Exhaust gas gas is undesirable, noxious, or toxic substances, such as carbon monoxide (CO) from incomplete combustion, hydrocarbons (properly indicated as CH, but typically shown simply as "HC" on emissions-test slips) from unburnt fuel, nitrogen oxides (NO) from excessive combustion temperatures, and particulate matter (mostly soot). Exhaust gas temperature (EGT) is important to the functioning of the catalytic converter of an internal combustion engine. It may be measured by an exhaust gas temperature gauge. EGT is also a measure of engine health in gas-turbine engines (see below). During the first two minutes after starting the engine of a car that has not
Exhaust manifold Exhaust manifold In automotive engineering, an exhaust manifold collects the exhaust gases from multiple cylinders into one pipe. The word "manifold" comes from the Old English word "manigfeald" (from the Anglo-Saxon "manig" [many] and "feald" [fold]) and refers to the folding together of multiple inputs and outputs (in contrast, an inlet or intake manifold "supplies" air "to" the cylinders). Exhaust manifolds are generally simple cast iron or stainless steel units which collect engine exhaust gas from multiple cylinders and deliver it to the exhaust pipe. For many engines, there are aftermarket tubular exhaust manifolds known as headers in American English,