GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information

Stuart R. Smith - Principal Investigator

GM Powertrain

May 17, 2013

2013 DOE Vehicle Technologies Program Annual Merit Review

Washington, DC

Lean Gasoline System Development 

for Fuel Efficient Small Car

Project ID: ACE063
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 2

TIMELINE

• Project start: May 2010

• Project end: Sept 2013

• Project duration: 3 yrs 3m

• Percent complete: 90%

BARRIERS

• Engine efficiency improvement >25%

• Engine controls to meet regulatory 

and consumer requirements 

• Emission control hardware cost 

competitiveness

BUDGET

• Total funding: $15,411,724

– DOE share: $7,705,862

– GM share: $7,705,862

– DOE Funding FY12 $3,014,435

– DOE Funding FY13 $276,308

PARTNERS

• 

• 

• 

Lean Gasoline System Development

Overview
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 3

Lean Gasoline System Development

Relevance – Program Objective

25% fuel economy improvement while meeting T2B2 emissions

 Lean Combustion - Generate fundamental lean 

gasoline combustion comprehension and design 

guidelines that would support implementation 

across multiple engine families

 Lean Aftertreatment - Optimize a lean 

aftertreatment system that combines passive NH3 

generation with active urea dosing for minimized 

urea consumption under lean operating 

conditions

 Lean Controls - Develop engine and passive and 

active aftertreatment controls that work within 

production controls constraints to ensure 

compatibility with future ECU architectures
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 4

Lean Gasoline System Development

Approach / Strategy – Targeted Efficiency Improvement

Advanced Dilute Combustion

(direct injection, cool EGR)

Lean Dilute Combustion

(closely-spaced multiple 

pulse injection)

Vehicle Integration

(12V stop/start, active 

thermal management)

Downsizing

(2.4L PFI to 

1.4L DI Turbo)

Projection 

7.5%

Projection

12.5%

Projection 

5%

* Projections formulated from dynamometer and SG5 vehicle data
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 5

Lean Gasoline System Development

Approach / Strategy – Technology Development Plan

Phase 2

Refinement

Phase 3

Optimization

Aug 

2013

1.4L Lean Downsize Boost Design & Build

2.2L SG5 NA Vehicle Integration & Calibration

Downsize Boost Simulation

Gen 2/3 Passive SCR Development

Active SCR Development

 Passive/Active SCR

S/S & ATM Integration

Demo

1.4L LDB Calibration

Lean Boost Controls

FE Optimization

Nov 

2012

May 

2013

May 

2012
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 6

SG5 Fuel Economy Limitations

 Lean operation shows significant 

fuel economy improvement at 

light to medium loads

 Needed to extend the lean 

operating range to higher loads

SG5 Systems Refinement

 Enabled development of controls 

around lean-stoich transitions

 Enabled exploratory boost 

performance investigations

 Enabled refinement of multiple 

aftertreatment systems

Lean Gasoline System Development

Accomplishments – Phase 2: SG5 NA Systems Refinement

 The SG5 NA engine would not meet FE targets. However, it enabled development of 

combustion system, lean aftertreatment (hardware and controls), and in-vehicle engine 

controls and calibration
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 7

Lean Gasoline System Development

Accomplishments – Phase 2: SG5 NA Fuel Economy Improvement

Fuel Economy Simulation

 BSFC data for high usage speed / 

load points from FTP tests used 

to project fuel economy 

improvements

 Data does not include 12V 

Stop/Start and Active Thermal 

Management which is projected 

to provide additional 4-6 % 

combined fuel economy benefit

 Good correlation between fuel economy projections and measured vehicle data

 SG5 NA Engine does not meet FE target

Speed 

(RPM) Load (n-m)

BSFC 

Improvement 

PFI to Lean NA

Idle 700 19 0%

Zone 2 1335 27 17%

Zone 3 1565 28 19%

Zone 4 1805 29 18%

Zone 5 1530 95 -1%

Zone 6 1821 80 3%

Zone 7 2250 101 0%

Zone 8 1410 51 18%

Zone 9 1669 60 9%

Zone 10 1461 114 0%

Zone 11 1692 100 0%

Projected FE 

Improvement

Measured FE 

Improvement

City 12% 12%

Hiway 8% 7%

Combined 10% 10%

Urban Highway
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 8

Lean Gasoline System Development

Accomplishments – Phase 2: Passive/Active Ammonia SCR System

Passive/Active Ammonia SCR System (PAASS)

 A portion of the NH3 is generated across three way catalyst with the remainder injected

 The selected TWC volume and formulation optimize the NH3 generation during lean-tostoichiometric transitions 

 The passive and active ammonia systems are combined to achieve the optimal 

aftertreatment to support lean and stoichiometric operation under all conditions

0

50

100

150

200

250

300

0

100

200

300

400

500

600

700

0 500 1000 1500 2000 2500

Vehicle Speed [mph]

Temps (DegC)

Time [sec]

Temperatures for SCR 4 Brick System-"Torpedo"

Torpedo 1 Torpedo 2 Torpedo 3

Torpedo 5 Torpedo 6 Torpedo 7

Torpedo 8 Torpedo 9 Vehicle Speed

MS03007020

1/4/2013

MS04008344

SCR Torpedo

1 2 3 4 5 6 7 8 9

Post O2 sensor NOx sensor Urea Injector 

~56.5” to front face of SCR 16.5

”

TWC-1

SCR volume = 4.0L

4.66” round substrates (4 substrates x 1.0L)

Cu-Fe-Fe-Cu

TWC-2

1.7 L Yoval

1.0 L round

Mixe

r
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information

*Diesel information is from T2B5 package

9 

Lean Gasoline System Development

Accomplishments – Phase 2: Comparison with Diesel Vehicle

Aftertreatment

 In order to achieve FE targets, engine-out NOx increases and the active urea system is 

incorporated to supplement the passive system

 Urea consumption is not linear with engine-out NOx due to passive NH3 generation and 

TWC reduction
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 10

Lean Gasoline System Development

Accomplishments – Phase 3: 1.4L LDB Combustion Optimization

 Transfer the desired combustion characteristics of the SG5 to the new LDB engine

 CFD analysis to simulate the spray pattern and in-cylinder air fuel ratio distribution

 Flow bench to measure and modify swirl and tumble ratio on the new LDB engine 

Fuel Spray Analysis

In-cylinder Fuel Equivalence 

Ratio Distribution Analysis Swirl & Tumble Flow Bench
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 11

Lean Gasoline System Development

Accomplishments – Phase 3: 1.4L LDB Engine Combustion Features

1.4L Boosted Stoich 1.4L LDB

 Fuel spray cone is targeted to the spark 

gap w/close-space injections

 Injector is pulled upward and spark 

plug is moved downward

 LE2 piston bowl is modified to match 

SG5 NA piston bowl 

 Piston crown is modified to result in 

10.5 compression ratio

 Added low pressure cooled EGR system

 Moved TWC catalyst location for 

meeting T2B2 HC emission level

 Start with 1.4L boosted stoichiometric-homogeneous combustion engine

 Modifications made to engine components to enable lean-stratified operation
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 12

Lean Gasoline System Development

Accomplishments – Phase 3: LDB Engine Procured, Built & Installed

Charge & Exhaust System

 Compact turbocharger to 

support high EGR, low RPM 

performance

 Cooled low-pressure EGR with 

gases taken downstream of 

the turbo 

 Air-to-water charge air cooler 

with independent low 

temperature coolant circuit & 

auxiliary pump

 Close Coupled TWC Catalyst 

integrated in turbine housing

 Four 1.4L Lean Downsize Boost (LDB) engines are designed, procured and built to 

support calibration, controls development, integration and fuel economy optimization 
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 13

Lean Gasoline System Development

Accomplishments – Phase 3: LDB Boosted Lean Combustion

 The LDB engine delivers ~15% improvement in fuel consumption at 25 to 30 Nm

 The SG5 naturally aspirated engine lean stratified operation limit is ~85 Nm 

 The LDB engine lean stratified operation limit is ~120 Nm, results in ~7% improvement 

in fuel consumption

BSFC comparison: PFI to NA Lean to Lean Downsize Boost

Normalized BSFC
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 14

Lean Gasoline System Development

Accomplishments – Phase 3: LDB Engine BSFC vs FSNOx Trade-off

0

10

20

30

40

50

60

245 250 255 260 265 270 275

BSFC (g/kwh)

FSNOx (g/kg Fuel)

245

250

255

260

265

270

275

0 10 20 30 40

EGR (%)

BSFC (g/kwh)

RPM 1669

BMEP 5.4 

bar

RPM 1669

BMEP 5.4 bar

Lean Downsize Boost Engine 

Calibration Strategy:

 When the engine is running lean, 

small amount of EGR will not have 

significant impact on BSFC

 Small amount of EGR will have 

significant impact on engine-out NOx 

emission

 One percent BSFC degradation point 

is selected to represent the best 

trade-off calibration point

1%

 Cooled EGR is added to reduce NOx emission until 1% BSFC degradation is observed
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information

Targeted Efficiency Improvement

 Downsizing 7-8 %

 Dilute & Lean 

Combustion 12-13% 

 Total from Engine 19-21 %

 12V Stop/Start & Active 

Thermal Management 5 %

15

Lean Gasoline System Development

Accomplishments – Phase 3: Vehicle Fuel Economy Projections

 The LDB engine in combination with 12V Stop/Start and Active Thermal Management 

is projected to meet the 25% fuel economy improvement target

FE Projections: PFI to NA Lean to Lean Downsize Boost

Speed 

(RPM) Load (n-m) PFI to Lean NA PFI to LDB

Idle 700 19 0% 0%

Zone 2 1335 27 17% 30%

Zone 3 1565 28 19% 31%

Zone 4 1805 29 18% 35%

Zone 5 1530 95 -1% 7%

Zone 6 1821 80 3% 9%

Zone 7 2250 101 0% 7%

Zone 8 1410 51 18% 16%

Zone 9 1669 60 9% 14%

Zone 10 1461 114 0% 3%

Zone 11 1692 100 0% 6%

City 12% 26%

Highway 8% 12%

Combined 10% 21%

BSFC Improvement

Projected FE Improvement

Urban Highway
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 16

Passive/Active SCR – LDB 1.4L Boosted 

 Apply as much as possible of the SG5 

exhaust architecture on LDB engine.

NOx sensor Urea Injector 

16.5”

SCR volume = 4.0L

4.66” round substrates (4 bricks x 1.0L)

Cu-Cu-Cu-Cu

Mixer

Lean Gasoline System Development

Accomplishments – Phase 3: Passive/Active Ammonia SCR System

0

50

100

150

200

250

300

350

400

450

1335 / 2.5 1565 / 2.5 1805 / 2.6 1821 / 7.1 1410 / 4.5 1669 / 5.4

TWC Inlet Gas Temp

Engine Speed / BMEP

0

50

100

150

200

250

300

350

1335 / 2.5 1565 / 2.5 1805 / 2.6 1821 / 7.1 1410 / 4.5 1669 / 5.4

SCR Inlet Gas Temp 

Engine Speed / BMEP

 Exhaust gas temperature into the catalyst is much lower than the SG5 (leaner AFR and turbo impact)

 TWC light-off temperature may be a challenge and require enrichment (FE effects unknown)

 SCR technology will start with copper zeolite which historically performs well at lower temperature

Engine Dyno Data
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 17

Lean Gasoline System Development

Collaboration – Key Supplier Involvement

Calibration and combustion performance evaluation 

of lean gasoline combustion technology enablers

Fuel injector to enable multiple close-spaced 

injection capability

Aftertreatment hardware formulations supporting 

passive and active ammonia systems integration

The program is partnering with the following suppliers in order to 

develop a common understanding of the integration challenges to 

implement lean gasoline systems in to production 
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information







18

Lean Gasoline System Development

Future Work – Remainder of FY13 and Project

Calibrate

 1.4L LDB engine fuel economy enhancing features

Integrate

 LDB engine

 12V Stop/Start

 Active Thermal Management system

 Passive/Active Ammonia SCR System (PAASS)

Optimize

 Lean boosted controls & calibration for drivability

Demo

 Demonstrate fuel economy & T2B2 emissions 
GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information GM Powertrain

Advanced Engineering

This presentation does not contain any proprietary, 

confidential, or otherwise restricted information 19

Lean Gasoline System Development

Summary – FY12 to FY13

Phase 2 – Complete 

 SG5 NA engine utilized in vehicle to develop engine and aftertreatment controls 

along with utilizing as a lean combustion emissions generator

 Passive and Active aftertreatment systems have been combined to provide the 

optimal lean gasoline aftertreatment system that minimizes urea consumption under 

all lean-stratified and stoichiometric-homogeneous operating conditions

Phase 3 (the last one) – In process, final system optimization 

 4 Lean Downsize Boost (LDB) engines have been designed, procured & built

 LDB engine calibration has supported optimization of the BSFC performance

 LDB engine, 12V Stop/Start, Active Thermal Management and Gen 4 PAASS 

aftertreatment systems are installed in a Malibu development vehicle

 Expect to meet FE and Emissions target

Timeline Evaluation Milestone (1) Evaluation Milestone (2)

12/23/11 Cold ftp & H FE > 13% - simulated Gen 2 A/T dyno results – achieved

12/21/12 C & H FE > 20% - projected Emissions < 150% w/PM - achieved

FY13 Goal C & H FE > 25% Emissions T2B2