74-32 DWP
Evaluation of Two Prototype
Suzuki Fronte Vehicles
May 1974
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air and Waste Management
Environmental Protection Agency
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Background
Suzuki Motor Company Limited contacted EPA requesting
confirmatory testing of a low emission prototype vehicle
powered by a two stroke engine. Because the vehicle had
demonstrated potential for achieving the 1976 statutory emis-
sion levels in tests run by Suzuki, EPA agreed to conduct
a series of tests on these vehicles.
Vehicle and Emission Control System Description
Two vehicles of a subcompact size going under the name
"Fronte" were tested. Both vehicles were identical and had
been driven approximately 6550 kilometers (4000 miles).
They were powered by three cylinder, water cooled two
stroke engines of 356cc displacement (21.7 CID). The
vehicles were of the rear engine rear drive type. Both
were equipped with four speed manual transmissions. Curb
weight of both vehicles was 546 kilograms (1200 pounds).
The emission control systems incorporated several novel
features. A fuel distillation system was used for cold
starting. A small quantity of the more volatile components
of the normal gasoline supply is distilled off using an
electric heater and stored for use during cold starts.
This feature lowers the requirement for enrichment during
cold start and thus reduces the cold start hydrocarbon
and carbon monoxide emissions.
These vehicles also used a thermal reactor in comb-
ination with an air pump and timed exhaust system spark
ignition for combustion of the hydrocarbon rich exhaust
found typically in two stroke applications. Suzuki calls
their thermal reactor system "Exhaust Port Ignition Cleaner"
(EPIC) .
To insure good displacement utilization two stroke
engines normally experience some over flow of fresh intake
air/fuel charge into the exhaust before compression is
initiated. This phenomena results in pulses of hydrocarbon
and air in the exhaust of a readily combustible mixture.
EPIC, by providing for a properly timed spark ignition source
in the exhaust system, combusts these fuel/air pulses.
An air pump is employed with this system. Air is
injected into the exhaust ports and thermal reactors only
when the throttle is less than 25% open and the engine speed
is greater than 2400 rpm. Due to the carburetion in this
mode the exhaust becomes overly rich thus more oxygen is
required for after combustion in the exhaust system.
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The vehicles control systems also used spark retard
during cold-start for rapid engine and thermal, reactor
warm-up.
Test Program
Several 75 FTP as described in the November 15, 1972,
Federal Register were conducted on each vehicle. In addition
one high speed non-metropolitan cycle was run on one of the
vehicles.'
Test Results
Test results are given in the attached table. It can
be seen that 1976 statutory emission levels can be met with
these vehicles. Fuel consumption measured during this
testing is below what would be expected for a car of this
weight class. 1975 FTP fuel consumption for a vehicle of
this weight class powered by a conventional four stroke
engine would be estimated at a minimum of 9.4 liters per
100 kilometers (25 mpg). The use of a two -stroke engine
is probably the cause of this poor economy.
The curb weight of these vehicles was 546 kilograms
(1200 pounds) each. Test inertia would thus calculate to
be 680 kilograms (1500 pounds). EPA's Ann Arbor laboratory
has a minimum capability of 794 kilograms (1750 pounds)
on its dynamometer. Thus all EPA testing was conducted
at 794 kilograms (1750 pounds). Suzuki tested these vehicles
at 680 kilograms (1500 pounds). Their typical 75 FTP
results at 680 kilograms (1500 pounds) are as follows:
0.12 g/km (0.20 g/mi) HC, 1.20 g/km (1.93 g/mi) CO, 0.14 g/km
(0.23 g/mi) NOX and 10.9 liters per 100 kilometers (21.5 MPG).
Conclusion
1) 1976 statutory emission levels were achieved con-
sistently with two low mileage subcompact Suzuki vehicles
powered by two stroke engines.
2) Fuel economy was at least 30% less than what would
be expected for a vehicle of this weight class.
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Test Results
•75 FTP Results
HC
g/km
0.096
0.131
0.195
0.065
0.079
0.113
g/mi
0.155
0.211
0.314
0.104
0.127
0.182
CO
g/km g/mi
0.
0.
2.
1.
7.
1.
764
839
96
22
36
63
1.23
1.35
4.77
1.97
3.80
2.62
NOx
g/km g/mi
0.
0.
0.
0.
0.
0.
15
14
12
12
11
13
0.24
0.22
0.19
0.20
0.18
0.21
Fuel Consumption
I/ 10 Okm MPG
13
13
13
12
13
13
.2
.2
.4
.9
.0
.1
17
17
17
18
18
17
.8
.8
.6
.3
.1
.9
Vehicle No.
6
6
7
7
7
Avg.
'76 Statutory
Standard 0.255 0.41 2.11 3.4 0.25 0.4
Highway Cycle Results
6 0.006 0.01 0.075 0.12 0.11 0.17 8.40 28.0
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