Expert Take On Flex Pipe For Car Exhaust: Are They Good?

By November 6, 2022Exhaust

A flex pipe is an excellent way to reduce the vibration in your exhaust system and protect it from cracking up. Manufacturers design the pipe so that it is flexible but not too flexible. This way, the pipe’s movement can counter the vibration while keeping connected exhaust pipes stable.

With the pipe, the risk of having an exhaust leak will drop drastically. You can use the pipe with turbochargers, and can connect the pipe with downpipes.

Personally, I have used flex pipe with my Honda Civic, and although there was no change in my engine’s performance, the sound of my exhaust was less disturbing. I have been using the pipe for a while now and have had no problems with my exhaust system. 

What Is a Flex Pipe?

Flex pipe, also called the exhaust flex pipe, is a solid but flexible tube made from steel materials. It serves as a connection between the engine and the exhaust system. It transports all exhaust gases created in the engine to the exhaust system for disposal. 

You can typically find the flex pipe beneath the vehicle, connected to the exhaust manifold. The pipe’s location allows for better movement of the engine when accelerating. Without this flex pipe in this position, your vehicle risks getting exhaust pipe damage during acceleration. 

Some people go the extra mile to fix the flex pipe in other vehicle regions, sometimes incredibly close to the engine, which is fine. For instance, people connect the flex at the exhaust side of their turbo engine. 

The flex pipe is not as rigid as many other parts of the exhaust system, it is more flexible, and this design is intentional. There is a lot of vibration caused in this area due to the engine’s activities. As a result, a more rigid pipe may crack and cause leaks. 

Moreover, with the flex pipe design, it can absorb the vibration coming from the engine. It can also absorb the vibration caused by all the rushing exhaust gases from the engine. By doing this, the flex pipe can protect parts of the exhaust system that could get damaged from the effect of the vibration and rushing gases. 

In addition, the design of the flex pipe is called a braided steel design. Braided steel is when steel materials intertwine like in baskets, but in this case, it is done in such a way that leaks are not allowed to happen. 

Flex pipes can have double or triple braiding, depending on the vehicle. In most cases, gasoline vehicles will be fitted with double-braided flex pipe, while diesel engines will have single-braided flex pipe. 

The braided design is responsible for the flex pipe’s flexible nature. It allows the pipe to bend in any direction without having cracks or breaking. Other designs for the flex pipe do not include braided steel; some have corrugations. 

Also Read: Exhaust Pipe Replacement: Can You Use EMT Conduit?

Using Flex Pipe For Exhaust Pipe: Is It Good?

Flex pipes are suitable for exhaust use and make an excellent exhaust pipe. The flex pipe has a design that can handle all the disadvantages of fast-moving exhaust. It can handle the excessive vibration caused by fast-moving gases, the corrosive chemicals that can cause rust, and much more.

The design of the flex pipe includes vibration-absorbing mechanisms. It has a braided design coupled with bellow corrugation, which allows the flex pipe to move from side to side during engine movement. 

However, your exhaust system does not need that much movement; this is where the below corrugation comes into play. It provides limited but precise flexibility and movement to the flex pipe, just enough to reduce vibration.  

If the flex pipe is too flexible, the exhaust pipes will easily get displaced by the movement of the gases. It will cause leaks and other exhaust issues in your vehicle.

Furthermore, the flex pipe also provides lesser restriction of exhaust gases in the exhaust system. Many exhaust pipes restrict exhaust gases, which may lead to loss of power and the creation of excessive back pressure. 

Flex pipes have enough inner room and no restriction for gases to flow freely. It will significantly improve the flow of gases from the engine to the exhaust system. 

All these features make the flex pipe worth trying out as an exhaust pipe. The only disadvantage of the flex pipe is that it may cost more to buy. The installation is pretty straightforward.

Also Read: Best Material For Exhaust Bolts: Is Stainless Steel Good?

Can You Use Flex Pipe for Turbo?

You can use flex pipe for your turbocharged engine, but you will need proper setup for your exhaust system and engine. As we know, turbocharged engines can be much heavier, which could be a problem.   

Using a flex pipe with a turbo is fine, as the pipe can handle the hot air released from the turbo system. You can use the flex pipes on the exhaust or turbine side of the turbocharger, attach the pipe to the downpipes, and more places in the turbocharger. 

With the larger flex pipe, your turbocharger will get better exhaust flow. The flex pipe will give you a more durable pipe and reduce the risk of having an exhaust leak with the turbocharger. It would achieve this by absorbing vibration from the turbocharger, which could have caused severe damage if you used regular pipes.

One crucial factor is where you will place the flex pipe. If you run the flex pipe to the turbo, there might be a problem. Because of the flexible nature of the pipes, when driving, the pipe may experience a lot of movement, especially with the fast-moving hot gases coming from the turbo. The movement could cause a lot of noise and displace the exhaust system.  

Also, the weight of the turbocharger and wastegate can be a problem for the flex pipe. The turbo weight may increase the movement of the flex pipe. 

To solve this problem, you will need to create a kind of support for the turbocharger. Many people decide to redesign the turbine or exhaust side so that it can carry the weight of the turbocharger. It may not work for you if your turbine side includes flex pipes. 

You can opt to create a bracket that will be attached to the engine to support the weight of the turbocharger, then running the flex pipe from the manifold to the turbo would work fine. 

Does a Flex Pipe Effect Sound?

A flex pipe does not make your vehicle louder; instead, it reduces the noise from the exhaust system. It can achieve this by reducing the movement and vibration in the exhaust system. 

The initial role of the flex pipe was to make vehicles more silent. Vehicles without flex pipes will likely experience more vibration in their exhaust system. Fast-moving exhaust gases in the engine can cause the pipe to vibrate out of control, making them collide with other parts of the vehicle creating some sounds. 

The pipe leaks if you hear a much louder noise from your exhaust system after installing a flex pipe. It may be in the form of a hissing, tapping, or rattling sound. 

When accelerating, your leaked flex pipe’s sound may become even more disturbing and disturbing. It will also come with exhaust fume smells and other symptoms. You must know the sound may not only be a result of leaking flex pipe but leak from any part of the exhaust system.  

How Long Do Flex Pipes Last?

Like every other exhaust pipe, your flex pipe should last between 10 to 15 years. It can reduce the effects of wear and tear caused by vibration, allowing it to last longer. 

Like every other vehicle part, the flex pipe is also prey to damage after some usage. After some years of absorbing vibrations, the pipe can get cracked, causing damage, but this will not happen anytime soon from when you installed the pipe. 

Cheaper aftermarket flex pipes will not last as long as the standard ones. If you get cheaper pipes, they will last between 2 to 5 years. The manufacturer uses inferior materials in making the pipe, making them unable to withstand as much shake from the engine and exhaust gases as standard pipes.

Furthermore, how you install the flex will determine how long the flex pipe will last. Many people ignore the proper procedure when installing their flex pipe. 

For instance, when installing a bigger flex pipe, you may need to use more than one mount to avoid movement. If you decide to have just one mount hold the pipe, the pipe could get damaged over time.  You must follow the proper procedure when installing the flex pipe. 

The flex pipe can get worse after absorbing vibration for a long time, and you must know how to tell if your flex pipe is bad. Below are some symptoms of a bad flex pipe:

  1. Loud Noise . The first sign of a bad or leaking flex pipe is a change in the sound. Typically, a flex pipe does not add or affect your vehicle’s sound in any way; if anything, it reduces the sound from the exhaust system.
  2. Bad Smell. Another sign that your flex pipe leaks are exhaust or fuel smell escaping into the vehicle. Remember that this fume is harmful and can cause health damage if inhaled for a while. Once you notice a significant change in the sound of your exhaust, it could signal that your flex pipe is terrible. The sound coming from the pipe could be hissing or tapping.
  3. Poor engine performance. A common sign of exhaust leaks or flex pipe is poor engine performance. The engine relies on the proper flow of gases to function correctly. Once there is a leak, the engine will begin to reduce performance.  Also, you will notice that your fuel consumption will increase significantly.

What Is the Price for a Flex Pipe?

Installing a new flex pipe will cost between $150 and $300. It can cost even more if you consider the cost of welding and labor and more. 

The price of a new flex pipe varies depending on some factors. Some of these factors may include the size of the pipe; the bigger the pipes, the more expensive. Brand type is also a contributing factor to the price of flex pipe. 

Some car brands may cost more to replace the flex pipes. Different professional mechanics often offer different costs to repair. It may be because this vehicle requires specific parts that may cost more or require a little more effort to change the part. 

There are cheaper flex pipes, but we do not recommend getting them. They will not last long, and you will spend more fixing or replacing them than you could have gotten a standard flex pipe.  


Q: How Do You Weld an Exhaust Pipe?

To properly weld an exhaust pipe, you need a good guide. Below is an easy-to-follow step to get your exhaust pipe welded properly

  1. Get your safety gear ready. Wear protective clothing, wear a face shield, and ensure the environment is adequately ventilated. Also, ensure that your vehicle’s battery is disconnected and completely stay away from welding near the gas tank.
  2. Set up your welding tool and ensure you familiarize yourself with the equipment. Go through the equipment manual properly.
  3. Get the pipes in place by using magnets or clamps. Proceed to apply a temporary weld to hold it in place for the next step.
  4. To start welding, you must start with low heat. Heat the pipe evenly. 
  5. Once you have heated the part, ensure that you wait for the equipment to cool down before packing the equipment.
  6. Allowing welded parts to cool down before cleaning, polishing, and applying finishes.  

Q: Does Flex Pipe Size Matter?

The size of your flex pipe does not matter as it does not increase horsepower nor contribute to the engine’s performance. Larger flex pipe benefits are better gas flow and reduced back pressure.

Q: Can You Wrap a Flex Pipe?

You can wrap your flex pipe, which is an excellent way to protect the pipe from external heat and improve exhaust flow. Wrapping the pipe will keep the heat inside and increase the pressure in the pipe. When wrapping your flex pipe, wrap it differently with a separate wrap. 

Ifandi L.

Ifandi L.

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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