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Headers are one of the most popular bolt-on accessories you can purchase
to improve an engine’s performance. The primary goal of a performance
headers is to make it easier for the engine to push exhaust gases out of
the cylinders.
During the exhaust stroke, a good way for an engine to lose power is
through back pressure. The exhaust valve opens at the beginning of the
exhaust stroke, and the piston pushes the exhaust gases out of the
cylinder. If there is any amount of resistance, power is wasted.
In a
normal engine, once the exhaust gases exit the cylinder, they end up in
the exhaust manifold. In a four-cylinder, there are four cylinders using
the same manifold. From the manifold, the exhaust gases flow into one pipe
toward the catalytic converter and muffler. It turns out that the manifold
can be an important source of back pressure because exhaust gases from one
cylinder builds up pressure in the manifold that affects the next cylinder
that uses the manifold.
The idea behind an
exhaust header is to eliminate the manifold’s back pressure. Instead of a
common manifold that all of the cylinders share, each cylinder gets its
own exhaust pipe. These pipes come together in a larger pipe called the
collector. The individual pipe’s are cut and bent so that each one is the
same length as the others. By making them the same length, it guarantees
that each cylinder’s exhaust gases arrive in the collector spaced out
equally so there is no back pressure generated by the cylinders sharing
the collector. |