74-18 AW
Evaluation of the Retronox
Clean Air System
November 1973
Test and Evaluation Branch
Emission Control Technology Division
Environmental Protection Agency
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Background
The Test and Evaluation Branch of the Emission Control
Technology Division is responsible for the testing of
devices designed to reduce emissions from automobile
engines. The Retronox Clean Air System manufactured by
Dana Corporation for use in light duty vehicles is one
such system. EPA was supplied with three Retronox systems
for evaluation. The vehicles used in the evaluation included
one uncontrolled car and two cars with a moderate degree of
emission control.
Device and Vehicle Description
The Retronox Clean Air System is an exhaust gas recirculation
system with a delayed spark advance. The spark advance is
controlled with a vacuum delay valve between the carburetor
and distributor. In addition, a modified PCV valve, giving
increased flow through the PCV line, is used to give overall
enleanment of the fuel-air mixture.
The system was tested on three vehicles, a 1963 Chevrolet
with a 4.6 litre (283 CID) engine, a 1970 Chevrolet with
a 5.7 litre (350 CID) engine, and a 1971 Ford with a 5.8 litre
(351 CID) engine. The 1970 Chevrolet and the 1971 Ford were
equipped with automatic transmissions. The 1963 Chevrolet had
a three-speed manual gearbox. The 1963 Chevrolet was a "smoker,"
producing a significant amount of blue exhaust smoke, which
could be the result of bad rings or valve guides. The results
of installing the Retronox system on this car are considered
significant, since vehicles in this condition would be
encountered when retrofitting a large market.
Test Program
Before testing, all cars were adjusted to manufacturer's
specifications. Initial tests were run in baseline configurations,
The devices were then installed on the vehicles and further
tests were run. No adjustments were made on the vehicles after
installation of the devices.
All tests were run as directed in the 1975 Federal Test
Procedure (Federal Register, Vol. 37, No. 221, Part II;
November 15, 1972).
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Results
Installation of the device resulted in significant reductions
in NOx emissions from the 1970 Chevrolet and 1971 Ford. The
Ford showed decreases in HC and CO, while the Chevrolet
showed a decrease in CO but an increase in HC. Since the
Chevrolet was running at very low levels of HC and CO in
baseline configurations, installation of the Retronox system
may have produced lean misfire.
The Retronox system installed on the 1963 Chevrolet resulted
in reductions in HC and CO but left NOx emissions unchanged.
The system did not show a consistant effect on fuel consumption.
The 1970 Chevrolet showed no change in fuel consumption when
the device was correctly installed. The 1963 Chevrolet decreased
its fuel consumption and the 1971 Ford increased its fuel
consumption. Both of these changes are within the range of
test-to-test variability.
Conclusions
Installation of the Retronox Clean Air System resulted in
significant emission control on two of the three vehicles
tested. The third vehicle installation, while demonstrating
reduced carbon monoxide and oxides of nitrogen levels, was
characterized by increased hydrocarbon emissions. This increase
in hydrocarbon may be due to lean misfire as the baseline
vehicle was operating quite lean. Fuel economy changes duja to
device installation were not consistent or significant.
An installation problem was encountered on the 1970 Chevrolet
which pointed up the need, with this system, for careful
attention by the installer. Even when the installation was
corrected, the high HC emission data suggest that final
carburetor checks or adjustments (which are not presently
called for) might be beneficial.
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Retronox - 1963 Chevrolet 283 CID
mass emissions in
grams/kilometer
(grams/mile)
Baseline
HC
CO
NOx
Average
7.22
(11.62)
7.05
(11.34)
7.25
(11.67)
7.17
(11.54)
61.24
(98.53)
61.24
(98.53)
65.11
(104.77)
62.53
(100.61)
0.83
(1.33)
0.81
(1.30)
0.89
(1.44)
0.85
(1.36)
Device Tests
Average
% Change
4.75
(7.65)
4.62
(7.44)
6.05
(9.74)
5.15
(8.28)
-28%
28.71
(46.19)
34.35
(55.27)
51.88
(83.47)
38.31
(61.64)
-39%
1.08
(1.74)
0.69
(1.11)
0.71
(1.15)
0.83
(1.33)
-2%
Fuel Consumption
16.1 1/100 km
(14.6 mpg)
16.2 1/100 km
(14.5 mpg)
16.6 1/100 km
(14.2 mpg)
16.2 1/100 km
(14.5 mpg)
14.8 1/100 km
(15.9 mpg)
15.2 1/100 km
(15.5 mpg)
16.8 1/100 km
(14.0 mpg)
15.6 1/100 km
(15.1 mpg)
+ 4%
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Retronox - 1970 Chevrolet 350 CID
mass emissions in
grams/kilometer
(grams/mile)
Baseline
HC
CO
NOx
1.14
(1.84)
1.19
(1.92)
1.18
(1.90)
Average 1.17
(1.89)
9.17
(14.75)
8.84
(14.22)
9.29
(14.94)
9.10
(14.64)
2.30
(3.70)
2.21
(3.55)
2.50
(4.02)
2.34
(3.76)
Fuel Consumption
18.2 1/100 km
(12.9 uipg)
18.4 1/100 km
(12.8 mpg)
18.8 1/100 km
(12.5 mpg)
18.5 1/100 km
(12.7 mpg)
Device Test
Average
% Change
2.03
(3.26)
1.72
(2.77)
1.88
(3.02)
+61%
5.72
(9.2)
5.78
(9.3)
5.75
(9.3)
-37%
1.27
(2.04)
1.27
(2.05)
1.27
(2.05)
-46%
18.8 1/100 km
(12.5 mpg)
18.7 1/100 km
(12.6 mpg)
18.8 1/100 km
(12.6 mpg)
-1%
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Retronox - 1971 Ford 351 CID
mass emissions in
grams/kilometer
(grams/mile)
Baseline
HC
CO
NOx
Average
1.24
(1.99)
2.46
(3.96)
1.29
(2.08)
1.67
(2.68)
8.93
(14.37)
8.78
(14.12)
9.60
(15.44)
9.10
(14.64)
2.86
(4.60)
2.97
(4.78)
3.03
(4.87)
2.95
(4.75)
Device Tests
Average
% Change
1.65
(2.66)
1.27
(2.04)
1.78
(2.87)
1.57
(2.52)
-6%
7.45
(11.99)
5.73
(9.22)
7.09
(11.40)
6.76
(10.87)
-26%
1.51
(2.43)
1.25
(2.01)
1.31
(2.10)
1.35
(2.18)
-54%
Fuel Consumption
18.1 1/100 km
(13.0 mpg)
19.0 1/100 km
(12.4 mpg)
18.4 1/100 km
(12.8 mpg)
18.5 1/100 km
(12.7 mpg)
20.6 1/100 km
(11.4 mpg)
17.7 1/100 km
,(13.3 mpg)
19.0 1/100 km
(12.4 mpg)
19.0 1/100 km
(12.4 mpg)
-2%
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