73-9
A Second Evaluation
of the
Questor Emission Control System
November 1972
Thomas C. Austin
Test and Evaluation Branch.
Division of Emission Control Technology
Environmental Protection Agency
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Background
EPA recently performed a short evaluation of a
vehicle prepared by Questor Automotive Products of
Toledo, Ohio. The vehicle equipped with the Questor
"Reverter" emission control system had been available
only long enough for one 1975 Federal Test Procedure
to be run. Because of the impressive emission levels
recorded during the first EPA test (nelow 1970 reauire-
ments) a decision was made to perform a more ext~nsive
evaluation at a later date.
Approximately 4,nnn miles had neen accumulated
on the Ouestor vehicle since the first test. Total system
mileage 'was approximately R,non at the heginning of this
test series. Questor representatives cl~imed that all
of the mileage 'had been accumulated using highly leaded
fuels. A lead determination, performed by EPA, on a
sample of fuel from the vehicle's tank indicated a lead
content of 2.5 grams per gallon.
Vehicle Tested
The Questor "Reverter" emission control system was
installed on a 1971 Pontiac Catalina equipped with a 400
CID V-8 engine, automatic transmission and air conditioning.
The heart of the system is a pair of non-noble reduction
catalysts sandwiched between partial thermal reactors.
Carburetor calibration and exhaust port air injection
rates are set such that a reducing ~tmosphere is still
present after the exhaust gas passes through the first
partial thermal reactor stage. After the exhaust gas
passes through the NOx catalyst, additional air is added
to cociplete combustion of the HC and CO remaining. Exhaust
gas recirculation (EGR) is not used. .
One "reverter" is used on each bank of a "-8 engine.
Figure 1 is an illustration of a reverter attached to a
cylinder head. "Limited oxidation" and "final oxidation"
takes place in the partial thermal reactors. The "reduction
zone" houses the expanded metal NOx c::itaJYst. Fi.gure 2
shows a cut-away reverter system installed on a cylinder
head. As can be seen from the picture, the construction
is double walled to reduce heat loss.
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The vehiclefs exhaust system is constructed of
double walled pipe. Air pump discharge is routed
to the rear of the vehicle and pumped into the
annular cavity surrounding the inner exhaust pipe.
The air is then heated by the hot inner pi~e as it is
pumDed toward the front of the vehicle where it is
removed from the annular cavity and injecten into the
partial thermal reactors at 80no F.
. IncorDorated in the Questor vehicle is a sub-system
to improve' fuel economy and reduce system temperatures
during high load operation. This. system, designated
"Normal Operating Temperature Control (N.a.T.C.)" senses
both load and time. When the vehicle is exposed to a
high enough load for a long enough period of time a
portion of the air pump discharge is diverted to the
intake manifold, causing en1eanment of the mixture.
The system is activated when two separate chambers are
pressurized by a portion of the air pump discharge.
The time required to pressurize the chambers depends.
on the air pump speed (a function of vehicle speed) and
the exhaust backpressure (a function of vehicle load).
Normally at loads below those required for a 50 mph
cruise the system will never activate because the air
pump discharge cannot overcome the built-in leakage
in the chambers. Above 50 mph the system will only
activate if the driver maintains a steady throttle
position and does not use his brakes. Brake application
causes one of the volumes to dump immediately.
As adjusted on this vehicle the N.D.T.C. system
would only be acti va ted during expressway or high\.ray
operation in light traffic. Activation causes a
considerable loss in ~Ox control but good HC and CO
control is maintained. Our previous testing of the
Questor vehicle indicated that fuel economy of better
than 15 miles per gallon could he achieven at on mph
cruise with the system activated.ProDerly ca1i~rated
the system would not be activated in heavy traffic
situations or stop and go driving. As installed on the
vehicle tested, the N.a.T.C. system was fully adjustable.
A'production version would use fixed orifices rather than
adjustable valves. The system was never activated during
the LA-4 driving cycle of the Federal Test Procedure.
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Test Program
The Questor vehicle was tested using the 1975
Federal Test Procedure with two different vehicle
weights simulated. Two tests were run at a S,oon
pound test weight, the "correct" test weight for the
full size Pontiac and two tests were run at a reduced
weight of 3,nnn pounds simulating a compact vehicle.
A description of the Federal Test Procedures is enclosed
(At tachmen t I).
In addition to the g~seous emission tests, the
vehicle was also testen for narticulate emissions. The
particulate testing was done by Dow Chemical of Midland,
Michigan through an existing EPA contract. The Dow
procedure. simulates an air auench of the vehicle's
exhaust gas by routing the exhaust into a 15-7/8 inch
diameter tube where it is diluted to a 500 cfm flow.
Twenty-seven feet downstream of the tailpipe samples
are pulled from the diluted exhaust through fiberglass
filters, millepore filters and an Anderson impactor.
Only the particulates still in suspension are captured.
While the Dow procedure is not necessarily going to end
up as a Federal Procedure, it does allow us to compare
particulate emission levels from different vehicles using
a common procedure.:
Test Results
Results are summarized in Tables I and II. Table
I lists gaseous emission test results using the 1975
Federal Test Procedure for test weights of both 5,onn
and 3,000 pounds. Emissions were u~der the 1976 ]evels
during each test. Hydrocarhon control was very good.
During the only test above .03 grams per mile HC (16-nOZ3)
the vehicle did not restart well after the ten minute
soak. NOx control was quite good. A 40% reduction in
test weight from 5,000 pounds to 3,OnO pounds caused a
36% reduction in NOx levels. CO levels were ~uch
lower than normally expected from vehicles using thermal
reactors to control CO.
Fuel economy at 5,000 pounds test weight averaged
6.93 miles per gallon. This represents a 20% penalty
compared to the average of all i973 certification pr~to-
types tested by EPA d~ring the spring and summer of 1972.
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(Corrections were made for the slight difference
in test procedure.) The fuel economy improvement
measured when the test weight was lowered to 3,00n
pounds was not very large because the carburet ion,
engine size, and driveline were poorly matched for
a lighter weight application.
Results of the particulate testing are listed in
Table II. At 60 muh steady state the particulate levels
were comparable to a vehicle using n.s grams per gallon
lead fuel. An EPA lead determination run on the gasoline
used during the questor testing indicated a lead level of
2.87 grams per gallon. A conventional (197n production.
Chevrolet) run with 3.n gram fuel emitted particulate.
levels over four times greater than the Questor vehicle.
More data points will be required to lend significance
to the results.
Conclusiohs
1. The Qu~stor emission control system can achieve
the 1976 Federal emission levels at low mileage. Durability
is yet to be demonstrated.
2. The Questor system causes a considerable ~2S%)
loss in fuel economy in stop and go driving. There
appears to be, however, potential for reducing this
penalty by modulating air injection as a function of
engine load which would allow leaner calibration.
3. Particulate emission levels from the Questor
system appear to be lower than those from conventional
systems using leaded fuels. Future testing will be
required to verify the preliminary results.
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TABLE I
Questor Emission Control System
1975 Federal Test Procedure.
(emission data in grams per mile)
5000# Test Weight
Test Number HC CO NO"\( mpg
--
~
16 - 0.0 23 .23 2.5'5 .34 6.89
16-0033 .01 1. 98 .31 6.96
Average .. - .12 2.27 .33 6.93
3000# Test Weight
Test Number HC CO NO" mpg
16-0029 .03 1. 66 .22 7.73
16-0034 .02 2.55 .20 7.70
Average .03 2.11 . .21 7.72
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"
.
Vehicle
Questor 101
1971 Chevrolet
1970 Chevrolet
.~
TABLE II
,.
Particulate Emissions
(all data in gram~
'Fuel
2.87 gpg Pb
3.0
.5
gpg Pb
gpg Pb
per mile)
Hot Start
72 FTP
.15
. .~.r
nn muh
steady state
.025
.1
.021
I
I
.110
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ATTACHMENT I
..
FEDERAL E},lISSION TESTING PROCEDURES
FOR LIGHT DUTY VEHICLES
The Federal procedures for emission testing of light
duty vehicles involves operating the vehicle on a chassis
dynamometer to simulate a 7.5 mile (1972 procedure) or
11.1 mile (1975 procedure) drive through an urban area.
The cycle is primarily made up of stop a~d go. driving and
includes some operation at speeds up to 57 mph~ The
average vehicle speed is approximately 20 mph. Both the
1972 and 1975 procedures capture the emissions generated
during a "cold start" (12-hour soak @ 68°F to 86°F before
start-up). The 197~procedure also includes a "hot start"
after a ten minute shut-down following the first 7.5 miles
of driving. .
Vehicle exhaust is drawn through a constant volume
sampler (CVS) during the test. The CVS dilutes the vehicle's
eihaust to a known constant volume with make up air. A
continuous sample of the diluted exhaust is pumped intq
sample bags during the test. .- '"
I .
I
Analysis of the diluted exhaust collected in the sample
bags is'used to determine the mass of vehicle emissions per
mile of operation (grams per mile). A flame ionization de9'.
tector. (FID) is used to measure unburned hydrocarbon (HC)
concentrations. Non-dispersive infrared (NDIR) analyzers are
used to measure carbon monoxide (CO) and carbon dioxide .(C02).
A chemiluminescence (CL) analyzer is used to determine oxides
of nitrogen (NOx) levels.
These procedures are used for all motor vehicles designed
primarily for transportation of property and rated at. 6,000
pounds G~v or less, or designed primarily for transportation of .
persons and having a capacity of twelve persons or less. Each
new light duty vehicle sold in the United States in model y~ars
. .1973 and 1974 must emit no more than 3.4 gp~ HC, 39. gpm CO
and 3.0 gpm NOx when using the 1972 procedure. In 1975 the
. standards will change to .41 gpm HC. 3.4 gpm CO and 3.1 gpm'NOx
using the 1975 procedure. In 1976 the standards will be .41
gpm HC, 3.4 gpm CO and .4 gpm NOx using the 1975 procedure.
. , ~.... - ..,.. .
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