Exhaust System: Description and Operation
Exhaust systemThe principal parts that comprise the engine exhaust system are warm-up catalytic converter, the front exhaust pipe, the catalytic converter, the pre-silencer and the main silencer. Each component is joined with a gasket to prevent exhaust leaks. The system is secured to the frame with five rubber supports. They provide support and isolation.
The engine exhaust gases consist mainly of nitrogen (N2). However, they also contain carbon monoxide (CO), carbon dioxide (C02), water vapor (H20), oxygen (02), nitrogen oxides (NOx) and hydrogen (H2) as well as various other unburned hydrocarbons (HC). Three of these exhaust gases, CO, NOx and HC are major air pollutants. Their emissions must be controlled. The warm-up catalytic converter is positioned as far upstream in the exhaust flow as possible to take advantage of the high exhaust temperatures in the manifold. The operating temperature of the warm-up catalytic converter increases very rapidly after initial cold start to decrease the amount of emissions emitted during cold engine operation.
The three-way catalytic converter is mounted, in-line, between the header pipe and the pre-silencer. It reacts with exhaust gases to convert them to less harmful products and therefore reduce the pollutant levels to within legally prescribed limits.
The catalytic metals are thin-coated onto and supported by a honeycomb-shaped, high temperature ceramic. The honeycomb is mounted inside the converter shell which is surrounded by a heat shield. This design produces little restriction to the flow of exhaust gases and has proven to be durable.
Caution: Do not touch the catalytic converter heat shield when the engine is running. The conversion process produces high heat. Even when the engine is not running, it remains hot a long time. It will remain hot after other pipes have cooled Touching the heat shield may produce a serious burn.