6.7L Cummins Emission Equipment
Meeting New Emissions Regulations
The new 6.7 liter Cummins meets stricter diesel emissions requirements established by the EPA for 2007. The complex system that controls diesel emissions makes the 6.7 the cleaniest Cummins diesel yet. The system is divided into three main parts; the diesel particulate filter (DPF), the exhaust gas recirculation system (EGR), and the exhaust aftertreatment system (active regeneration).
Diesel Particulate Filter:
The 6.7 liter Cummins is equipped with a diesel particulate filter, or DPF. Exhaust gases reach the DPF prior to flowing into the muffler. Diesel particulate filters drastically decrease the amount of diesel particulates (soot) and unburned hydrocarbons released from the combustion of diesel fuel. The honeycomb structure of the DPF captures soot as it passes through the filter. The Cummins diesel particulate filter reduces diesel particulate matter emissions by approximately 90 percent. The problem associated with DPF's is that over time, soot collecting in the DPF can clog it, resulting in decreased performance and fuel efficiency.
Exhaust Aftertreatment:
The answer to DPF clogging issues is an exhaust aftertreatment known as active regeneration. Sensors tell the engine when excessive particulate matter has built up in the DPF, and active regeneration mode is triggered. During active regeneration, the engine idle is increased to help heat the DPF, and diesel fuel is injected during the exhaust stroke, allowing fuel to enter the exhaust system and burn in the DPF. The combusition of diesel fuel in the DPF generates the heat necessary to burn off soot within the filter, essentially cleaning it. During active regeneration, the DPF can exceed temperatures of 1,000 degrees F. The main downfall of active regeneration mode is that it dramatically decreases fuel economy. Also, occasional maintenance is required to remove excess ash from the DPF that is left behind by exhaust aftertreatment.
Exhaust Gas Recirculation:
Exhaust gas recirculation, also known as EGR, is a technology that is not specifc to the diesel industry. EGR systems have been used for years in both diesel and gasoline powered vehicles because they help to lower greenhouse gas emissions. In a diesel, the primary function of the EGR system is to lower the amount of Nitrous Oxides (NOx) produced by the combustion of diesel fuel. A portion of the engines exhaust gas is recirculated into the engine and combusted again. This lowers the amount of excess oxygen and lowers peak combustion temperatures. Since NOx formation occurs much faster at high temperatures, the EGR limits the generation of NOx. NOx is primarily formed when a mixture of nitrogen and oxygen is subjected to high temperatures. Despite the reduction of NOx, Exhaust gas recirculation systems have negative effects on performance and fuel economy, and other exhaust treatments are necessary because EGR systems increase the amount of diesel particulate matter produced by the engine.
Additional Information:
- The muffler on 6.7 powered Dodge Rams is isolated from the emissions control system so that it may be easily removed & replaced.
- The 6.7L Cummins features a variable geometry turbocharger and multi-injection event capable fuel system that further aids in limiting harmful emissions.
- The 6.7L Cummins meets 2010 EPA NOx emissions standards a full 3 years in advance. Cummins is the only diesel engine manufacturer to have an engine certified to meet the 2010 requirements.
- 6.7L Cummins are designed to safely operate on B5 Biodiesel.