How Exhaust Works
The exhaust system in your car has three main functions. First it transfers poisonous exhaust gases from the engine to the rear of the car. Secondly, it quiets down the engine sound while running. Finally, it converts unspent fuel into spent fuel with the help of a catalytic converter. The exhaust system consists of an exhaust manifold, exhaust pipe, catalytic converter, muffler and tail pipe. There are endless configurations of exhaust systems from the very loud free flow, low restriction system to the barely audible system depending on application and driver preference.
Exhaust Manifold An exhaust manifold is used to transfer exhaust gases from the exhaust port of the cylinder head to the exhaust pipe. Most exhaust manifolds collect between 3 and 6 ports depending on application. The exhaust manifold sometimes houses the fuel management system oxygen sensor. The mounting port for the primary oxygen sensor is located in the beginning section of the exhaust system, before the catalytic converter. The secondary sensor is located downstream of the catalytic converter. These sensors are used to monitor the density of exhaust gases and relay information to the main PCM controller.
Primary Exhaust System
This is a typical primary exhaust system. The function of the primary system is to transfer the exhaust from the exhaust manifold through the head pipe and flex pipe to the catalytic converter. The catalytic converter has a heat shield to protect the floorboard from the extreme heat it creates. An exhaust system is held in place by rubber exhaust hangers to help dampen engine vibration and to allow the system to flex without breaking. Most exhaust systems are made of aluminized metal or stainless steel to prevent corrosion. Engines produce water along with the exhaust gases as a natural byproduct of the combustion process. This is why a small amount of water and steam is observed coming from the exhaust pipe when the car is cold. As the engine heats up the water is vaporized quickly so the moister is not visible.
Muffler (Secondary Exhaust System) The muffler in your vehicle serves one main purpose; to quiet the natural sound made by internal combustion engines. Mufflers come in all sizes and applications, from the stock quiet one, to the throatier sound of a performance muffler. There are basically two types of mufflers; noise canceling and material packed. In the noise canceling (usually performance) barriers are welded into the muffler to reflect the sound back into itself to cancel it out. In a material style there is a packing, usually around a perforated tube that dampens the sound. The secondary exhaust system is used to transfer the exhaust from the catalytic converter through the muffler and out the rear of the vehicle through the tail pipe. System Components
- Exhaust Manifold - Bolted to the cylinder head and is used to gather exhaust gases from the many cylinder ports to one location where the head pipe is connected.
- Head Pipe - The tube that connects the exhaust manifold with a exhaust flange and the other end to the catalytic converter
- Exhaust Flange - The connector union between the exhaust manifold and the head pipe
- Exhaust Pipe - The pipe that is used to connect the various components of the exhaust system
- Muffler - Used to reduce the audible sound frequency developed by the engine.
- Catalytic Converter - Used to convert unused fuel into completely spent fuel
- Secondary Muffler - Sometimes called a resonator the secondary muffler furthers the sound deadening of the engine exhaust.
- Exhaust System Hanger - A metal strap connecting the exhaust system to the bottom of the car. They are usual made with a rubber insulator.
- Tail Pipe - The tube that is connected to the muffler that continues to the back of the car.
A performance exhaust system can be anything from a simple "cat-back" system to give you a little better sound to a full tuned set of headers to replace the restrictive exhaust manifolds. Always consult state and federal emissions laws before modifying your vehicles exhaust system. There have been numerous advances in the technology for performance exhaust systems. While standard exhaust systems are designed as cost efficient as possible, a performance system is usually made from a higher grade of material with a more performance-oriented design. The exact type of performance exhaust often varies depending upon the vehicle and application. Adding performance exhaust systems is easily handled with just a few tools and will boost performance immediately. Inspect your exhaust system on occasion to ensure that there are no cracks, holes or rust. Only inspect the exhaust system after the engine has cooled down to avoid burns. When exhaust replacement is required a performance exhaust system might be a good consideration. After a new exhaust system has been installed it is normal for funny smells to be produced. This condition will stop once the exhaust system has been heated and cooled a few times. The reason for the smell is a new system is manufactured using oils and paint and until the impurities are burned off it will create an odor. If further technical assistance is needed, our certified car repair technicians are ready to answer your car questions. Common Problems
- Defects or corrosion in the exhaust system causes exhaust gases to be consumed causing asphyxiation
- After driving long distances the exhaust system can become very hot causing ignition of dried timber or grass under vehicle
- Only inspect exhaust system when the engine is cold to avoid burns
- Exhaust Questions
- How to Test a Catalytic Converter
- How to Replace an Oxygen Sensor
- How to Test an Oxygen Sensor
- Why Does the Exhaust System Keep Breaking
- How an Emission System Works