PB 270 709
EPA-AA-CORR 76-1
Toyota-EPA Emission Laboratory
Correlation Study
April 1976
Environmental Protection Agency
Office of Air and Waste Management
Office of Mobile Source Air Pollution Control
Emission Control Technology Division
Standards Development and Support Branch
Ann Arbor, Michigan
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Abstract
A laboratory correlation program between the Ann Arbor Toyota
Emission Laboratory and the EPA Motor Vehicle Emission Laboratory has
been completed. The results of hot start exhaust emission tests, highway
fuel economy tests, and a gas cross check analysis show acceptable
correlation between laboratories.
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Introduction
EPA received a written request dated February 2, 1976 from Toyota
Motor Sales, USA, Inc. to conduct a specific correlation program.
Toyota requested an individual correlation program with EPA prior to the
JAMA-EPA program due to CO and NOx instrument replacements, and CVS and
dynamometer repairs. EPA agreed to run the Toyota correlation program
and on February 12-17 a modified version of Toyota's requested program
was conducted at the EPA-MVEL.
1. Test Design
1.1 Test Sequence
The correlation program involved a series of hot start exhaust
emission tests (2 sample bags), EPA'Highway Fuel Economy Tests, and
gas cross checks of HC, CO, NOx, and C0? cylinders.
The test sequence at each test site consisted of the following
emission and fuel economy tests:
Toyota Corolla 3 Hot-start, 2 bag tests
2250# IW
2 Highway Fuel Economy Tests
Toyota Hi-Lux 3 Hot-start, 2 bag tests
@ 3000// IW
2 Highway Fuel Economy Tests
In addition, 1 HC, 6 CO, 1 NOx, and 2 C0» cylinders were
analyzed at each laboratory.
2. Test Vehicles
The test vehicles used for this program were a 1976 Toyota Corolla,
2250# IW, 1.6 litre, 4 speed manual transmission; and a 1976 Toyota Hi-
lux Pickup, 3000// IW, 2.2 litre, 4 speed manual transmission. Each
vehicle was tested using leaded Indolene fuel. The same test driver
drove all tests at Toyota and EPA.
2.1 Preconditioning:
Each test vehicle was used to stabilize the dynamometer and
set the indicated absorbed horsepower at 50 mph. This was equiva-
lent to 15 minutes of operation at 30 mph, 5 minutes at 50 mph, and
approximately 1 minute at idle. The previous emission or fuel
economy test was used for preconditioning for the sequential
emission or fuel economy tests.
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2.2 Facilities
2-2-1 Equipment: Emission and fuel economy tests were
performed using the dynamometer, sampling system, and analytical
equipment which is devoted exclusively, to all emission testing at
the Toyota Ann Arbor Laboratory.
Tests at the EPA-MVEL used dynamometer No. 1, CVS 21C, analysis
train #9; and dynamometer No. 2, CVS 23C, and analysis train #19.
A complete description of the Toyota and EPA equipment used
for the correlation program is presented in Table 1.
2.2-2 Calibration: Prior to the tests at Toyota and EPA,
dynamometers, CVS's, and analytical systems were determined to be
in good operating condition. Checks and calibrations were per-
formed in accordance with current Federal Register requirements.
3. Test Results
3.1 Emission and Fuel Economy Results
Test results are summarized in Table 2 for the Toyota Corolla,
and in Table 3 for the Toyota Hi-Lux. Values for YWT (hot transient)
and YW (hot stabilized) have units of grams per phase. Cpmposite
values are computed in grams/mile and fuel economy in miles/gal.
NOx results are reported as corrected values.
3.2 Gas Cross Checks
Ten gas cylinders of known concentration were analyzed at each
laboratory using the same analysis equipment that was used for the
emission and fuel economy tests. The results of the gas'cross
check are presented in Table 4.
The largest difference between measurements was 3.4% for a
single CO cylinder. All other comparisons checked within 3 percent
of all concentrations.
3.3 Discussion of Test Results
The mean values of the hot start emission results and fuel
consumption that were measured by Toyota and EPA are compared by
using the independent "t" statistic, and presented in Tables 5 and
6. An examination of the test results shows generally good cor-
relation between laboratories. At the 99% confidence level no
statistically significant differences were proven. At the 90 and
95 percent confidence levels differences were observed in measurements
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Table 1
TEST SITE INSTRUMENTATION
Analyzer
HC
. -LCO
HCO
co2
NOx
Analyzer Bench
CVS
Dynamometer
Driver's Aid
Computer
EPA #9 & 19 •
Beckman AGO
0-50, 100 ppmP
H2/N2 fuel
Bendix 8501
0-250, 500
MSA 202
0-1000
MSA 202
0-2.5%
TECO 10
0-100, 250
Homebuilt
Aeronutronic Ford CFV
Clayton CTE-50
Flywheel Driven
Inertia Simulation
Varian, 5" FS = 60 mph
4"/roin. Preprinted trace
IBM 370, Off-line
Toyota
Horiba FIA 21
0-100, 200 ppmC
H2/N2 fuel
Horiba AIA 21-AS
0-100, 300
Horiba AIA 21-AS
0-1000
Horiba AIA-21
0-2.0%
Horiba CLA-31
0-50, 200, 500
Horiba MEXA-1500
Horiba PDF
Clayton CTE-50
Flywheel Driven
Inertia Simulation
Varian, 5" FS = 60 mph
4"/min. Preprinted trace
Fuj itsu
Facom-230-45S
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Table 2
Toyota Corolla
Test Site Toyota
Date 2/11 2/11 2/11
Inertia Ibms. 2250
Bar. Pressure in Hg. 29.17 29.19 29.19
Dry Bulb/Wet Bulb 77.5/55.7 76.6/55.4 76.6/55.4
°F
Relative Humidity 22 22 22
%
NOx Corr. Factor 0.827 0.826 0.826
#1
2/12
29.02
74.5/56.0
30
0.852
EPA
#1
2/12
2250
28.85
75.0/55.5
28
0.844
#1
2/12
28.82
73.5/54.0
25
0.832
2 Bag LA-4
Hot Start
(gin/phase)
Ys(gm/phase)
HC
CO
NOx
co2
HC
CO
NOx
co2
HC
CO
NOx
CO^
2.68
27.76
7.72
1126.9
2.66
41.03
4.38
1381.9
0.71
9.17
1.61
334.5
3.27
24.96
8.17
1134.2
3.15
39.72
4.70
1445.8
0.86
8.63
1.72
344.0
3.36
26.05
8.03
1134.9
3.17
40.53
4.62
1437.0
0.87
8.88
1.69
342.8
2.97
28.20
8.74
1119.3
3.15
41.35
4.86
1441.2
0.82
9.27
1.81
341.4
2.81
'28.69
8.60
1120.7
2.86
42.47
4.74
1421.0
0.77
9.49
1.78
338.9
3.56
26.79
8.54
1130.9
3.08
40.96
4.82
1440.4
0.89
9.03
1.78
342.8
HFET (mpg)
37.0
37.3
35.3
36.8
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Table 3
Toyota Hi-Lux
Test Site
Date 2/11
Inertia Ibms.
Bar. Pressure in Hg. 29.21
Dry Bulb/Wet Bulb 77.2/54.0
°F
Relative Humidity 18
NOx Corr. Factor
0.813
Toyota
2/11
3000
29.22
77.5/54.0
18
0.812
2/11
29.22
77.9/54.0
17
0.811
#1
2/13
29.15
74.5/54.0
23
0.825 .
EPA
#1
2/13
3000
29.15
73.5/54.0
25
0.830
#3
2/17
28.99
77.5/61.5
40
0.923
2 Bag LA-4
Hot Start
HC
Y (gm/phase) CO
HT NOx
CO,,
HC
Y (gm/phase) CO
NOx
CO,,
HC
YCOMP(8m/mi) C0
W wX
CO,,
HFET (mpg)
1.94
*
10.09
1442.2
2.57
*
5.30
1847.2
0.60
*
2.05
438.6
2.51
25.73
10.26
1453.2
2.68
35.60
5.18
1845.9
0.69
8.18
2.06
439.9
2.61
23.58
10.15
1410.7
2.62
35.07
5.08
1821.1
0.70
7.82
2.03
430.9
2,17
28.79
10.08
1407.4
2.36
35.92
4.79
1811.2
0.60
8.63
1.98
429.2
2.56
25.85
10.15
1409.5
2.37
35.40
4.86
1813.2
0.66
8.17
2.00
429.7
2.14
31.74
9.04
1424.46
2.53
35.89
4.79
1888.1
0.62
9.02
1.84
441.7
29.1
29.4
* Toyota CO result deleted, possible incorrect span setting.
** Fuel Economy Tests on site #3.
29.9
30.1
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Table 4
GAS ANALYSIS
T—P
Cylinder Concentration (ppm) . —— x 100%
C3Hg 78.50 80.4 78.5 -2.3
CO 49.8 51.2 49.8 -2.7
+1.2
+0.2
+3.4
+0.5
-0.03
NOx 87.9 93.3 90.9 -2.6
C02 % 1.76 1.72 1.74 +1.2
Concentration (ppm)
Nominal
78.50
49.8
101.0
290.0
982.0
1550.0
2720.0
87.9
1.76
3.02
EPA
80.4
51.2
97.7
277.5
936.9
1542.4
2730.9
93.3
1.72
3.07
Toyota
78.5
49.8
98.9
278.0
969.0
1550.0
2730.0
90.9
1.74
3.02
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Table 5
Toyota Corolla
Toyota
EPA
(XT - XE:
1
2
3
X
a
c.v.
1
2
3
X
a
c.v.
»
v inny
HC
0.71
0.86
0.87
0.813
0.090
11.0
HC
0.82
0.77
0.89
0.827
0.060
7.3
-1.7
CO
9.17
8.63
8.88
8.893
0.270
3.0
CO
9.27
9.49
9.03
9.263
0.230
2.5
-4.0
NOx
1.61
1.72
1.69
1.673
0.057
3.4
NOx
1.81
1.78
1.78
1.790
0.017
1.0
-6.5
co2
334.5
344.0
342.8
340.4
5.2
1.5
co2
341.4
338.9
342.8
341.0
2.0
0.3
-0.3
FET
37.0
37.3
37.15
0.21
0.6
FET
35.3
36.8
36.05
1.06
2.9
+3.0
t-statistic ' -0021 -1.80 -3.40 -0.19
t-value
99% C.L. ND* "ND ND ND
4.60
95% C.L. ND ND D** ND
2.78
90% C.L. ND ND D ND
2.13
*No Difference exists
**Difference exists
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fable 6
Toyota Hi-Lux
Toyota
EPA
(5L - x
T E
x_
E
1
2
3
X
a
c.v.
1
2
3
X
a
c.v.
,)
• x 100%
t-statistic
t-value
99% C.L.
4.60
95% C.L.
2078
90% C.L.
2.13
HC
0.60
a. 69
0.70
0.663
0.055
8.3
HC
0.60
0.66
0.62
0.627
0.031
4.9
+5.7
+2.96*
ND
D
D
CO
8.18
7.82
8.00
0.255
3.2
CO
8.63
8.17
9.02
8.607
0.425
4.9
-7.1
-1.76
ND
5.84
ND
3.18
ND
2.35
NOx
2.05
2.06
2.03
2.047
0.015
3.1
NOx
1.98
2.00
1.84
1.940
0.087
4.5
+5.5
+2.09
ND
ND
ND
co2
438.6
439.9
430.9
436.47
4.86
lol
co2
429.2
429.7
441.7
433.53
7.08
1.6
+0.7
+0.59
ND
ND
ND
FET
29.1
29.4
29.25
0.21
0.7
FET
29.9
30.1
30,00
0.14
0.5
-2o5
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of oxides of nitrogen for tests with the Corolla and hydrocarbons
for tests with the Hi-Lux. The percent difference between Toyota
and EPA is -6.5% (Toyota measuring lower) for the NOx results from
the Corolla and +5.7% (Toyota measuring higher) for the hydrocarbon
results from the Hi-Lux. No other significant differences were
apparent for measurements of HC, CO, NOx, C0« or calculated fuel
economy.
Ambient conditions were not thought to affect the correlation
between laboratories. Changes in barometric pressure were slight
(a maximum difference of 0.37 in Hg) and relative humidity,
although low at both laboratories, remained between 17 and 30 per-
cent for all but one test. The dry bulb temperature remained
between 73 and 78°F for all tests.
Emissions and fuel economy test results at both laboratories
are very repeatable. Only the hydrocarbon test results from the
Hi-Lux have a coefficient of variation over 10%. The emission
differences between laboratories are less than 7% for all tests
except the Hi-Lux hydrocarbon results. The conditions where
statistically significant differences are observed are not thought
to be important. This is because the emission levels are low and
the absolute differences small; the differences were not repeatable
for both vehicles; and the sampling and analysis equipment were
checked and determined to be operating satisfactorily during all
tests.
4. Conclusions
1) tfC, CO, NOx, C02, and fuel economy results agree closely
between Toyota and EPA.
2) The statistically significant differences in emission
results are not thought to be important because of the low absolute
differences in emission results, the significant differences were
not observable on both test vehicles, and calibration and gas cross
checks results were satisfactory.
i
5. Recommendations
1) Improved humidity control at both test facilities is
needed. Absolute levels of humidity were very low resulting in NOx
correction factors near 0.8.
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