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Create the Perfect Exhaust Note with Performance Mufflers

6/2/2021
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Turn Heads with The Right Mufflers

We are going to step out on a very short limb and here and state that most of our customers have a V8 engine under the hood of their hot rod, muscle car, or classic truck. Brand loyalties aside, we understand the allure of a good old American small block or big block V8 bolted to the front frame rails is what makes an enthusiast want to twist that ignition key and go for a fun ride down some two-lane blacktop. Almost as important as having a V8 engine under the hood is how that V8 sounds going down said two-lane road. There is something very personal about how a vehicle sounds to the owner and obviously that sound is also very subjective. What is one person’s perfect exhaust note may be too “sharp” for someone else.

That is where the exhaust system’s mufflers come into play. While tubing diameter and even length of the system’s pipes have some effect on overall exhaust note, the muffler is where the musical magic happens. A muffler’s internal design, case material, shape, and more are all designed to create a specific exhaust note. Of course, the engine itself, from its camshaft to its firing order, effects this exhaust note as well and a well-educated hot rodder’s ear can tell what is under the hood just by the exhaust note. Sorry, but you are never going to get that small block Chevy in your Ford hot rod to sound like a small block Ford!

How Does a Muffler Work?

The typical internal combustion engine features an exhaust port for each cylinder of the engine (though there are exceptions, like Ford’s Flathead V8). The exhaust, which is the byproduct of the engine’s combustion process, is forced out of the combustion chamber via the rising connecting rod and piston assembly while the camshaft holds open the exhaust valve. The exhaust that leaves the engine is traveling as a high frequency sound pulse which repeats with each firing of the cylinder. Multiply that by 8 cylinders and you can see that these high frequency pressure waves create some substantial noise. Open headers might sound great at the racetrack, but no one wants to go deaf cruising Main Street for some ice cream. This is where mufflers come in to save the day.

The sound pressure waves coming down the exhaust pipe need to be attenuated in some manner to provide for an enjoyable driving experience and for safety. We all love a nice exhaust note but having too loud of an exhaust can not only raise an eyebrow of the local constabulary, but it makes it hard to hear what is going on around you and under the hood of your own ride. A muffler’s job is to reduce the noise level of these exhaust pressure waves in some manner, either via sound absorption material, or controlling the sound frequencies with resonance, chambers, and perforated tubing. Some brands will use a combination of these sound control features.

What Types of Performance Mufflers Are There?

The most common performance muffler is one with a casing filled with sound absorbing material within. This is referred to as a dissipative muffler. It removes the energy from the sound waves, dissipating the pressure into the material, often fiberglass, but you will also see mufflers with stainless mesh (think like a steel wool pot scrubber material, only larger). This type of performance muffler is very common in OEM applications and some classically styled mufflers. It is also relatively cost efficient, as the muffler cases are often rolled steel, galvanized, or aluminized for corrosion protection, with crimped end plates.

The original “glasspack” term used to describe some performance mufflers is from this style of muffler with fiberglass material as the sound absorption product. These mufflers feature a straight through design to reduce backpressure and increase performance. The MagnaFlow muffler cutaway shown above is but one example. The straight through tube is perforated and surrounded by the absorption material. Often a performance muffler that uses the “turbo” nomenclature has a similar internal design with either fibrous or metallic sound absorbing materials but uses an S-bend perforated path instead of a straight through single tube from inlet to outlet. Turbo-styled mufflers will often give up a small bit of performance to provide a bit quieter exhaust note.

The other popular performance muffler design is the reactive muffler. A reactive muffler works off the principal of a sound chamber and uses the inner walls and dividers to reflect the sound back towards the source. The reactive muffler is often tuned to a specific frequency of attenuation, which is why the typical reactive muffler design is often offered in various sound level series to provide a quiet/aggressive/very loud type of escalating sound offering to the customer. Reactive mufflers are often made from heavier gauge steel and are usually fully welded designs, as the reactive design works off the metal resonating at a certain frequency. These mufflers are often referred to as “chambered” mufflers and you may have even seen “two chamber” or “three chamber” terminology in marketing materials. The more chambers the quieter the muffler will be, as the exhaust gas pulses must pass through more deflectors/chambers before exiting, vibrating more metal surface area. The Flowmaster 40-Series muffler is an example of a chambered muffler and is the “OG” two-chamber muffler heard on thousands of muscle cars.

Is Muffler Material Important?

The type of metal your mufflers are crafted from is often a consideration that is not very high up on the shopping list, but it is indeed one you should be aware of when you are looking for performance mufflers for your ride. The basic budget replacement muffler you might have installed on your daily driver is most likely made from aluminized steel. This is a basic grade of steel with an aluminum coating to resist (note we did not say prevent!) rust through or perforation of the muffler body. These mufflers are usually the heaviest when comparing similar size mufflers in different materials and are usually crimped case ends and not fully welded. The aluminized steel body is popular with glasspack and turbo muffler designs. However, some glasspack designs are not aluminized and simply come painted. You will find chambered mufflers are often built from some type of steel and are fully welded.

A better solution is either an aluminum or stainless-steel muffler. These materials have a much higher corrosion resistance and will usually outlast your car. Aluminum and stainless-steel mufflers can be either welded or crimped case. You will find turbo, chambered, and even some glasspacks in aluminum or stainless-steel variants. A bonus of both materials is that if they are highly visible on your hot rod or muscle car they can be polished to a chrome-like mirror finish to bring attention to your ride.

What Size Muffler Do I Need?

If all you are doing is replacing your stock mufflers or perhaps a set of worn-out aftermarket mufflers the decision is easy. Measure the old case size so you know the maximum case dimensions you can search for, and measure the inlet and outlet bushing diameters and location to determine the current system’s pipe diameter. This will ensure the mufflers you order will not only fit the area but that the mufflers will easily connect to the current pipe diameter of your exhaust system.

However, if we are talking a complete rebuild of the exhaust system or your project build is ready for its first exhaust system, then much more needs to be taken into consideration. Obviously, there is still the muffler case dimensions that are the primary focus. Where will you be mounting the mufflers and how much room do you have for the muffler case itself. That needs to be your fist trip under your ride. Secondly would be the muffler case’s inlet and outlet bushing locations. You will see inlet and outlet specs listed as “offset” or “centered” in our product details. Determining inlet pipe routing and tailpipe routing over/around your rear suspension will help you confirm where the muffler’s inlet and outlet bushings should be on the muffler casing. Popular muscle cars, classic trucks, and so forth will often find easier solutions via complete exhaust system kits with mufflers and pre-bent piping to mate to the headers or exhaust manifolds. However, deviating from the stock suspension and chassis configuration, or building a truly custom hot rod will require careful measuring and mock-ups.

With a new installation or any time you plan to upgrade the remainder of your exhaust system, including inlet pipes, crossover, and tailpipes, you need to consider your engine’s exhaust flow needs. Cubic displacement, horsepower, and rpm operating range all play an integral part in deciding pipe diameter. A typical rule of thumb is small block V-8 and/or up to 250 horsepower 2-1/4-inch pipes will suffice. Larger displacement small blocks, such as stroker engines, and big block engines, with power up to 500 horsepower usually work best with 2-1/2-inch piping. Over 500 horsepower it is often best to move to 3-inch pipe if it will fit your vehicle’s chassis routing. Tailpipe length does not really do much for horsepower gain but can affect overall tone of the mufflers you are using, so keep that in mind when determining muffler location and how far you want the tailpipes to go (side exit, turn downs, or to the rear bumper/valance area).

How Do You Install Mufflers?

Muffler installation can be accomplished in one of two methods, either fully welding the muffler to your exhaust inlet pipes and tailpipes or using various styles of exhaust clamps. Welding is more permanent and will absolutely eliminate any movement between the pipes and mufflers due to vibration or thermal expansion and is often the preferred method of fabricating an exhaust system and installing new mufflers. That said, some applications my require a bolt together or clamped system to allow servicing of the drivetrain or access to suspension components. Furthermore, not everyone owns a welder or knows how to properly lay a MIG or TIG bead, so using a muffler clamp is usually the most common method. At the very least we have seen enthusiasts clamp their mufflers and exhaust in place and then take their project vehicle to a competent local exhaust shop to be aligned and finish welded.

If you do plan to utilize exhaust clamps in your muffler install know that you will require the correct diameter clamp to match your exhaust system pipe diameter and muffler bushings. The standard steel tube clamp is the most common clamp used in muffler installations, but their installation often crimps the muffler bushing to the point that the muffler is not easily removed in the future. We have also seen cases with thick steel mufflers the bushing will not crimp down at all, allowing the muffler to move. V-band clamps are a popular option many high-end builders incorporate into their builds. The V-band clamp requires welding to the exhaust component, but once welded provides a leak-free seal that is easily disconnected for service work on the chassis. Lastly, there are band and tube clamps that not only have great holding power and are reusable, but do not crimp or damage the exhaust pipe or muffler bushing, allowing the components to easily come apart as well. Do not forget hangers and other exhaust fabrication parts are just a click away if you are really getting into a wild custom fabricated exhaust solution that is becoming more common with modern drivetrain swaps where there is simply nothing premade that will bolt right on or if you are using a custom chassis for your build. The one thing we do not sell for your performance muffler install are muffler bearings. You will have to find some NOS muffler bearings for your application at your favorite swap meet we are afraid!

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