74-35 DWP
EVALUATION OF JAPAN AIRCRAFT MAINTAINANCE CO. LTD,
DIGITAL FUEL CONSUMPTION METER
May 1974
Test and Evaluation Branch
Emission Control Technology Division
Environmental Protection Agency
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Background
The Japan Aircraft Maintenance Co. Ltd. approached EPA
relative to the potential purchase of one of their digital
fuel consumption meters. EPA being involved in measuring
fuel economy in its laboratory obtained loan of one of
these instruments for evaluation. The Test and Evaluation
Branch of the Emission Control Technology Division conducted
an evaluation on one of these meters.
Device Description
The fuel meter tested was a Japan Aircraft Maintenance Co.
Ltd. (JAM) model CM-1. The device uses a positive displacement
transducing element, which is tied into a digital counter
and display. Included in the instrument plumbing is a hydro-
meter for measuring the fuel density, a thermometer for fuel
temperature and a pressure gauge to measure pressure into
the fuel meter.
Test Program
The fuel meter was used to test fuel consumption of several
vehicles. Various driving modes were used. They included
portions of the LA4 driving cycle, steady state, and the
highway driving cycle. The carbon balance technique and/or
a fuel weigh technique was used to compare the fuel meter
results.
Test Results
The attached Figure 1 gives the calibration obtained for the
fuel meter. A calibration was obtained by comparing a weigh
scale reading with the JAM fuel meter reading. The weighed
fuel was corrected to volume by measuring the fuel specific
gravity and correcting to volume. The calibration is very
linear as shown in Figure 1. The meter calibration was
measured at 0.9717 cc/meter unit.
The attached Tables I, II and III give the individual test
results. All data were corrected to a fuel density of 0.7389
kilogram/liter.
The mean ratio of JAM meter fuel consumption to carbon balance
fuel consumption was 1.030. This gives a mean JAM meter fuel
consumption that is 3% higher than the carbon balance value.
The higher consumption given by the JAM meter may reflect
evaporative fuel losses which the carbon balance technique
does not take into account. The data had a range varying
from plus 7% to minus 8% of this mean.
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-2-
The mean ratio of JAM meter fuel consumption to weigh
technique fuel consumption was 0.956. The data had a
range of plus 10% to minus 6% from this mean. The large
spread of data and the poor comparison of data seen with
the weigh data raises suspicion as to possible anomalies
in the weigh data.
Conclusions
The Japan Aircraft Maintenance Co. Ltd. model CM-1 fuel
consumption meter obtained a mean fuel consumption value
3% higher than when compared with the carbon balance
technique. The higher average may be associated with
evaporative fuel losses which are not measured in the
carbon balance technique. The difference in measurement
methods ranged from plus 7% to minus 8%.
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JAM meter
carb. bal.
weighed
Ratio:
JAM/carb. bal.
JAM/weighed
TABLE I
1963 Chevrolet Biscayne
1975 FTP
Steady State
Bags 1&2
1/100 km
14 . 81
14.48
16.37
1.023
0.905
Bag 3
1/100 km
13.56
12.83
15.11
1.057
0 . 897
Idle
1/hr
1.332
1.302
1.4.61
1.023
0.912
15 mph
1/100 km
12.48
12.40
12.78
1.006
0.977
30 mph
1/100 km
8.484
8.932
NA
0.950
NA
45 mph
1/100 km
10.080
9.603
9.530
1.050
1.058
60 mph
1/100 km
11.30
NA
11.42
NA
0.989
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TABLE II
1968 Chevrolet Impala
Hot '72 FTP Highway Cycle Highway Cycle
1/100 km 1/100 km 1/100 km
JAM meter 14.25 10.84 10.64
carb. bal. 13.92 10.50 10.64
Ratio:
JAM/carb. bal. 1.024 1.032 1.000
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TABLE III
1971 Chevrolet Vega
JAM meter
carb.
bal.
'75 FTP
1/100 km
11.02
11.09
•75 FTP
1/100 km
9.647
9.151
' 75 FTP
1/100 km
10.32
10,03
'75 FTP
1/100 km
8.779
8.490
Hwy.
1/100 km
6.652
6.426
Hwy.
1/100 km
6.377
6.305
Hwy.
1/100 km
6.651
6.339
Hwy.
1/100 km
6.408
5.969
Hwy.
1/100 km
6.766
6.157
Ratio:
JAM/carb.bal. 0.994 1.054 1-029 1.034 1.011 1.011 1.049 1.074 1.099
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