# Technical Report May 2015



# Certification Test Approach for the Phase II

Greenhouse Gas Regulations

Erik Dykes and Mihai Dorobantu, Eaton

### Acknowledgements

The authors would like to recognize Eaton and its customer colleagues , specifically, the Environmental

Protection Agency, Paccar, Navistar, Cummins, and Allison who provided the many hours of technical

discussion and support to execute this work.

### TABLE OF CONTENTS

I. Introduction

................................ ................................ ................................ ................................ ........................ 4

II. Primary Certification Approach

................................ ................................ ................................ .......................... 4

Engine Fuel Mapping Procedure

................................ ................................ ................................ ............................ 4

The Greenhouse Gas Emission Model (GEM) Simulation

................................ ................................ ...................... 4

Powertrain Test Methodology

................................ ................................ ................................ ............................... 5

III. Alternate Certification Approach

– Fuel Mapping

................................ ................................ ......................... 6

IV. Test Configuration

................................ ................................ ................................ ................................ .......... 6

Altern ate Certification Approach

– Engine Fuel Mapping

................................ ................................ ...................... 6

Powertrain Test Methodology

................................ ................................ ................................ ............................... 8

V. Certification Test Procedures

................................ ................................ ................................ ............................. 9

Alternate Certification Approach

– Engine Fuel Mapping

................................ ................................ ...................... 9

Powertrain Test Methodology

................................ ................................ ................................ ............................ 10

VI. Analysis

................................ ................................ ................................ ................................ ........................ 11

Alternate Certification Approach

– Fuel Mapping

................................ ................................ .............................. 11

Powertrain Test Methodology

................................ ................................ ................................ ............................ 15

VII. Conclusions

................................ ................................ ................................ ................................ .................. 18

Appendix A

- Vehicle Configurations for Alternate Fuel Mapping Approach

................................ .......................... 20

Appendix B

– Alternate Fuel Mapping Approach Test Results

................................ ................................ ................ 21

Appendix C

- Vehicle Configurations for Powertrain Test

................................ ................................ ....................... 22

Appendix D

– Powertrain Test Results

................................ ................................ ................................ .................... 23

Appendix D

– Powertrain Test Results (Cont’d)

................................ ................................ ................................ ...... 24

### I. Introduction

The United States Environmen ta l Protection Agency (U.S. EPA) and the National Highway Traffic Safety

Administration (NHTSA ) are currently developing the testing protocols and stringencies for the second

phase of the Heavy

- Duty (HD) Greenhouse Gas (GHG) R egulations. The complementary U.S. EPA and

NHTSA standards that make up the Heavy

- Duty National Program apply to combination tractors (semi

trucks), heavy

- duty pickup trucks and vans, and vocational vehicles ( including buses and refuse or

utility trucks). The first phase of the HD GHG program went into effect in 2014 and will continue

through 2018. A joint phase 2 effort is underway with the U.S. EPA and NHTSA to develop a more

stringent HD Carbon Dioxide ( CO 2 ) standard beyond 2018. The analysis is focusing on technology, cost

feasibility and methods to verify and track CO 2 and fuel economy levels. The testing and certification

protocols that are under development involve an engine fuel mapping procedure , updates to the

accuracy, validity, and further refines the existing Greenhouse Gas Emission Model (GEM) and a

powertrain test option that shows the deep engine

- transmission integration fuel efficiency ( FE )

benefits

. T he development of updated test proce dures and certification methods to include the

powertrain efficiencies ensure new technologies are credited for reduction in CO 2 levels and ensure

the long

- term investment development of new engine and transmission technologies.



### II. Primary Certification Approach

Engine Fuel Mapping P rocedure

A 143

- point engine fuel mapping procedure is being implemented in the regulation as the primary

approach to characterize and construct a steady

- state fuel map for use in the Greenhouse G as

Emissions Mo del (GEM)

. A fuel map is g enerated for each engine hardware and software combination

over a series of steady

- state engine operating points to determine a series at a minimum of 13 equally

s paced speed points ranging from idle to the maximum speed and 11 e qually spaced, normalized

torque values ranging from zero torque to maximum torque at each of the speed points making a total

of 143 steady state tests points . The normalized torque values are expressed as a percentage of

maximum torque , at a given engine speed. This type of mapping approach is currently being

developed for the European Commission, which is in the process of establishing test procedures and a

vehicle simulation model Vehicle Energy Consumption Calculation Tool (VECTO) that will be used to

certify heavy duty vehicle CO 2 emissions as part of the type

- approval procedure.

The Greenhouse Gas Emission Model (GEM) S imulation

The Greenhouse Gas Emission Model (GEM) was developed by the EPA as a means to track compliance

with the proposed HD GHG and fuel efficiency standards which covers Class 7 and 8 tractors and Class

2b

- 8 heavy

- duty vehicles

. The GEM is similar in concept to a number of vehicle simulation tools

developed by commercial and government entities. The customized simulation model us es pre

- defined

parameters that are consistent across various manufacturers to predict the CO2 emissions from HD

trucks by using a set of pull

- down menus determined by the truck configuration ( engine, transmission,

driveline, vehicle frontal area, rolling r esistance, mass, tire radius, aerodynamic drag, etc...) as shown in

Figure 1

. The GEM simulation model uses various inputs to characterize a vehicle’s configuration (such

as weight, aerody namics, and rolling resistance) and predicts ho w the vehicle would behav e on the

road when it follows a driv ing cycle (vehicle speed versus time). The agency use s these standardized

input parameters in the simulation model for all seven proposed subcategories of combination

tractors. The vehicle compliance model archite cture, which is comprised of six systems: Ambient,

Driver, Electric, Engine, Transmission, and Vehicle . The GEM produces a cycle

- weighted gramsCO2/ton

- mile and gallons/1,000 ton

- mile result which incorporates the drive cycle weightings of the

ARB trans ie nt cycle, 55 mph cycle , and 65 mph cycle depending on class of vehicle.

Figure 1: Greenhouse Gas Emission Model (GEM) m ain i nterface

EPA Greenhouse Gas Emission Model , V ersion 1.0. Available at http://www. EPA.GOV

Powertrain Test M ethodology

A p owertrain test includes both the en gine and transmission coupled to a real

- time vehicle model

which encompasses the remaining vehicle systems. The power absorber / generator (dynamometer) is

connected directly to the transmission output shaft to act as th e drive wheels of the test vehicle. The

dynamometer accommodate s the additional rotational inertia and speeds associated with the inclusion

of the transmission and individual transmission gear ratios

. The dynamometer generates speed and

torque at the output side of the transmission to mimic a real world driving condition while fully

exercising the engine and transmission controls. The transmission will cause the engine to mimic the

same driving conditi ons as witnessed during the actual vehicle drive cycles. The GEM vehicles cycles

can be utilized by the powertrain test so the results can be directly input into the GEM model for

certification. Figure 2 depicts the actual powertrain system test configur ation that is utilized to

exercise the real vehicle controls. The p owertrain test provides an opportunity to evaluate the complex

interactions of engine and transmissions in a controlled, repeatable, high fidelity manner and

quantifies the engine

- transmiss ion deep integration optimization. Powertrain testing is a tool that

allows improved optimization of powertrain performance, emissions, and fuel economy and fully

exercises the real engine and transmission controls through the vehicle model.Figure 2 : Powertrain test c onfiguration



### III. Alternate Certification Approach

– Fuel Mapping

An alternate certification approach was examined to characterize and construct a steady

- state fuel

map for use in the Greenhouse G as Emissions Model (GEM)

. An alternate metho d was investigated to

determine if a feasible, reliable, repeatable, cost effected approach could be determined without

adding additional test burden to the OEM. The procedure is addressed in detail under the certification

test procedure section of this r eport. In summary the alternate method constructs a 9

- point surface

for each regulatory cycle (55 MPH with road grade , 65 MPH with road grade , and ARB) by generating

engine speed and torque profiles based on the intended applications and vehicle characteristics (mass,

Crr, Cd, frontal area, axle ratio) using GEM. The profiles generated are then run on an engine

dynamometer to determine the BSFC for each profile. The steady state BSFC maps are then input into

GEM with the specific vehicle paramet ers to determine the vehicle BSCO 2 certification results



### IV. Test Configuration

This section includes a description of engine test cell used to generate the alternative certification

approach for the engine fuel mapping as well as a description of the powertrain test set

- up and

methodology. The engine, aftertreatment system, transmission, test cell set

- up and specific tes t cycles

utilized to generate the results are shown

. The engine calibrations tested was emission certified for

2013 CARB and EPA.

Alternate Certification A pproach

– E ngine Fuel M apping

The engine

- only test cell as shown in Figure 3 was sized to accommodate a heavy

- duty (HD) engine . A

Cummins 15 liter ISX engine rated to 336kW (450 hp) with peak torque of 2375 Nm (1750 ft

- lb) was

used for the evaluation. A HD aftertreatment system was installed to meet the EPA and CARB

emissions standards. The aftertreatment system utilized both a Diesel Particulate Filter (DPF) and a

Selective Catalytic Reduction (SCR) system

. To maintain a baseline condition for the DPF during test ing

a DPF regeneration was forced prior to each set of tests to clean the DPF of stored particulates . The

SCR system was operated during testing as would be witnessed in

- vehicle operation to reduce NOx

. The e xhaust emissions were collected conti nuously using a Horiba Mexa7100 D emission bench directfrom the exhaust stream post aft ertreatment system

. The fuel was measured continuous during each

test cycle using a ReSol RS438A

- 200 Fuel Flow Measurement System. The testing is completed using

ultra low sulfur diesel fuel with a maximum su lfur concentration of 15 PPM . The engine inta ke air is

temperature, humidity and pressure controlled to 25°C, 53% and 99kPa, respectively. All

temperatures, pressures, fuel flow and emissions measurements were logged at a rate of 10 Hz.

Figure 3 : Engine o nly configuration

– alternative certification a pproach

The test cycles utilized for the engine

- only alternate fuel mapping approach were generated using

GEM. An example 65MPH speed and load trace used for the engine

- only set

- up is shown in Figure 4.

Three separate vehicle configuration were input into the GEM model and the speed and load points

generated for each of the regulatory cycles (ARB, 65MPH, and 55 MPH). A total of nine traces were

generated for each cycle. A total of 27 engine tests were ran (3 vehicle configurations x 3 tes t cycles x

3 axle ratios)

. Each individual cycle was repeated two times consecutively and emission data sampled

during the second cycle.

Figure 4: 65MPH engine

- only cycle g enerated using GEMPowertrain Test M ethodology

The powertrain test cell as sho wn in Figure 5 was sized to accommodate a powertrain from a relatively

heavy

- duty vehicle. The vehicle test weight was 30,391 kg [67,000 lbs.]. The powertrain tested

included a Cummins 15

- liter ISX engine with an Eaton 10

- speed automated manual transmiss ion. The

engine maximum rated performance was 336kW (450 hp) at 1800 rpm with peak torque of 2375 Nm

(1750 ft

- lb) at 1000 rpm and was operated using two separate calibrations; one base calibration for

testing with the 10

- speed UltraShift PLUS LAS transmis sion and an additional calibration with

SmartTorque2 (ST2) technology for testing in conjunction with the 10

- speed Fuller Advantage TM (FASA)

transmission. Both engine calibrations tested were emission certified for 2013 CARB and EPA. The

dynamometer was sized to accommodate the engine’s peak torque multiplied by the transmission’s

maximum gear reduction. The aftertreatment system utilized both a Diesel Particulate Filter (DPF) and

a Selective Catalytic Reduction (SCR) system

. To main tain a baseline condition for the DPF during

test ing a DPF regeneration was forced prior to each set of tests to clean the DPF of stored particulates

. The SCR system was operated during testing as would be witnessed in

- vehicle operation to reduce

Nitric o f Oxides (NOx). The exhaust emissions were collected continuously using a Horiba Mexa7100D

emission bench direct from the exhaust stream post aftertreatment system

. The fuel was measured

continuous during each test cycle using a ReSol RS438A

- 200 Fuel Flo w Measurement System. The

testing is completed using ultra low sulfur diesel fuel with a maximum su lfur concentration of 15 PPM

. The engine intake air is temperature, humidity and pressure controlled to 25°C, 53% and 99kPa,

respectively. All temperature s, pressures, fuel flow and emissions measurements were logged at a rate

of 10 Hz.

Figure 5 : Heavy

- Duty (HD) powertrain test cell c onfiguration

Three regulatory drive cycles were tested to verify the Powertrain methodology 1) the California Air

Resources Board (ARB) Transient cycle, 2) a 65 mph [ 105 kph ] cycle with road grade , and 3) a 55 mph

[ 88 kph ] cycle with road grade

. Each individual cycle was repeated two times consecutively and

emission data sampled during the secon d cycle. Figure 6 a shows a vehicle speed trace for the ARB

transient test cycle having an average vehicle speed of 15.3 mph [ 24.6 kph ] and a maximum speed of

47.5 mph [ 76.5 kph ]

. The cycle distance is 2.8 miles. The transient cycle is operated for 668 s econds

and emissions collected the entire duration. Figure 6 b shows a vehicle speed trace for the 65 mph test

with road grade. The road profile was fully reflective of real world driving as it included a +/

- 2% gradechange with a cycle distance of 12.4 miles. Figure 6 c shows a vehicle speed trace for the 55 mph test

with road grade. The road profile was fully reflective of real world driving as it included a +/

- 2% grade

change with a cycle distance of 12.5 miles.

Figure 6 : a) Califo rnia Air Resources Board (ARB) t ransient cycle, b) 65 mph [105 kph] cycle with road

grade , and c) 55 mph [88 kph] cycle with road grade



### V. Certification Test Procedures

Alternate C ertification A pproach

– E ngine Fuel M apping

An alternate certification approach was evaluated for mapping the brake specific fuel consumption

(BSFC) of an engine. An alternate method was investigated to determine if a feasible, reliable,

repeatable, cost effected approach could be achieved in place of the primary approach of a 143

- point

steady state engine fuel mapping procedure being implemented in the phase 2 HD GHG regulation

. The vehicle application range was first determined with the intent of selecting the correct range to test

the engine to its full operating capacity

. The method investigated generate d an engine speed and

torque profile based on the intended applications for each of the regulatory drive cycle s (55 mph cycle

with road grade , 65 mph cycle with road grade , and ARB transient ). Three separate pre

- defined vehicle

configuration were used to generate the regulatory cycles through the GEM simulation tool

. The pre

defined vehicle configurations were chosen to span a wide range of engine speed over vehicle speed

[rpm / mph] values that the engine may be subject

. A total of 9 tests were generated for each

regulatory cycle. Once the speed and torque traces were created the profiles were then used to

construct a total of 27 engine tests (3 g eneric vehicles x 3 test cycles x 3 axle r atios). Each of the test

cycles was then run on an engine dynamometer to generate a nine ( 9 ) point BSFC surface plot for each

regulatory cycle. The engine BSFC data generated was input into GEM and used with the specific set of

vehicle para meters (tire size, Crr, Cd, axle ratio, transmission gear ratio, and mass) to generate the

vehicle CO2 [g/ton

- mile] certification results as shown in Figure 7

. ( a ) ( b ) (c )Figure 7 : Procedure for a lternate certification a pproach

– engine fuel mapping

Powertrain T est M ethodology

A powertrain test methodology was developed to recommend a powertrain test procedure using

actual hardware in

- place of EPA’s GEM simulation tool to determine brake specific fuel consumption

(BSFC). The test methodology as shown in Figure 8 prov ided an opportunity to evaluate the complex

interactions of engine and transmissions in a controlled, repeatable, high fidelity manner, quantifying

any engine

- transmission deep integration optimization that may not be captured in GEM . The

powertrain test procedure first defined the intended application range for the powertrain being

evaluated, and for each regulatory drive cycle determined the correct range of vehicle applications.

The intent of selecting the correct vehicle application range was to test the powertrain to its full

o perating space. A set of matric es were then generated for each regulatory cycle (ARB transient,

65mph cycle with road grade , and 55mph cycle with road grade ) from the powertrain test results using

the decided application range as shown in Figur e 8 . A total of 27 powertrain tests were executed

assuming 3 drive cycles x 3 vehicles x 3 axle ratios. The cycle work was calculated using GEM for the

specific vehicle parameters (Cd, Crr, frontal area, and mass) for each drive cycle. The specific cycle

work was then used to interpolate from the matrix generated from the powertrain test the actual BSFC

point. The single BSFC point was then input into GEM to determine the final certification data. If a

specific vehicle cycle work or a xle ratio is outside the vehicle application range tested, then

interpolation is not valid and a powertrain test for that vehicle may be necessary.Figure 8 : Powertrain test m ethodology



### VI. Analysis

Alternate Certification Approach

– Fuel M apping

The BSFC surface plots shown in Figure 9 represent GEM simulation runs for the alternate approach

completed on 192 different truck configurations over each regulatory drive cycles (55, 65 mph SS and

ARB transient). Average engine speed divided by average vehicle speed (denoted as N/V) has been

used as a map axis to represent the nature of the engine speed operation on the cycle. Engine c ycle

work has been used as a second map axis to represent the engine loading on the cycle. The BSFC

results pr ovided a well behaved surface plot for each of the drive cycles. The initial GEM results

showed promise for the alternate map approach providing a well behaved surface for extrapolation

.

Figure 9 : a) ARB Transient, b) 65 MPH, c) 55 MPH GEM BSFC surface plot s

– 192 truck configurations

Three separate pre

- defined vehicle configuration were used to generate t he test cycles through GEM

. A total of 9 tests were generated for each regulatory cycle (3 pre

- defined vehicles x 3 axle ratios). The

cycles were then configured and run on engine dynamometer. Average engine speed divided by

average vehicle speed (denoted as N/V) has been used as a map axis to represent the nature of the

engine speed operation on the cycle. Engine c ycle work has been used a s a second map axis to

represent the engine loading on the cycle. BSFC surface plots were generated using a grid fit method

for each cycle as shown in Figure 10 . The BSFC relationship is well behaved as also observed from the 65 70 75 80

11 12 13 14 15 160 170 180 190 200

N/V [rpm/mph] ARB Transient

Work [bhp-hr]BSFC [g/bhp-hr]

10 20 30 40

25 30 35 40 45 50 140 160 180 200

N/V [rpm/mph] 65MPH SS

Work [bhp-hr]BSFC [g/bhp-hr]

10 15 20 25 30

20 25 30 35 40 140 160 180 200

N/V [rpm/mph] 55MPH SS

Work [bhp-hr]BSFC [g/bhp-hr] a) b) c)GEM simulation outputs shown in Figure 9

. The results provide a well behaved surface for

extrapolation.

Figure 10 : a) ARB transient , b) 65 mph, c) 55 mph BSFC surface plot s

To validate the engine BSFC surface fit two additional vehicle configurations were generated to provide

values t hat fell between the original 3 vehicle configurations

. The speed and load traces were

generated through GEM and ran using the engine

- only set

- up for each of the drive cycles (ARB

Transi ent, 65 MPH, and 55 MPH )

. Average engine speed divided by average vehicle speed (denoted as

N/V) has been used as a map axis to represent the nature of the engine speed operation on the cycle.

Engine c ycle work has been used as a second map axis to repre sent the engine loading on the cycle.

T he new BSFC points as generated fell on the surface plot between the o riginal points as shown in

Figure 11.

Figure 11 : a) ARB transient, b) 65 mph, c) 55 mph BSFC surface plots with fit points

The primary and alternate BSFC fuel mapping approaches were compared a s shown in Figure 12

. The

a lternate approach performed similar or better than the primary a pproach as witnessed . The alternate

approach seem s to capture well the trans ient content of the cycle as seen when comparing the two

approaches

. The 55 and 65 cycles for the two approaches output similar results as shown in the plot,

however for ARB, the results from alternate engine mapping (Cycle Average map based a pproach) are

better than the results from steady state engine map based approach. The alternate approach for

both the steady state and transient tests fall on the mean average line as well as the primary approach

for the 55 and 65 MPH cycles. 60 65 70

10 11 12 13 14 15 140 160 180 200

N/V [rpm/mph] ARB

Work [bhp-hr]BSFC [g/bhp-hr]

15 20 25

25 30 35 40 45 130 140 150 160 170

N/V [rpm/mph] 65 MPH

Work [bhp-hr]BSFC [g/bhp-hr]

15 20 25

25 30 35 40 140 150 160 170

N/V [rpm/mph] 55 MPH

Work [bhp-hr]BSFC [g/bhp-hr]

60 65 70

10 11 12 13 14 15 140 160 180 200

N/V [rpm/mph] ARB

Work [bhp-hr]BSFC [g/bhp-hr]

15 20 25

25 30 35 40 45 130 140 150 160 170

N/V [rpm/mph] 65 MPH

Work [bhp-hr]BSFC [g/bhp-hr]

15 20 25

25 30 35 40 140 150 160 170

N/V [rpm/mph] 55 MPH

Work [bhp-hr]BSFC [g/bhp-hr] a) b) c)

a) b) c)Figure 12 : BSFC comparison between alternate and steady state map approach

To validate the engine BSFC comparison plot two additional vehicle configurations were generated to

provide values that fell between the original 3 vehicle configurations. The speed and load trace s were

generated through GEM and ran using the engine

- only set

- up for each of the drive cycles (ARB

Transient, 65 MPH, and 55 MPH). The new BSFC points as generated and shown in Figure 13 trended

as seen from the original BSFC points as shown in Figure 12

. The alternate approach for both the

steady state and transient tests fall on the mean average line as well as the primary approach for the

55 and 65 MPH cycles.

Figure 13: BSFC comparison between alternate and steady state map approach with fit points

Table 1 shows the cycle times for the primary and alternate engine fuel mapping approaches. The

engine warm

- up times are the same for both methods taking the engine temperatures approximately

20 minutes to stabilize per 40 CFR 1065.510(b)(2). To maintai n a baseline condition for the DPF during

test ing a DPF regeneration was forced prior to running each approach to clean the DPF of storedparticulates . The emission bench was purged with Nitrogen and calibrated before testing was

launched and after every 40 minutes of test cycle time. Each purge and calibration took 20 minutes.

The primary and alternate approaches had 2.4 and 5.9 hours of emission calibration time, respectively.

The primary approach stabilize d the engine for 90 seconds at each of the 143 steady state points and

measured emissions for the last 30 secon ds, reporting the mean values. The total test time for the

primary approach was 4.5 hours. The alternate approach ran nine different vehicle configurations for

the three different regulatory cycles (3 g eneric vehicles x 3 test cycles x 3 axle ratios) . The ARB

transient, 65 MPH cycle with grade , and 55 MPH cycle with grade times were 1336, 1443, and 1693

seconds, respectively as each of the cycles were repeated twice consecutively and emissions measured

during the second cycle. The first cycle of each test sequence was used to pre

- condition the system.

The total test time to complete the 27 different tests was 5.6 hours. The total pre

- condition time was

5.6 hours for the 27 different tests. The test and emission calibration times can be reduced for the

alternate approach if the amoun t of pre

- conditioning is decreased

. The alternate approach could be

reduced by only running one preco nditioning cycle per three test cycles completed. This would reduce

the amount of preconditioning time to 1.9 hours and also reduced the emission calibration time to 1.1

hours as shown in Table 1 (alternate

- reduce pre

- conditioning )

.

Cycle Primary

[Hours] Alternate

[Hours] Alternate

– Reduced Pre

Conditioning [Hours]

Engine Warm

- Up 0.3 0.3 0.3

DPF Regeneration 1.0 1.0 1.0

Emission Purge & Calibration 2.4 5.9 1.1

Pre

- conditioning 3.3 5.6 1. b 9

Time at Test 1.2 5.6 5.6

Total Time 8.3 18.4 9.9

Table 1: Total test time for engine fuel mapping for primary and alternate approaches

Table s 2 and 3 show a comparison of the GEM simulated and engine test results for both engine brake

specific fuel consumption ( BSFC ) [g/bhp

- hr] and brake specific Carbon Dioxide ( BSCO 2 ) [g/ton

- mile]

. The payload of the vehicle was assumed to be 19 ton for calculation of the BSCO 2 results. The results

show that the e ngine and GEM simulations correlate very well for the 55MPH and 6 5MPH with road

grade , but t he ARB transie nt cycle had a slightly higher offset

. The higher BSFC and BSCO 2 offset for

the ARB transient can be directly related to the dissimilarities between the steady state fuel map

utilized and the transient ARB cycle completed.

Regulatory Cycles ARB

[g/bhp

- hr] 65 MPH

[g/bhp

- hr] 55 MPH

[g/bhp

- hr]

Engine BSFC GEM 163.6 145.2 145.4

Engine

- Only 172.3 147.5 148.1

Difference [%] 5.3 % 1.6 % 1.9 %

Table 2 : Comparison of GEM versus engine

- only BSFC resultsRegulatory Cycles ARB

[g/ton

- mile] 65 MPH

[g/ton

- mile] 55 MPH

[g/ton

- mile]

Engine BSCO 2 GEM 120.8 73.7 63.5

Engine

- Only 129.7 72.6 61.9

Difference [%] 7.4 % 1.6 % 2.5 %

Table 3 : Comparison of GEM versus engine

- only BSCO 2 results

Powertrain Test M ethodology

The BSFC surface plots shown in Figure 1 4 represent GEM simulation runs for the powertrain test

methodology completed on 3 different truck configurations over three different regulatory drive cycles

(55, 65 mph SS and ARB transient). Average powertrain speed divided by average vehicle s peed

(denoted as N/V) has been used as a map axis to represent the nature of the powertrain speed

operation on the cycle. Powertrain c ycle work has been used as a second map axis to represent the

engine loading on the cycle. The BSFC results provided a w ell behaved surface plot for each of the

drive cycles. The initial GEM results showed promise for the powertrain test option providing a well

behaved surface for extrapolation

.

Figure 14 : a) ARB transient, b) 65 mph SS, c) 55 mph SS BSFC GEM BSFC surface plots

Three separate pre

- defined vehicle conf iguration were used to generate the powertrain test

. A total of

9 tests were executed for each regulatory cycle (3 pre

- defined vehicles x 3 axle ratios). Average

powertrain speed divided by average vehicle speed (denoted as N/V) has been used as a map axis to

represent the nature of the powertrain speed operation on the cycle. Powertrain c ycle work has been

used as a second map axis to represent the powertrain loading on th e cycle. BSFC surface plots were

generated using a grid fit method for each cycle as shown in Figure 15

. The BSFC relationship is well

behaved for the ARB, 55 mph, and 65 mph as also observed from the GEM simulation outputs shown in

Figure 14

. 20 25 30

10 10.5 11 11.5 12 160 170 180 190 200

N/V [rpm/mph] ARB

Work [bhp-hr]BSFC [g/bhp-hr]

20 25 30

25 30 35 40 45 140 150 160 170

N/V [rpm/mph] 65 MPH

Work [bhp-hr]BSFC [g/bhp-hr]

20 25 30

25 30 35 40 140 150 160 170

N/V [rpm/mph] 55 MPH

Work [bhp-hr]BSFC [g/bhp-hr] a) b) c)Figure 15 : a) ARB transient, b) 65 mph SS, c) 55 mph SS BSFC surface plots

To validate the engine BSFC surface fit two additional vehicle configurations were generated to provide

values that fell between the original 3 vehicle configurations. The configurations were input into the

vehicle model and the powertrain test completed for each of the drive cycles (ARB Transient, 65 MPH,

and 55 MPH ) . The new BSFC poi nts as generated fell on the surface plot between the o riginal points as

shown in Figure 16

.

Figure 16 : a) ARB transient, b) 65 mph SS, c) 55 mph SS BSFC surface plots with fit points

Tables 4 and 5 show a comparison of the GEM simulated and powertrain test results for both the

powertrain brake specific fuel consumption (BSFC) [g/bhp

- hr] and brake specific Carbon Dioxide

(BSCO 2 ) [g/ton

- mile]. The payload of the vehicle was assumed to b e 19 ton for calculation of the

BSCO 2 results. The 9 tests executed for each regulatory cycle were averaged to determine the overall

cycle results. The results show that the GEM simulation and actual powertrain tests correlate very well

for the 55MPH and 65MPH with road grade as well as the ARB transient.

Regulatory Cycles ARB

[g/bhp

- hr] 65 MPH

[g/bhp

- hr] 55 MPH

[g/bhp

- hr]

Powertrain BSFC GEM 181.9 153.5 154.0

Powertrain 180.9 148.8 150.5

Difference [%] 0.5 % 3.1 % 2.3 %

Table 4: Comparison of GEM versus powertrain BSFC results 15 20 25

10 10.5 11 11.5 12 160 170 180 190 200

N/V [rpm/mph] ARB

Work [bhp-hr]BSFC [g/bhp-hr]

20 25 30

25 30 35 40 140 150 160 170

N/V [rpm/mph] 65MPH

Work [bhp-hr]BSFC [g/bhp-hr]

20 25 30

25 30 35 140 150 160 170

N/V [rpm/mph] 55MPH

Work [bhp-hr]BSFC [g/bhp-hr]

15 20 25

8 9 10 11 12 160 180 200 220

N/V [rpm/mph] ARB

Work [bhp-hr]BSFC [g/bhp-hr]

20 25 30

25 30 35 40 140 150 160 170

N/V [rpm/mph] 65MPH

Work [bhp-hr]BSFC [g/bhp-hr]

20 25 30

25 30 35 140 150 160 170

N/V [rpm/mph] 55MPH

Work [bhp-hr]BSFC [g/bhp-hr] a) b) c)

a) b) c)Regulatory Cycles ARB

[g/ton

- mile] 65 MPH

[g/ton

- mile] 55 MPH

[g/ton

- mile]

Powertrain BSCO 2 GEM 117.7 73.6 63.7

Powertrain 119.3 69.9 61.3

Difference [%] 1.3 % 5.0 % 3.7 %

Tabl e 5 : Comparison of GEM versus powertrain BSCO 2 results

Powertrain results comparing a SmartAdvantage and baseline powertrains are shown in Table 6 . The

baseline powertrain is a standard ISX engine and Eaton 10

- speed line haul transmission . The

SmartAdvantage p owertrain is a deeply in tegrated Eaton and Cummins powertrain solution of the ISX

engine and Eaton 10

- speed line haul transmission. These two powertrains were tested on the

powertrain dynamometer against potential regulatory drive cycles (65 and 55 mph with up to +/

- 2%

grade, and the A RB transient cycle) u nder various weightings of the drive cycles that correspond to

either long haul, or mixed city delivery and high speed, and with m ultiple vehicle configurations. T he

test show 3.4

– 4.9% GHG reduction of the SmartAdvantage po wertrain versus the baseline , with

greater than 98 % repeatability coefficient as shown in Table 7

.

Powertrain ARB

[g] 65 MPH

[g] 55 MPH

[g]

Baseline 2.32 6.00 5.05

SmartAdvantage 2.02 5.79 5.07

Application Cycle weights Fuel

Line haul 86% 65mph, 9% 55mph, 5%ARB 3.4%

Mixed city / high speed 22% 65mph, 28% 55 mph, 50% ARB 4.9%

Table 6 : Fuel consumption [kg] measured against 3 drive cycles (top) and % fuel improvement across

two different drive cycle weightings (bottom)

The improvements are due to active controls shared between the engine and transmission as well as

advanced lubrication strategies . The GEM simulation of these powertrains can only account for

approximate 100 rpm engine down

- speeding in top gear because the overdrive ratios of the t wo

transmissions are 0.73 and 0.796, which results in approximate 1% fuel savings when in top gear. The

balance of the 3.4

– 4.9% GHG reduction is due to the deep integration between the engine and

transmission and the advanced lubrication system in the t ransmission that are not modeled in GEM.

This is an example where powertrain testing accounts for advanced technologies not modeled in GEM.

Table 7 represents six 55 mph cycles with road grade that were repeated consecutively over multiple

days. The tes ts were repeated to verify test

- retest reliability for the powertrain set

- up. The

repeatability coefficient showed a probability of greater than 98 % between the two worst case cycles

representing that the absolute difference measured between two test cycles showed a very high

correlation of repeatability

.Powertrain

Test 55 MPH Cycle

Cycle Work [bhp

- hr] BSFC [g/bhp

- hr] N/V [rpm/mph] FE [mpg]

PT #1 27.0 151.7 26.9 4.10

PT #2 27.0 150.6 26.9 4.07

PT #3 27.0 152.1 26.9 4.11

PT #4 27.0 151.0 26.9 4.08

PT #5 27.0 151.4 26.9 4.09

PT #6 27.0 152.8 26.9 4.13

CoR

Std. Dev.

Difference

Difference 10 0%

0 .0 0

0 .0%

0.0 98.5 %

0 .80

1.4%

1.8 100 %

0 .0 0

0 .0%

0.0 98.5 %

0 .02

1.5%

0.06

Table 7 : Powertrain c ycle to cycle repeatability



### VII. Conclusions

The Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration

(NHTSA) are currently developing the testing protocols and stringencies for the second phase of the

Heavy

- Duty (HD) Greenhouse Gas (GHG) R egulations

. The testing and certification protocols that are

under development involve an engine fuel mapping procedure , updates to the accuracy, validity, and

further refinement of the existing Gr eenhouse Gas Emission Model (GEM) and a powertrain test

option.

An alternate fuel mapping method was investigated and tested by a consortium of vehicle, engine, and

transmission OEM’s to determine if a feasible, rel iable, repeatable, cost effective alte rnate to the

primary steady state fuel mapping approach could be developed. The alternate method tested

provided a scheme of a reduced number of test points creating an average map which provided the

same accuracy as the primary engine fuel mapping method

. The overall test burden to collect the

engine BSFC data for the alternate approach was shown to be roughly double as executed in this study

while supplying equivalent accuracy to the primary approach

. The pre

- conditioning portion of the

alternate approach can be reduce d to decrease the overall test burden as still obtain the accuracy and

repeatability of the data sets. The a lternate method average BSFC map was well behaved as also

observed from the GEM simulation outputs. The alternative approach also produce d CO 2 results that

agree d with the vehicle data as well as the primary mapping approach. The primary and alternate fuel

mapping approaches were compared and the alternate performed similar or better than the primary

capturing better the transient content of the cycle. To further validate the alternate engine BSFC

mapping approach two additional vehicle configurations were generated to verify the surface fit. The

additional points generated verified that the BSFC po ints as predicted fell on the surface plot

generated from the o riginal points for each of the test cycles (ARB, 65 MPH, & 55 MPH)

.

A powertrain test methodology was also developed and shown to be a controlled, repeatable, high

fidelity solution to meet the agencies GHG verification needs. The powertrain procedure is able to

show the specific GHG emissions and fuel efficiency improvements from powertrain enhancements

that would otherwise not be recognized in simulation, engine testing, o r full vehicle evaluation.

Powertrain testing provide d a consistent and repeatable measure independent of vehicle platform or

powertrain technology and includes conditions reflective of real

- world operation. Vehicle parameters

such as road friction, vehicle mass, rolling radius, wheel inertia, vehicle frontal area, drag coefficientand final drive ratio were implemented into the driver model to reflect on

- road vehicle operation of a

class 8 vocational truck as defined by EPA i n the GEM model as part of the GHG phase 1 rule

. The

powertrain was tested using r egulatory cycles ( ARB, 65mph and 5 5mph) and were fully reflective of

real

- world driving as they include d a +/

- 2% road grade profile. The BSFC results prov ided a well

behaved surface plot for each of the drive cycles. To validate the powertrain BSFC mapping approach

two additional vehicle configurations were generated to verify the surface fit for each cycle. The

additional points verified that the BSFC po ints as predicted fell on the surface plot between the o riginal

points generated.

Powertrain dynamometer test rigs have been developed on which the entire powertrain, including the

real controllers, can be tested against drive cycles. These test rigs and procedures offer ways to

quantify the GHG performance of deeply integrated and highly optimized powertrains. PT utilizes

established testing protocols (CFR) producing high fidelity data. The powertrain test captures real

world performance differentiation among drivetrains as shown with the deeply integrated Eaton and

Cummins SmartAdvantage powertrain which provided a 3.4

– 4.9% GHG reduction versus the baseline

under various weightings of the drive cycles that correspond to either long haul, or mixed city delivery

and high speed

.

The PT methodology test

- to

- test repeatability was examined by running six 55 MPH cycles

consecutive ly and verifying the consistency of the test and set

- up. The repeatability coefficient showed

a probability of greater than 98 % an d also exhibited a low standard deviation for the powertrain

configuration tested. Both the high repeatability coefficient and low standard deviation values indicate

that the cycle to cycle correlation for the powertrain tests were very repeatable. The c ycle to cycle

correlation also indicates that the powertrain test procedure is very robust and a reliable method for

verifying performance, emissions, and fuel economy in a controlled, repeatable, high fidelity manner.

P owertrain dynamometers as extensi ons of engine dynamometers, where the motor is connected to a

transmission output shaft rather than the engine flywheel, and the controls simulate a vehicle route,

rather than the usual engine cycles. From this perspective, the powertrain dynamometer has the

advantage of relative small incremental capital costs (less than $600,000 capital investment in

converting an engine test cell to a powertrain test cell). In the context of certification, the calibration

of a new powertrain is also a small incremental effort relative to the engine dynamometer calibration.

Thus a new powertrain can be installed and calibrated by experienced staff in less than two weeks,

while a variation can be in stalled in two days.

### Appendix A

- Vehicle Configurations for Alternate Fuel Mapping Approach

Vehicle

Configuration Aero Drag

Coefficient Vehicle

Mass [kg] Frontal

Area [m 2 ] Tire Radius

[m] Rolling

Resistance

1 0.7 30391 9.8 0.489 0.006

2 0.55 30391 9.8 0.489 0.0053

3 0.41 30391 9.8 0.489 0.0045

4 0.625 30391 9.8 0.489 0.0057

5 0.48 30391 9.8 0.489 0.0049

### Appendix B

– Alternate Fuel Mapping Approach Test Results

Cycle Vehicle

Configuration Actual Engine Cycle

Work [bhp

- hr] Engine BSFC

[g/bhp

- hr] CO 2 [g/ton

- mile] N/V

[rpm/ m ph] FDR

55MPH 1 36.49 147.2 64.9 18.3 2.64

55MPH 1 36.52 146.8 72.2 19.8 2.85

55MPH 1 36.96 147.2 73.1 21.4 3.08

55MPH 2 31.76 147.4 57.3 18.4 2.64

55MPH 2 32.08 147.1 63.4 19.8 2.85

55MPH 2 32.23 148.6 64.4 21.4 3.08

55MPH 3 27.28 149.2 50.0 18.3 2.64

55MPH 3 27.67 149.6 55.8 19.8 2.85

55MPH 3 27.76 149.5 56.0 21.4 3.08

55MPH 4 37.90 146.4 71.5 19.1 2.75

55MPH 4 34.45 148.0 68.8 20.6 2.97

55MPH 5 29.79 149.0 59.8 19.1 2.75

55MPH 5 29.91 148.8 59.7 20.6 2.97

65MPH 1 41.42 145.8 80.89 18.4 2.64

65MPH 1 42.33 145.8 82.67 19.8 2.85

65MPH 1 43.25 147.5 85.33 21.4 3.08

65MPH 2 36.31 146.2 70.90 18.3 2.64

65MPH 2 36.76 146.9 72.16 19.8 2.85

65MPH 2 37.29 148.3 73.94 21.4 3.08

65MPH 3 31.25 148.2 61.96 18.4 2.64

65MPH 3 31.24 148.2 61.94 19.8 2.85

65MPH 3 31.41 150.6 63.22 21.4 3.08

65MPH 4 38.96 146.0 76.70 19.1 2.75

65MPH 4 39.79 147.3 79.14 20.6 2.97

65MPH 5 33.42 147.2 66.11 19.1 2.75

65MPH 5 33.89 148.7 67.73 20.6 2.97

ARB 1 13.32 171.2 135.56 66.3 2.64

ARB 1 13.10 169.5 131.98 64.6 2.85

ARB 1 12.87 170.2 130.84 63.5 3.08

ARB 2 13.09 173.4 135.04 65.8 2.64

ARB 2 12.58 171.7 128.57 64.6 2.85

ARB 2 12.42 171.5 126.95 63.5 3.08

ARB 3 12.48 174.7 130.39 65.8 2.64

ARB 3 12.02 173.9 124.36 64.4 2.85

ARB 3 11.98 174.5 123.98 63.5 3.08

ARB 4 13.14 172.8 135.54 66.4 2.75

ARB 4 12.63 172.6 129.66 63.3 2.97

ARB 5 13.14 172.8 135.54 66.4 2.75

ARB 5 12.18 174.1 126.11 63.3 2.97

### Appendix C

- Vehicle Configurations for Powertrain Test

Vehicle

Configuration Aero Drag

Coefficient Vehicle

Mass [kg] Frontal

Area [m 2 ] Tire Radius

[m] Rolling

Resistance

1 0.7 30391 9.8 0.489 0.006

2 0.55 30391 9.8 0.489 0.0053

3 0.41 30391 9.8 0.489 0.0045

6 1.4 37989 19.6 0.489 0.013

7 1.4 30391 19.6 0.489 0.013

8 0.7 37989 9.8 0.489 0.0065

9 0.41 15195 9.8 0.489 0.0065

10 0.41 22000 9.8 0.489 0.0065

11 0.53 30391 9.8 0.489 0.0065

12 0.5 30391 9.8 0.489 0.0045

### Appendix D

– Powertrain Test Results

Cycle Vehicle

Configuration Powertrain Cycle

Work [bhp

- hr] Powertrain BSFC

[g/bhp

- hr] CO 2 [g/ton

- mile] N/V

[ rpm/m ph] FDR

55MPH 1 33.90 148.4 70.17 26.9 2.64

55MPH 1 33.86 149.1 70.40 26.9 2.85

55MPH 1 33.89 148.7 70.48 23.0 3.08

55MPH 2 29.48 150.6 61.18 24.8 2.64

55MPH 2 29.40 150.7 61.05 23.0 2.85

55MPH 2 29.44 150.1 60.89 26.8 3.08

55MPH 3 25.27 151.6 52.39 26.9 2.64

55MPH 3 25.29 153.0 52.66 26.9 2.85

55MPH 3 25.28 152.3 52.86 26.9 3.08

55MPH 11 31.16 152.4 66.11 26.9 2.64

55MPH 12 27.05 154.9 58.55 26.9 2.64

55MPH 11 31.10 153.4 66.48 26.9 2.85

55MPH 12 27.03 155.0 58.76 18.3 2.85

55MPH 11 31.19 152.6 66.22 19.8 3.08

55MPH 12 27.06 156.7 59.44 21.4 3.08

55MPH 1 33.89 148.7 70.12 18.3 2.64

55MPH 1 33.85 148.3 69.80 19.8 2.85

55MPH 11 31.16 151.2 65.86 21.4 2.64

55MPH 12 27.02 151.0 57.30 18.3 3.08

55MPH 12 27.02 151.7 57.78 19.8 3.08

55MPH 12 27.02 150.6 57.49 21.4 3.08

55MPH 12 27.02 152.1 58.00 18.3 3.08

55MPH 12 27.02 151.0 57.74 18.3 3.08

55MPH 12 27.02 151.4 57.78 19.8 3.08

55MPH 12 27.02 152.8 58.37 19.8 3.08

65MPH 1 39.55 145.9 81.00 21.4 2.64

65MPH 1 39.72 147.5 81.08 21.4 2.85

65MPH 1 39.82 149.2 81.95 26.9 3.08

65MPH 2 33.91 146.6 68.97 26.9 2.64

65MPH 2 34.09 148.1 69.53 23.0 2.85

65MPH 2 34.15 149.9 70.45 24.8 3.08

65MPH 3 28.51 148.7 58.13 23.0 2.64

65MPH 3 28.57 150.5 58.77 26.8 2.85

65MPH 3 28.59 152.9 59.32 26.9 3.08

65MPH 11 35.55 149.4 73.95 26.9 2.64

65MPH 12 31.09 151.2 65.49 26.9 2.64

65MPH 11 35.64 150.7 74.42 26.9 2.85

65MPH 12 31.26 152.3 66.02 26.9 2.85

### Appendix D

– Powertrain Test Results ( Cont’d)

Cycle Vehicle

Configuration Powertrain Cycle

Work [bhp

- hr] Powertrain BSFC

[g/bhp

- hr] CO 2 [g/ton

- mile] N/V

[rpm/kph] FDR

65MPH 1 39.52 146.5 80.53 18.3 2.64

65MPH 1 39.82 149.4 81.75 21.4 2.85

65MPH 11 35.53 146.9 72.73 18.3 2.64

65MPH 12 31.29 150.8 65.34 21.4 3.08

65MPH 12 31.29 150.5 65.48 21.4 3.08

65MPH 12 31.28 150.9 65.52 21.4 3.08

65MPH 12 31.30 153.0 66.10 21.4 3.08

65MPH 12 31.29 151.5 65.61 21.4 3.08

65MPH 12 31.29 151.2 65.54 21.4 3.08

65MPH 12 31.29 151.2 65.41 21.4 3.08

ARB 1 11.10 181.1 125.09 57.0 2.64

ARB 1 11.28 179.1 125.68 56.5 2.85

ARB 1 11.57 176.3 125.36 56.2 3.08

ARB 2 10.71 183.0 120.75 56.6 2.64

ARB 2 10.89 180.9 120.72 56.0 2.85

ARB 2 11.11 178.2 121.22 56.1 3.08

ARB 3 10.22 185.9 110.69 56.9 2.64

ARB 3 10.44 183.9 112.65 56.0 2.85

ARB 3 10.74 179.7 111.53 56.2 3.08

ARB 6 17.90 168.2 203.39 65.7 2.64

ARB 7 16.10 168.9 169 59.5 2.64

ARB 8 13.78 174.2 148.04 59.6 2.64

ARB 9 5.97 232.8 84.41 54.7 2.64

ARB 10 10.08 187.5 113.86 55.3 2.64

ARB 6 18.74 166.0 199.85 62.7 2.85

ARB 7 16.17 170.7 170.38 60.0 2.85

ARB 8 13.80 173.9 146.58 58.1 2.85

ARB 9 5.92 234.8 84.4 54.7 2.85

ARB 10 8.39 199.0 101.73 54.8 2.85

ARB 6 18.61 166.0 198.07 61.0 3.08

ARB 7 16.36 168.7 171.54 58.3 3.08

ARB 8 13.75 173.8 147.23 59.2 3.08

ARB 9 5.93 236.1 86.06 55.8 3.08

ARB 10 8.42 199.5 102.48 55.5 3.08