1-7/8” vs. 1-3/4” Headers: Which Is Better For Your Engine?

A header can improve engine performance by improving exhaust scavenging. Headers are available in many different sizes and lengths. In this article, we will compare 1-7/8” vs. 1-3/4” headers.

At first glance, 1-7/8″ and 1-3/4″ headers are not much different from each other. Specifically, they only differ one-eighth of an inch. So, do they make a difference? Let’s dive right in!

Overview Of Exhaust Headers

Before comparing 1-7/8″ vs. 1-3/4″ headers, let’s take a look at the basic information about the header.

What Are Exhaust Headers?

The header is one of the most accessible bolt-on accessories you can use to improve the motor’s performance. For example, it can help the engine push the exhaust gas out of the cylinder more efficiently.

A header usually consists of three main parts: the flange, the primary tubes, and the collector.

  • The flange is the flat surface that screws into the cylinder head
  • The primary tubes (consisting of 4 separate tubes) are tubes welded to the flange.
  • The collector is where the four separate tubes of the primary tubes come together. It is a large diameter tube.

About Exhaust Header Diameter

Common header sizes include 1-1/2″, 1-5/8″, 1-3/4″, 1-7/8″, 2″, 2-1/8″, 2-1/4″, and 2-3/8″.

In most cases, the header size is the diameter of the primary tubes. As a result, a 1-7/8” header will have primary tube diameters of 1-7/8”.

The larger the size of the header, the greater its flow capacity. Hence, bigger engines will have to come with larger headers as they need to draw more emissions than smaller displacement engines. However, that does not mean choosing the headers with the largest size is the best.

Choosing the correct header diameter is extremely important. With all other things being equal, proper header size helps you get a superior scavenging effect.

To learn how tube size affects horsepower and torque, watch the video.

1-7/8” vs. 1-3/4” Headers: Similarities and Differences

1. Similarities

Both 1-7/8” and 1-3/4” headers have a “4-1” configuration. In general, they are the perfect choice for smaller, low-performance engines.

2. Differences

The controversy between 1-7/8″ and 1-3/4″ headers seems to be raging all over the place.

As we all know, their diameter is not much different; So do they make a difference?

Specifically, 1-3/4″ and 1-7/8″ headers are only one-eighth of an inch apart. This difference does not appear to be significant. However, you will see a difference when you install them in the engine.

In fact, an eighth of an inch difference can be enough to change performance. As mentioned above, the primary tube diameter and discharge velocity are related. Therefore, a larger diameter header can draw more exhaust while the velocity of the exhaust stream will be lower.

That means the 1-3/4″ header offers more incredible exhaust velocity at lower engine speeds. As a result, it produces more horsepower and low-end torque.

In contrast, the 1-7/8″ header has dropped velocity at low engine speeds, resulting in lower horsepower and torque. For higher engine speeds, the 1-7/8″ provides more horsepower and torque than the 1-3/4″ header.

Which Is Better: 1-7/8” Header or 1-3/4” Header?

The difference between 1-7/8″ and 1-3/4″ headers are not too dramatic, although they can make a difference in engine performance.

Many people assume bigger is better – It is a widespread mistake. There are many factors that you need to consider when choosing a header diameter, and these include engine size, horsepower, the intended use of the vehicle, and more.

So, when choosing a header, always remember that “Bigger isn’t always better.”

For example, a 1-7/8″ header might be considered overkill for your street driven 350. Meanwhile, a street application 350 will benefit well from a 1-3/4″ header.

On the other hand, for racing applications such as sprint car racing, a 350 engine commonly be outfitted with a 1-7/8″ header for racing applications.

Frequently Asked Questions

Does the length of the primary tubes affect engine performance?

The short answer is yes.

Shorter primary tubes can improve top-end power, while longer primary tubes can increase low-end torque.

How to choose the right header?

Currently, there are many types of headers available in the market. To choose a good header for your application, consider these five factors:

Header size: The bigger header is not always better.

Header Dimensions: Full-length headers, shorty headers, and mid-length headers

Header Configuration: Tri-Y and 4-1.

Header Material: Mild steel and stainless steel.

Ceramic coating or other finishes?

What is the difference between stainless steel and mild steel headers?

Headers are usually made from stainless steel or mild steel. The main difference between them is durability and cost.

Mild steel headers will be slightly cheaper, but they will sacrifice longevity and durability. As a result, they will rust and corrode more quickly than stainless steel headers.

In contrast, stainless steel headers will not rust or corrode. But, of course, their cost is usually higher.

What are the pros & cons of full-length headers and shorty headers?

Full-length headers


  • Perfect for racing and high performance
  • Best for maximum power
  • Available in a variety of sizes
  • Improved torque in some applications


  • Less clearance everywhere
  • Installation is more difficult
  • More expensive

Shorty headers


  • Easy to install
  • Available in a variety of sizes
  • Improved ground clearance
  • Inexpensive
  • Designed for space-limited installations


  • Reduce torque in high power and high RPM applications


All in all, 1-7/8″ and 1-3/4″ headers are not too different. However, this 1/8 inch disparity can add a massive exhaust volume capacity, and that’s enough to change the engine’s performance.

So to know which is right for you, you need to consider several factors like engine size, horsepower output, average operating RPM, the intended use of the vehicle, and more.

Hopefully, this article contains valuable information for you. Thank you for reading!

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