Tech Corner: Fabricating Your Own Exhaust

Maybe you blew your budget on other parts, maybe your first part-time job can only support so much, or maybe you’re just ready to test your skills—whatever the reason, you’ve decided that you want to try your hand at fabricating your own exhaust. It’s something many of us have dabbled with—and for good reason. With just some pipes and a muffler you can create a setup that is both functional and totally unique.

Tools & Experience Define Your Product

As you roll around the idea of fabricating your own exhaust, you’re going to ask yourself: Can I do this? If you have patience, focus, and a means to get a vehicle up in the air, then chances are yes. How well you can do it is another question entirely. Therefore, if this is your first time attempting such a project, don’t set the bar too high. There’s no shame in admitting you won’t build a custom exhaust system that can rival the likes of Corsa and Borla.

This is also something to exercise at your own risk. Fabbing up an exhaust system is not rocket science, but it does require attention to detail and at least some basic skill. Plus, if you plan to tackle the welding by yourself, it’s important you take the necessary precautions, investing in good equipment and safety gear.

There are a few reasons to fabricate your own exhaust system. While some people simply want to take on a new challenge, many others do so to actually save a bit of money. Whether or not building your own exhaust system will save you money depends on what you’ve got to work with.

Before you start…

In addition to sourcing parts, you’ll need special tools. Do you already own a welder or do you need to buy one? Remember that purchasing one could outweigh the price of buying a new exhaust system, especially if you’re just learning to weld. That being said, if you plan on jumping into several more fabrication projects, it might be worth the investment.

Another thing to consider is that you generally can only source pre-bent pipes in “known degrees,” i.e. 45-, 90-, and 180-degree bends. Often, you’ll need slightly different angles. And that means, you’ll need access to more tools, like a chop saw, grinder, or pipe bender. Let’s not forget those cuts translate to more welding. Again, you’re looking at a situation where the price of equipment can lead to an end result where fabricating your own exhaust system will cost more than purchasing a pre-made kit.

Other things to factor into your build plan are your local and state laws. The last thing you want is to spend time and money on illegal modifications. Additionally, make sure you have a solid understanding of your vehicle’s setup. For example, a turbocharged system will generally require larger exhaust piping than a naturally-aspirated setup. Likewise, if your project car is still in early days, aim for an exhaust system that will serve your vehicle further down the timeline. (Otherwise, you might end up fabricating another new exhaust.)

Routing

Routing of an exhaust system is dependent on the application, preference, and what components are present. For example, if you’re building a system to just run mufflers off a set of headers, the fabrication process will differ from that of a full system.

Before you begin, look at the existing system (or what’s left of it) to help determine routing. If you don’t have that, then take note of the underside of the vehicle, where the exhaust can pass through and where the existing hangers are, as they will be necessary to secure the system to the vehicle. It’s no secret that you won’t be able to predict every bend and length just by sight. You will need to fit and build at the same time, which makes this project a bit of an art.

Fool-Proof Process

You always want to start with the furthest section forward and then move your way back. This can be a bit of a trick, because you need to determine the necessary flange type and size, along with the shape and length of pipe that needs to come directly off of it. This tends to be the most difficult part as it almost always requires welding to fit the mating flange to the section of pipe. However, once that first length of pipe/flange is in place, you can begin fitting each part of the system together section by section.

Locking each section tightly to one another is critical to getting a proper fit so as you slip the system together, ensure that you give each section a “clock” mark where the joints match up. The use of clamps and/or slip joints here will make life a lot easier. If you’d rather weld as you go, then remove the section from the vehicle, line those marks up, and weld that portion together, reinstalling it before moving onto the following sections.

As you work, you want to keep things as high and tight as possible. Take your time to make sure every angle in the system is exactly where you need it to be. Rushing through this can result in a sagging system or one that binds or bumps on crossmembers and mechanical components, causing rattling and damage. Similarly, if you intend to weld, don’t weld the system solid. Giving it the ability to flex with joints will prevent stress and cracks in the system as the vehicle moves.

The types of joints you use throughout the system is something you will need to decide. Slip joints with clamps and V-Bands are both viable options, but perhaps you should consider using ball flanges pairing portions of the system. “Ball flanges offer a durable junction without requiring gaskets, so they can be disassembled and reassembled repeatedly without issue,” point out the folks over at Hot Rod Network. When they decided to tackle an exhaust upgrade for their ’69 Camaro, they opted for a ball flange from Flowmaster. “Our idea was to install the ball flanges at the back of the H-pipe so the center portion of the exhaust could be dropped to make driveline maintenance easier. The inspiration came from the stock setup used on 5.0-liter Mustangs.”

Builders Kits and Crossovers

Obviously, it’s always nice to make less work for yourself. You can purchase exhaust pipe in various lengths from the local parts store but unless you’ve got a trained hand and keen eye, you may be making several runs to and from the shop as you construct your system. Builders kits are very helpful in making easy work of this, as they supply pretty much every bend or length necessary for common applications. There are a ton of suppliers of these systems but Pypes is a go-to favorite, as you can get builders kits in a variety of sizes and materials including 304 Stainless Steel.

This is a creative process and that means you don’t need to limit yourself to what the vehicle originally calls for. If space is limited, you may want to integrate a Y-pipe. If performance is desired, an X-pipe or an H-pipe may be added. Skilled fabricators obviously have the option of making their own crossovers, but many suppliers offer pre-made sections to add to the system.

Hangers

As you know, you will need to make hangers. Hangers come in many shapes and sizes and what you choose can be dictated by the vehicle. You can use universal hangers that you mount to the vehicle wherever you want with the use of nuts and bolts. You can also purchase factory-style hangers that mount to the factory locations. In many cases, builders will simply purchase a length of round stock they cut to length and bend appropriately to fit into place.

Remember, fabricating your own exhaust is not a “one size fits all” ordeal. It’s relative and requires a level of creativity, skill, resources, and experience. It can be super simple or very complex. But what’s nice about it is—as the builder—you have the freedom to go with either. My only bit of advice is to start where you feel comfortable but always push yourself to achieve more. Plus, I can promise you that when you fire that thing off and hear a killer exhaust note that you know you’re responsible for producing, you’ll feel like a total boss.