When it comes to bent exhausts, there is a lot of debate out there on which is the best method. There is lots of different, contradicting information that can make it confusing to know which is truly the best method. Today, we’re going to look at Mandrel Bent Exhaust vs Press Bent

The two common ways of bending an exhaust is Mandrel bending and press bending. They come with their differences, and it can be difficult to know which is the best considering all the conflict. Hopefully we’re able to fix some of those conflicting statements.


A common statement is that there are dyno results that show that pressure bending gives better results and more power when compared with mandrel bending.


NASCAR dynomometer, which is used in a controlled environment for maximum, accurate results, has shown in the the past that mandrel bending actually has better results. This is usually something that is said to convince people to use their services as they only offer pressure bending and don’t want to lose customers or income.


You can find many places that will give  you honest opinions, such as Magnaflow or Flowmaster. They’re unbiased and will advise on what is best for you, not what is best for their wallets and business accounts.


There are many analogies that explain it properly, such as imagining a straw or a hosepipe. If you take a garden hose pipe that is just a rubber tube with a spray nozzle attached, while the rubber pipe is straight with no folds, it’ll work perfectly. Water will flow through it with the right pressure and give you the results you want. However, if you bend the rubber piping, and create an angle in it, you’ll find the water trickles through slower.


This is equivalent to pressure bending.


Now, if you take a garden hose pipe that has a flexible head on it, with a structure within the piping to allow for bends, you’ll get the same results from the hose as you would if the piping was straight. This is because there is something in there that allows for the bend while not constricting   the piping and effecting how the water gets through.


This is equivalent to mandrel bending.


When you chose pressure bending for your exhaust engine, you’re basically allowing for an angle to be placed into the pipe without any structure to support the inside of the pipe and keep it open. So it restricts the airflow that can get into the engine and the combustion system. However, when  you choose mendrel bending, it allows for the steel to expand over the bend and stay open, keeping air flow going.


Another common statement is that mendrel bending is pointless on cars that don’t have a high horse power output. This is, again, inaccurate. Even if the engine you want to modify does not have high horse power, adding a mendrel bend can actually give you an increase of horse power up to 5% which can make a very big difference.


This is the same for those that claim that engines are too small to use mendrel bending. Regardless of the size of your engine, you’ll see an increase in horse power and torque. The bigger that the engine is, though, the more that you’ll see. Overall, however, the actual size of the engine doesn’t make any difference. It can be used on any size engine.


Most people will defend the option they used themselves, but it’s important to remember that when this is happening, they don’t have the other option currently in use on their engine and can’t make a fair comparison. It’s fine for someone to claim that they’ve had pressure bending and that it runs just fine – but they haven’t ran their car on mendrel bending either and cannot accurately compare which is better for their vehicle. If they could, it would make the process a lot easier and there’d be no reason for debate.


A pipe that has been carefully bent around a structure designed to keep airflow moving will work much better than a pipe that has been forced to bend and has decreased the area where the air flows – it’s common sense.  Again, think about the hose pipes. Would you rather one that was slow, had bad water pressure and seemed to take forever, or one that worked as advertised, had high pressure, and didn’t feel like the water was crawling through the rubber tubing?


Why should the decision that you make for your car be any different when it comes to air flow?


Some might try and tell you that if you’re only going for a small number of bends then pressure bending is fine but this is again another comment that makes no sense. Regardless of how many bends you get put in, you want that air flow to be unrestricted. One bend with a pressure bender causes a restriction. Two causes an even bigger one.


Keeping that pipe open is the best way to get more power and a better response and air flow into the combustion engine, which increases the efficiency of fuel and how well the vehicle runs and how  much power is behind it. Don’t sacrifice power and efficiency because someone’s told you that for the small modification you’re making, it’s unnecessary.


Mendrel bending is becoming the lead option, and this is shown with many new manufactures of cars offering it at factory installation. You can purchase from them directly, and have it fitted, showing that they have faith in it and it is their preferred method of bending.


Of course, people are entitled to their own opinions, whether they’re wrong or right. It’s important to make sure you read everything before you make modifications so you can make the best decision available to you. Keep in mind that you want something that will improve the power of your vehicle and not hinder it, though,  and that the decision you make will one way or another affect this.