78-1 AB
Emissions and Fuel Economy Testing of
a Naval Academy Heat Balanced Engine (NAHBE)
April 1978
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
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Background
For several years personnel at the Naval Academy have been involved in
research efforts directed toward improving the combustion cycle of spark
ignition engines. They have developed a technique which is stated to be
based on pressure exchange between two zones in the combustion chamber
thereby achieving a heat balanced cycle (NAHBE) which combines the best
characteristics of the Diesel and Otto cycles. The developers claim
that their technique: increases engine efficiency; provides more complete
fuel oxidation and therefore lowers HC and CO emissions; reduces peak
cylinder pressures; reduces engine temperature; and reduces engine knock
tendencies. The hardware utilized by the Naval Academy personnel in
implementing this concept consists of a standard Otto cycle engine in
which the head of the piston has been modified to establish two distinct
combustion volumes and the intake system has been modified through
enleanment of the carburetor and the addition of an air bleed with
claimed stratification of the intake charge.
In 1977 EPA was requested to test an engine modified to the NAHBE con-
figuration. EPA was furnished two new, military, motor/generator sets
(one NAHBE and one stock) for evaluation of the NAHBE concept. The
required break-in of the new engines delayed the completion of testing
until early 1978.
The primary responsibility of the EPA Motor Vehicle Emission Lab is to
test and evaluate vehicles. Therefore, there are only limited facilities
and resources available to test a motor-generator set. A comprehensive
evaluation of the NAHBE concept was, therefore, neither planned nor
conducted. The testing conducted was, however, complete enough to
characterize the fuel economy and emissions of the test engines under
the operating conditions permitted by the motor-generator configuration.
The conclusions drawn from this EPA evaluation test can be considered to
be qualitatively and quantitatively valid only for the specific, motor-
generator set used; however it is reasonable to extrapolate the results
from the EPA test to other types of engine applications in a qualitative
manner, i.e., to suggest that similar results are likely to be achieved
on other types of engines using similar emission control technology for
similar applications.
Summary of Findings*
1. As delivered and operating on gasoline under steady state condi-
tions, the NAHBE engine HC and CO emissions were substantially
lower than the stock engine; NOx emissions were substantially
higher than the stock engine and the thermal efficiency was signi-
ficantly higher than the stock engine.
*A11 HC, CO, and NOx comparisons are based on grams per kW hr. All
thermal efficiency comparisons are based on kW hr per BTU of fuel.
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2. Operation of the stock engine with the induction system and car-
buretor from the NAHBE engine resulted in changes in emissions and
thermal efficiency which, within the constraints of experimental
error, were identical to those observed with the NAHBE engine.
3. Operation of the NAHBE engine on alcohol caused an incease in HC
emissions and a substantial reduction in NOx emissions relative to
operation on gasoline. CO emissions and thermal efficiency were
unchanged.
4. When operated on gasoline, the NAHBE engine, the stock engine, and
the stock engine with the NAHBE induction system and carburetor
performed satisfactorily with changes in load and under steady load
conditions. Operation of the NAHBE engine on alcohol resulted in
unsastifactory operation both under steady state and changing load
conditions. When operated on alcohol, carburetor adjustments were
required at each load change.
5. Exhaust gas temperatures of the NAHBE engine were, in general,
significantly higher than those of the stock engine.
6. Test results from this program were compared to data from an EPA
contractor test program on several commercial engines of similar
size and type. This comparison showed that:
a) HC emissions from the stock engine were, on average, higher
than those from gasoline fueled commercial engines and much
higher than those from diesel engines.
b) HC emissions from the NAHBE engine were lower than those from
gasoline fueled commercial gasoline engines and up to 200
times higher than those from the diesel engines.
c) CO emissions from the stock engine were on average, twice as
high as those from commercial gasoline engines and up to 200
times higher than those from diesel engines.
d) CO emissions from the NAHBE engine were significantly lower
than from the commercial gasoline engines while being up to
five to ten times higher than those from diesel engines.
e) NOx emissions from the stock engine were lower than those from
the commercial gasoline engines and substantially lower than
those from the diesel engines. '
f) NOx emissions from the NAHBE engine were higher than those from
the diesel engines and significantly higher than those
from the commercial gasoline engines.
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g) The thermal efficiency of the stock engine was between 3% and
39% lower than the worst commercial gasoline engine, between
32% and 57% lower than the best commercial gasoline engine
used in the comparison and between 46% and 71% lower than the
diesel engines used in the comparison.
h) The thermal efficiency of the NAHBE engine was between 14%
higher and 16% lower than the worst commercial gasoline engine
used in the comparison, between 20% and 41% lower than the
best commercial gasoline engine and between 37% and 60% lower
than the diesel engines used in the comparison.
Conclusions'"'
The stock engine used in the NAHBE engine project is not representative
of similar commercial engines and is therefore not a good engine for
comparative purposes because it provides misleadingly large improvements
for the NAHBE concept. When compared to representative commercial
engines, the NAHBE engine is at a significant disadvantage both with
respect to thermal efficiency and NOx emissions, while appearing to
offer some benefits in HC and CO emissions relative to gasoline engines
through enleanment of the air/fuel mixture. The ability to sustain this
apparent HC and CO benefit is questionable, however, because many engines
of this type depend on charge cooling (operating fuel rich) as a method
for attaining acceptable engine life.
All of the emission and fuel consumption characteristics of the NAHBE
engine can be reproduced on the stock engine through the substitution of
the NAHBE induction system (modified intake manifold and a modified
carburetor with a modified metering rod) for the stock components. It
appears, therefore, that the modified piston which is used in the NAHBE
concept and which is claimed to be its major feature, did not contribute
significantly to the observed changes in performance of the test engine.
Performance of the NAHBE engines on alcohol, as built, was unsatisfactory.
It is not clear whether this poor performance is inherent with the NAHBE
concept or whether it is the result of inadequate development of the
test engine.
The results of this test and evaluation project indicate that the NAHBE
concept did not offer any benefits in either emissions or fuel economy
when compared to similar gasoline and diesel engines.
Test Engine Description
The engines delivered for testing were 10 hp military motor generator
sets designed to produce 5 kW of continuous power. The generator is
*A11 HC, CO, and NOx comparisons are based on grams per kW hr. All
thermal efficiency comparisons are based on kW hr per BTU of fuel.
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directly attached to the engine crankshaft and operates at engine rpm.
The units are self contained and designed to be operated at all ambient
temperatures. They are skid mounted in a tubular frame. The engines
and generators are manufactured to military specifications by several
manufacturers. Therefore, although the two engines tested were manu-
factured by Wisconsin and Hercules, they are identical in all respects
and have complete parts interchangeability. A complete description of
the motor-generator sets is given in Appendix A at the end of this
report.
The conversion of a stock engine to NAHBE configuration principally
consists of changes to the piston (see Figures 1 & 2) and the fuel/air
induction system by using modified metering rods and by introducing
small air bleeds (see Figure 3). The piston is modified by the addition
of a cap which separates the combustion chamber into two zones (a primary
combustion zone and a balancing combustion zone). According to the
developers, this design, coupled with the air bleed, stratifies the
combustion fuel-air mixture by introducing additional air through the
auxilary air inlet at the start of the intake stroke. During compression
the leaner mixture is forced into the balancing chamber. This balancing
chamber mixture is compressed during ignition and subsequently flows out
to the main chamber during the later stages of combustion. The combustion
process is thereby prolonged and allowed to achieve a greater degree of
completion than the stock engine.
However, the calibrated orifices of the auxilary air bleeds are very
small (about 1/8" diameter) and therefore appear to introduce little air
when compared to the one inch manifold tube. This air is introduced
before the intake valve, thus there is no special means for assuring
that this air enters the balancing chamber undiluted as claimed.
The NAHBE is designed for multi-fuel capability. Because the BTU content
per unit volume is higher for gasoline than for alcohol, operation of
the ,NAHBE engine with gasoline requires lower volumetric fuel flow than
with alcohol. The developers furnished metering rods designed to
accomplish this. The developers indicated that the stock metering rod
was'to be used with gasoline and that the modified metering rod was to
be used with alcohol. Additional enleanment is also provided on the
NAHBE by the carburetor to intake manifold air bleed.
The fuel system components were not modified for sustained operation on
alcohol. To prevent deterioration of fuel system components the engine
must be switched over to gasoline prior to shutting down.
Test Procedures
Testing procedures for the engines in this project were adapted from the
procedures used in the testing of heavy-duty engines by EPA for emis-
sions certification and in the development of engine performance maps by
engine manufacturers. Testing was performed at the governed (rated)
speed of the engines and represents, therefore, modes 8 through 12 of
the heavy-duty diesel procedure. These modes are 100, 75, 50, 25 and 0
percent of rated load at rated (governed) speed.
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Standard
Geometry
Valves
Valves
(17° inclined)
Spark Plug
Hemispheric Head
•Piston
STOCK ENGINE
NAHBE Changes in Basic Geometry
Head Modification
Balancing Chamber Geometry
Solid Addition
NAHBE ENGINE
Figure 1 - NAHBE Changes in Basic Combustion Chamber Geometry
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Chamber
Cap
Clearance to
cylinder wall
.075 in.
Standard
Piston \
NAHBE MODIFICATION
Figure 2
Schematic of NAHBE Piston Modification
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Calibrated
Orifice
Bleed Valve
fr
r
i
j
1
!
TJ
r~~Z NAHBE Addition
Stock induction
Calibrated
Orifice
Figure 3 - Fuel Air Induction System
speed of the engines and represents, therefore, modes 8 through 12 of
the heavy-duty diesel procedure. These modes are 100, 75, 50, 25 and 0
percent of rated load at rated (governed) speed.
Gaseous exhaust emission tests were run using the analytical equipment
and sampling system specified in the 1977 Federal Test Procedure ('77
FTP) described in part 40 of the Combined Federal Register of July 1,
1976 for light-duty vehicles. All tests were steady state and followed
the heavy-duty diesel test schedule. A thermocouple was installed in
the muffler outlet to monitor exhaust gas temperature (EGT) as an aid in
evaluating test results.
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The engines/generators were loaded by using a resistive load bank to
dissipate the engine/alternator power. Alternator voltage, current, and
frequency were controlled and monitored for all testing. The voltage
was held at 110V and the frequency at 60 cycles during engine break-in
and during all testing. The engine exhaust was collected by the con-
stant volume sampling (CVS) procedure which gives exhaust emissions of
HC, CO, C0_ and NOx in grams per kW hr. Fuel economy was calculated by
the carbon balance method. The fuels used were Indolene 30, a leaded
100 RON gasoline, and denatured ethyl alcohol (190 proof, 95% ethyl
alcohol). All fuel consumption results for tests using alcohol are
given as gallons of denatured alcohol. All tests were conducted at 3600
rpm (governed speed).
Testing
When delivered the engines were "green". The stock engine/alternator
had 3.2 total hours and the NAHBE had 6.1 total hours. Apparently both
had only been operated during manufacturing inspection check out and
following modification to the NAHBE concept. Therefore, before testing,
the engines were broken in by operating them to 50 hours total operating
time. Break-in consisted of a repetitive cycle of running the engines
for two hours at each load (50, 75, and 100 percent of full load). All
break-in was done with Indolene 30 fuel.
Exhaust emissions were periodically measured throughout the break-in to
establish whether or not emission levels had stabilized prior to of-
ficial testing. Also during break-in a few tests were performed to
determine the potential effects of fuel/air mixture changes on the two
engines. These break-in results are tabulated in Tables C-l and C-2 at
the end of this report.
After the engines had accumulated approximately 50 total hours the
engines were tested for emissions and fuel consumption. Both engines
were extensively baseline tested with their respective standard induction
system. The baseline configuration for the NAHBE used the NAHBE induction
system consisting of the modified intake manifold and a modified car-
buretor with a modified metering rod. The baseline configuration of the
stock engine used the stock induction system consisting of a stock
intake manifold and a stock carburetor with a stock metering rod.
The induction systems of both engines were changed from their baseline
configuration to investigate the effects of changes in fuel/air ratio on
the engines emissions and fuel consumption performance. The NAHBE was
tested with the modified intake manifold, modified carburetor and the
stock metering rod. The stock engine was tested with modified intake
manifold, modified carburetor, and both the stock and modified metering
rods.
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According to the engine developers, the NAHBE induction system, as
delivered, had a modified fuel metering rod installed which was cali-
brated for the larger fuel flow required for alcohol. When tested with
alcohol, the NAHBE surged badly apparently because of too lean a mixture.
The engine developer who was witnessing the tests raised the float level
and readjusted the idle mixture to stop the heavy surge. However, after
running a few minutes, the engine again surged slightly. Also the
engine required additional manual adjustment whenever the load was
changed. Therefore, with the necessary warmup, stabilization, the high
fuel consumption and the restart, only a few tests were possible with
alcohol before the limited supply was used up.
These engine test configurations are summarized below:
Engine Intake Manifold Carburetor Metering Rod
NAHBE Modified Modified Modified (both
(Baseline gasoline and
configuration) alcohol)
NAHBE Modified Modified Stock
(Configuration A)
Stock Stock Stock Stock
(baseline configuration)
Stock Modified Modified Stock
(Configuration A)
Stock Modified Modified Modified
(Configuration B)
The results of the above tests are tabulated in Tables C-l and C-2 and
are summarized in Tables B-l through B-5 as NAHBE and stock engines.
Discussion of Results
Included in Tables B-l through B-5 are the results of similar tests on
other small utility and small heavy-duty engines. A description of
these engines is included in Appendix A. These teslp^ were conducted by
Southwest Research Institute under an EPA contractViy and are included
here to establish a basis for comparison of the relative merits of the
NAHBE concept and the stock engine used as a baseline in this project.
(1)
Exhaust Emissions from Uncontrolled Vehicles and Related Equipment
Using Internal Combustion Engines. Part 4, Small air cooled spark
ignition utility engines, and Part 5, Heavy-Duty Farm, Construction
and Industrial Engines. APTD report numbers 1494 and 1495.
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10
Also Included in Tables Bl through B5 are the results for the NAHBE and
stock engines restated to account for the generator losses. Based on
discussions with the army engineering contracts office responsible for
the procurement and production testing of these untis, a generator
efficiency of 90% was selected as being most representative of the effi-
ciency encountered during EPA testing.
A comparison of the test results (using gasoline) shows little difference
in thermal efficiency or HC, CO, or NOx emissions between the NAHBE with
the stock metering rod (NAHBE configuration A) and the baseline stock
engine. However, a comparison of the tests of the NAHBE with the stock
metering rod and the modified metering rod (NAHBE baseline) show a
marked difference. With the modified metering rod installed, the NAHBE's
HC emissions were reduced by factors of 3 to 15; CO emissions were
reduced by factors of 20 to 50; NOx emissions increased by factors of 1
to 5; and thermal efficiency increased by 10 to 20 percent. These
results show that the modified metering rod reduces the quantity of fuel
supplied to the engine rather than increasing it as planned by the
designers. A review of the thermal efficiency and the HC, CO, and NOx
emissions of the stock engine shows that it was designed to operate very
fuel rich. The HC and CO emissions are the highest of the group of
engines listed and, conversely, the thermal efficiency and NOx emissions
are the lowest. Therefore, by enleanment alone, the stock engine should
show improvements in HC, CO, and efficiency with a possible increase in
NOx emissions. These improvements were observed in the test data.
Since the preceding results indicated that a large part of any benefits
of the NAHBE concept were due to enleanment, a series of tests was run
on the stock engine using the NAHBE induction system (modified carburetor
and modified intake tubes) and the two metering rods. When the stock
engine (with the NAHBE induction system) was tested with the stock
metering rod installed (stock configuration A), the HC, CO, NOx emissions
and thermal efficiency were very similar to the baseline tests of the
stock engine and the tests of the NAHBE with the stock metering rod .
(NAHBE configuration A). The only major change was at 100% load where
the CO emissions were halved and the NOx emissions doubled. Also, when
the stock engine with the NAHBE induction system was tested with the
modified metering rod (stock configuration B) the results were very
similar to the NAHBE under the same conditions. Therefore from the
viewpoint of emissions or thermal efficiency: 1) the benefits of the
NAHBE concept, as tested, can be ascribed to fuel enleanment alone, 2)
this enleanment can be readily accomplished by modifying the induction
system on the stock engine through the use of a leaner metering rod and
3) the NAHBE pressure balance concept requiring piston modification
showed no benefit in this series of tests.
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11
Due to the previously reported limited volume of alcohol, only a few
tests of the NAHBE were run on alcohol. Compared to the NAHBE with the
modified metering rod and running on gasoline, HC emissions were up by a
factor of 2 to A, CO emissions were unchanged, NOx emissions were reduced
by a factor of 7 to 10, and thermal efficiency ranged from unchanged to
10% worse.
A comparison of the NAHBE (baseline configuration, using gasoline) test
results with those of the other engines in Tables B-l through B-5 shows
few if any benefits. In thermal efficiency the NAHBE at best only
equals the poorest of the group. The developers hoped for efficiency of
the heat balanced cycle is not evident. Its thermal efficiency is only
half that of the diesel under all conditions and several of the gasoline
engines better it by more than 30 percent most of the time. The diesels
are consistently better than the NAHBE in HC and CO emissions. Although
the NAHBE HC and CO emissions are better than some of the gasoline
engines, these gasoline engine emisssions could also be reduced by
enleanment. In NOx emissions the NAHBE is similar to a few and greater
than many by a factor of two. Thus if the other gasoline engine HC and
CO emissions were reduced by enleanment, many have a considerable NOx
cushion before their NOx emissions would exceed the NAHBE emission
levels.
One question left unanswered by the test program is the potential effects
on engine durability due to the reduction in charge cooling and increase
in exhaust gas temperature (EGT) resulting from the NAHBE conversion.
The stock engine was designed for use in a military motor/generator set.
The induction system was designed specifically for this military application
and was designed to run fuel rich. As shown by the test data in Tables
C-l and C-2, enleanment raised the muffler EGT by 50° to 200°F. The
effects of this on piston, valve component, cylinder head, and exhaust
system life is unknown. Although both engines experienced similar
exhaust gas temperature rises when leaned out, the effect on engine
durability may not be identical for both engines. The developers presented
only limited durability data on the NAHBE.
Several problems were encountered during testing. On alcohol the NAHBE
could not be properly adjusted to a low speed idle since it would surge
or stall. At higher power settings the NAHBE surged moderately after a
few minutes of steady state testing even after the developer had adjusted
the carburetor. In addition it required additional adjustment whenever
the load was changed. The NAHBE air injection tube broke during testing
and had to be repaired. The modified metering rod was improperly fabricated
so that it did not seat exactly in the center of the metering jet.
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12
Appendix A
Heat Balanced Engine
Test System Description
5 kW generator set, military standard DOD model MEP-017A with heat
balanced engine
Engine
Nomenclature
Manufacturer, Type
Cooling
Bore and Stroke
Displacement
Compression Ratio
Rated HP
Maximum HP
Speed Range
Governed Speed
Ignition
Fuel Metering
Fuel Requirement
Military standard model 2A042 III.
Piston, combustion chamber, and
induction system were modified
by the Naval Academy
Wisconsin (mfr. of stock engine)
4 stroke, Otto cycle, OHV, 2 cyl.
opposed air cooled. Modified by
Naval Academy to heat balanced
engine concept.
Air cooled
76.2 x 76.2 mm/3.00 x 3.00 in.
695 cc/42.4 cu. in.
8.5 to 1 (modified piston and
cylinder head)
7.5 kW/10 hp at 3600 rpm (stock
engine rating)
13.0 kW/17.5 hp at 3600 RPM
(stock engine rating)
None. Controlled at 3600 RPM
3600 RPM
Magneto
Stock single, side draft, 1 venturi
carburetor with air bleed
Regular leaded 91 octane automotive
or ethyl alcohol. Tested with
Indolene 30, RON 100; and also
with ethyl alcohol
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13
Generator
Manufacturer
Output Power
Output Voltage
Frequency
Power Factor
General
Frame
Size
Weight
Mounting
Total System Operating Time
Appendix A
Heat Balanced Engine (Continued)
Fermont
5 kW AC
120/240 V single phase, 120/208 V
three phase
60 hertz
0.8
Tubular frame, skid mounted
101.0 cm long x 76.2 cm wide x 63.5 cm
high; 39 3/4 in long x 30 in wide x
25 in high
217.3 kg/479 pounds
Engine directly coupled to generator.
5 hours when received
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14
5 kW Generator Set,
Engine
Nomenclature
Manufacturer
Type
Cooling
Bore and Stroke
. Displacement . ••
Compression Ratio
Rated hp
Maximum hp
Speed Range
Governed Speed
Ignition
Fuel Metering
Fuel Requirement
Appendix A
Stock Test System Description
Military Standard, DOD Model MEP-017A
Military standard model 2A042-II1
Hercules (Identical to engine manu-
factured by Wisconsin)
4 stroke, Otto cycle, OHV, 2 cyl.
opposed
Air cooled
76.2 x 76.2 mm/3.00 x 3.00 in.
695 cc/42.4 cu. in.
6.9:1
7.5 kW/10 hp at 3600 RPM
13.0 kW/17.5 hp at 3600 RPM
3000 to 4000 RPM
3600 RPM
Magneto
Single, side draft, 1 venturi
carburetor
Regular leaded, 91 octane automotive
gasoline (tested with Indolene 30,
RON 100)
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15
Generator
Manufacturer
Output Power
Output Voltage
Frequency
Power Factor
Appendix A
Stock Engine (continued)
Fermont
5 kW AC
120/240 V single phase; 120/208 V
three phase
60 hertz
0.8
General
Frame
Size
Weight
Total System Operating Time
Tubular frame, skid mounted
101.0 cm long x 76.2 cm wide x
63.5 cm high; 39 3/4in. long x 30 in.
wide x 25 in. high
217.3 kg/479 pounds
3 hours when received
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Appendix A (continued)
Specification of Comparison Engines
Manufacturer
Model
Cylinders
Bore & Stroke in.
3
Displacement, in
Compression Ratio
Rated HP @ RPM
Rated Torque (fr Ibf) @ RPM
Cooling
Ignition
Fuel Metering
Fuel Type
Aspiration
Comb. Chamber
Briggs &
Stratton
92908
1
2.56 x
1.75
9.02
6.20:1
3.5 @
3600
5.2 @
3100
Air
mag.
1 V
gasoline
Briggs &
Stratton
100202
1
2.50 x
2.13
10.43
6.20:1
4 @
3600
5.9 @
3100
Air
mag.
1 V
gasoline
Wisconsin
SD 12
1
3.50 x
3.00
28.86
6.35:1
12.5 @
3600
21.5 @
2200
Air
Batt & mag.
1 V
gasoline
Kohler
K482
opposed-2
3.25 x
2.88
48.0
6.00:1
18 @
3600
31.7 @
2400
Air
Batt & mag.
1 V
gasoline
Mercedes
Benz
OM636
1-4
2.94 x
3.94
108
19.0:1
29 @
2400
60 @
2000
Water
CI
FI
diesel
natural
Onan
DJBA
1-2
3.25 x
3.63
60
19.0:1
14.6 @
2400
36 @
1800
Air
CI
FI
diesel
natural
Wisconsin
VH4D
V-4
3.25 x
3.25
108
5.50:1
30 @
2800 M
66 @
1700
Air
Batt
1 V
gasoline
pre-cup pre-cup
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17
Table B-l
HC Emissions
gm/kW hr
% full load @ rated RPM
0* 25 50 75 100
ENGINE W/GENERATOR
NAHBE w/modified MR 13.5 7.2 4.3 2.6 3.9
NAHBE (alcohol) - - - 11.9 5.7
NAHBE w/standard MR 189.4 67.3 30.3 16.3 9.8
Stock 55.8 57.0 31.3 20.4 13.3
Stock w/NAHBE induction
& modified MR - - 4.4 2.0 1.8
Stock w/NAHBE induction &
Standard MR 260.2 90.8 29.3 15.5 9.2
ENGINE
NAHBE w/modified MR 13.5 6.5 3.9 2.3 3.5
NAHBE (alcohol) - - - 10.9 5.1
NAHBE w/standard MR 189.4 60.6 27.3 14.7 8.8
Stock 55.8 51.3 28.2 18.4 12.0
Stock w/NAHBE induc-
tion & modified MR - - 4.0 1.8 1.6
Stock w/NAHBE induc-
tion & Standard MR 260.2 81.7 26.4 14.0 8.3
B&S 92908 17.7 49.1 31.4 29.8 14.5
B&S 100202 4.18 ' 8.43 6.85 6.05 5.03
Wisconsin SD12 73.3 33.6 23.6 20.5 17.0
Kohler K 482** 120 40.0 22.4 22.2 21.1
Mercedes-Benz OM 636 20.7 5,29 1.93 -78 .36
Onan DJBA 20.2 5.29 2.08 .99 1.18
Wisconsin VH4D 120 24.56 13.07 8.34 8.11
MR - Metering rod
* - grams/hr
** - Emissions from the test engine may be higher than typical
due to the carburetor setting
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18
Table B-2
CO Emissions
gm/kW. hr
% full load @ rated RPM
0* 25 50 75
100
ENGINE W/GENERATOR
NAHBE w/modif ied MR
NAHBE (Alcohol)
NAHBE w/ standard MR
Stock
Stock w/NAHBE induc-
tion & modified MR
Stock w/NAHBE induc-
tion & standard MR
ENGINE
NAHBE w/modified MR
NAHBE (Alcohol)
NAHBE w/standard MR
Stock
Stock w/NAHBE induc-
tion & modified MR
Stock w/NAHBE induc-
tion & standard MR
B&S 92908
B&S 100202
: Wisconsin SD12
Kohler K482**
Mercedes-Benz OM 636
Onan DJBA
Wisconsin VH4D
50
-
2813
2175
-
2582
50
-
2813
2175
-
2582
134
20.6 '
1540
1970
69.9
70.3
2636
33
-
2151
2172
-
2269
30
-
1936
1955
-
2042
619
38.0
838
424
7.30
13.69
680.5
19
-
996
1041
33
1008
17
—
896
937
30
907
440
53.4
729
419
4.81
4.77
429.5
20
19
489
687
18
406
18
17
440
618
16
365
510
80.3
670
356
3.06
2.43
318.1
18
12
394
428
14
201
16
11
355
385
13
181
199
48.
636
723
11.
3.
233.
9
83
37
6
MR
*
**
Metering rod
grams/hr
Emissions from the test engine may be lower than typical
due to the carburetor setting
-------
19
Table B-3
NOx Emissions
gm/kW hr
0*
% full load @ rated RPM
25 50 75
100
ENGINE W/ GENERATOR
NAHBE w/modified MR
NAHBE (Alcohol)
NAHBE w/ stock MR
Stock
Stock w/NAHBE induc-
tion & modified MR
Stock w/NAHBE induc-
tion & standard MR
ENGINE
NAHBE w/modified MR
NAHBE (Alcohol)
NAHBE w/ stock MR
Stock
Stock w/NAHBE induc-
tion & modified MR
Stock w/NAHBE induc-
tion & standard MR
B&S 92908
B&S 100202
Wisconsin SD12
Kohler K482**
Mercedes-Benz OM 636
ONAN DJBA
Wisconsin VH4D
7.11
2.03
3.0
5.28
7.11
2.03
3.0
5.28
4.30
3.14
3.21
5.44
19.0
15.1
6.83
14.45
2.91
3.24
4.26
13.01
2.62
2.92
3.83
6.40
14.63
2.91
3.68
5.91
13.83
3.69
14.46
2.81
2.50
18.92
3.97
13.01
2.53
2.25
17.03
3.57
4.71
18.0
2.38
5.23
5.10
9.44
6.05
7.33
1.04
6.00
3.20
9.75
5.92
6.60
.94
5.40
2.88
8.78
5.33
2.66
19.2
1.66
3.87
4.39
6.66
10.26
16.76
1.63
7.84
6.35
15.29
16.00
15.08
1.47
7.06
5.72
13.76
14.4
5.42
24.3
2.21
3.74
2.97
4.70
11.60
MR - Metering rod
* - grams/hr
** - Emissions from the test engine may be lower than typical
due to carburetor setting
-------
20
Table B-4
Fuel Economy
kW hr/gal
% full load @ rated RPM
0* 25 50 75
100
ENGINE W/GENERATOR
NAHBE w/modified MR
NAHBE.(alcohol)**
NAHBE w/stock MR
Stock
Stock w/NAHBE induc-
tion & modified MR
Stock w/NAHBE induc-
tion & standard MR
ENGINE
NAHBE w/modified MR
NAHBE (Alcohol)**
NAHBE w/stock MR
Stock
Stock w/NAHBE induc-
tion & modified MR
Stock w/NAHBE induc-
tion & standard MR
B&S 92908
B&S 100202
Wisconsin SD 12
Kohler K482***
Mercedes-Benz OM 636
Onan DJBA
Wisconsin VH4D
1.6
1.2
1.4
-
1.1
1.6
1.2
1.4
-
1.1
6.3
7.0
1.6
1.1
1.7
3.2
.8
1.9
1.5
1.4
-
1.4
1.7
1.4
1.3
-
1.3
2.6
3.6
2.5
2.7
5.9
5.2
3.5
3.4
2.7
2.7
3.4
2.7
3.1
2.4
2.4
3.1
2.4
4.3
5.1
3.4
4.3
8.5
7.9
5.1
4.4
2.4
3.9
3.5
4.4
3.8
4.0
2.2
3.5
3.2
4.0
3.4
5.2
6.2
4.3
4.8
9.8
9.6
6.2
5.1
3.1
4.5
4.3
5.2
4.9
4.6
2.8
4.1
3.9
4.7
4.4
7.8
7.0
4.9
5.2
10.0
8.8
7.1
MR -
*
**
*** _
Metering rod ,
hr/gal.
alcohol, gal are gal alcohol (190 proof, 95% ethyl alcohol)
Fuel economy from the test engine may be lower than typical
due to the carburetor setting
-------
21
Table B-5
Thermal Efficiency %
ENGINE W/ GENERATOR
NAHBE w/modified MR
NAHBE (alcohol)
NAHBE w/ stock MR
Stock
Stock w/NAHBE induction
& modified MR
Stock w/NAHBE induction &
modified MR
ENGINE
NAHBE w/modified MR
NAHBE (Alcohol)
NAHBE w/stock MR
Stock
Stock w/NAHBE induction
& modified MR
Stock w/NAHBE induction &
modified MR
B&S 92908
B&S 100202
Wisconsin SD12
Kohler K 482*
Mercedes-Benz OM 636
Onan DJBA
Wisconsin VH4D
% of
25
5.2
4.0
3.8
3.7
5.8
4.4
4.2
4.1
7.1
9.8
6.9
7.2
14.4
12.8
9.4
full load
50
9.3
7.2
7.4
9.3
7.3
10.3
8.0
8.2
10.3
8.1
11.6
14.0
9.4
11.7
20.9
19.4
14.0
@ actual
75
12.0
10.9
10.5
9.6
11.9
10.4
13.3
12.1
11.7
10.7
13.2
11.6
14.2
16.9
11.9
13.2
24.2
23.5
16.9
RPM
100
13.9
14.1
12.3
11.8
14.1
13.4
15.4
15.7
13.7
13.1
15.7
14.9
21.4
19.0
13.5
14.1
24.4
21.6
19.3
MR - Metering rod
* - Thermal efficiency from the test engine may be lower than
typical due to the carburetor setting
-------
0% Load
78-6459
78-6632
78-6808
79-0048
25% Load
50% Load
Table C-l
Heat Balanced Engine/Generator
Test No. Comment
(1)
(1)
Eng ine
Hours
21.0
51.8
58.4
60.7
Power
kW
EGT*
°F
gm/kW hr
HC
CO
CO
78-6456
78-6461
78-6468
78-6475
78-6815
78-6810
(3)
(3)
13.3
20.1
41.0
51.2
57.9
59.8
2.3
2.2
2.2
2.5
2.5
2.4
805
795
640
635
(1)
(2)
'(3)
(4)
(5)
*
Gm/hr, hr/gal
Manifold air bleed closed
Standard (stock) metering rod
Carburetor air bleed blocked off
Alcohol, gal are gal alcohol
Exhaust gas temperature
NOx
Fuel Economy
kW hr/gal
78-6460
78-6467
78-6631
78-6809
78-6811
(3)
(3)
20.2
41.2
51.8
58.2
59.9
1.1
1.2
1.3
1.3
1.3
800
790
590
590
6.6
5.9
7.2
74.9
59.7
28
28
33
2344
1958
5128
4932
4717
2542
2652
12.02
14.26
14.45
2.61
3.20
1.7
1.8
1.9
1.4
1.5
17
23
19
19
1079
913
3043
2817
2915
2554
1611
1777
10.72
11.70
15.34
14.46
2.39
3.23
2.9
3.1
3.0
3.4
2.6
2.7
Thermal
Efficiency %
4.4
4.4
3.0
3.3
4.6
4.9
5.2
3.8
4.1
7.9
8.5
8.2
9.3
7.1
7.4
NJ
-------
Test No.
75% Load
Table C-l (can't)
Heat Balanced Engine/Generator
Power EGT* gm/kW hr
kW °F
HC
CO
CO-
Fuel Economy
NOx kW hr/gal
78-6457
78-6462
78-6464
78-6471
78-6469
78-6474
78-6630
78-6816
78-6813
78-6807
(2)
(2)
(2)
(5)
(3)
(3)
13.6
19.5
19.8
39.7
40.9
50.9
51.6
56.0
57.7
59.8
3.5
3.5
3.5
3.6
3.8
3.7
3.8
3.8
3.8
3.8
685
825
815
730
958
705
710
3.4
1.8
9.1
15.9
4.6
2.6
15.2
11.9
18.1
14.4
11
14
467
486
17
20
392
19
564
413
2240
1885
1481
1480
1980
1956
1613
2132
1428
1539
9.64
12.65
4.22
4.47
17.86
7.33
7.80
1.04
5.08
6.92
3.9
4.6
4.0
3.9
4.4
4.4
3.9
2.4
3.7
4.0
100% Load
78-6458 13.8 4.5
78-6463 19.1 4.6
78-6465 (2) 19.3 4.6
78-6472 (2) 39.4 4.8
78-6470 39.9 4.9
78-6473 50.7 5.0
78-6629 (2) 51.4 5.0
78-6791 (2), (4) 52.7 5.0
78-6633 (4) 52.8 5.0
78-6812 (5) 55.2 5.0
78-6817 (5) 55.7 5.0
78-6814 (3) 57.5 5.0
78-6806 (3) 58.9 5.0
78-0049 61.2 5.0
(1) Gra/hr, hr/gal
(2) Manifold air bleed closed
(3) Standard (stock) metering rod
(4) Carburetor air bleed blocked off
(5) Alcohol, gal are gal alcohol (190
* Exhaust gas temperature
765
920
895
830
760
840
930
940
780
775
845
proof,
1.9
2.2
5.9
9.5
2.7
3.9
8.7
13.4
6.7
5.6
5.8
12.7
13.6
5.9
95%
7
9
233
203
13
18
134
384
89
12
12
381
406
36
ethyl
1867
1766
1371
1393
1730
1696
1577
1281
1588
1670
1689
1318
1310
1602
alcohol)
12.60
9.06
8.48
9.95
12.93
16.76
17.55
7.10
17.55
1.66
1.60
7.84
7.83
19.52
4.7
5.0
5.0
5.1
5.0
5.1
4.9
4.6
3.1
3.1
5.1
4.5
4.5
5.3
Thermal
Efficiency %
10.6
12.6
10.9
10.6
12.0
12.0
10.6
10.9
10.1
10.9
12.8
13.7
13.7
13.9
13.7
13.9
13.4
12.6
13.9
14.2
13.9
12.3
12.3
14.5
to
U)
-------
Table C-2
Stock Engine/Generator
Test No.
0% Load
78-6483
78-6488
78-6624
78-6819
78-6819
25% Load
78-6484
78-6489
78-6625
78-6820
78-6926
50% Load
78-6482
78-6482
78-6485
78-6490
78-6502
78-6542
78-6821
78-6822
78-6922
78-6923
78-6927
Comment
(1)
(1)
(1)
(D,(3)*
(D,(3)*
(3)*
(3)*
(2)*
A
*
(3)*
(3)*
Engine
Hours
18.9
40.9
53.4
57.7
59.7
19.1
40.7
53.1
57.9
59.9
9.9
10.5
19.3
40.2
48.4
52.5
55.1
56.0
56.8
58.0
56.9
Power
kW
1.22
1.21
1.28
1.2
1.3
2.4
2.4
2.2
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
EGT **
°F
555
540
620
635
630
610
645
640
690
680
680
730
845
840
695
700
HC
24.3
35.0
55.8
249.8
270.6
34.4
51.3
57.0
90.9
90.7
21.0
21.0
22.7
29.4
30.1
32.5
13.3
4.0
4.8
28.2
30.4
gm/kW
CO
1109
1090
2175
2480
2684
1811
1771
2172
2208
2330
1405
1407
1180
987
1009
1073
326
28
38
980
1035
hr
CO 2
3581
3375
2781
3211
3033
3149
2961
2630
2703
2681
1753
1727
1865
1644
1541
1618
2034
2560
2556
1686
1693
NOx
4.83
4.95
3.00
6.34
4.22
3.81
4.13
3.24
4.57
3.95
2.32
2.18
2.66
2.58
2.45
2.54
11.76
19.23
18.60
3.98
3.96
Fuel Econom;
kW hr/gal
1.6
1.7
1.4
1.1
1.1
1.5
1.5
1.4
1.4
1.3
2.2
2.2
2.3
2.7
2.8
2.6
3.4
3.4
3.4
2.7
2.6
Thermal
Efficiency %
(1)
(2)
(3)
A
A*
Gm/hr, hr/gal
Manifold air bleed closed
Standard (stock) metering rod
Modified Carburetor and modified intake tubes
Exhaust gas temperature
4.1
4.1
3.8
3.8
3.5
6.0
6.0
6.3
7.4
7.6
7.1
9.3
9.3
9.3
7.4
7.1
N3
-------
Test No.
75% Load
78-6481
78-6481
78-6486
78-6491
78-6501
78-6503
78-6917
78-6918
78-6921
78-6924
78-6929
100% Load
78-6480
78-6480
78-6487
78-6499
78-6500
78-6626
78-6627
78-6629
78-6919
78-6820
78-6818
78-6925
78-6929
Comment
(2)*
*
*
(3)*
(3)*
(2)*
*
*
(3)*
(3)*
Engine
Hours
.1
,2
9.5
10.3
21.6
39.9
48.
52.
54.9
55.8
56.6
58.8
60.3
9.3
10.
21,
39.
47.9
52.0
53.9
54.
54.
55.6
56.4
59.1
60.5
,1
.4
,7
.1
,7
Table C-2 (con't)
Stock Engine/Generator
Power EGT **
kW °F
3.5
3.5
3.4
3.8
3.7
3.7
3.8
3.8
3.8
3.8
3.8
4.5
4.5
4.8
5.0
4.6
5.0
755
750
750
805
935
930
965
780
805
810
830
940
920
900
945
945
855
875
(1) Qtt'/hr, hr/gal
(2) Manifold air bleed closed
(3) Standard (stock) metering rod
* Modified Carburetor and modified intake tubes
** Exhaust gas temperature
gm/kW hr
Fuel Economy
HC
13.8
15.4
19.0
23.1
20.1
20.7
8.4
2.0
2.0
15.2
15.8
10.5
12.1
12.8
16.5
14.0
12.5
1.6
2.2
3.6
1.5
1.6
9.0
9.3
cp_
1022
1109
865
784
687
687
158
18
18
498
314
798
818
615
560
461
395
14
16
31
13
13
202
199
CO 2
1435
1388
1636
1315
1362
1362
1691
2052
1971
1484
937
1296
1319
1169
1180
1377
1304
1722
1692
1533
1670
1640
1444
1502
NOx
2.30
2.00
3.65
2.40
3.22
3.17
13.96
9.86
9.64
7.15
4.69
2.69
2.63
2.62
3.07
6.15
6.54
15.19
21.68
17.44
12.19
12.08
15.09
16.90
kW hr/gal
2.9
2.8
2.9
3.4
3.5
3.5
4.5
4.3
4.4
3.8
3.8
3.5
3.4
4.1
4.2
4.1
4.5
5.1
5.1
5.6
5.2
5.3
5.0
4.8
Thermal
Efficiency %
7.9
7.6
7.9
9.3
9.6
9.6
12.3
11.7
12.0
10.4
10.4
9.6
9.3
11.2
11.5
11.2
12.3
13.9
13.9
15.3
14.2
14.
13.
13.1
------- |