What do headers look like

The tubes converse to a single "collector" pipe, through which the exhaust gases pass before exiting out of the muffler. Why are headers are a better choice than an exhaust manifold? As stated above, exhaust manifolds create back pressure, which lowers performance. Because each cylinder of the engine is given its own tube, however, headers eliminate this problem; thus, allowing the gases to exit without the creation of back pressure.

There are some potential disadvantages to using exhaust headers, however, such as noise production. Because they are thinner than manifolds, they naturally produce more noise than their counterpart.

This isn't a huge disadvantage, but it's still something that drivers need to be aware of when choosing between an exhaust manifold and headers. The goal of headers is to make it easier for the engine to push exhaust gases out of the cylinders. When you look at the four-stroke cycle in How Car Engines Work , you can see that the engine produces all of its power during the power stroke.

The gasoline in the cylinder burns and expands during this stroke, generating power. The other three strokes are necessary evils required 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 the 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 the flow by making the hole that the exhaust gases travel through larger. In a normal engine, 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 manifold. It turns out that the manifold can be an important source of back pressure because exhaust gases from one cylinder build 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. Mostly because they both look like a collection of pipes. However, there are a few differences between an exhaust header and an exhaust manifold. Firstly, manifolds are typically made of cast iron, while headers are usually stainless steel, JB Tools reports. Cast iron is cheap and retains heat well, which improves catalytic converter efficiency. A few vehicles, like the 4 th -gen Toyota 4Runner and NB Miata, had pre-cats built into their exhaust manifolds to take advantage of the added heat.

However, repeated heating-and-cooling cycles can cause the manifolds to crack. Secondly, manifolds feed the exhaust gases quickly into one space, CJ Pony Parts explains. Headers, on the other hand, have longer, individual tubes. To avoid the cracking issue, exhaust manifolds typically have to be made with thicker walls than the headers. This shrinks the space gases can travel through.