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
North British Locomotive Company Railways (BR) designs pre-TOPS British Rail Class D3/1 (later D3/4), and later designated Class 21, Class 22, Class 41, Class 43 (Warship) and Class 251 (Blue Pullman) None of these were particularly successful: constructional shortcomings with the MAN engines made them far less reliable than German-built examples. A typical example of this was the grade of steel used for exhaust manifolds in the Class 43s – frequent manifold failures led to loss of turbocharger drive gas pressure and hence loss of power. More importantly, the driving cabs of the locomotives would fill with poisonous exhaust fumes. BR returned many North