Cummins Westport natural gas engines feature spark-ignited stoichiometric combustion with cooled exhaust gas recirculation, and a simple maintenance-free, Three-Way Catalyst (TWC) for consistent emissions control. For 2018 products, Cummins Westport leverages the experience gained from over 80,000 engines in service to improve reliability and durability while adding new electronic engine, ignition, and On-Board Diagnostics (OBD) emission control features.
All Cummins Westport 2018 engines – the B6.7N, L9N, and ISX12N - will feature a new Engine Control Module (ECM), model number CM2380. New features include OBD capability, 500 kbaud data link, new wiring harnesses, and improved ECM durability and heat resistance.
The OBD system continuously monitors the engine and after-treatment system. With the ability to recognize the potential for an out-of-range event, the system can provide a real-time alert of the entire emissions control system. OBD systems also give the vehicle owner or repair technician electronic access to the status of the various vehicle subsystems for diagnostic purposes. A Malfunction Indicator Lamp (MIL) is connected to the OBD system and is located on the vehicle’s instrument panel. If the OBD system detects a malfunction related to the emissions control system, the MIL will illuminate and alert the operator. The engine will continue to operate normally until a diagnosis is made.
A Closed Crankcase Ventilation system (CCV) reduces engine emissions by capturing crankcase emissions and rerouting these gases back to the engine.This offers the opportunity for more complete combustion and lower emissions.Engine-related emissions of methane are reduced by up to 70%. The B6.7N, L9N, and ISX12N all feature CCV systems.
The ISX12N includes all of the product improvements made on the previous 12-litre engine, and features a new one-piece fuel system designed with fewer parts for better performance. An engine-mounted, electric CCV system is also featured.The L9N leverages the improvements made in the base ISL G to a new level of emissions and performance.
The Cummins Westport ISL G, ISX12 G, and ISB6.7G spark-ignited natural gas engines use Stoichiometric combustion with cooled exhaust gas recirculation (EGR) and a Three-Way Catalyst (TWC).This technology was developed to meet the stringent 2010 EPA emission requirements and was introduced with the ISL G in June 2007.
The cooled-EGR system takes a measured quantity of exhaust gas and passes it through a cooler to reduce temperatures before mixing it with fuel and the incoming air charge to the cylinder. Stoichiometric combustion in combination with cooled-EGR creates the ideal combustion process with the chemically correct mixing of fuel and air, offering increased power density and thermal efficiency. It also reduces in-cylinder combustion temperatures and creates an oxygen-free exhaust, which then enables the use of a TWC for nitrogen oxide (NOx) control.
A TWC is a simple, passive device that reduces three harmful emissions: hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxide (NOx). The end products are water (H2O), carbon dioxide (CO2) and nitrogen (N).
Packaged as a replacement muffler, and maintenance-free, TWCs offer consistent performance across all duty cycles.