Headers are special exhaust pipes leading from the cylinder head to the exhaust pipe that give greater performance and are made of steel and are thinner than stock. The steel shows the heat from the exhaust gases easier than the stock cast iron exhaust system.
The gases coming directly from the combustion chamber are over 700 degrees Fahrenheit during normal driving. Spirited driving pushes the temperature well over 900 degrees Fahrenheit. Steel begins to glow red at that temperature. Race cars develop average exhaust gas temperatures of 1,500 degrees Fahrenheit.
Race car headers don't glow because of a special ceramic coating that keeps the heat inside the pipes. As soon as the exhaust gases cool, they shrink and slow down, creating back pressure inside the exhaust header. The temperature of the outside of a ceramic-coated header will measure half that of a non-ceramic header.
Diesel engines run hotter than gas engines because they require much higher compression ratios. Compressing air creates extra heat inside the combustion chamber, enough heat to ignite the fuel/air mixture without the use of a spark plug. Headers installed on diesel engines will glow red if not equipped with a ceramic coating.
