The Different Types of Exhaust Bends and Their Pros and Cons

Exhaust pipes direct exhaust fumes away from the engine and passengers, and they do so effectively thanks to the way they’re bent. There are various types of exhaust bends, each with its own pros and cons.

Why Are Some Exhaust Pipes Bent? 

Exhaust bends aren’t just for show. While they can certainly add to the aesthetic value of your car, they also have other functions. Here are some reasons why exhaust pipes are bent:

Fits Against Other Parts Better

In most vehicles, you’ll find the engine located under the hood in front of the cabin. An exhaust pipe can’t just run straight through the cabin to the vehicle’s rear. It can’t take any shortcuts, so it has to navigate around different parts underneath your vehicle. This is where exhaust bends come in. A bend in the exhaustcan help the pipe fit better against the suspension, chassis, and other components.

Promotes Better Heat Dissipation

A longer exhaust means improved heat dissipation since exhaust gases can cool down before they exit the exhaust. Bent pipes can also change the directional flow of the exhaust gases.

Can Improve Engine Performance

A bent exhaust pipe can help maintain your vehicle’s exhaust back pressure, which can significantly improve your engine performance. However, this only applies if the vehicle was designed with bends. If you have bends that weren’t there originally, then the back pressure could be higher, creating problems. Some exhaust bends can also reduce engine noise.

If you have exhaust bends that were not there originally, then the back pressure could be higher, creating problems.

–Anthony Harlin, ASE Certified Master Automobile Technician

What Are the Different Types of Exhaust Bends?

There are several types of exhaust bends, but let’s focus on those produced by three common techniques.

Mandrel Bends

The mandrel bend is one of the most popular types of exhaust bends. Utilizing a popular rotary draw technique, the bent exhaust pipe is formed using either a hard or soft rod called a mandrel, which is inserted into the tube during bending.

The mandrel prevents the tube from collapsing as the material stretches during bending. In most cases, manufacturers use a hard mandrel for a soft tube and a soft mandrel for a hard pipe. Some common examples of mandrels include steel, chrome, and bronze rods.

Pros of Mandrel Bending

Mandrel bending comes with its fair share of advantages, such as the following:

• Mandrel pipes are typically durable and unlikely to break.
• You can repeat the process and expect consistent and accurate results.
• The resulting exhaust pipes are less likely to return to their original shape.
• Mandrel bending works with most types of exhaust metals, such as aluminum, titanium, and steel.
• Mandrel exhaust pipes have the same internal diameter or roundness throughout the bend.

Cons of Mandrel Bending

Here are some of the cons of mandrel bending:

• The process can be time-consuming.
• The machinery and equipment used can be expensive.
• Only a few shops have the equipment required for mandrel bending.

Crush Bends

Also known as compression or press bending, crush bending occurs when a pushing force bends the pipe material to the desired shape. It’s one of the simplest types of exhaust bends, and it typically makes use of the following materials:

• Bend die
• Clamp die
• Pressure die
• Wipe die
• Mandrel

In compression bending, the bend die applies pressure on the pipe as the clamp die holds it firmly in place. Meanwhile, the wiper die prevents any defects from happening during the entire process. Some manufacturers also use a mandrel, but it’s more commonly used in mandrel bending.

Pros of Crush Bends

Here are some of the advantages of crush bending:

• It’s a fairly simple and quick process.
• It doesn’t require a lot of complex tools, making it cost-effective.
• You also don’t need to use oil or lube inside the pipe, which saves you the trouble of a messy clean-up.

Cons of Crush Bends

Here are some of the disadvantages of crush bending:

• Because crush bending is such a simple process, it can’t produce complex formations.
• Production can sometimes be slow.
• In some cases, it can be hard to create duplicate pipes.
• Too much compression can accidentally crush the pipe beyond repair.

Wrinkle Bends

When it comes to unique bending techniques, wrinkle bending is one of the first to come to mind. Wrinkle bending uses heat to shape pipes. It requires the use of an oxyacetylene flame, which heats the pipe to a red-hot state before you can bend the tube to your desired shape.

Pros of Wrinkle Bending

Here are some of the advantages of wrinkle bending:

• Wrinkle bending is fast compared to the other types of exhaust bending.
• There are fewer connections on the pipe, so there’s also less chance of exhaust leaks.
• Wrinkle bends are less likely to get deformed during the process.

Cons of Wrinkle Bending

Here are some of the disadvantages of wrinkle bending to consider:

• You have to heat the pipe first, which can take some time.
• Wrinkle bending can be expensive.

Each type of exhaust bend comes with its own fair share of advantages and disadvantages. At the end of the day, the best method is whichever suits you and your vehicle’s needs.