How Do You Bend An Exhaust Pipe?

Would you like to know how to bend an exhaust pipe, and if you should? Well, we have researched exhaust pipe bends and have answers for you.

You can use a mandrel pipe bender or bend without using the filled pipe technique to bend an exhaust pipe. To use the filled pipe technique, follow these steps:

  • Measure the length of the pipe to where you want the bend to be and make a mark.
  • Pack the pipe full of sand and cap the ends.
  • Secure the pipe in a vise with the mark from step 1 just visible on the edge of the vise.
  • Heat the area where you want to make the bend with a blow torch.
  • Bend the pipe by pulling towards you.
  • Remove the pipe from the vise and check if it is correct.
  • Rebend the pipe if adjustments are necessary.
  • Flush the pipe with water to remove all of the sand.

This article will teach you how to bend an exhaust pipe with and without a mandrel pipe bender. This can be useful for saving money when replacing or adjusting your exhaust pipe. We will also cover related exhaust pipe questions. Keep reading to learn more.

A car suspension and exhaust pipe, How Do You Bend An Exhaust Pipe?

How To Bend An Exhaust Pipe

There are two primary ways to bend an exhaust pipe. One method uses a mandrel pipe bender, and the other method uses the filled pipe technique. First, we will cover how to use the mandrel pipe bender and then the filled pipe technique.

Auto repairman bending under bottom of car while fixing exhaust system of car

Mandrel Pipe Bender

A mandrel pipe bender is a device that can bend a pipe without causing crimping, which can help to improve airflow. The mandrel pipe bender does this by having a solid insert inserted into the pipe to hold the pipe's form and prevent deformation.

The first step to using a mandrel pipe bender is to measure the pipe to where you want the bend and then make a mark. This measurement should be from the edge of the pipe to where you want the far wall of the curve to be after bending.

Now line up the mark you made with the indicator mark on your mandrel pipe bender. This should look like a diamond or a triangle.

Next, you can use the mandrel pipe bender to bend the pipe to the desired angle. Once finished, check that the pipe is at the correct angle and make adjustments as needed.

Using a mandrel pipe bender would typically be the way you want to go for consistent, reliable pipe bending. That said, they can be expensive. A good mandrel pipe bender can cost anywhere from 10,000-50,000 dollars. For this reason, many people opt for a cheaper at-home method of bending their exhaust pipes. We will now cover the filled pipe technique.

Filled Pipe Technique

The filled pipe technique is a technique to bend a pipe at home without buying an expensive mandrel pipe bender. This technique uses sand to help the pipe resist deformation. Here are the steps.

Measuring To The Bend

First, you will want to measure from the end of the pipe to where you want the far wall of the bend to be after bending. Be sure to include three inches of pipe overlap where you will clamp the exhaust pipe back to the vehicle. At this point, make a mark on the pipe that you will use later.

Packing The Pipe With Sand

Next, you want to fill the pipe with sand. Be sure to pack the sand in tightly. Now cap the ends of the pipe, so the sand doesn't leak out. If you don't have caps, you can use bunched-up newspaper. Just be sure to pack the newspaper very well to prevent leaks.

Securing The Pipe In A Vise

Take the pipe and secure it tightly in a vise. Line up the mark you made earlier to just past the edge of the vise so that it is visible. Tighten the vise to secure the exhaust pipe but not so tight that it dents the metal.

Heating The Bend Location

Next, take a blow torch and heat the metal where you want the bend to be. Heat the metal until it is malleable. You will want to heat the inside of the pipe more than the outside because if the outside is overheated, it may cause the metal to tear when stretched. The pipe will be more forgiving to compression, so the inside is fine to be hotter. 

Bending The Pipe

Now bend the pipe by pulling towards you. Be sure to wear welding gloves as metal is good at conducting heat, and the heat may spread quickly down the pipe. Pull in a steady and non-jerky manner to decrease the likelihood of creases or tears.

Verify The Bend

Now take the pipe and hold it up to where you need to install it. See if the bend is sufficient or if adjustments need to be made.

Making Adjustments

If adjustments need to be made, put the pipe back in the vise and reheat the bend. Pull the pipe a little in the needed direction and check again until the pipe fits.

Flush The Pipe With Water

Once the exhaust pipe is in the correct shape, it is time to clean the sand out of it. Start by removing the caps and pouring out the sand. Some sand may stick to the inside of the pipe, so flush the pipe out with water. Once all the sand is removed, be sure to dry your pipe before installing it on your vehicle. This can help prevent unnecessary corrosion.

If you followed these steps closely, your exhaust pipe should now be bent to the correct angle. It Still Runs covers both of these methods if you want to read more on them. Now let's discuss if you should bend an exhaust pipe in the first place.

Should You Bend An Exhaust Pipe?

You absolutely should make sure to bend your exhaust pipes so that they fit correctly to the bottom of your vehicle. As long as the bend isn't so sharp that it restricts airflow, then there shouldn't be a reason not to bend your exhaust pipe.

How Is Exhaust Bend Measured?

Pipe bent products from 3D pipe bending machine

Exhaust bend is measured by finding the distance from the center of the pipe at the start of the bend to the center of the pipe in the center of the bend. This distance is the bend radius. The distance from one leg of the bend to the other leg should be twice the bend radius, also called the bend diameter.

This can be a little difficult to calculate, but measuring devices can also help you find your pipe's bend radius. Jim's Custom Exhaust goes into more detail on calculating the bend radius of an exhaust pipe.

Is A Bent Exhaust Pipe Bad?

A bent exhaust pipe isn't bad for your vehicle. If the bend is restricting airflow, then it can be important to get it fixed quickly. When the airflow is restricted, the engine must work harder to move the vehicle, and engine performance can dip. Over time this can put unnecessary stress on your engine and potentially cause damage to internal parts.

Does Damaged Exhaust Affect Car Performance?

A damaged exhaust does affect car performance. If there is a blockage or restriction to airflow, the engine will have built-up pressure to work against, reducing engine performance.

If there is a hole in the exhaust line, the engine could lose precious vacuum, decreasing performance. Overall if you have damage to your exhaust, it can be a good idea to get it fixed as soon as possible.

How Do You Fix A Hanging Exhaust Pipe?

If you have a hanging exhaust pipe, it can be important to repair it before you damage it by dragging it on the ground. While you can repair it by buying a replacement rubber clamp, it will cost over 30 dollars and only last about ten years. There is a technique that lasts longer and only costs a few cents. The wire-hanger technique.

It's really simple to do. First, take a wire hanger and make a loop to go around the exhaust pipe. Then secure that loop to the frame where the rubber clamp is supposed to attach. That's all there is to it.

Your exhaust pipe will no longer be hanging and will last a lot longer than the rubber clamps that are intended to hold up the exhaust pipe. If you would like to watch a video on how to do it, Dannys Cam has a great video on Youtube.


Final Thoughts

Bending an exhaust pipe is something that you can do yourself if you know the right techniques. While a bent exhaust pipe isn't an issue for vehicle performance, if the pipe is so sharply bent that it restricts airflow, then you will need to remedy that issue. We also learned that you can fix a hanging exhaust pipe yourself with a metal coat hanger.

We hope you enjoyed this article. If you would like to learn more, check out these other posts below:

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