EPA-AA-TAEB 76-11
An Evaluation of the Electro-Dyn Super Choke
January 1976
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
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Background
The Environmental Protection Agency receives information about many
devices for which emission reduction or fuel economy improvement claims
are made. In some cases,-both claims are made for a single device. In
most cases, these devices are being recommended or promoted for retrofit
to existing vehicles although some represent advanced systems for
meeting future standards. .
The EPA is interested in evaluating the validity of the claims for
all such devices, because of the obvious benefits to the Nation of
identifying devices that live up to their claims. For that reason the
EPA invites proponents of such devices to provide to the EPA complete
technical data on the device's principle of operation, together with
test data on the device made by independent laboratories. In those
cases in which review by EPA technical staff suggests that the data
submitted hold promise of confirming the claims made for the device,
confirmatory tests of the device are scheduledtat the EPA Emissions
Laboratory at Ann Arbor, Michigan. The results of all such confirmatory
test projects are set forth in a series of Technology Assessment and
Evaluation Reports, of which this report is one.
The conclusions drawn from the EPA confirmatory tests are necessarily
of limited applicability. A complete evaluation of the effectivenss of
an emission control system in achieving its claimed performance improve-
ments on the many different types of vehicles that are in actual use
requires a much larger sample of test vehicles than is economically
feasible in the confirmatory test projects conducted by EPA. _!/ For
promising devices it is necessary that more extensive test programs be
carried out.
The conclusions from the EPA confirmatory tests can be considered
to be quantitatively valid only for the specific type of vehicles used
in the EPA confirmatory test program. Although it is reasonable to
extrapolate the results from the EPA confirmatory test to other types of
vehicles in a directional or qualitative manner, i.e., to suggest that
similar results are likely to be achieved on other types of vehicles,
tests of the device on such other vehicles would be required to reliably
quantify results on other types of vehicles.
In summary, a device that lives up to its claims in the EPA confir-
matory test must be further tested according to protocols described in
footnote JL/ to quantify its beneficial effects on a broad range of
vehicles. A device which when tested by EPA does not meet the claimed
results would not appear to be a worthwhile candidate for such further
testing from the standpoint of the likelihood of ultimately validating
the claims made. However, a definitive quantitative evaluation of its
effectiveness on a broad range of vehicle types would equally require
further tests in accordance with footnote I/.
I/ See Federal Register 38 FR 11334, 3/27/74, for a description of the
test protocols proposed for definitive evaluations of the effectiveness
of retrofit devices.
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The Electro-Dyn Choke Corporation of Niagara Falls, New York has
developed a thermostatically controlled, electric-assist choke which it
claims will reduce fuel consumption when compared to conventional chokes.
Two Electro-Dyn choke assemblies were made available to the EPA for
evaluation purposes.
Test Vehicle and Device Description
The vehicle used in the evaluation is part of the EPA fleet of test
vehicles. It is a 1971 Ford Galaxie powered by a 351 cu in./5753 cc V-8
engine. The transmission is a three speed automatic. A tabulation of
vehicle characteristics is given on the Test Vehicle Description sheet
at the end of this report.
The standard choke assembly on the 1971 Ford uses a bimetallic
spring to control the position of the choke blade. Hot air from the
exhaust manifold is transported through an insulated tube to the housing
containing the bimetallic spring. When the engine is cold, the choke
blade is fully closed. After the engine is started, hot air rising from
the exhaust manifold heats the bimetallic spring, causing the choke
blade to move gradually to the open position.
The Electro-Dyn Choke also uses a bimetallic spring to control the
opening of the choke blade. However, the spring is electrically heated,
and the insulated heat tube is not used. The voltage supplied to the
heating element is regulated by a temperature sensor that is mounted on
the engine block (see Figure 1). In the case of this installation, the
temperature sensor was mounted under the right front head bolt. This
sensor is designed to control the opening of the choke as a function of
engine temperature. In addition, the sensor is designed to prevent the
choke from closing during warm starts after engine cool down unless the
block has cooled sufficiently to require choke usage.
The installation instructions call for the initial adjustment to be
made with the choke cover and spring at about 70 F. The bimetallic
spring housing is rotated until the choke blade just closes. If stalling
is a problem in cold weather, then the bimetallic spring housing is
rotated 1/8 inch in the "rich" direction.
Test Program
All tests were conducted in accordance with the 1975 Federal Test
Procedure ('75 FTP). Evaporative losses were "hot measured.
Two baseline tests were run with the vehicle adjusted to the
manufacturer's specifications. After completion of baseline tests, the
Electro-Dyn choke was installed on the test vehicle. Two choke kits
were supplied to the EPA, and a series of three tests was run on the
test vehicle with each unit installed. After completing the testing of
the two choke installations, the original Ford choke was re-installed,
and two more baseline tests were run. u
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Test Result^
Exhaust emission data, summarized below, illustrate the effects of
the Electro-Dyn choke.
'75 FTP Composite Mass Emissions
grams per mile
(grams per kilometer)
Baseline - average
of 4 tests
Choke #1 - average
of 3 tests
% Change
Choke #2 - average
of 3 tests
% Change
HC
2.82
(1.75)
2.86
(1.78)
+1%
2.74
(1.70)
-3%
CO
20.2
(12.6)
20.0
(12.4)
-1%
16.4
(10.2)
-19%
NOx
3.58
(2.23)
3.72
(2.31)
+4%
4.01
(2.49)
+12%
Fuel Economy
(Fuel Consumption)
14.1 mpg
(16.7 A/100 km)
14.1 mpg
(16.7 a/100 km)
0
13.9 mpg
(16.9 fc/100 km)
-1%
(+1%)
-» The '75 FTP contains three regimes of engine operation. These are
the""cold transient, stabilized and hot transient conditions of operation.
The Electro-Dyn choke would be expected to have no effect on exhaust
emissions during the stabilized and hot transient portions of the test.
The cold transient (Bag 1) portion of the test should contain all the
effects of the Electro-Dyn choke, since the engine is started "cold" at
the beginning of the cold transient section and is fully warmed-up at
the end of the cold transient section.
The following table contains the exhaust emissions and fuel economy
measured during the cold transient periods.
'75 FTP Cold Transient (Bag 1)
Mass Emissions in
grams per mile
(grams per kilometer)
Baseline - average
of 4 tests
Choke #1 - average
of 3 tests
% Change
Choke #2 - average
of 3 tests
% Change
HC
3.44
(2.14)
3.39
(2.11)
-1%
3.37
(2.09)
CO
47.1
(29.3)
45.3
(28.2)
-4%
30.9
(19.2)
-34%
NOx
4.47
(2.78)
4.74
(2.95)
+6%
5.10
(3.17)
+14%
Fuel Economy
Consumption)
12.5 mpg
(18.8 X./100 km)
12.7 mpg
(18.5 Jl/100 km)
+2%
(-2%)
12.8 mpg
(18.4 fc/100 km)
+2%
(-2%
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Both the composite emissions and the Bag 1 emissions indicate that
the first choke installation had a negligible effect on exhaust emissions,
Changes in emissions and fuel economy were well within the limits of
test variability.
The second choke installation reduced composite CO emissions 19%
and increased NOx emissions 12%. No significant change in HC emissions
or fuel economy occurred. The Bag 1 emission data indicate that the
Electro-Dyn choke reduced CO emissions during the cold start by 34% and
increased the NOx emissions by 14%. Changes in fuel economy were within
test variability.
In addition to the measurement of exhaust emissions, the voltage
applied to the choke heating element under the ambient conditions of the
'75 FTP was measured. At an ambient temperature of 78°F, 12 volts were
applied to the heating element as soon as the ignition key was switched
on. This indicates that the temperature sensing unit was requiring
minimum choking action, which would be the expected behavior at 78 F.
One of the claims made for the Electro-Dyn choke is that the
temperature sensor will prevent the choke from closing during warm
starts after engine cool down unless the block has cooled sufficiently
to require choke usage. Because of the limited nature of the test
program, this claim was not evaluated. No quantitative evaluation of the
Electro-Dyn choke was made outside the temperature range of the '75 FTP.
Conclusions
Under the conditions of the '75 FTP, the Electro-Dyn choke did not
demonstrate any significant advantages over the standard choke on the
test car. The reduction in CO, emissions coupled with the increase in
NOx emissions is not considered an acceptable trade-off. No significant
improvement in fuel economy was noted.
The substantially different results obtained with the two choke
assemblies indicate some possible quality control problem or sensitivity
to initial adjustment. As far as it was possible to determine, both
choke assemblies were installed in an identical manner.
Because these tests did not explore the behavior of the Electro-Dyn
choke at low ambient temperatures, further testing would be necessary to
establish the effect on emissions, fuel economy and driveability under
such conditions.
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6
Table 1
'75 FTP
Mass Emissions in
Grams per Mile
(Grams per Kilometer)
Test
HC
CO
CO,
NOx
MPG (1/100 km)
Baseline
76-3378
76-3379
77-3
77-4
Average
Choke #1
76-3427
76-3428
76-3488
Average
Choke #2
76-3456
76-3441
76-3584
Average
2.92
(1.81)
2.87
(1.78)
2.81
(1.75)
2.66
(1.65)
2.82
-, (1.75)
2.84
(1.77)
2.76
(1.72)
2.99
(1.86)
2.86
(1.78)
2.78
(1.73)
2.65
(1.65)
2.79
(1.73)
2.74
(1.70)
20.7
(12.9)
19.1
(11.9)
22.2
(13.8)
18.6
(11.6)
20.2
(12.6)
15.7
(9.8)
18.6
(11.6)
25.8
(16.0)
20.0
(12.4)
14.8
(9.2)
14.3
(8.9)
20.1
(12.5)
16.4
(10.2)
JT
586.
(364.)
582.
(362.)
592.
(368.)
605.
(376.)
591.
(367.)
599.
(372.)
579.
(360.)
587.
(365.)
588.
(365.)
596.
(370.)
613.
(381.)
601.
(374.)
603.
(375.)
3.41
(2.12)
3.68
(2.29)
3.72
(2.31)
3.49
(2.17)
3.58
(2.23)
3.98
(2.47)
2.93
(1.82)
4.26
(2.65)
3.72
(2.31)
4.09
(2.54)
4.21
(2.62)
3.73
(2.32)
4.01
(2.49)
14.1
(16.7)
14.3
(16.5)
14.0
(16.8)
13.8
(1-7.0)
14.1
(16.7)
' • . '
14.0
(16.8)
14.4
(16.3)
13.9
(16.9)
14.1
(16.7)
14.1
(16.7)
13.8
(17.0)
13.8
(17.0)
13.9
(16.9)
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Test #
Table II
Individual Bag Emissions in Grams per Mile
HC
1: Cold Transient
CO " C0n NOx MPG
HC
Bag 2: Stabilized
CO CO,, NOx
MPG
HC
Bag 3: Hot Transient
CO C00 NOx
MPG
Baseline
76-3379
76-3378
Choke //I
76-3427
76-3428
76-3488
Choke #2
76-3456
76-3441
76-3584
Re-baseline
77-3
77-4
3.25
3.34
3.48
3.18
3.52
3.25
3.41
3.46
3.80
3.36
43.2
48.4
38.8
40.3
56.7--"
25.9
28.0
38.7
50.1
46.6
T
621.
620.
623.
605.
619.
615.
641.
633.
628.
638.
4.60
4.24
5.23
4.40
4.60
5.16
5.42
5.10
4.50
4.52
12.7
12.5
12.8
13.1
12.3
13.3
12.7
12.4
12.3
12.3
2.66
2.71
2.51
2.75
2.91
2.60
2.53
2.73
2.76
2.62
13.5
14.9
9.9
14.0
19.9
12.9
11.0
17.2
17.9
12.7
£•
588.
598.
619.
593
602.
621.
628.
602.
600.
615.
2.74
2.59
3.02
1.27
3.56
3.27
3.31
2.92
2.86
2.61
14.4
14.1
13.8
14.2
13.8
13.7
13.6
13.9
13.9
13.8
2.98
3.00
2.98
2.46
2.74
2.76
2.30
2.39
2.16
2.21
11.7
10.8
9.4
11.0
13.8
10.3
10.3
11.4
9.5
8.9
540.
537.
543.
532.
536.
535.
562.
568.
549.
563.
4.79
4.35
4.89
5.01
5.34
4.84
4.99
4.55
4.77
4.39
15.6
15.7
15.7
15.9
15.7
15.9
15.2
15.0
15.5
15.2
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TEST VEHICLE DESCRIPTION
Chassis model year/make - 1971 Ford Galaxie
Emission control system - Engine Modifications
Engine
type 4 stroke, Otto cycle, V-8, ohv
bore x stroke 4.00 x 3.50 in./101.6 x 88.9 mm
displacement 351 cu in./5753 cc
compression ratio 9.0:1
maximum power @ rpm 240 bhp @ 4600 rpm/179 kW @ 4600 rpra
fuel metering ... 2 barrel carburetor
fuel requirement .
Drive Train
type front engine, rear wheel drive
tire size H 78 x 15
curb weight 4115 lbs./1867 kg
inertia weight 4500 Ibs
passenger capacity 6
Emission Control System
basic type improved combustion
durability accumulated on system . 15500 mi./24900 km
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