There are several types of exhaust systems. Most recently the latest Honda Civic Type R has served to make the triple exhaust outlet more mainstream even though we first saw it on the Lamborghini Aventador.
But the two main exhaust systems you’re sure to see most often either have a single outlet or dual outlet.
Usually, you’ll find dual exhausts on bigger engines and single exhausts on smaller engines.
While each produces a different sound intensity, how loud one is over the other is a different story.
In what follows we’ll look at the differences between dual and single exhausts. We’ll also consider their advantages and disadvantages as we determine which is louder.
A Brief Look at How an Exhaust System Works to Help Us Understand Why a Dual or Single Exhaust May Be Louder.
Combustion happens when fuel mixes with oxygen and the spark from a spark plug causes these elements to explode.
The byproduct of this mini explosion is exhaust gases. Exhaust gases need to exit the combustion chamber so that the next combustion cycle can happen.
An exhaust system allows an internal combustion engine to expel spent gases. These harmful gases enter the exhaust system through an exhaust manifold which is bolted on to the combustion chamber side of an engine.
The exhaust gases then travel through the catalytic converter making these toxic gases less harmful.
The less harmful gases continue their travel through the rest of the exhaust system arriving at the muffler where the gases receive one last cleaning.
This is also where the sound of their travel is dampened before exiting the tail pipe.
Dual Exhaust Provides Exhaust Gases Two Channels by Which to Exit an Engine While a Single Exhaust Only Has One.
That’s why dual exhaust outlets are more common on automobiles with bigger engines and why you’ll find single exhaust systems connected to engines with smaller displacements.
A dual exhaust system gives exhaust gases two routes by which to exit the combustion chamber compared to a single exhaust which only provides one means of escape.
While not necessarily louder, a dual exhaust system has a comparatively better sound quality than a single exhaust setup.
A Dual Exhaust Isn’t Necessarily Louder Than a Single Exhaust. But…
If you’re considering an exhaust upgrade, you’ll hear the improvement on the quality of sound more distinctly on a performance engine.
In this way, the bigger an engine is, the louder the exhaust note will sound. For instance, if you upgrade a V8 engine from a single exhaust to a dual exhaust.
You’ll get more sound than if you upgrade a four-cylinder engine with a single exhaust to a dual exhaust.
So, if what you’re after is a louder exhaust there are much better ways to achieve this goal instead of installing a dual exhaust system.
Below are a few things that can make your vehicle sound louder.
Upgrade the Exhaust Pipe Diameter for a Louder Sound.
Upgrading your single or dual exhaust system to a larger diameter pipe will do more to increase the sound of your exhaust – but not by much.
A larger diameter allows greater exhaust flow which makes the exhaust sound louder by deepening the exhaust note.
A wider diameter will actually make the exhaust sound throatier while a narrower diameter can make the exhaust sound raspier.
Note that when you change the diameter of exhaust pipes what you’re really doing is increasing exhaust performance.
By increasing the diameter of an exhaust pipe, you allow a greater amount of exhaust to exit the tail pipe helping the exhaust system relieve back pressure.
(We’ll talk more about how back pressure affects the loudness of a dual or single exhaust as you keep reading).
Pipe Configuration Plays a Major Role on the Sound Quality of a Dual or Single Exhaust.
Single exhaust systems are typical on four-cylinder engines. There’s only one pipe connecting the exhaust manifold to the exhaust tip which is supported by a Y-Pipe configuration.
You can also find this configuration on some six-cylinder engines.
Dual exhaust systems are reserved for bigger engines. Two pipes connect from the exhaust manifold on either side of the engine where exhaust gases exit two exhaust tips.
A true dual exhaust system uses either an X-Pipe or H-Pipe configuration.
An X-Pipe crosses in the middle for better exhaust flow and less loss of power. An H-Pipe doesn’t have as good an exhaust flow. But it will give your vehicle a higher amount of low-end torque.
An H-Pipe on a dual exhaust setup will create a smoother sound, while a dual exhaust with an X-Pipe configuration will sound raspier.
An Aftermarket Exhaust Muffler Will Make Your Dual or Single Exhaust Pipe Sound Louder.
Whether you choose a single or dual exhaust, a stock exhaust system isn’t going to provide as much noise or performance as an aftermarket exhaust system.
There are great aftermarket options to kick the sound of your exhaust up an octave or two.
Some aftermarket single exhaust mufflers even come with dual exhaust tips.
But just because you decide to go with an aftermarket system doesn’t mean that it has to be shouty.
I for one prefer an exhaust note that’s more audible than what you get from factory without necessarily announcing my presence everywhere I go.
An aftermarket single exhaust system will produce a deeper sound than stock. While an aftermarket dual exhaust will have a throatier sound.
Upgrading to Dual Exhaust Does More to Improve Performance Than Loudness on Smaller Engines by Reducing Back Pressure.
Even though upgrading from a single to a dual exhaust system does little to change how loud an exhaust is on a small displacement engine.
It nevertheless can improve performance by reducing back pressure, even on a four-cylinder engine.
Simply put back pressure is a force acting against the flow of exhaust.
A dual exhaust setup eases back pressure by allowing exhaust gases to flow through two pipes instead of just one.
This dual setup means exhaust gases can leave the combustion chamber faster to make room for the next combustion cycle – this improves engine performance.
But you don’t have to upgrade to a dual exhaust system if what you’re primarily after is a louder sound.
Plus, if you prefer the look of a dual outlet system on a small engine. There are plenty of powerful single exhaust systems with dual exhaust outlets.
Although the exhaust velocity will be higher than dual exhaust. They’re also more lightweight and less expensive while still looking like a dual exhaust setup.
A Dual Exhaust System Can Help Your Vehicle Improve Fuel Consumption.
While a dual exhaust may not be any louder than a single exhaust. Along with more horsepower, a deeper exhaust note, and a cooler engine.
An engine with a dual exhaust system runs more efficiently. This efficiency equates to better gas mileage.
This is achieved through the fact that since back pressure is reduced, the engine doesn’t have to work as hard resulting in better fuel economy numbers – The more efficient the engine, the slower the rate at which fuel is burned.
Also helping your miles per gallon is the fact that dual exhaust allows the combustion process to happen faster since spent gases get two channels by which to escape instead of just one.
Does a Dual Exhaust System Make Turbocharged Engines Sound Louder?
There are a lot of things to consider when making modifications to your vehicle.
But which ones will lead to the results you’re after?
For example, if your engine has a turbo. Will adding a dual exhaust make it sound louder?
Indeed, a large, turbocharged engine will see the most benefits from an upgrade to a dual exhaust system.
But this is more in terms of performance than the loudness of the exhaust note.
A smaller, four-cylinder turbo engine, however, will be just fine with a single exhaust system since the displacement doesn’t produce enough exhaust gases to warrant and additional outlet.
Upgrading from a Single Exhaust to Dual Exhaust Pipes Requires a Tune.
Anytime you change how much air comes into an internal combustion engine or how much exhaust leaves, you’ll need a tune.
It doesn’t matter if you’re installing a dual or single exhaust.
In fact, some aftermarket exhaust systems come with a plug-and-play tune which you can plug into your OBD II port to ensure you get the most of your new exhaust.
Failure to tune will result in check engine lights, lackluster performance and poor fuel economy.
That’s because the new exhaust will cause readings from the O2 sensors to be different from stock.
A proper tune will ensure the ECU adjusts system parameters to reflect the new readings.