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What Does a Muffler Do?

An aged muffler from under a vehicle.

You might not think much of a muffler until it breaks or a rusty section or clamp gives way and it sounds like you’re driving a piece of heavy-duty equipment that you can hear for miles. So, what does a muffler do? Besides reducing the volume of sound, a muffler also reduces emissions. How a muffler accomplishes these tasks is a mystery we will explore.

Your Vehicle’s Exhaust SystemMeasuring a muffler to ensure an accurate fit.

So what is a muffler? A muffler is the last section of an exhaust system that includes an exhaust pipe, catalytic converter, additional pipes, tubes, clamps, hangers and, finally, the exhaust tip. The system starts at the exhaust manifold, which is connected to the engine’s cylinder head. There, it begins the process of moving harmful carbon monoxide as well as noise through the system. By the time the emissions reach the muffler, most harmful particles are removed. Thus, the muffler truly lives up to its name as the car’s sound dampener apparatus.

You may have heard about another exhaust component called a resonator. If you want to know what is the difference between a muffler and resonator check out our article here.

Made From Steel

So what is inside a muffler? The answer is usually just metal, but sometimes there is sound deadening fiberglass material. The vehicle manufacturer determines what type of muffler goes with a particular model. Notably, stock or original equipment manufacturer (OEM) mufflers are made from 400-series steel. The material is light, durable and designed to last. Even so, wear, salty roads and potholes are enemies of any muffler. A seven-year lifespan is normal, but a muffler may quit sooner if you don’t drive your vehicle enough. That’s because condensation buildup will rot a muffler through, something regular trips of 30 minutes on average will reduce.

Aftermarket Exhaust Options

Replacing your current exhaust system with a stock one is the usual choice for car owners. A like-for-like swap ensures no change to your vehicle’s behavior. When swapping out a muffler, check the entire exhaust system, examining it for holes and replacing brackets as needed.

Because a muffler dampens noise, a driver who wants a performance-oriented ride might choose another route that creates sound equal to the engine’s size and performance.

Three Aftermarket Mufflers

Typically, performance enthusiasts will look at three types of muffler designs: chambered, straight-through (glasspack) and turbo.

With a chambered muffler, internal chambers and specially shaped baffles within them produce a distinct, deep resonance. Moreover, the shape of the baffles usually enhances power. Performance car owners and pocket rocket fans love these.

Straight-through or glasspack design mufflers feature a straight, perforated pipe wrapped in fiberglass packaging or some other sound-absorbing material. Exhaust gas flows through the muffler with ease and with less reduction than chambered versions. Racing fans, rat rodders and vintage muscle car owners gravitate to this design.

Turbo mufflers are all about increasing power while delivering a smooth, throaty sound. An S-shaped design controls backpressure without reducing power but also manages noise. Turbo mufflers are ideal for any application and are the choice for owners who want a step up from stock mufflers.

Purchase Factors

Cost is an important factor in every muffler-buying decision. Stock mufflers are the least expensive, with more complex designs correspondingly higher in cost. Stainless steel mufflers will eventually rust while aluminized mufflers are corrosion resistant, provided they remain abrasion-free.

Check out all the exhaust system parts available on NAPAonline, or trust one of our 17,000 NAPA Auto Care locations for routine maintenance and repairs. For more information about what is a car muffler and what does a muffler do, chat with a knowledgeable expert at your local NAPA Auto Parts store.

Photo courtesy of Wikimedia Commons.

Matthew C. Keegan View All

Matt Keegan has maintained his love for cars ever since his father taught him kicking tires can be one way to uncover a problem with a vehicle’s suspension system. He since moved on to learn a few things about coefficient of drag, G-forces, toe-heel shifting, and how to work the crazy infotainment system in some random weekly driver. Matt is a member of the Washington Automotive Press Association and is a contributor to various print and online media sources.

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