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An exhaust header is an after market automotive part designed to improve vehicle performance. The small gain in performance facilitated by an exhaust header is important to high performance drivers who often make other modifications to their vehicles in order to increase speed. These modifications include the installation of larger intake vents for the engine. An exhaust header modifies the exhaust system to prevent back pressure, meaning that the cylinders do not have to work as hard to push exhaust out as they do in a traditional system. There are different types of exhaust headers depending on the needs of the drivers, with some tuned for low performance and others aimed at high performance on the open road.
In a conventional exhaust system, after the cylinders combust, they push the exhaust out into the exhaust manifold, which routes the exhaust out of the vehicle through the exhaust pipe. However, the exhaust manifold can create a back pressure which pushes against the cylinder, meaning that it has to exert more energy to push the exhaust out and prepare for the next firing. As a result, some efficiency can be lost.
An exhaust header works differently, essentially creating a miniature exhaust pipe for each cylinder and routing the exhaust to a centralized collector which is much larger. The pipes of an exhaust header are bent to fit under the hood and cut to the same length so that the exhaust gases will arrive sequentially in the collector as each cylinder fires. This eliminates the back pressure problem and allows the cylinders to operate more effectively.
In some cases, an exhaust header can be tuned to pull at the exhaust valve of the next cylinder and suck the exhaust out, meaning even less work for the cylinder. Drivers who desire more power for around town driving and better acceleration under a heavy load usually opt for a low performance exhaust header, while drivers who are looking for speed on the open road prefer high performance headers.
A variety of manufacturers make exhaust headers for a dizzying assortment of vehicles, and it is important to install the exhaust header designed for your car. Because exhaust leaks can be dangerous, the exhaust header should be installed with care, or professionally if there is any uncertainty. An improperly installed header could lead to an exhaust leak which vents into the cabin of the vehicle, causing symptoms of carbon monoxide poisoning in the driver and passengers.