Exhaust headers are the first component in the exhaust system of a car. Typically, headers are designed using circular steel tubes that bend into a single outlet. Depending on the vehicle’s number of exhaust valves, headers come in a variety of shapes and sizes that are specifically designed to remove exhaust from the vehicle. From the headers, exhaust is passed though the catalytic converter and then out of the muffler to allow for sufficient exhaust flow.
Correct header design can help improve the performance of an engine by reducing the amount of exhaust back-pressure that is created by combustion. The main purpose of the exhaust header is to quickly and efficiently remove exhaust waste that would prevent a proper air/fuel mixture in the pistons. Each piston gets its own exhaust pipe that is of equal length with the others. These pipes are then connected by a bigger pipe called a collector. With a collector, exhaust is sure to pass safely out of the engine and not cause back pressure.
Headers come in a variety of styles and materials that can vary between manufacturers. Aftermarket companies such as Jegs, Hooker Headers, Dynatech, and Edelbrock, manufacture high-performance headers that can be finished in cast iron or even powder-coated porcelain. Various header designs can also improve engine performance by increasing horsepower. While BMW’s would rarely ever need a boost, aftermarket headers are known to increase horsepower by up to 20 percent as a general rule of thumb. This rule may vary depending on the engine that the exhaust headers are placed on. Different headers come with specifications that can help improve exhaust removal in different applications which include drag cars, stock vehicles, and even motorcycles.
Headers can be custom-built by metal shops to the exact specifications that may be required for different vehicles. However, aftermarket materials and design equipment can make custom-built headers more expensive than those purchased from a high-quality manufacturer.