Development, Demonstration and Commercialization of a 0.20 g/hp-hr NOx Natural Gas Engine

This page updated April 20, 2007.

Cummins Westport, Inc.

Development, Demonstration and Commercialization
of a 0.20 g/hp-hr NOx Natural Gas Engine

Technology and Innovation
The spark ignited (SI) / cooled exhaust gas recirculation (EGR) technology combines the low-emissions advantages of stoichiometric combustion and three-way catalyst technology with the high torque, durability and efficiency enabled by cooled EGR systems. Cummins Westport intends to commercialize this new technology on its 8.9 liter engine platform, which will be marketed as the “ISL G” engine.

The SI / EGR technology is significantly different than conventional stoichiometric combustion technology, and also differs from the lean-burn spark-ignited (LBSI) technology in Cummins Westport’s current engines. Traditional stoichiometric engine technology has been limited by high in-cylinder temperatures, leading to very high engine out NOx emissions, knock limited power density, poor thermal efficiency and lower durability. Cummins Westport’s current natural gas engines utilize LBSI in order to provide a significantly improved combination of emissions, torque, durability and fuel economy vs. traditional stoichiometric engines. However, LBSI systems are likely to experience difficulties in achieving future NOx and NMHC reductions, as further leaning of the air / fuel ratio mixtures to reduce NOx would result in ignition and combustion difficulties.

<However, increased power density and increased fuel efficiency may be achieved by utilizing cooled EGR with a stoichiometric combustion principle, in combination with a TWC. Use of EGR technology is made possible by the recent availability of cooled EGR subsystems for diesel engine platforms. The resulting SI / EGR platform has demonstrated 0.20 g/bhp-hr NOx emissions over the Federal Transient Procedure (FTP) emissions certification test procedure.
Emission Benefit
The ISL G will be certified at 0.20 g/bhp-hr NOx and 0.01 g/bhp-hr PM beginning in 2007. Therefore, the ISL G will be compliant with ARB’s 2010 emission requirements at commercial launch in 2007, and will offer significant NOx reductions vs. model year 2007-2009 diesel engines, which are widely expected to utilize the phase-in provisions of the 2007 ARB standard, resulting in an average NOx certification level of approximately 1.2 g/bhp-hr NOx. ISL G engines in medium-duty and heavy-duty vehicle applications in California, including transit buses, refuse trucks, shuttle buses, street sweepers, medium-duty trucks, and yard hostlers, will generate approximately 83 percent lower NOx emissions than model year 2007-2009 diesel engines.
Project Description
CWI will conduct two field demonstrations of the ISL G engine at California fleet locations to demonstrate the ISL G performance in medium-duty truck and school-bus applications. CWI anticipates that these field tests will be conducted over approximately 12 months.

Funding Source

Funding Amount








ICAT Funded Projects