EPA-AA-TAEB 75-11
Evaluation of the MSU 4-Cylinder
Conversion Technique for V-8 Engines
October 1974
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Air and Waste Management
Environmental Protection Agency
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Background
The Environmental Protection Agency receives information about many
systems and devices for which emission reduction or fuel economy improve-
ment claims are made. In some cases, both claims are made for a single
device. In most cases, these devices are being recommended or promoted
for retrofit to existing vehicles although some represent advanced systems
for meeting future standards.
The EPA is interested in evaluating the validity of the claims for
all such devices, because of the obvious benefits to the Nation of iden-
tifying devices that live up to their claims. For that reason the EPA
invites proponents of such devices to provide to the EPA complete technical
data on the device's principle of operation, together with test data on
the device made by independent laboratories. In those cases in which
review by EPA technical staff suggests that the data submitted holds
promise of confirming the claims made for the device, confirmatory tests
of the device are scheduled at the EPA Emissions Laboratory at Ann Arbor,
Michigan. The results of all such confirmatory test projects are set
forth in a series of Technology Assessment and Evaluation Reports, of
which this report is one.
The conclusions drawn from the EPA confirmatory tests are necessarily
of limited applicability. A complete evaluation of the effectiveness of
an emission control system in achieving its claimed performance improvements
on the many different types of vehicles that are in actual use requires
-a;much larger sample of test vehicles than is economically feasible in the
confirmatory test projects conducted by EPA. JL/ For promising devices
it is necessary that more extensive test programs be carried out.
The- conclusions from the EPA confirmatory tests can be considered
to be quantitatively valid only for the specific type of vehicle.used
in the EPA confirmatory test program. Although it is reasonable to
extrapolate the results from the EPA confirmatory test to other types of
vehicles in a directional or qualitative manner, i.e., to suggest that
similar results are likely to be achieved on other types of vehicles,
tests of the device on such other vehicles would be required to reliably
quantify results on other types of vehicles.
In summary, a device or system that lives up to its claims in the
EPA confirmatory test must be further tested according to protocols described
in footnote ±1, to quantify its beneficial effects on a broad range of
vehicles. A device which when tested by EPA does not meet the claimed
results would not appear to be a worthwhile cnadidate for such further
testing from the standpoint of the likelihood of ultimately validating
the claims made. However, a definitive quantitative evaluation of its
effectiveness on a broad range of vehicle types would equally require
further tests in accordance with footnote _!/.
I/ See Federal Register 38 FR, 3/27/74, for a description of the test
protocols proposed for definitive evaluations of the effectiveness
of retrofit devices.
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ECTD was contacted by Professor Gerrish of Michigan State University
concerning testing of a four cylinder conversion technique for V-8 engines.
The main purpose of this conversion is to reduce vehicle fuel consumption.
Due to EPA's interest in fuel conservation,tests were conducted at the
Ann Arbor laboratory.
Vehicle Description
The vehicle tested was a 1968 Chevrolet Impala with a 307 cubic
inch V-8 engine and automatic three-speed transmission. The car is
described in detail in the Vehicle Description table attached.
As per the attached figure 1 the four operating cylinders were
cylinders number 2, 3, 5, and 8. Cylinder numbers 1, 4, 6, and 7 were
made inoperative by disconnecting the valve train as shown in figure 2.
The lifter was held off the cam by a hose clamp. The stock push rod
was replaced by a shortened push rod and the rocker arm was snugged
down. In tnis manner both the intake and exhaust valves of the inoperative
cylinders remained closed.
The vehicle transmission shift point was adjusted to shift at a higher
speed. The carburetor was also modified. The stock carburetor was a
Rochchester two—barrel. The throttle plate of one venturi was fixed in
the closed position. A small part of this fixed throttle plate was cut
off to provide minimal air flow so that idle mixture control could be
used on this side of the carburetor. The main jet* power jet and accelerator
pump orifice to the unused venturi were blocked. The main jet to the
working venturi was increased from a number 52 to a 55. The accelerator
pump stroke was cut to 2/3 of its original stroke.
Test Program
All testing on this vehicle was done at 4500 pounds inertia.
Initially several '75 FTP's and EPA highway cycles were planned both
for the baseline 8 cylinder configuration and the 4 cylinder modified con-
figuration. Cold start driveability problems were encountered during the
8-cylinder baseline testing. Thus, all LA-4 results are presented on a
'72 hot FTP basis instead of '75 FTP cold start basis. Initial 4-cylinder
testing indicated overly rich operation. It was found that additional
carburetor modifications were required. The vehicle was returned to
Professor Gerrish for modification. After these modifications testing
was conducted on the vehicle in the 4-cylinder configuration. Several
'75 FTP and highway cycles were run.
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Results
The summary of results is given in the attached table I. A 19%
improvement in fuel economy was observed over the LA-4 driving cycle as
a result of the 8-cylinder to 4-cylinder conversion. It should be noted
that the vehicle was unable to follow the trace during the high speed
(57 mph) acceleration. Emissions or hydrocarbons decreased 24%, carbon
monoxide increased 58%, and NOx decreased 5% over the LA-^4 as a result
of this modification. Highway cycle results showed a 16% improvement in
fuel economy. Hydrocarbon emissions decreased by 47%, carbon monoxide
decreased by 33%, and NOx increased by 36%.
Conclusions
1. The "eight to four" conversion technique tested showed potential
for modest (15-20%) fuel economy improvements.
2. Significant performance penalties resulted from the modification,
3. The carburetor modifications required could cause significant
increases in exhaust emissions unless exhaust emission testing is used
to determine the specific changes required for each engine/vehicle com-
bination to be modified.
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TEST VEHICLE DESCRIPTION'
Chassis model year/cake - 1968/Chevrolet Impala
Enission control sy^tera - Eugine nod.
Engine
type V-8
bore x stroke 3.875" x 3.25" (97.7cc x 82.5cc)
displacement 307 CID (5020cc)
compression ratio 9.0
naxinua power Q rpa 20° hP @ A60° rPm
fuel r.etering 2v carb
fuel requireaent regular gasoline
Drive Train
transmission type automatic 3 spd
final drive ratio .3:23
Chassis . . • -'
type . . . body/frame, front engine, rear wheel drive
tire size 8.25 x 14
curb weight 3622 pounds
inertia weight 4500 pounds
passenger capacity ...6
Emission Control System
basic type Engine mod
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Appendix I
Hot Start '72 FTP Results
Test No.
15-4097
15-4090
16-5929
16-5911
Comment
V-8 baseline
V-8 baseline
4-cylinder
4-cylinder
HC
g/mi
4.06
4.64
3.29
3.34
CO
g/mi
18.04
27.27
33.87
37.98
C0£
g/mi
484
550
382
393
NOx
g/mi
4.63
4.47
4.44
4.21
Economy
mpg
16.9
15.7
19.9
19.2
Test No.
15-4097
15-4090
16-5929
16-5911
Appendix II
Highway Cycle Results
Comment
V-8 baseline
V-8 baseline
4-cylinder
4-cylinder
HC
J/ml
3.17
4.14
1.87
1.89
CO
g/mi
17.73
24.68
13.76
14.72
C02
g/mi
363
344
312
319
NOx
g/mi
4.49
5.02
6.35
6.55
Economy
mpg
22.1
22. ^
26.1
25.5
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Table I
Summary of Average Results
baseline
4 cylinders
% chg. from
baseline
baseline
4 cylinders
% chg . from
baseline
HC
g/mi g/km
4.35 2.70
3.32 2.06
-23.7%
3.66 2.27
1.88 1.17
-48.6%
Hot '72 FTP Results
CO NOx
g/mi g/km g/mi g/km
22.7 14.1 4.55 2.83
35.7 22.3 4.33 2.69
58.1% -4.8%
Highway Cycle
21.2 13.2 4.76 2.97
14.2 8.8 6.45 4.01
-32.9% 35.5%
Fuel
Economy
mpg
16.4
19.5
18.9%
22.3
25.8
15.7%
Fuel
Consumption
1/100 km
14.3
12.1
-15.7%
10.5
9.1
-13.2%
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Appendix I
Hot Start '72 FTP Results
Test No.
15-4097
15-4090
16-5929
16-5911
Comment
V-8 baseline
V-8 baseline
4-cylinder
4-cylinder
HC
g/mi
4.06
4.64
3.29
3.34
CO
g/mi
18.04
27.27
33.87
37.98
C02
484
550
382
393
NOx
g/mi
4.63
4.47
4.44
4.21
Economy
mpg
16.9
15.7
19.9
19.2
Test No.
15-4097
15-4090
16-5929
16-5911
Appendix II
Highway Cycle Results
CO
Comment
V-8 baseline
V-8 baseline
4-cylinder
4-cylinder
HC
g/mi
3.17
4.14
1.87-
1.89
17.73
24.68
13.76
14.72
C02
g/n»i
363
344
312
319
NOx
g/mi
4.49
5.02
6.35
6.55
Economy
mpg
22.1
22.4
26.1
25.5
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