Thursday, December 5, 2013
The Anatomy of the Exhaust System
Automotive exhaust systems muffle exhaust noise and reduce exhaust emissions. While materials and configuration differ among various cars and trucks, all exhaust systems can be broken down into three general sections: the exhaust manifold/headers, the mid-pipe and the muffler/tailpipe.
Exhaust Manifold/Headers
Looking to the front of the engine, the first portion of an exhaust is referred to either as an exhaust manifold or a header. Generally, a header will have individual runners for each exhaust cylinder, whereas an exhaust manifold is one large section, which contains a collector into which all the exhaust gases dump. Many manufacturers now include a catalytic converter into this portion to help reduce cold-start emissions. Note that V8, V10 and V12 engines have two banks and thus a manifold on each side of the engine.
Mid-pipe
The mid-pipe will be the middle portion of an exhaust, starting under and behind the engine, where it meets the exhaust manifold/header. This portion usually contains the mufflers of an exhaust system. In V8 applications, this portion may be an H or X pipe, where the two sides are connected to help equalize gases in a dual exhaust. While a V8 has only a single exhaust, a crossover pipe will run from one side to meet up with the single mid-pipe. Catalytic converters are typically mounted at this point, between the exhaust manifold and the mid-pipe.
When a company refers to a "cat-back" exhaust system, it usually means a system which starts at the mid-pipe, and thus starts behind the catalytic converter.
Some systems may have resonators, devices designed to help muffle the exhaust gas notes, in this portion of the system.
Muffler/Tail-pipe
The tailpipe will meet the mid-pipe near the rear of the vehicle and directs the exhaust gases out to the atmosphere. Some smaller vehicles may have the muffler integrated into the tailpipe section, as the muffler can only go where there is sufficient space.
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