Exhaust

The combustion cycle involves pulling an air/fuel mixture into the cylinder head through the intake valves, igniting the mixture, and then expelling it out the exhaust valves. At the exhaust ports of the cylinder head, a cast iron exhaust manifold is bolted, which combines and directs the gases into the exhaust system. Some 4-cylinder engines … Read more

The EGR valve allows a certain amount of exhaust gases to circulate from the exhaust side to the intake side. The inert, oxygen-depleted exhaust gases are used to cool the combustion chambers, reduce emissions, and improve the operating efficiency of a gas engine. Modern EGR valves use a “stepper motor” to operate. Rather than simply … Read more

The exhaust manifold is the outlet from the engine. It lets spent exhaust gasses exit the engine while also collecting them together to send them down the exhaust piping and safely out the back of the vehicle. The exhaust manifold is normally a cast iron piece that is bolted to the side of the cylinder … Read more

The catalytic converter is a part of the exhaust system that is located after the exhaust manifold and before the muffler. The active part of a catalytic converter is a honey-comb matrix coated with precious metals through which the exhaust flows. Its main job is to react with and remove harmful gases from the exhaust … Read more

As an engine runs, it pushes the exhaust gases out through the exhaust valves into the exhaust manifold and down through the exhaust to the muffler. The muffler quiets the exhaust noise and creates some resistance to airflow in the process. This means that the exhaust system upstream of the muffler must hold some amount … Read more