72-13
EXHAUST EMISSIONS FROM THE LAFORCE FALCON
December 1971
Thomas C. Austin
Test and Evaluation Branch
Division of Emission Control Technology
Mobile Source Pollution Control Program
Environmental Protection Agency
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Background
The exhaust emission characteristics of a 1967 Ford .Falcon
extensively modified by Mr. Robert LaForce of Beaver,
Pennsylvania, were previously evaluated using the 7-mode
test cycle at EPA's old Willow Run Laboratory. Several
modifications were made to the system after that test.
The LaForce vehicle was scheduled for additional evaluation
using the 1975 test procedure to determine if the latest
configuration could approach emission levels required for
1975 and 1976.
Vehicle Tested
The LaForce system consisted of numerous modifications to
a 1967 Ford Falcon. The basic power train was a 200 cubic
inch six coupled to an automatic transmission.
The production carburetor had been replaced by an extensively
modified Holley two barrel. The carburetor utilized two
different air inlets. The primary inlet passed air through
the venturi's where it was mixed with fuel. A second inlet
on the back of the carburetor by-passed the venturi's and did
not mix any fuel with the air. 'The second inlet was used
during deceleration to eliminate the high unburned hydrocarbon
levels which occur during high manifold vacuum conditions on
uncontrolled vehicles. To further reduce hydrocarbon emissions
the accelerator pump cam was modified to reduce the pump shot
to the minimum the engine "required. The carburetor's power
valve was also modified. Air velocity in the primary inlet
was measured and the power valve would not fully open until
a predetermined velocity xvas reached.
The carburetor's float bowl had overflow ports on each side
to drain fuel back to the tank on cornering. The bowl was
also equipped with a drain that allowed fuel to be pumped
from the bowl back to the tank after the engine was shut-off
to reduce evaporative emissions.
The exhaust manifold had been insulated. Air was pumped into
an air space between the manifold and the insulation where it
was preheated before being injected into the exhaust ports to
induce further oxidation of pollutants which were not completely
burned in the cylinder. At the exit of the exhaust manifold
was a venturi. Exhaust gases flowing through the venturi caused
more air from the preheater to be drawn into the exhaust.
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Modifications had also been made to provide for increased
spark advance during start up in an effort to reduce the
.high hydrocarbon levels that occur when a vehicle is cold
started.
The camshaft had been retarded 6° to increase the exhaust
gas dilution of
Tests Conducted
gas dilution of the next charge.
The 1972 Federal Test Procedure was used to compare the
emissions from the LaForce car to the 1972, 1973, and 1974
Federal Standards. This test involves starting the vehicle
after it has been parked in a 68-86°F ambient for at least
12 hours and operating it on a chassis dynamometer for a
simulated 7.5 mile urban drive. Vehicle exhaust is diluted
to a constant volume and a portion of the dilute exhaust is
collected continuously throughout the 23 mile test in a Tedlar
(inert plastic) sample bag. The concentrations of pollutants
in the sample bag are then measured. A flame ionization
detector (FID) is used to determine unburned hydrocarbon (HC)
concentration. Non-dispersive infrared (NDIR) analyzers are
used for carbon monoxide (CO) and carbon dioxide (C02). A
chemiluminescent (CL) analyzer is used to determine nitric
oxide (NO) concentration. Nitrogen dioxide (N02) concentration
was not measured as the N02 converter was not operational
during the test. Had the N02 converter been operational the
NOx values would have been slightly higher. Emission results
are reported as grams per mile.
The 1975 Federal Test Procedure was used to show how the
LaForce car compares to the 1975 and 1976 Federal Standards.
The 1975 pro.cedure is similar to .the 1972. procedure except
that a portion of the dilute exhaust is pumped into three
different sample bags. The first bag is filled during
the first 3.6 miles of the 7.5 mile cycle, the second bag during
the last 3.9 miles and the third bag during the first 3.6 miles
after a 10 minute shut down. The pollutant concentrations
are read with the same instrumentation used for the 1972 pro-
cedure. Mass emissions in grams per mile of vehicle operation
are calculated after weighting factors are applied to the cold
and hot start bags.
Test Results
Test results are summarized in Table I. The first part of
Table 1 compares the test run using the 1972 procedure to
the 1972, 1973, and 1974 Federal Emission Standards. The
LaForce vehicle produced lower emission levels than required
by the 1972 Federal Standards.
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The second part of Table I compares the data using the 1975
Federal Test Procedure to the 1975 and 1976 Federal Standards
Emission levels from the LaForce car were more, than five
times higher than required.
Summary and Conclusions
The modifications made to the vehicle enabled a previously
uncontrolled, car to meet emission levels required by the
1972 Federal exhaust emission standards. The modifications
made were much more complex and extensive than required to
obtain the emission levels produced. Many features of the
system were apparently ineffective. The emission levels were
far above the 1975 and 1976 requirements and the system
was too complicated to be considered as a retrofit package
for uncontrolled vehicles.
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Table I
EMISSION TEST RESULTS
(All Data in Grams Per Mile)
1972 Federal Test Procedure
Pollutant
HC
CO
NOx
Pollutant
HC
CO
NOx-
LaForce
Falcon
2.28
38.5
2.71*
1975 Federal Test
LaForce
Falcon
1.73
22.25
2 . 96-
1972 Federal
Standards
3.4
39.0
Procedure
1975 Federal
Standards
.41
3.40
3.0
1973-74 Fed.
Standards
3.4
39.0
3.0
1976 Federal
Standards
.41
3.40
.40
*NO only, N02 not measured.
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