Summary:
1. Introduction
Function and types of car exhaust
The function of a vehicle’s exhaust system is to channel and expel to the outside the gases burned by the engine during the combustion phase.
It not only prevents these harmful gases (carbon monoxide, nitrogen oxide and hydrocarbons) from entering the passenger compartment, but also reduces their toxicity before they enter the environment.
Depending on its shape, length, diameter and the material used, the exhaust system can also help to increase engine performance.
Apart from the original equipment, there are different types of exhaust: sport for use mainly on the road, or racing for use on the circuit or track.
Various characteristics of the exhaust system
Depending on its use, the exhaust will have different properties. First of all, in terms of design, it can be sober or, on the contrary, more flashy with, for example, a large exhaust pipe.
This appearance can have an influence on the sound level of the system, especially if it has insulation such as rock wool or other acoustic fibers, as well as the metal from which it is constructed: steel, stainless steel, titanium…
The weight of the system will depend on this material.
Secondly, the shape and diameter of the pipes will affect the flow of gases and therefore the power and torque produced by the engine. A system that is not very restrictive will have significant gains over an exhaust system with many silencers, elbows, baffles, etc.
The diameter will have to be studied according to the type of engine, its displacement, its aspiration (natural or forced induction)… In terms of exhaust, large tubes do not always generate great performance!
Today, there are many reference brands in exhaust systems offering products suitable for leisure use as well as for motor sports, among which: HKS, Milltek, Cobra, Tomei, GReddy, Blitz, Tonnka, Devil, Walker, Borla, Magnaflow, Supersprint…
The essential parts of the exhaust system
Let us now detail the most sought-after components on the market concerning a sports or racing exhaust system:
2. Exhaust silencer
The role of the rear silencer or muffler is to attenuate the engine noise. On performance exhausts, it modulates this sound which can go from low to high depending on the model for a sporty and pleasant effect.
A silencer is usually round or oval in shape and may have a single or dual tailpipe. It usually discharges the gases at the rear center or at the sides.
The silencer can have chambers, baffles and other devices to reduce noise or feature a more direct design to maximize gas exit velocity.
3. Exhaust tips
The exhaust tip is fixed at the end of the silencer and allows to embellish the tailpipe(s) for a superior finish. Most often, it is round, square or oval and is fixed by means of screws, clamps or welding.
It is found in a single or double form. There are also adjustable tips that allow you to straighten your tailpipe, for example.
Different types of finishes are available, such as polished stainless steel, chrome, satin, titanium or carbon.
4. Exhaust manifolds
The exhaust manifold is used to collect the gases leaving the cylinders and discharge them to the exhaust pipe(s). Depending on the shape, size and length of the tubes, it can improve engine performance. It is most often made of cast iron, steel, stainless steel or titanium.
On a 4-cylinder engine, there are 4-1 and 4-2-1 (also called “tri-Y”) manifolds. As a rule, the former improves one particular operating range (high rpm) while the latter favors two (mid and high rpm).
5. Custom exhausts
By purchasing the various components that make up the exhaust system, from the manifold to the silencer, it is possible to build a custom exhaust system yourself.
Sport catalysts, straight pipes, elbows, center sections, reducers, flex pipes, clamps and other junctions are available on the market to make up a complete exhaust system in stainless steel or other materials.
These custom exhausts are ideal for swaps or rare vehicles for which there are few or no specific products.
Photo sources: Ericsson / Milltek / HKS / Blitz / Borla / Supersprint / Magnaflow