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Racing Headers - The Basics
Written by Phil White - Posted October 19, 2019
Racing Headers are one of the best bolt-on performance items you can buy to improve an engine's performance. The mission of headers or header
is to make it easier for the engine to push exhaust gases out of the cylinders.
The engine produces all of its power during the power stroke. The gasoline in the cylinder burns and expands during this stroke, thus generating
power. The other three non-power producing strokes are necessary to make the power stroke possible. If these three strokes consume power, they
are a drain on the engine.
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 then the piston pushes exhaust gases out of the cylinder. If there is any amount of resistance that the piston has to push
against to force the exhaust gases out, power is wasted. Using two exhaust valves rather than one improves flow by making the hole that the
exhaust gases travel through much larger.
Once the exhaust gases exit the cylinder they end up in the exhaust manifold. In a four-cylinder or eight-cylinder engine, there are four cylinders
using the same exhaust manifold. From the exhaust manifold, the exhaust gases flow into one pipe to the catalytic converter and muffler. It turns
out that the exhaust manifold can be a major source of back pressure because exhaust gases from one cylinder can build up pressure in the
exhaust manifold; this affects the next cylinder that is trying to push out exhaust gases into the same exhaust manifold.
The idea behind an exhaust header is to eliminate the manifold's back pressure as much as possible. Most stock exhaust manifolds are an
inefficient design when it comes to reducing back pressure, with a good set of headers; each cylinder gets its own primary exhaust pipe. These
pipes come together in a larger pipe called the collector. The individual pipes are cut and bent so that each one is the same length as the others. By
making all the primary pipes the same length, it guarantees that each cylinder's exhaust gases arrive to the collector in equal proportions, thus
allowing for very little back pressure generated by the cylinders sharing the collector.
So invest in a good set of performance headers, your engine will breathe a bit easier.