Exhaust Headers & Fuel Economy: Why Headers Improve Mileage

Running aftermarket exhaust headers can improve gas mileage because it reduces backpressure significantly – resulting in more oxygen in the combustion chamber that can utilize injected fuel completely. 

Personally, I have run my car with multiple sets of headers. For most of them I notice a minor improvement in fuel consumption.

The best was My Camaro where it went from 18mpg using stock manifolds to 20 mpg using an aftermarket exhaust header. Not significant but it’s an improvement. 

Even more so when we consider that headers are designed for power and not for fuel economy!

In this article, I will dive deeper into exhaust headers and gas mileage. Specifically some topics below:

  1. Why exhaust headers can improve gas mileage
  2. Do you need tuning to improve gas mileage with headers?
  3. Short tube Vs Long tube headers for gas mileage
  4. My personal tips to improve gas mileage

Excited? Well, I hope you are.

Why Exhaust Headers Can Improve Gas Mileage

Now let’s see why and how exhaust headers improve gas mileage. 

  1. Exhaust headers reduce backpressure. This means more air in the combustion chamber and all injected fuel can be fully utilized – resulting in a much more efficient engine.
  2. Exhaust headers are lighter. Aftermarket exhaust headers are typically made from stainless steel – which is great to prevent rusting and better yet, they are lighter! Meaning, your engine doesn’t have to work as hard. 

It is proven that exhaust headers which are tuned for economy, can improve the gas mileage by a small margin. And this is around 2-3 mpg improvement on the highway or city. 

This isn’t significant compared to the performance they deliver. Therefore it doesn’t fit the category for people that aim to get more fuel efficiency out of their cars.

Exhaust Header And Manifold

Aftermarket exhaust headers reduce backpressure by allowing exhaust gases to flow easily,

The car enthusiasts are running these aftermarket headers for pure performance. With proper tuning, these performance headers can improve the horsepower rating by 20-30 horses, and that is definitely a huge boost. 

20 hp increases may sound a little, but when you are behind the wheel (Oh yeah!) you will instantly experience the improvement in power.

The lesson? Exhaust headers do increase gas mileage by a little. But don’t buy headers for the mileage. Instead, get them for the power.

Why Some People Argue Headers Reduce Gas Mileage

Some people experience a drop in gas mileage after installing headers because they are unnecessarily revving the engine more.

Mostly because they are excited over the new power and sound from headers. 

Exhaust headers do make sound better. If you are here, you know this well. 

When a car sounds good, most drivers usually will put on throttle for a longer duration to experience more of the “music” their car is making. (Haha! I’ve been there)

This practice may also reduce the gas mileage of your car. Since you are revving high the engine draws more fuel and there comes the reduction of the mileage.

I am not saying you should avoid this. But know that excessive revving could significantly reduce gas mileage. 

Related article: Will Headers Make Car Sound Better?

Do you need tuning to improve MPG with headers?

You definitely need to tune your car after installing exhaust headers. This is required to fix the air/fuel ratio – which will give you the boost in performance and improvement in gas mileage.

Aftermarket headers are not meant to work with your engine from the factory. You need a tune to make sure your engine injects more fuel and get the air/fuel ratio right again. 

Remember, exhaust headers provide more oxygen in the combustion chamber. You also need to tune your car to inject more fuel. Without tuning, your car will run lean and overheat. 

I have an article here discussing more about tuning for exhaust headers. Do I Need A Tune After Installing Exhaust Headers?

Long Tube Headers Vs Short Tube For Gas Mileage

Short tube headers are much better for improving gas mileage because they are designed to work on the low to mid RPM range. This is the RPM range where you will be driving most.

Go for long tube headers if you want performance. They are designed to work well on high RPM ranges.

This is the RPM range you need to worry about for performance and racing in general.

short tube headers

Short tube headers

Tips To Improve Gas Mileage

Headers will boost the torque on high rpm and also boost your horsepower count by 15-30 hp at ease, especially if they are long tube headers that work the best for performance applications.  

If your only aim is to improve your gas mileage, do not go for aftermarket headers. Yes, it will deliver more mileage, few mpg improve with a proper tune, but not a lot. 

Here are five better ways on how you can improve gas mileage instead-

  1. Bring your car to a tune. If you really care about fuel efficiency and want to go above and beyond, tuning your car’s computer for fuel economy is actually a great choice. 
  2. Remove unnecessary load in the car. Unnecessary stuff like golf equipment that you don’t even use regularly can add extra load and worsen fuel economy. Remove them if unused!
  3. Keep the pressure in your tires in check. Tires operating with correct pressure will deform and add unnecessary drag. Make sure your tires are inflated correctly to improve fuel economy.
  4. Use the right tires for the weather. Don’t drive with winter tires in the summer. Winter tires use more power than summer tires.
  5. Get a smaller diameter tire. Running smaller diameter tires means that there is less grip on the tarmac and that will mean that your car will roll easier on these tires.

Final Thoughts

Exhaust headers are one of the coolest mods out there and for sure are one of the best ways of making a ton of power, while also improving a little of your vehicle’s fuel economy. 

Which muffler is your car right now?

Especially if you run a big beefy V8 under the hood. Even better if it’s a stroker engine, strokers are meant to run these mods and deliver the best performance with these headers. 

These stroker engines make a lot of power and deliver a lot of torque as well. 

Install aftermarket headers only if you aim for performance on the road and as well as on the track.

Because that’s the reason why these headers are designed, making car enthusiasts happy by delivering a ton of power. And also, plenty of sound.

If you only want better fuel economy, there are cheaper ways if you want to get better gas mileage.

Chai WJ.

Chai WJ.

I am a car enthusiast and a passionate rider who loves to discover new places. Since the pandemic, I can't go to places and I started to blog and share information that I learned. I'm not easily distracted, I just... OMG, do I hear a Supra?

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