       (7)

Where:

        Kh =     NOx factor

         H =     Absolute humidity, grams of  water per kilogram
                 of dry air.

The NOx factor used for all calculations was 0.9.

     Once the mass  of  each emission in the bag sample is known,
it is now possible to calculate  a  brake  specific  emission value
so  that  direct comparisons of  different  tests could be made.
First the brake horsepower needs to be calculated by:

     BhP   =     Tn/5252.1                                   (8)

Where:

     BhP   =     brake horsepower

     T     =     engine output torque, ft-lbs

     n     =     engine speed,  rpm.

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                             D-3
                      APPENDIX D (CONT'D)

               EXHAUST MASS EMISSION CALCULATION
                        WITH  2H2/CO FUEL
     By  knowing the  time  of  each  bag  sample,  brake  specific
emission values can be found by:

   BSY     =     Ymass/(BhP)(t)                              (9)

Where:

   BSY     =     brake specific emissions, grams/BhP-hour

  Ymass    =     mass value of each emission, grams

   BhP     =     brake horsepower

     t     =     time of emission bag sample, hours.

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