Understanding the anatomy of an exhaust system
Unless you spend a lot of time crawling around under greasy chassis, the image of an exhaust system is probably just that of the short pipe sticking out from the rear of your vehicle. But that stubby bit of pipe is merely the tip of the exhaust iceberg. Thankfully, AutoAnything is here to explain the various parts of your exhaust, starting at the engine and moving backwards.
The starting blocks for your exhaust flow. An exhaust manifold bolts onto the head of your engine, directly over the cylinders. Each cylinder gets its own piece of pipe, and each of these disparate pipes joins together to form a single exit point, which connects to the head pipe. Depending on the size of your engine, you may have one or two exhaust manifolds. V-8 and V-6 engines have two because there are cylinders on both sides of the engine.
Headers are aftermarket performance replacements for clunky, cast-iron exhaust manifolds. They are mandrel bent for superior flow, and are finished with special coatings that reduce heat in your engine compartment.
Constituting the first section of piping, head pipes have the all important job of linking the exhaust headers to the mufflers. In between that distance, the head pipe is interrupted by the catalytic converter. Depending on the automobile, head pipes generally do not have a lot of bends, so they can run straight back to the muffler.
While a catalytic converter looks a lot like a muffler, it performs quite a different function in your exhaust system. Its job is to stop excess hydrocarbons, carbon monoxide and nitrogen oxides from exiting your vehicle and entering the atmosphere. To curtail these pollutants, a catalytic converter converts these dangerous particles into harmless elements.
How does it perform this pollution prestidigitation? A catalytic converter is filled with ceramic honeycomb or ceramic beads that are coated in platinum and palladium. When hydrocarbons, carbon monoxide and nitrogen oxides run into this treated ceramic, a chemical reaction occurs, transforming them into carbon dioxide (the good oxide), nitrogen, oxygen and water vapor. Once changed, the exhaust flows on until it reaches the muffler.
Just as a catalytic converter filters out chemicals that are harmful for your lungs, mufflers protects your ears from noise pollution. If you have ever heard an engine running without a muffler, you know that it sounds like a burst from a WWI-era German machine gun shooting into an iron door. Not pleasant! The muffler's job is to turn down the volume of your exhaust a few notches. It does this by channeling the flow of spent gases through a series of chambers, which cause the sound waves to bounce into each other and, eventually, cancel each other out.
Some mufflers dampen more noise than others, and performance exhaust mufflers are tuned to enhance the natural rumble of your exhaust. Some mufflers have a splitter at their backside that converts a single head pipe into dual exiting tailpipes, giving the cars, trucks and SUVs the appearance of a dual exhaust. True dual exhausts, though, have two mufflers - one for each exhaust manifold.
The last stretch of piping that runs from the muffler to the back, or side, of your vehicle is called the tailpipe. Usually, these pipes have the most bends because they have to curve up and over your rear axle. Better performance exhaust systems will finish their tailpipes with chrome tips, which add a brilliant touch to your vehicle's expression. Of course, you can easily equip your exhaust with a chrome tip, which come in a host of shapes, including round, square and oval.