Does a loud exhaust use more fuel?

By July 12, 2020January 23rd, 2021Common Questions

So you want to install a loud exhaust, but worried if they will consume more fuel? Or you are simply curious. It doesn’t matter – because I will cover the topic in detail, while also making it simple for everybody!

In short – no. Louder exhaust does not use more fuel. In fact- there’s no correlation between them. A car engine creates combustion to deliver power – which generates a lot of noise. An exhaust system is equipped with a muffler to reduce this noise. The loudness of your exhaust depends largely on the type of muffler you equip. 

Sometimes, a car that’s loud has bad fuel consumption. At other times, a car that’s loud could also have a good fuel consumption. Confusing? This is because the exhaust noise and fuel consumption are not correlated! Exhaust noise is a byproduct of engine combustion – not the other way round. 

Let me explain in more detail.

Summary

  • Sound of exhaust is not correlated with fuel consumption. Louder exhaust noise does not consume more fuel.
  • Sound of exhaust can be made quieter or louder depending on the muffler.
  • If you only want a better sound – you should look into cold air intake instead.
  • Easy way to improve fuel efficiency:
    • Regularly clean air filter
    • Reduce the load in your car
    • Ensure tire pressure is optimal

How Is Fuel Consumed in a car?

To deliver power to your wheels, fuel is used to create combustion in the combustion chamber. This combustion then consumes oxygen – which comes from the surrounding air. Fuel/air ratio must be optimal. 

Too much fuel for a given amount of air will cause a bad fuel consumption. Not all of the injected fuel gets burned up – causing it to exit the exhaust pipe as a black smoke. Too little fuel will decrease the performance of the car, where the combustion becomes too small! Every car is equipped with a small computer (ECU) and a bunch of sensors to calculate exactly how much fuel should be injected for the available air. 

The most common method to increase car performance is to increase the amount of air flow in the car. More air allows for more fuel to be injected in the combustion chamber – creating bigger combustion for more power.

What Does An Exhaust Do? 

Remember I mentioned power in your car is created by combusting fuel? This combustion generates toxic exhaust gasses and sound vibrations (noise)  in the process. These exhaust gasses and sound vibrations exit the combustion chamber into the exhaust system – where they will be expelled out of the car. 

While flowing through the exhaust system, these exhaust gasses and sound vibrations will go through a catalytic converter (CAT) and muffler. A catalytic converter converts these toxic exhaust gasses into less harmful gasses like carbon dioxide and water vapor. Whereas a muffler reduces the sound vibrations – ensuring the noise generated from your car is well within the government regulations.

The Relation Between Noise & Fuel Consumption

I mentioned that the noise from your exhaust has nothing to do with fuel consumption. The noise is simply an output from combustion. Making your car sound louder will not consume more fuel! 

To prove this, let’s go through a typical scenario: Straight piping an exhaust is done to improve car performance. Straight piping is done by removing the catalytic converter (CAT) and muffler from the exhaust system. This is done to increase airflow in the car – allowing the exhaust gasses to directly exit the car without going through the CAT and muffler.

The faster these exhaust gasses and sound vibrations can exit the car, the more fresh air can enter the combustion chamber – resulting in the next combustion to be more powerful. I cover straight piping exhaust in this article, if you want to know more. 

By removing the muffler, your exhaust noise will significantly be louder. However, the fuel consumption will not be affected at all! In fact – you might even experience a better fuel consumption after installing a straight exhaust pipe. More air can enter the combustion chamber. Thus, reducing the amount of wasted fuel in every combustion. 

Should I Install Aftermarket Exhaust? 

If you considered on installing a new exhaust just for the sound, I recommend you look into installing a cold air intake instead. A cold air intake will greatly improve the noise generated by your engine – while being relatively cheap and easy to install. A cold air intake re-routes the air intake of your car to ensure more cold air can enter your car engine – for improved performance, fuel consumption and engine sound! I covered cold air intake in this article if you are interested. 

You could also check out aftermarket muffler. It’s a cheap install and you will definitely improve the sound of your engine. I have an article here where I discuss what you need to look for when purchasing a muffler and what I recommend.

However, if you want more than just the sound, then you should definitely look into an aftermarket exhaust. Installing one could provide you with an increased performance and better fuel consumption. This is because an aftermarket exhaust will allow for better air flow – causing the exhaust gasses to exit the car quickly. 

There are many types of aftermarket exhaust that you could go for – they are mostly decent. The only advice I would like to provide is to stay away from a straight pipe exhaust. Straight piping your exhaust comes with too many drawbacks such as deafening engine noise and significant increase in car emission. Straight piping exhaust only works if you drive on the race track.

If you are looing for an aftermarket exhaust, I have an article over here where I discuss what to look for and my recommendation.

Image of aftermarket exhaust

How Do I Improve Fuel Efficiency?

Since we are already in the subject of fuel efficiency, let’s also discuss how you could increase fuel efficiency. There are a lot of extreme ways to increase fuel efficiency. For example – removing components from your car to reduce weight, removing catalytic converter and muffler to increase airflow – which will improve fuel efficiency. I will not be discussing these extreme measures. Instead, I will discuss the easy ways to improve fuel efficiency that you could immediately do.

 

Regularly clean air filter

Your car sucks in air from the surrounding for combustion. Air filter is in place to ensure dust particles and other impurities do not get into your engine. As time passes, your air filter is bound to get dirtier – causing it to limit airflow into your car.

At this point, you should already know that limited airflow is bad for your car. It limits combustion – causing your car to produce less power and not utilize all the injected fuel. These unused fuel will then escape the car from your exhaust pipe as black smoke. What a waste! 

If you have a stock paper based air filter, replace it every 15,000 miles. If you have a reusable performance air filter, clean it every 50,000 miles. I cover performance air filters in this article if you are interested. 

Image of dirty air filter vs clean air filter

Reduce weight load in your car

On average, every 100 points increases fuel consumption by 2%. Knowing this, it’s important for you to keep your car light. I am not encouraging you to go to the extreme like removing car seats or to always keep your car fuel tank half empty. 

All I am asking is to remove any unnecessary items in your car. For instance:

  • Old and heavy toolbox fill with questionable equipment 
  • Golf clubs set that you use once a week
  • Unnecessary additional tires – one is enough!

This point impacts smaller cars much more. So be mindful of what you leave in your car. 

 

Inflate tires to correct pressure

Flat tires will bend much more when it’s flat. This increases tire rolling resistance – causing your engine to work to move the car. To prevent this, simply ensure your tire is at the correct pressure at all times. Remember to refill your tires on a weekly basis. Or at the least, refill it when you go for a refuel. 

 

Stop revving 24/7

Yes, I understand you! Revving is cool and all. But each time you up the rpm, your fuel efficiency suffers. When driving on the street, shift your gear when it reaches 2500 rpm. This ensures for maximum fuel efficiency. When you are on the track though, rev that engine and show what it’s made of 😉

Which muffler is your car right now?

Conclusion

In this article we have proven that a loud exhaust does not consume more fuel. There is no correlation between exhaust sound and fuel consumption – you could have an excellent fuel consumption while also having an extremely loud exhaust. 

If you simply want a louder engine noise, I recommend you to look into cold air intake instead. They are cheap, easy to install and will greatly improve the sound from your engine. If you want more than just engine noise, then you could look into an aftermarket exhaust. Though, I recommend that you don’t install a straight pipe exhaust. Unless you are driving on the race track. 

I hope this article is beneficial to you. Check out more of my articles for resources on car performance! 

Ifandi S.

Ifandi S.

Passionate about everything mechanical. Ifandi has been involved with motorcycles and cars since the old days - in his family's auto parts shop. Want to keep in touch? Scream "STRAIGHT PIPEEEEE" at the top of your lungs and Ifandi will show up.

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