72-6
Exhaust Emissions Prom Two Passenger Vehicles
Equipped with the ADAKS Device
September 1971
Henry L. Gompf
Office of Air Programs
ENVIRONMENTAL PROTECTION AGENCY
-------
Background
The ADAKS Vacuum Breaker demonstrated impressive emission re-
ductions when evaluated on five vehicles by a commercial labora-
tory. It was desired to conduct confirmative testing utilizing
the 1972 Federal emission test procedure. Two units were pro-
vided by ADAKS Products,' Inc. of Rochester, New York.
Device
The ADAKS Vacuum Breaker is basically an air bleed device
resulting in leaner engine combustion. A valve activated by
high manifold vacuum, with oil damping to preclude undesireable
oscillations, allows air to flow through a filter to a base
plate inlet beXow the carburetor. Flow is shut off when the
vehicle is operating under load conditions - low manifold vacuum.
Installation of the device seemed to require considerable effort.
The carburetor had to be removed to facilitate installation of
the base plate or air inlet. Some automatic choke linkages
(typically Chrysler Corporation vehicles) would require modi-
fication. Carbon monoxide at idle must be set at a rich level
(about 6.5% without AVB) . The AVB valve required adjustment '(
while monitoring manifold vacuum. Thus, installation of the \
AVB system' requires good shop equipment as well as several
hours of a-competent mechanic's time.
Test Program
Two vehicles were outfitted with the AVB system. A 1963 Chevrolet
Impala with a 283 cubic-inch engine and manual three-speed trans-
mission and a 1970 Plymouth Valiant with a 225 cubic-inch engine
and automatic transmission were employed. T
A series of 1972 Federal emission tests, as described in the \
November 10, 1970, Federal Register, were performed on both \
the Chevrolet and the Plymouth equipped with AVB. This testing
employed the LA4-S4 driving cycle and the constant volume sampling
technique to obtain bag samples. These samples were analyzed
using NDIR analysis for carbon monoxide and carbon dioxide, FID
analysis for hydrocarbons, and chemilu,minescent analysis for
oxides of nitrogen.
The Plymouth Valiant was driven 2000 miles subsequent to this
testing and then retested as described above. This additional
analysis was desired to note any degradation or improvement of
emissions with "mileage.
Results
The emission results for the Chevrolet and Plymouth are presented
in Table I and II respectively in the appendix. As indicated in ,
Table I, hydrocarbons were reduced 14% and carbon monoxide 31% from
-------
baseline on the Chevrolet. Similarly Table II indicates a
36% reduction in hydrocarbon, and a 75% reduction in carbon
monoxide from baseline for the Valiant prior to mileage accumu-
lation. In both cases carbon dioxide and oxides of nitrogen
increased. For the Chevrolet these increases above baseline
were 20% and 7%. For the Valiant increases of 7% and 19% were
noted.
In addition to these baseline comparisons, data is presented
on another device evaluated on the Chevrolet. The GM retro-
fit device employs enleanment of the carburetor in addition
to vacuum advance disconnect. Hydrocarbon levels were lower
with the GM device than ADAKS while carbon monoxide was higher.
Table II also presents emission data acquired after 2000 miles
were driven in the Valiant. As is shown, the toxic emissions
dropped somewhat during this mileage accumulation. Carbon
dioxide increased during this time. It is of interest to note
that no adverse driveability effects were reported during the
mileage accumulation, indicating that the Valiant was operating
rich enough to tolerate the enleanment effect.
Conclusions
The ADAKS Vacuum Breaker is an effective control system for
the reduction of carbon monoxide. The system has a lesser
effect on hydrocarbon emissions. As was anticipated oxides of
nitrogen rose as a result of the enleanment process. This
increase is minimized, however, by the cutoff of excess air
at high load operation. Carbon dioxide increased with the
installation of the ADAKS device indicating a potential increase
in fuel consumption.
When considering an air bleed device it should be kept in mind
that in the population .of vehicles currently in operation there
exists a significant proportion already operating near the lean
limit of combustion. It is probable that installation of any
device whose operation is similar to that of the ADAKS device,-
an enleanment effect'will result in misfire, and/or severe adverse
driveability affects on those vehicles.
-------
Table I
Emission Data - 1972 FTP
1963. Chevrolet Impala, 283 ,CID
Standard Transmission
ADAKS Equipped
Average
Baseline (no
Average
% Reduction
over Baseline
HC
SE
7.
7.
7.
6.
r.
•m
3
2
4
4
1 gpm
device)
8 . 3 gpm
14
,
CO
83.8
82.2
76.1
70.4
78.1 gpm
113.8 gpm
31%
C02
gpm
467
510
496
469
486
404
20%
.5
.8
.1
.8
.1 gpm
.5 gpm
increase
NOx
1.
1.
1.
1.
1.
1.
7%
1
7
3
7
5
5
i
gpm
gpm
Lncri
GM Retrofit Device
Average 6.5 gpm 92.3 gpm
% Reduction
over Baseline 22% 19%
-------
Table II
Emission Data - 1972 CID
1970 Plymouth Valiant, 225 CID
Automatic Transmission
ADAKS Equipped (prior to mileage accumulation)
HC
1.8
1.6
1.9
CO
£P_
13
8
13
C02
m gpjn
.5
.7
.3
494
433
434
.7
.9
.0
NOx
gpm
7
5
8
.7
.9
.9
Average 1.8 gpm 11.8 gpm 454.2 gpm 7.5 gpm
Baseline (no device)
Average 2.8 gpm 48.0 gpm 426.0 gpm 6.3 gpm
% Reduction
ADAKS over
Baseline 36% 75% 7% increase 19%'increase
ADAKS Equipped ( after 2000 miles accumulated)
HC
g_pjn
1.7
1.4
1.5
CO
gpm
10.9
10.1
11.0
C02
gpm
489.0
641.2
497.9
NOx
gpjn
5.9
5.5
6.0
Average 1.5 10.7 542.7 5.8
------- |