Exhaust System

Racing Header Basics

Racing Headers are one of the best bolt-on performance pieces you can use to improve an engine's performance. The mission of headers 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, 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 toward 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. 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 pipes 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.

So invest in a good set of performance headers, your engine will breathe a bit easier.

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