Particulate Emissions from a Pre-Emissions Control Era Spark-Ignition Vehicle: A Historical Benchmark Page: 4 of 7
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have put forward data that show the PM emissions of
vehicles during the 1980s and 1990s (5,6), however, the
PM emissions from earlier vehicles in proper operating
condition are a relative unknown. This is due largely to
the lack of advanced instrumentation during the period.
This study aims to provide a historical perspective on
emissions from a gasoline pre-emissions control vehicle
using both leaded and unleaded fuel to augment avail-
able data. Although the gaseous emissions from vehi-
cles of this era are well-documented, newer technologies
for the characterization of particulate emissions make it
worthwhile to revisit the particulate emissions of vehicles
of the pre-control era.
SELECTION OF TEST VEHICLE - In order to best repre-
sent the emissions from a new vehicle in the 1960s, a
near-pristine vehicle from this era was required. Most
vehicles of this age have accrued a larger-than-desirable
amount of mileage; hence, a vehicle was sought that had
recently undergone an engine re-build using only factory
replacement parts. Based on these criteria, a 1967
Chrysler 300 was identified. This vehicle (Figure 1) had
94,000 original miles on the chassis. The engine and
exhaust system were rebuilt with factory replacement
parts at 74,000 miles. The spark timing, carburetor tune,
and other pertinent parameters were brought within fac-
tory specifications. The vehicle was equipped with a 6.3-
liter (383 cubic-inch-displacement) V-8 engine. The car-
buretor was a factory unit, but was not necessarily
exactly the same as the original unit. Prior to testing, the
exhaust system was leak-checked. In addition, two full
Federal Test Procedure (FTP) tests were performed to
prepare the vehicle for reportable tests.
Figure 1. 1967 Chrysler 300 test vehicle
EVALUATION PROCEDURE - In order to determine the
differences in the vehicle's emissions characteristics
when operating on leaded and unleaded fuel, the vehicle
was subjected to repetitive FTP tests. Three tests were
performed with each fuel, beginning with unleaded fuel
(UTG96). The leaded fuel was produced by adding
appropriate levels of tetraethyl lead (TEL) to the unleaded
base fuel. The lead level was raised to approximate the
lead levels in gasoline in the late 1960s (0.8 grams/liter).
The aromatic content of the base fuel was 32.2%. This
was slightly lower than the aromatic content during the
late 1960s. However, since both fuels had relatively high
aromatics, the authors do not believe that significant dif-
ferences in the PM emissions resulted from this small dif-
ference in aromatic content. No engine re-tuning was
performed during the evaluations.
In addition to regulated gaseous emissions, the particu-
late (PM) emissions of the vehicle during each of the
tests was measured. Both PM mass and mass-based
size distribution were investigated. Samples for transmis-
sion electron microscopy (TEM) were collected as well.
The TEM samples were collected using carbon-film grids
temporarily attached to impactor substrates. This
allowed TEM analysis of the PM emissions in a size-frac-
tionated fashion. The elemental composition of the PM
samples was determined by both energy dispersive X-ray
spectroscopy (EDS) and inductively-coupled plasma
mass spectroscopy (ICP-MS). FTP tests and sample col-
lection were performed by Automotive Testing Laborato-
ries, Inc. (ATL) of East Liberty, Ohio. ATLs emissions-
grade test cell utilizes a Horiba AC electric dynamometer
and Horiba analytical emissions sampling bench. Supple-
mental analyses of particulate samples were conducted
by Oak Ridge National Laboratory (ORNL).
The results showed a large effect of lead in the fuel on
PM emissions, but not on gaseous emissions. Figure 2
shows the composite emissions results for hydrocarbons
(HC), oxides of nitrogen (NOx) and carbon monoxide
(CO). The data are for an average of three tests. Note
the similarity in the results for each of the species. Figure
3 shows the PM mass emissions for the composite cycle
as well as each individual bag averaged over three runs.
Overall, the PM emissions were much higher for the
leaded fuel. The data show the high and variable PM
results for Bag 1, the cold start portion of the FTP. This is
to be expected as a large displacement engine with a
carburetor will have relatively poor control of fuel delivery
especially during cold start conditions. The PM values
for Bags 2 and 3 were much less variable.
10.000 CO emissions are
E shown divided by
Figure 2. Gaseous pollutant emissions for the FTP
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Storey, John M.E.; Sluder, C. Scott; Blom, Douglas A. & Higinbotham, Erin. Particulate Emissions from a Pre-Emissions Control Era Spark-Ignition Vehicle: A Historical Benchmark, article, June 19, 2000; (digital.library.unt.edu/ark:/67531/metadc725347/m1/4/: accessed February 18, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.