75-19 BM
An Evaluation of the
Econo-Mist Device
March 1975
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
-------
Background
The Emission Control Technology Division (ECTD) was contacted by
the General Services Administration (GSA) concerning a vapor injection
device for use with automobile engines. The device is called the Econo-
Mist and is a product of the FAP Corporation of Albuquerque, New Mexico.
GSA had received information that the Econo-Mist reduced hydrocarbon
and carbon monoxide emissions and increased fuel economy. At the
request of GSA, ECTD agreed to test the device. A sample of the device
was brought to the EPA laboratory in Ann Arbor, Michigan by FAP
Corporation personnel on January 13, 1975.
The Environmental Protection Agency receives information about many
devices for which emission reduction or fuel economy improvement 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
identifying 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. \J For promising devices
it is necessary that more extensive test programs be carried out.
I./ See Federal Register 38 FR 11334, 3/27/74, for a description of the
test protocols proposed for definitive evaluations of the effective-
ness of retrofit devices.
-------
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 extra-
polate 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 that lives up to its claims in the EPA
confirmatory test must be further tested according to protocols described
in footnote I/, 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 candidate 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 _!/.
Device Description
The Econo-Mist device is a vacuum vapor induction system which
attaches to the Positive Crankcase Ventilation (PCV) line of an internal
combustion engine. A mixture of water and methanol of approximately
2.5 parts water to 1 part methanol is contained in a glass bottle which
can be attached by means of a bracket to a wall in the engine compart-
ment. A hose and fitting are supplied so that a connection between
the bottle and the PCV line of the engine can be made.
With the device in operation, vacuum from the engine pulls ambient
air through a small orifice in the cap of the bottle and down through a
tube which is immersed in the liquid. At the bottom of the bottle the
air is released through small holes and bubbles up through the liquid.
The resulting vapor is drawn through the vacuum hose which is connected
to the cap of the bottle, through the PCV line, and into the engine
induction system to be mixed with the fuel and air mixture.
An illustration of the device is on the following page. The device
tested has one difference from the figure; in place of the screw (29)
for adjusting air flow, the device has a fixed orifice of .022 inch
diameter in the top of the cap. FAP Corporation personnel stated that
this fixed orifice size gives satisfactory air flow for all vehicles.
When the device was installed on the EPA test vehicles they agreed that
it was performing satisfactorily, having made a visual inspection of
the bubbling occurring within the bottle.
L
-------
ECONO-MIST
To PCV
2oY\ 29-> 21
20 \ \ ^ 15 24 18
'
-------
One gallon of fluid reportedly lasts for about 4000 miles of
vehicle travel. For the vehicle tested this would mean that of the
total volume of liquid entering the engine, the methane1 and water
mixture contributes only about 0.6 percent.
The device was installed by EPA with representatives from FAP
Corporation observing. Installation took about 20 minutes.
• • . > .
Test Procedure ;
Exhaust emissions tests were conducted according to the 1975
Federal Test Procedure ('75 FTP), described in the Federal Register of
November 15, 1972. Additional tests included the EPA Highway Cycle.
All tests were conducted using an inertia weight of 3000 pounds (1361 kg)
with a road load setting of 10.3 horsepower (7.68 kW) at 50 miles per
hour (80.5 km/hr). A 1970 Plymouth Valiant from the EPA test fleet
was used for the test program. A complete description of this vehicle
is given on a following page. •'
The vehicle was tested in three different configurations, first
at the baseline condition, second with the device installed, and third
with the device connected but the bottle of fluid empty. This last
condition was run in order to distinguish the effects of the vapor
induction from the enleanment effect of simply increasing the air-
fuel ratio.
Before the test program began, the vehicle was tuned to the
manufacturer's specifications. The carburetor idle mixture adjust-
ment was set to about 0.15% idle CO. This was a setting at which
the vehicle had previously shown good driveability and fuel economy
and which corresponds to the way a good mechanic would tune the
vehicle. No adjustments were made after the device was installed;
the idle CO did not noticeably change, even though additional air
was entering the engine due to the device, and driveability remained
good.
A schedule of the tests run is given below.
1. Baseline tests without device (2 FTP's and 2 Highway Cycles).
2. Baseline tests with device installed and 25 miles accumulated
on system (2 FTP's and 2 Highway Cycles).
3. Tests with device installed and more than 300 accumulated
miles on system (3 FTP's and 2 Highway Cycles).
4. Tests with device installed but bottle empty of fluid and
more than 300 accumulated miles in this configuration (2 FTP's and
2 Highway Cycles).
-------
TEST VEHICLE DESCRIPTION
Chassis model year/make - 1970 Plymouth Valiant
Emission control system - Engine Modification
Engine
type 4 stroke Otto Cycle, OHV, in-line 6 cyl.
bore x stroke 3.40 x 4.12 in.786.36 x 104.78 mm
displacement 225 CID/3688
compression ratio 8.4:1
maximum power @ rpm 145 hp/108 kW @ 4000 rpm
fuel metering 1-V carburetor
fuel requirement 94 RON gasoline
Drive Train
transmission type 3 speed automatic
final drive ratio .. 2.76:1
Chassis
unitized construction, front engine,
type rear wneel drive 6
tire size FR 78-14
curb weight 2920 lbs/1325 kg
inertia weight 3000 Ibs
passenger capacity 5
Emission Control System
basic type positive crankcase ventilation, engine
modification
mileage on vehicle at start of test program: 17,850
-------
Test Results
Exhaust emissions data summarized below illustrate that the EPA
test vehicle, when fitted with the Econo-Mist device and with 300 miles
accumulated with the device installed, achieved reductions in HC and CO
emissions of 12% and 24% respectively and an increase in fuel economy
of 7%. NOx emissions increased by 1%. Accumulating 300 miles in the
system did not significantly change either emissions or fuel economy
compared to results when the device was initially installed. When the
fluid was emptied and only air was being bled to the engine through the
device, the emissions and fuel economy remained essentially the same
as they were with the fluid.
• 75 FTP Composite Mass Emissions
grams per mile
(grams per kilometre)
Baseline - Avg. of 2
tests
Device at low mileage
avg. of 2 tests
Device with 300 miles
avg. of 3 tests
HC
1.82
(1.13)
1.56
(.97)
1.60
(.99)
CO
NOx
Device with no fluid and 1.60
300 miles - avg. of 2 tests (.99)
12.0 5.93
(7.44) (3.68)
9.52 6.02
(5.90) (3.73)
9.13 6.01
(5.66) (3.73)
9.43 5.96
(5.85) (3.70)
Fuel Economy
(Fuel Consumption)
20.0 miles/gal
(11.8 litres/100 km)
21.5 miles/gal
(10.9 litres/100 km)
21.1 miles/gal
(11.1 litres/100 km)
20.7 miles/gal
(11.4 litres/100 km)
On the EPA Highway Cycle, the Econo-Mist device had the effect
of decreasing HC, CO, and NOx emissions by 2%, 19%, and 3% respectively
when the device had accumulated 300 miles. Fuel economy increased
by 2%. When the fluid was emptied the emissions and fuel economy
remained essentially the same.
Highway Cycle Mass Emissions
grams per mile
(grams per kilometre)
HC
Baseline - avg. of 2 tests .93
(.58)
Device at low mileage - .87
avg. of 2 tests (.54)
Device with 300 miles - .91
avg. of 2 tests (.56)
Device with no fluid and .97
300 miles - avg. of 2 '*•]< (.60)
tests
CO
2.31
(1.43)
2.09
(1.30)
1.87
(1.16)
NOx
6.88
(4.27)
6.63
(4.11)
6.67
(4.14)
2.17 7.24
(1.35) (4.49)
Fuel Economy
(Fuel Consumption)
27.8 miles/gal
(8.5 litres/100 km)
28.9 miles/gal
(8.1 litres/100 km)
28.3 miles/gal
(8.3 litres/100 km)
28.2 miles/gal
(8.3 litres/100 km)
-------
Conclusions
The changes in emission and fuel economy which were noted on the
test vehicle are attributed to the enleanment effect of the Econo-Mist
device and might be matched by bleeding more air to the carburetor.
This could be accomplished by leaning out the idle mixture and/or
the primary jets, or increasing the flow through the PCV line.
Accumulating over 300 miles on the device did not yield any
improvements compared to the results when the device was initially
installed.
-------
Appendix
Table I
'75 FTP Composite Results
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Test Type
Baselines (no device)
Device Baselines
Device with 300 miles
Device with no fluid
HC
1.89
1.76
1.61
1.52
1.64
1.50
1.67
1.55
1.65
CO
13.5
10.4
9.33
9.72
9.57
6.82
11.0
8.45
10.4
co2
422
419
397
389
396
410
398
404
411
NOx
5.54
6.32
6.54
5.49
5.54
6.08
6.41
5.33
6.58
Fuel Ec(
19.8
20.1
21.3
21.7
21.3
20.8
21.1
21.0
20.5
-------
Table II
'75 FTP Individual Bag Results
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Test Type
Baselines (no
device)
Device Base-
lines
Device with
300 miles
Device with
no fluid
Bag 1 Cold
HC CO
3.21
2.54
2.43
2.24
2.59
2.15
2.63
2.29
2.68
53.9
38.5
36.3
36.1
39.1
24.8
41.9
30.8
38.4
Transient
C02 NOx
433
423
412
406
421
421
414
422
436
6.28
7.22
7.65
6.35
7.07
7.70
7.67
6.56
7.89
Fuel
Economy
16.8
18.1
18.6
18.9
18.1
19.0
18.2
18.6
17.6
Bag 2
HC
1.42
1.36
1.28
1.24
1.34
1.31
1.35
1.24
1.32
Hot Stabilized
CO CO- NOx
2.11
2.03
1.80
2.56
1.21
1.57
2.65
2.23
2.26
432
432
408
398
404
422
405
424
417
4.80
5.33
5.68
4.69
4.50
4.71
5.28
4.48
5.55
Fuel
Economy
20.2
20.2
21.4
21.9
21.7
20.7
21.5
20.6
20.9
Bag
HC
1.79
1.94
1.62
1.52
1.50
1.37
1.56
1.59
1.50
3 Hot
CO
4.71
5.19
3.39
3.47
3.28
3.32
3.55
3.50
4.96
Transient
C02 NOx
393
390
365
361
362
381
374
351
381
6.41
7.53
7.36
6.36
6.39
7.46
7.61
6.01
7.58
Fuel
Economy
21.8
22.0
23.6
23.9
23.9
22.7
23.1
24.5
22.5
-------
10
Table III
EPA Highway Cycle
Emissions Results and Fuel Economy
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Test Type
Baselines (no device)
Device Baselines
Device with 300 miles
Device with no fluid
HC
.94
.92
.89
.84
.90
.92
.95
.98
CO
2.28
2.34
2.01
2.17
1.86
1.87
2.05
2.27
co2
312.4
313.0
296.3
305.5
305.8
309.6
309.5
305.5
NOx
7.01
6.74
7.09
6.17
6.23
7.10
6.72
7.75
mpg
27.8
27.8
29.4
28.5
28.5
28.1
28.1
28.4
------- |