76-2 GS
Test Results on a Mercedes-Benz 220D
Diesel Sedan Equipped with a
Comprex Pressure Wave Supercharger
August 1975
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
-------
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 benefits to the Nation from the
identification of systems that can reduce emissions, improve 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 show promise, attempts are made
to schedule tests at the EPA Emissions Laboratory at Ann Arbor, Michigan.
The results of all such 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 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 car used; however, it
is reasonable to extrapolate the results from the EPA 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.
The Diesel engine has long been recognized as a vehicle powerplant
capable of achieving excellent fuel economy. It also has inherently low
gaseous emissions. Because of these qualities EPA is interested in the
Diesel for use in light duty vehicles. As the domestic automotive
industry does not produce anything but conventional gasoline engine
powered automobiles, it was necessary to obtain Diesel powered test
vehicles from foreign manufacturers. Report no. 75-21 by the Technology
Assessment and Evaluation Branch summarizes the results of the emission
characterizations of several Diesel vehicles.
-------
One drawback of the Diesel engine has been its lower power-to-
weight ratio compared to the conventional gasoline engine. For a given
engine weight Diesels routinely have only about 60% of the power output
of gasoline engines. The Diesel powered vehicles covered in report 75-
21 had less horsepower than their gasoline engine powered counterparts.
The vehicle weight-to-horsepower ratio for the cars tested was in the
range of 40 to 45 Ib/hp, which was considerably higher than the 25 to
30 Ib/hp ratio average of vehicles produced in the United States. This
lack of power by domestic standards could be an obstacle to achieving
customer acceptance in the United States.
Supercharging is one method of increasing a Diesel's power output.
Daimler-Benz has investigated supercharging and has recently reported
its experience with a relatively new type of device: the Comprex pressure
wave supercharger developed by Brown-Boveri of Switzerland. Daimler-Benz
and Brown-Boveri have permitted EPA to test the Comprex supercharged
220D Mercedes-Benz developed in their investigation. This report presents
the results of our tests on that vehicle. Also included for comparative
purposes are the results of similar tests on a standard 1975 Mercedes-
Benz 240D.
System Description
For those readers unfamiliar with the mode of operation of the
Comprex pressure wave supercharger, the following description from the
Daimler-Benz paper is included:
MODE OF OPERATION - Figure 1 shows the general arrange-
ment and the mode of operation of the Comprex on the engine.
The crankshaft of the engine (a) drives the cell wheel
(b) of the Comprex via a V-belt drive (c), the multiplication
ratio being constant. The ambient air sucked in at (f) is
compressed in the Comprex and flows, highly compressed (e),
into the engine. The hot high-pressure exhaust gas (d), which
flows from the engine after combustion, transmits a large
proportion of its energy within the Comprex to the air and
flows into the exhaust system at (g).
The Comprex supercharging system is based on the direct
exchange of pulses between the exhaust gas, which is under
increased pressure, and the fresh air using controlled pressure
waves. In detail the process is shown in Figure 2.
E. Eisele, H. Hiereth and H. Polz, "Experience with Comprex Pressure
Wave Supercharger on the High-Speed Passenger Car Diesel Engine,"
Paper 750334, presented at SAE Congress, Detroit, February 1975.
-------
Pressure Wave Mach/ne COMPREX
Supercharging Application
« Engine .
b ttll wheel
t belt drive
rf high pressure erhaust gas HPC
e high pressure air HPA
f hw pressure fir intjke LPA
g low pressure tthaust LPG
BBC SkHTLTHCS 1373
Figure 1
-------
The exhaust gases of the individual cylinders are
collected in the receiver, thus smoothing the exhaust
pulses of the individual cylinders. The exhaust gases
(HPG), which are under increased pressure, flow from
the receiver into the cells of the cell wheel. Since
these cells are filled with fresh air (LPA), the exhaust
gases expell this air. Compression is produced by a
pressure wave which propagates in the static air at
sound velocity and causes an increase in pressure and
an acceleration of the air column in the cell. In this
way energy is directly transmitted from the exhaust gas
to the intake air.
When the pressure wave reaches the high-pressure
air side (HPA) of the cell wheel, the cell must be
connected with the boost air manifold to the engine.
The correct sequence of the cells, that is, the flow
position of the cells, is achieved by the revolving
cell wheel. In order to prevent the flow being disturbed
by the reflected pressure waves, the inlet port of the
exhaust gas is closed when the cell is turned further.
For the same reason, the connection with the boost air
manifold is also interrupted one wave sequence later.
The correct choice of the opening timing point on
the low pressure exhaust gas side (LPG) enables the
exhaust gases, which are still under pressure in the
cell, to be completely expelled into the exhaust. The
resulting depression wave allows fresh air to flow into
the cell from the low-pressure air side (LPA). Part of
the fresh air serves only to cool and completely scavenge
the cells. As soon as the cell is completely refilled
with fresh air, the process is repeated.
The circumferential velocity of the cell wheel and
the sonic speed of the gases have a decisive influence
on the pressure wave process with respect to its function.
If cell wheel speed and engine load are completely
unmatched, this process would be disturbed and consequently
the pressure wave supercharger would no longer function.
For this reason so-called pockets (KT, ET, and GT) are
additionally arranged in the side walls beside the cell
wheel. These are the functional prerequisites for
using the Comprex as a supercharger on an internal
combustion engine, and especially on a passenger car
diesel engine with its wide speed and load ranges.
-------
Receiver
Compression
Pocket
Compression
Wave
iigh Pressure
Gas
High Pressure Air
Expansion Pocket
Expansion Wave
Front Between Gas
and Air
Low Pressure Air
KT For dismatched
ET Speed and load
GT
a Speed of Sound
c Air (Gas) Velocity
u Circumferential Speed
Low Pressure
Gas
/—Scavenging Air
Cell Wheel Unrolled
Velocity Diagram
Figure 2
-------
Because the Comprex was originally designed for truck Diesel en-
gines, the Cxl25 unit was about 50% heavier and 35% longer than one
optimally designed for the higher speed 220D engine. The gross dimensions
and weight of the Cxl25 are given in the vehicle identification sheet of
the 220D Comprex (Table 1).
- The Comprex was belt driven from the engine in a manner similar to
common accessories, with a Comprex-to-engine speed ratio of 4.5:1. As
this resulted in a speed range of the Comprex 50% higher than encountered
with truck engines, internal modifications of the Comprex were required.
Adaptation of the engine to accommodate the supercharger also necessitated
modifications. Briefly these included the following: increasing the
compression ratio from 21:1 to 22:1; modification of the prechamber to
minimize pumping losses of the higher quantity of fuel and air; additional
cooling passages in the .cylinder head; piston redesign; addition of
spray nozzles in the crankcase for continuous oil spray cooling of the
piston head bottoms; crankshaft strengthening by salt bath nitriding
treatment and rolling of crank pin fillets; fuel injection pump plungers
were increased in size to provide increased fuel delivery; injection "
nozzle opening pressure was increased; the governor was modified to
conform to the altered injection quantity characteristics for full load.
Most of the above modification would also be required for more
conventional superchargers providing a similar degree of supercharging.
The Comprex has approximately 100% supercharging above 3500 rpm at full
load. The exhaust.and intake manifolds were replaced by a boost air
manifold and an exhaust gas receiver respectively. Because the Comprex
requires the lowest possible flow resistance in the Intake and exhaust
systems, their redesign was necessary to minimize pressure drops while
handling approximately twice the normal flow rates. Compounding the
design problems of.the intake and exhaust system is the requirement for
noise silencing, since the high speed rotation of the Comprex cell wheel
produces a characteristic siren type noise above 1000 Hz. For the air
intake, adequate noise damping was not entirely achieved due to the
pressure drop requirement and space limitations of the engine compartment.
During cold starts the Comprex does not work well and must be
bridged by an intake air bypass. A solenoid operated flap valve in the
boost air manifold separates the high pressure air section of the Comprex
from the engine. When this flap valve is closed air is drawn into the
engine through vacuum-controlled spring-loaded check valves located in
two tubes connecting the air intake to the boost air manifold at a
location between the flap valve and the engine. Above 500 rpm the solenoid
operated flap valve is open and the boost air pressure supplied by the
Comprex closes the bypass valves.
-------
Figure 3 is a photograph of the Comprex supercharged 220D and the
standard 240D. Figure 4 and 5 are photos of the respective engine
compartments of the 240D and 220D, identifying various components of the
two systems. These two photos give an indication of the difference in
complexity and packaging necessitated by the installation of the Comprex.
Vehicle descriptions of the 220D Comprex and 240D are given in Tables 1
and 2.
Figure 3. 220D Comprex (left)
240D (right)
Test Description
Both vehicles were tested for gaseous emissions, fuel economy and
performance. The emissions testing consisted of the 1975 Federal Test
Procedures ('75 FTP) as described for Diesel vehicles in the Federal
Register of August 7, 1973; the EPA Highway Cycle (HWC), described in
the EPA Recommended Practices for Conducting Highway Fuel Economy Tests;
and steady state driving modes of idle, 15, 30, 45, and 60 miles per
hour. All of these tests were conducted on a chassis dynamometer and
employed the Constant Volume Sampling (CVS) procedure. Per the Federal
Register, hydrocarbon emissions were measured by continuous analysis of
the diluted exhaust by a heated flame ionization detector (HFID), and
carbon monoxide, carbon dioxide, and oxides of nitrogen were analyzed
from the bag samples. Fuel economy for the above tests were determined
by the carbon balance method. -In most cases duplicate runs were made
for each test on each vehicle.
-------
Figure 4. Engine Compartment of 240D
Check Valves
Boost Air Manifold
Silencing
Start U
by-pass
I tubes
Flap Valve Location
Solenoid
Flao Valve
Air Intake
Ducting
Comprex Belt Drive
Figure 5. Engine Compartment of 220D Comprex
-------
Performance was measured by a speed-time trace of full accelerator
depression acceleration from 0 to 60 mph on the chassis dynamometer.
Shifting was done at speeds yielding the best overall acceleration time.
Driveability characteristics that were apparent in the driving cycles
were reported. Diesel Fuel #2 was used for all tests. The starting
procedure for the 240D was conducted according to the owners manuals.
The 220D Comprex, due to special glow plugs, required a longer preglow
time (a minimum of 45 seconds) before cranking.
Results
The zero to sixty mph acceleration times were 18.0 and 25.5 seconds
respectively for the 220D Comprex and 240D. Figure 6 is a comparison of
the speed versus time traces of those accelerations. The greater
acceleration rates of the 220D Comprex throughout the speed range are an
indication of the quick response time of the Comprex during accelera-
tion. This is an advantage over turbine driven superchargers which do
not provide high boost pressures as quickly as the Comprex device because
of a time lag which results as the turbine accelerates itself and the
compressor to the high rotational speeds required to provide full boost.
Turbosuperchargers are not able to continuously remain at the high
rotational speeds they require for the generation of high boost pressures
because inadequate exhaust energy is available during light-load or no-
load conditions. The Comprex supercharger has no inertia induced lag as
it is directly driven by the engine. Direct drive of centrifugal compressors
of the type used in turbosuperchargers is not considered practical
because of the high power consumption that would be required at low
loads. With the Comprex pressure-wave device, however, the parasitic
losses at steady state conditions are minimal.
Also shown on Figure 6 are acceleration curves for typical mid-
sized gasoline powered cars with V-8 and six cylinder engines. The
acceleration performance of the Comprex equipped car is similar to that
of the gasoline cars powered by six cylinder engines.
Table 3 gives the '75 FTP Composite results; individual bag results
are given in Appendix I. Both vehicles had similar emission levels.
While the 220D comprex's average hydrocarbon emissions of 0.26 grams/mile
were roughly 25% greater than that of the 240D they were still well
within even the 1978 Federal Statutory level of 0.41 grams/mile. Similarly,
the 220D Comprex's average carbon monoxide emissions of 1.34 grams/mile
exceeded that of the 240D by approximately 15%; but were still well
below the 1978 Federal Statutory level of 3.4 grams/mile. For oxides of
nitrogen, the Comprex, at 1.4 grams/mile, averaged 10% less than the
240D, and was below the 1977 Federal NOx level of 2.0 grams/mile. The
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60
50
I 40
M
0)
Crt
0)
rH
O
•H
« 20
>
10
Figure 6
0 to 60 MPH
Speed vs. Time Trace
220 D Comprex (4 cyl.)
240 D (4 cyl.)
6 cyl. 3500 Ib. I.W.1
8 cyl. 4500 Ib. I.W.2
1975 Ford Granada 250 C.I.D.
1975 Chevrolet Malibu 350 C.I.D.
10 12 14 16 18
Time (Seconds)
20
22
24
26
28
30
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11
Table 1
TEST VEHICLE DESCRIPTION
Chassis model year/make -Comprex supercharged 1974 Mercedes-Benz 220D
Emission control system -Engine Modification (RFDV)
Engine
4 stroke Pre-chamber Diesel, overhead
type .... camshaft, in-line 4 cylinder
bore x stroke 3.43 in. x 3.64 in. (87.0 mm x 92.4 mm)
displacement 134 CID (2197 cc)
compression ratio 22:1
maximum power @ rpm 88.5 bph (66 kW) @ 3800 rpm
fuel metering high pressure fuel injection, in-line pump
fuel requirement Diesel Fuel #2
Drive Train
transmission type 4 speed manual
final drive ratio 3.46:1
Chassis
type 4 door sedan, front engine, rear drive
tire size 175 SR 14
curb weight 3307 Ibs (1500 kg)
inertia weight 3500 Ibs (1590 kg)
passenger capacity 5
Emission Control System
basic type Engine modification (Reverse Flow
Damping Valve)
additional features Supercharged by a Cxl25 Comprex pressure
wave supercharger with Comprex-to-engine
drive ratio of 4.5:1
Cxl25 Comprex:
Length 13.82 in. (351 mm)
Diameter 6.50 in. (165 mm)
Weight 28.6 Ib. (13 kg)
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12
» ' Table 2
.1 -
> TEST VEHICLE DESCRIPTION
Chassis model year/make - 240D - 1975 Mercedes-Benz
Emission control system - Engine Modification (RFDV)
Engine
4 stroke Pre-chamber Diesel, overhead
' type .... camshaft, in-line 4 cylinder
j bore x stroke 3.58 in. x 3.65 in. (91.0 mm x 92.5 mm)
I displacement 146.5 CID (2400 cc)
i compression ratio ... 21:1
maximum power @ rpm 62 bhp (46 kW) @ 4000 rpm
;' fuel metering high.pressure fuel injection, in-line pump
I fuel requirement Diesel Fuel //2
1 '*•*'.
I Drive Train
transmission type 4 speed manual
final drive ratio 3.69
Chassis
type 4 door sedan, front engine, rear drive
tire size 175 SR 14
curb weight 3190 Ib. (1450 kg)
inertia weight 3500 Ib. (1590 kg)
passenger capacity . . 5
Emission Control System
basic type Engine Modification
additional features RFDV (Reverse Flow Damping Valve)
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Table 3
1975 FTP Composite Results
Mass Emissions in grams per mile
(grams per kilometre)
Vehicle
Mercedes
220 D Comprex
Average
Mercedes
240D
Average
1976 Federal Emission
Standard
1977 Federal Emission
Standard
1978 Federal Statutory
Emission Standard
Fuel Economy in miles per gallon
(litres per 100 kilometres)
HC
0.23
(0.14)
0.29
(0.18)
0.26
(0.16)
0.21
(0.13)
0.125*
(0.08)*
0.21+
(0.13)
1.5
(0.93)
1.5
(0.93)
.41
(0.25)
CO
1.35
(0.84)
1.34
(0.83)
1.134
(0.84)
1.14
(0.71)
1.17
(0.73)
1.16
(0.72)
15.0
(9.32)
15.0
(9.32)
3.4
(2.1)
C02
408
(254)
403
(250)
406
(252)
413
(257)
406
(252)
410
(254)
NOx
1.39
(0.86)
1.39
(0.86)
1.39
(0.86)
1.57
(0.98)
1.53
(0.95)
1.55
(0.96)
3.1
(1.93)
2.0
(1.24)
0.4
(0.25)
Fuel
Economy
24.8
(9.49)
25.1
(9.37)
25.0
(9.43)
24.5
(9.60)
24.9
(9.45)
24.7
(9.52)
u>
* Not Hot FID
+ Non Hot FID value not included
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14
lower level of NOx produced by the 220D Comprex in spite of its higher
combustion temperatures and pressure may be due to the exhaust gas
recirculation effect of the Comprex. As exhaust gas is in actual contact
with incoming air, in the Comprex cell wheel a certain amount of mixing
results in some exhaust being pumped back into the engine.
The 75 FTP fuel economies of the two Diesels were almost identical
at 25 miles per gallon. The Highway Cycle fuel economies and composite
Urban - Highway fuel economies are given in Table 4. (Detailed results
of the Highway Cycles, including gaseous emissions, are given in Appendix
II). For the Highway Cycles, the 220D Comprex at 34.3 miles per gallon
was almost 2 miles per gallon better than the 240D. Figure 7 is the
comparison of the two Diesels' '75 FTP fuel economies with those of the
gasoline powered 1975 model year light duty vehicles certified for sale
in the 49 states and California. The three curves on this figure represent
the maximum, minimum and sales weighted average fuel economies versus
inertia weight of these 1975 vehicles. The two Diesels' fuel economies
were higher than the fuel economy range of the 1975 cars. Figure 8 is a
similar comparison for the Highway Cycle fuel economies. Again the fuel
economies of the 240D and 220D Comprex exceeded the fuel economy range
for their 3500 inertia weight class by a wide margin.
Complete results of the steady state driving modes are shown in
Appendix III. Although not tested in 4th gear at 30 mph, it is expected
that the 220D Comprex fuel economy would have been roughly 25% higher in
top gear than in 3rd gear.
Both cars displayed good driveability. The 220D Comprex had noticeable
smoke during start up and hard accelerations away from idle, while the
240D had nearly invisible exhaust under all modes observed. The 220D
Comprex, with its characteristic high frequency whine, had higher interior
and exterior noise levels. Its interior noise level was tolerable, but
the exterior noise, particularly with the engine compartment hood open,
was annoying at higher speeds. Detailed test results covering smoke,
noise, odor and particulate emissions are yet to be obtained for these
cars by EPA contractor Southwest Research Institute.
Conclusions
The 220D Comprex demonstrated the ability of the Comprex super-
charger to significantly improve Diesel engine performance. The 30%
decrease in the 0-60 mph acceleration time over the standard 240D is
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15
Table 4
Fuel Economies of the 220D Comprex and Standard 240D
in miles per gallon (litres per 100 kilometres)
220D Comprex 240D
Average '75 FTP Fuel Economy 25.0 (9.43) 24.7 (9.52)
Highway Cycle Fuel Economies 34.8 (6.76)
33.8 (6.96) 32.2 (7.31)
34.2 (6.88) 32.8 (7.17)
Average 34.3 (6.86) 32.5 (7.24)
Average Urban-Highway Fuel Economy* 28.5 (8.26) 27.7 (8.50)
* Urban-Highway Fuel Economy = I/[.55(I/'75 FTP F.E.) + .45(l/Hwy F.E.)]
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16
Figure 7
c
o
n)
o
-------
17
Figure 8
e
o
n)
O
CO
0)
Highway Cycle Fuel Economy of 220D Comprex and
240D Diesels vs. 1975 Gasoline Powered Certification Cars
40
35
30
25
20
15
10
220D Comprex
2500
Sales Weighted Average
Minimum
_L
3000
3500
4000
4500
5000
5500
Inertia Weight
-------
18
impressive particularly when it was achieved with no loss in the charac-
teristically good Diesel fuel economy. With the exception of a 25%
increase in hydrocarbons, the gaseous emissions were nearly the same as
those of the 240D. The emissions of both cars were well below the 1977
Federal levels.
The 220D Comprex, as tested, was a low mileage experimental system
with uncertain durability. A Comprex specifically designed for the
smaller high speed engine, and an engine completely redesigned to accommodate
the supercharging should be capable of acceptable reliability. Whether
or not the added weight, bulk, noise silencing, and complexity can be
resolved in an economically viable system, however, remains to be seen.
Further improvements over the prototype Comprex-equipped vehicle
tested in the areas of noise control and transient smoke emission seem
desirable. An investigation into the potential for lower NOx emissions
with a Comprex-equipped engine also appears to be in order.
-------
Appendix I
1975 Federal Test Procedure Individual Bag Results
Mass Emissions in Grams per Mile Fuel Economy in Miles per Gallon
TEST NO.
Mercedes 220D
Comprex
16-9062
16-9085
Mercedes 240D
16-9239
15-9215
BAG NO.
1
2
3
1
2
3
1
2
3
1
2
3
HC
.21
.27
.18
.28
.33
.21
.22
.23
.17
.14*
.22
.16
CO
1.40
1.41
1.20
1.36
1.40
1.19
1.19
1.22
.95
1.17
1.27
.99
CO?
416
422
376
424
416
363
424
424
386
423
414
380
NOx
1.39
1.39
1.38
1.43
1.42
1.31
1.50
1.63
1.51
1.56
1.53
1.50
FUEL BARO. P.
ECONOMY "HG
24.3 28.83
24.0
26.9
23.9 29.15
24.3
27.8
23.9 28.69
23.9
26.3
23.9 29.05
24.5
26.7
TEMP F RELATIVE
DRY WET HUMIDITY
76.0 60.0 38%
76.0 59.0 35%
75.0 61.0 44%
76.5 60.0 37%
Not Hot FID
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Appendix II
'75 Highways Fuel Economies
Mass Emissions, Grams Per Mile
Fuel Economy, Miles Per Gallon
TEST TYPE
Mercedes 220D Comprex
Average
Mercedes 240D
HC
0.12
0.11
0.13
0.12
0.09
0.09
CO
0.77
0.77
0.77
0.76
0.65
0.68
co2
291
300
297
296
316
310
NOx
1.21
1.19
1.23
1.21
1.45
1.44
FUEL
ECONOMY
34.8
33.8
34.2
34.3
32.2
32.8
BARO. P.
"HG
28.87
28.83
29.15
28.69
29.05
TEMP RELATIVE
DRY WET HUMIDITY
76.0
76.0
76.0
75.0
76.5
63.0
60.0
59.0
61.0
60.0
55%
49%
46%
52%
49%
TEST NO.
15-9124
16-9062
16-9065
16-9239
15-9215
10
O
Average
0.09 0.66 313
1.45
32.5
-------
Mercedes 220D
Comprex
Mercedes 240D
Grams/hour
Hours/gallon
APPENDIX III
Steady State Driving Modes Results
Mass Emissions Grams Per Mile Fuel Economy Miles Per Gallon
Speed
0
15
30
45
60
0
15
30
45
60
0
15
30
45
60
0
15
30
45
60
Gear
N
2
3
4
4
N
2
3
4
4
N
2
4
4
4
N
2
3
4
4
Emissions
HC CO C02
3.24+
0.35
0.23
0.11
0.14
4.44+
0.44
0.24
0.21
0.26
8.76
1.60
1.17
0.70 -
0.89
8.52+
1.44
0.98
0.69
0.89
0.996+6.72+
0.25
0.07
0.11
0.05
2.16+
0.20
0.19
0.42
0.33
1.56
0.48
0.40
0.56
7.2+
1.43
0.97
0.66
0.62
190
385
279
257
320
191+
476
707
271
344
146+
366
220
265
343
152+
370
290
269
361
NO*
10.86+
1.25
0.69
0.74
1.68
10.20+
1.26
0.72
0.78
1.75
9.6+
2.32
2.06
0.67
1.88
6.12+
1.17
1.01
1.11
1.80
Fuel
Economy
3.85*
26.3
36.2
39.5
31.6
4.35*
26.5
35.7
37.3
29.4
5.78*
27.6
46.2
38.2
29.6
5.56*
27.3
34.8
37.6
28.1
Baro. P.
"HG
29.0
29.0
29.0
29.00
29.00
28.90
28.90
28.90
28.90
28.90
28.85
28.85
28.85
28.85
28.85
29.2
29.2
29.2
29.2
29.2
Temp.
Dry Wet
75.0
75.0
75.0
74.5
74.5
75.0
75.0
75.0
77.0
77.0
78.0
80.0
80.0
84.0
84.0
76.0
76.0
76.0
76.0
76.0
61.0
61.0
61.0
60.5
60.5
60.0
60.0
60.0
60.0
60.0
61.0
61.5
62.0
63.0
63.0
58.5
58.5
58.5
58.0
58.0
Hum.
52%
52
52
52
52
50
50
50
48
48
49
49
50
49
49
45
45
45
45
45
Test No.
15-9140
15-9140
15-9140
15-9141
15-9141
16-9101
16-9101
16-9101
16-9102
16-9102
15-692
15-732
15-731
15-658
15-730
16-9390
16-9390
16-9390
16-9391
16-9391
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