Cummins Westport Inc., a joint venture company owned by Cummins and British-Columbia-based Westport Innovations, announced that its new 8.3-liter natural gas engine, the C8.3G Plus, has obtained low-emissions certification from the California Air Resources Board.

With the California certification, purchasers of vehicles with C8.3G Plus engines will be entitled to low-emissions financial incentives provided by that state.
Cummins Westport also announced advanced features of the new engine, including a capability to operate on a wide range of natural gas compositions. This capability is significant because natural gas, which is not a refined fuel, contains concentrations of hydrocarbons that can vary by region and sometimes even in the same region on a seasonal basis. The C8.3G Plus is equipped with new electronics and sensors that accommodate for and adjust instantly to variations in fuel composition. This can prevent engine damage or loss of performance that might otherwise result.
The C8.3G Plus, with up to 280 horsepower, is intended mainly for buses and urban work trucks like refuse haulers and pickup and delivery trucks. This engine replaces the original C8.3G, which has been manufactured by Cummins since 1996. Production of the C8.3G Plus began in June.
The C8.3G Plus features a Electronic Control Module derived from the Cummins Interact System for engine management used on the ISC diesel fuel version of this engine. This module makes the C8.3G Plus compatible with Cummins diesel diagnostic tools for troubleshooting repairs and Cummins engineers have developed a version of Cummins INSITE diagnostic software specifically for use with this engine.
With the ECM and new sensors, the C8.3G Plus can monitor and control knocking, a condition of uncontrolled combustion related to unexpected changes of fuel composition or external conditions that can lead to expensive power cylinder component damage. Engine makers deal with the fuel composition problem by specifying a minimum requirement based on an index of fuel quality typically expressed as a Methane number. With the C8.3G Plus, fleet operators can refuel with confidence even if the natural gas composition is as low as a Methane number of 65, compared with a required minimum Methane number of 80 for the original C8.3G.
"No competing engine in this class can operate on a 65 Methane number," said Mostafa Kamel, the chief engineer responsible for development of the C8.3G Plus. "With this advantage, the C8.3G Plus should reduce downtime for fleets and expand the market to parts of the world where natural gas vehicles couldn't previously operate."
In testing for emissions certification, the C8.3G Plus produced emissions of 1.53 grams per horsepower hour of oxides of nitrogen, 0.21 g/hp-hr of non-methane hydrocarbons and 0.008 g/hp-hr of particulate matter. This emissions performance is significantly better than the standard set by the U.S. Environmental Protection Agency for October 2002 of 2.5 g/hp-hr for NOx and NMHC combined and 0.1 g/hp-hr of PM.