EPA-AA-TAEB-80-10
Evaluation of the Ram-Jet Device,
a PCV Air Bleed
January 1980
by
Edward Anthony Earth
Test and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
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Background
The Environmental Protection Agency receives information about many
systems which appear to offer potential for emission reduction or fuel
economy improvement compared to conventional engines and vehicles.
EPA's Emission Control Technology Division is interested in evaluating
all such systems, because of the obvious potential benefits to the
Nation from the identification of systems that can reduce emissions,
improve fuel economy or both. EPA invites developers of such systems to
provide complete technical data on the system's principle of operation,
together with available test data on the system. In those cases for
which review by EPA technical staff suggests that the data available
shows promise or EPA is requested to test the device by other governmental
agencies, attempts are made to schedule confirmatory tests at the EPA
Motor Vehicle Emission Laboratory at Ann Arbor, Michigan. The results
of all such test projects are set forth in a series of Test and Evaluation
Reports, of which this report is one.
The Ram-Jet is a retrofit device marketed by Ed Almquist. It is designed
to bleed in extra air to the engine by allowing ambient air to bypass
the carburetor under high engine load conditions. The manufacturer
claims the device reduces emission pollutants and improves fuel economy.
EPA has tested several PCV air bleed devices previously and disseminated
the test results. However, due to the increased recent interest in fuel
economy and emissions reduction by the public, EPA has received a large
number of governmental and private inquiries about the benefits of
retrofit devices. To better respond to these requests, EPA is endeavoring
to perform additional tests. Therefore, in response to a request from
the Federal Trade Commission, EPA conducted a series of tests on the
Ram-Jet device.
The conclusions drawn from the EPA evaluation tests are necessarily of
limited applicability. A complete evaluation of the effectiveness of an
emission control system in achieving 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
evaluation test projects conducted by EPA. For promising systems it is
necessary that more extensive test programs be carried out.
The conclusions from the EPA evaluation test can be considered to be
quantitatively valid only for the specific test vehicles used; however,
it is reasonable to extrapolate the results from the EPA test to other
types of vehicles in a directional manner, i.e., to suggest that similar
results are likely to be achieved on other types of vehicles.
Summary of Findings (Test Vehicles grouped together)
Overall, the Ram-Jet device did not significantly affect the vehicle's
HC emissions for either the FTP or HFET.
Overall, the Ram-Jet device did not significantly affect the vehicle's
CO emissions for either the FTP or HFET. The results for individual
vehicles and tests were mixed. There were small increases and decreases
in CO emissions.
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Overall, the Ram-Jet device did not significantly affect the vehicle's
NOx emissions.
Overall, the Ram-Jet device did not significantly affect the vehicle's
fuel economy. However, the Ram-Jet device tended to cause a small decrease
in fuel economy for some vehicles.
Device Description
The Ram-Jet is an after-market device designed to bleed in extra air to
the engine under moderate to heavy load conditions (see figure 1). The
device is installed in a vehicles' PCV line. Since the carburetor PCV
hose fitting is below the carburetor venturi, any flow through this line
bypasses the venturi thus leaning out the air/fuel charge reaching the
engine.
Fresh Air
PCV Plus
Fresh Air
Figure 1: Cross Sectional View of the Ram-Jet
In operation, air enters the top of the Ram-Jet, is filtered, passes
through an adjustable ball-and-spring type valve, and enters the PCV
line. Under conditions of high manifold vacuum (i.e., idling, coasting,
or cruising at moderate speeds) the ball-and-spring valve is designed to
close. This prevents extra ambient air from being drawn through the Ram-
Jet and into the PCV line and then to the engine below the carburetor
venturi. Thus the vehicle operation should be identical to the unmodified
condition. Under conditions of low manifold vacuum (i.e., accelerating,
high speeds, hill climbing and pulling a load) the valve is designed to
open. This allows extra ambient air to enter the intake system below
the carburetor venturi thus leaning out the carburetor fuel/air mixture.
The manufacturer claims the following benefits for his device:
-reduced HC, CO and NOx emissions
-increased fuel economy
-better engine performance
-reduction in combustion chamber deposits
-reclaims wasted blow by condensates
-improves carburetion and PCV efficiency during all operating
conditions whether the air valve is open or not.
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Th e manufacturer claims these benefits are immediately obtained except
for the reduction in combustion chamber deposits which only occurs
gradually.
Test Vehicle Description
The three test vehicles used in this study were:
A 1979 Chevrolet Impala equipped with a 5.7 litre V-8 engine, automatic
transmission and air conditioning. This vehicle used EGR and an oxidation
catalyst for emission control.
A 1979 Chrysler LeBaron equipped with a 318 CID Lean Surn v-8 engine,
automatic transmisssion and air conditioning. This, vehicle was equipped
with EGR and an oxidation catalyst for emission control. -
A 1975 Dodge Dart equipped with a 225 cubic inch inline 6-cylinder
engine and an automatic transmission. This vehicle was calibrated to
meet the 1975 California emission standards. This vehicle used an air
pump, EGR, and an oxidation catalyst for emission control.
A complete description of these vehicles is given in the test vehicle
description in Appendix A.
Test Procedure
Exhaust emission tests were conducted according to the 1977 Federal Test
Procedure (FTP) described in the Federal Register of June 28, 1977 and
the EPA Highway Fuel Economy Test (HFET) described in the Federal Register
of September 10, 1976. The vehicles were not tested for evaporative
emissions.
Prior to baseline testing, each vehicle was give a specification check
and inspection. The ignition timing, idle speed, and fast idle speed
were checked for agreement with the manufacturer's specifications given
on the Vehicle Emission Control Information label affixed to the engine
compartment. Each vehicle met its manufacturer's specification and
therefore no adjustments were required.
The vehicles were inspected for engine vacuum leaks, proper connection
of vacuum hoses, functioning PCV valve, oil and water levels and general
condition of engine compartment. Each vehicle was in satisfactory
condition when initially inspected.
The vehicles were tested in the baseline (stock) configuration and with
the device installed. At each test condition, a minimum of two FTP and
HFET tests were conducted.
For tests with the Ram-Jet .installed, the device was adjusted per. the
device manufacturer's instructions so that it closed at idle and opened
at moderate loads.
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Test Results
The objective of this test program was to determine if the Ram-Jet
caused a significant beneficial change in vehicle emissions or fuel
economy.
The test results are summarized in Tables I and II below. The results
of individual tests are given in Tables III and IV in the appendix.
Table I
FTP Mass Emissions
grams per mile
Test Condition HC CO^ C02 NOx MPG
Chevrolet Impala
Baseline Avg. (3 tests) 0.63 4.80 565 1.27 15.5
Ram-Jet Avg. (2 tests) 0.61 3.96 581 1.19 15.0
Chrysler LeBaron
Baseline Avg. (3 tests) 0.77 8.47 566 1.30 15.2
Ram-Jet Avg. (2 tests) 0.68 7.48 577 1.46 15.0
Dodge Dart
Baseline Avg. (2 tests) 0.44 6.53 550 2.05 15.8
Ram-Jet Avg. (2 tests) 0.61 6.92 551 1.93 15.7
Table II
Highway Fuel Economy Test Mass Emissions
grams per mile
Test Condition HC CO C00 NOx MPG
2.
Chevrolet Impala
Baseline Avg. (4 tests) 0.12 0.41 410 1.60 21.6
Ram-Jet Avg. ( 3 tests) 0.12 0.61 413 1.50 21.4
Chrysler LeBaron
Baseline Avg. (2 tests) 0.20 1.33 392 1.35 22.5
Ram-Jet Avg. (2 tests) 0.18 0.99 390 1.40 22.6
Dodge Dart
Baseline Avg. (2 tests) 0.05 0.21 359 3.14 24.7
Ram-Jet Avg. (2 tests) 0.05 0.08 364 2.78 24.3
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1. Federal Test Procedure
The Ram-Jet device did not significantly affect the HC emissions from
the Impala or the LeBaron. It did tend to increase the Dart's HC emissions,
The use of the Ram-Jet caused mixed results on CO emissions. The Impala's
FTP CO emissions were significantly reduced. The LeBaron's FTP CO
emissions tended to be reduced. However this change was not significant
due to the test-to-test variability in the LeBaron's CO emissions. The
Dart's CO emissions tended to be increased by the use of the Ram-Jet.
Again this change was not significant due to the variability in the
Dart's CO emissions.
The use of the Ram-Jet caused no significant change in NOx
emissions for the FTP. The Impala's emissions were not affected by the use
of the Ram-Jet. The LeBaron's NOx emissions tended to be increased.
The Dart's NOx emissions tended to be decreased.
The Ram-Jet did not significantly affect the vehicle's fuel economy.
The device did tend to cause a small loss in fuel economy for the Impala
and LeBaron.
2. Highway Fuel Economy Test
The HC emissions on all three vehicles were low both with and without
the Ram-Jet. The HFET HC emission results were identical.
Again, the Ram-Jet caused mixed results on CO emissions. The Impala's
HFET CO emissions tended to increase with the use of the device. The
LeBaron's and Dart's HFET CO emissions were significantly reduced by the
Ram-Jet.
On one baseline test, the Dart's NOx emissions were appreciably higher.
However, overall, all three vehicles' HFET NOx emissions and fuel economy
were not significantly affected by the use of Ram-Jet.
3. Other
On one FTP and one HFET, the LeBaron ran roughly when the Ram-Jet device
was installed. The Dart stalled on one baseline test. There were no
other noticeable changes in vehicle performance.
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Discussion of Vehicle operating and maintenance tips furnished with Ram-Jet
The Ram-Jet installation instructions contain numerous tips to help the
driver increase fuel economy. They can be classified into two broad
categories-careful driving habits and vehicle maintenance. The instructions
also note that due to variability in the operator's usage of a vehicle,
fuel economy should be averaged over at least ten tankfuls of gasoline
(about 2500-3000 miles).
A driver who conscientiously follows the careful driving habit recommendations
and tune-up suggestions should notice a significant improvement in
vehicle fuel economy. Drivers who bought the Ram-Jet to improve fuel
economy would be expected to follow these suggestions. They would
therefore, be expected to note a significant improvement in fuel economy
which they might tend to attribute to the device. However, for a driver
to properly determine the benefits of the Ram-Jet, the driver would
first have to drive without the device (after just purchasing Ram-Jet)
and then with the device, using the same driving and vehicle maintenance
procedures.
Many users would be unwilling to delay usage for so long. And therefore
the driver would have a built in bias for believing that the device
improved fuel economy.
Conclusions
Overall the Ram-Jet showed no significant beneficial change in the test
vehicles' emissions or fuel economy. HC emissions were generally unaffected
by the device. CO emission results were mixed. There were small increases
and decreases in CO emissions caused by the device. NOx emissions were
unaffected by the use of Ram-Jet.
Fuel economy was either unaffected or tended to decrease with the use of
the Ram-Jet.
EPA has tested several PCV air bleed devices in the past. These devices
did not improve fuel economy. Small reductions in HC or CO emissions
and small increases in NOx emissions occurred in some of these tests.
However, these same effects can be achieved through carburetor enleanment
and ignition retard. For most vehicles, these are simple adjustments.
The Ram-Jet PCV air bleed did not exhibit any significant change in this
trend.
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Appendix
TEST VEHICLE DESCRIPTION
Chassis model year/make-1979 Chevrolet Impala
Vehicle I.D. 1L47L9S115799
Engine
type Otto Spark, V-8
bore x stroke 4.00 x 3.48 in/101.6 x 88.4 mm
displacement 350 CID/5.7 liter
compression ratio 8.3:1
maximum power @ rpm 170 hp/ 126 k W
fuel metering 4 venturi carburetor
fuel requirement Unleaded, tested with indolene HO unleaded
Drive Train
transmission type 3 speed automatic
final drive ratio 2.41
Chassis
type 2 door sedan
tire size FR 78 x!5
curb weight 3840 lb/1742 bg
inertia weight 4000 Ib.
passenger capacity 6
Emission Control System
basic type EGR
Oxidation Catalyst
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A|>pi'inl I :••: A
TEST VEHICLE DESCRIPTION
Chassis model year/make-1979 Chrysler LeBaron
Vehicle I.D. FM41G9F150932
Engine
type Otto Spark, V-8
bore x stroke 3.91 x 3.31 in/99.3 x 84.1 mm
displacement 318 CID/5211 CC
compression ratio 8.61:1
maximum power @ rpm 145 hp/108 k W
fuel metering 2 Venturi carburetor
fuel requirement Unleaded, tested with indolene HO unleaded
Drive Train
transmission type 3 speed lockup automatic
final drive ratio 2.50
Chassis
type 4 door sedan
tire sj.ze FR 78 X 15
curb weight 3660 Ib. /1660 kg
inertia weight 4000 Ib.
passenger capacity 6
Emission Control System
basic type EGR
Oxidation catalyst
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Appendix
TEST VEHICLE DESCRIPTION
Chassis model year/make-1975 Dodge Dart
Emission Control System-Air Pump, Catalyst EGR
Vehicle I.D. LH41C5B290359
Engine
type Inline 6, 4 cycle
bore x stroke 3.40 X 4.125 in.
displacement 225 CID/3687 cc
compression ratio 8.4:1
fuel metering ». 1 Venturi, carburetor
fuel requirement unleaded, tested with Indolene HO unleaded
Drive Train
transmission type 3 speed automatic
final drive ratio 2.75
Chassis
type 4 door sedan
tire size D78 X 14
inertia weight 3500 Ibs.
passenger capacity 6
Emission Control System
basic type air pump
oxidation catalyst
EGR
calibrated to 1975 California standards
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Table III
FTP Mass Emissions
grams per mile
Test Condition
Chevrolet Impala
Baseline
Baseline
Baseline
Ram-Jet
Ram-Jet
Chrysler LeBaron
Baseline
Baseline
Baseline
Ram-Jet
Ram-Jet
Dodge Dart
Baseline
Baseline
Ram-Jet
Ram-Jet
Test//
HC
CO
CO,
NOx
MPG
80-0573
80-0575
80-0446
80-0442
80-0443
.72
.59
.58
.66
.56
4.85
4.54
5.01
4.12
3.80
569
565
560
586
575
1.29
1.29
1.23
1.20
1.17
15.3
15.5
15.6
14.9
15.2
80-0585
80-0556
80-0587
80-0552
80-0554
.74
.69
.87
.64
.72
5.86
9.51
10.05
6.62
8.33
567
575
557
577
577
1.34
1.31
1.24
1.57
1.35
15.3
15.0
15.4
15.0
15.0
80-0246
80-0735
80-0292
80-0294
.38
.50
.66
.55
6.06
7.00
7.25
6.59
547
553
550
552
1.99
2.11
1.86
2.00
15.9
15.7
15.7
15.7
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Table IV
Highway Fuel Economy Test Mass Emissions
grams per mile
Test Condition
Chevrolet Impala
Baseline
Baseline
Baseline
Baseline
Ram-Jet
Ram-Jet
Ram-Jet
Chrysler LeBaron
Baseline
Baseline
Ram-Jet
Ram-Jet
Dodge Dart
Baseline
Baseline
Ram-Jet
Ram-Jet
Test//
HC
CO
C00
NOx
MPG
80-0438
80-0574
80-0445
80-0886
80-0439
80-0441
80-0444
.13
.13
.11
.10
.12
.12
.11
.46
.29
.35
.54
.69
.72
.42
399
415
422
402
415
410
414
1.57
1.60
1.67
1.55
1.52
1.51
1.47
22.2
21.3
21.0
22.0
21.3
21.6
21.4
80-0586
80-0557
80-0553
80-0555
.20
.19
.17
.18
1.40
1.26
.76
1.22
396
387
388
392
1.34
1.35
1.40
1.40
22.2
22.8
22.8
22.5
80-0316
80-0734
80-0293
80-0295
.05
.06
.05
.05
.19
.22
.08
.08
356
362
367
361
2.79
3.48
2.79
2.76
24.9
24.5
24.2
24.6
* US. GOVERNMENT PRINTING OFFICE: 1980- 651-112/02U
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