3 Definitive Muffler Types (You Should Be Aware Of)

Used muffler on grass

Mufflers are the noise suppressors in our motorcycles and cars. They come in different shapes and sizes too. But the vast majority can be classified into three main types.

So, what are the muffler types?

There are 3 main types of mufflers:

  • Straight-through muffler (absorption type)
  • Chambered muffler (reflection type)
  • Turbo muffler (combined type)

Straight-through or absorption mufflers moderate noise by absorbing it into a soft material.

Chambered mufflers, or reflection mufflers, reduce the noise by reflecting and canceling out the sound waves.

Turbo mufflers reduce the engine noise by both reflecting and canceling the waves as well as absorbing the sound waves.

Let’s deep dive into each of these muffler types and their pros and cons one by one.

What is a muffler

Exhaust Muffler and parts

A muffler, as the name suggests, reduces (muffles) a loud sound. In this case, the muffler reduces the engine’s exhaust sound.

The purpose of a muffler (also called a silencer) in a motorcycle or a car is to help in managing the engine’s exhaust sound levels at lower decibels.

If you ever run your motorcycle without a muffler, the motorcycle will be too noisy. You will hate the noise unless you are one of those high decibel ear-shattering noise lovers.

One key thing to note here. The muffler also acts as the passage for the exhaust gases.

So, the muffler has both the exhaust gases and the sound waves flowing through it. Both are different. And a good muffler will have these characteristics:

  • minimal restriction on the flow of exhaust gases
  • reduce the sound waves

The exhaust gases and the sound pressure waves are two distinct things. We need to bear that in mind. The muffler should allow an easier flow of exhaust gases but should reduce or restrict the sound waves.

Muffler types

There are 3 main types of mufflers:

  • Straight-through muffler (absorption type)
  • Chambered muffler (reflection type)
  • Turbo muffler (combined type)

Each of these muffler types reduces sound through different noise reduction methods.

Let’s deep dive into them one by one.

#1: Straight-through muffler (absorption type)

Straight-through or absorption mufflers moderate noise by absorbing it into a soft material. This soft material in most mufflers is a glass fiber-like insulation.

In these absorption-type mufflers, there is a straight pipe, which is perforated, that runs all the way through. The absorbing material is packed around this perforated straight pipe in the muffler.

That’s the design. The muffler has two main things inside – a perforated straight pipe and an absorbing material surrounding the pipe.

The exhaust gases simply flow through this straight perforated pipe.

The sound waves, on the other hand, escape through all the perforations on the pipe into the packed absorbing material.

Since glass fibers are mainly used in these mufflers as the absorbing material, straight-through mufflers are also called glass pack mufflers.

Straight through muffler working diagram

Strictly speaking, what happens with these sound waves is the energy or the movement of the gas vibrates the absorbing material strands. The kinetic energy of the sound waves is converted into heat energy in the absorber. The converted heat energy escapes the system through the muffler outer cover.

That’s why the muffler or the silencer outer cover is usually so hot.

Absorption type or straight-through mufflers are popular in motorcycles. They do not restrict the flow of exhaust gases much and have less risk of back pressure.

But, the noise reduction in these mufflers is not so great. Straight-through mufflers are not the best for noise cancellation. They are good and do a decent job for motorcycles though.

Pros:

Minimal restriction on the flow of exhaust gases.

Cons:

Noise reduction is not great. The engine noise will still be higher.

#2: Chambered muffler (reflection type)

Chambered Muffler

Chambered mufflers, or reflection mufflers, reduce the noise by reflecting and canceling out the sound waves.

In these types of mufflers, there are chambers designed in such a way that the sound waves are reflected onto each other. The reflected sound waves cancel out each other resulting in noise cancellation.

As a result, the final resultant sound waves exiting the exhaust will have far reduced noise decibels.

Chambered muffler working diagram

As for how the sound waves cancel each other, the sound waves of opposite amplitudes collide with each other to cancel out in what is known as a phenomenon called destructive interference.

It is amazing how the sum of two waves in a destructive interference can be less than either of the waves, alone, and can even be zero.

The sound waves which are out of phase with each other collide and cancel out to a large extent, resulting in noise cancellation. That’s how a reflective type or a chambered muffler works.

The chambers in these mufflers are designed to bounce off the sound waves so that they can collide and cancel out.

Chambered Muffler

Chambered mufflers are used in some cars but they are not popular. An improved version of these mufflers, which are called turbo mufflers (discussed in the next section) is widely used.

Pros:

Noise reduction is better than straight-through mufflers.

Cons:

Neither the best in noise reduction nor in the easier flow of exhaust gases.

#3: Turbo muffler (combined type)

Turbo Muffler

Turbo mufflers reduce the engine noise by both reflecting and canceling the waves as well as absorbing the sound waves.

The turbo muffler usually has three perforated tubes through which the exhaust gases flow in an ‘S’ or multiple ‘U’ shaped pattern. These perforated tubes are covered with absorbing material just like in straight-through mufflers.

Turbo Muffler

In addition, the turbo muffler has chambers called baffles that make the sound waves bounce around the side to side in the baffle. These sound waves collide with each other and cancel out due to destructive interference. Just like how a reflection baffler works.

So, the perforated tubes covered in absorbing materials absorb the sound wave energy. And the baffle cancels out the noise by reflecting the sound waves.

No wonder the turbo mufflers are called combined type (both absorption and reflection) mufflers.

Turbo muffler working diagram

In addition to baffles, the turbo mufflers also have a resonating chamber called Helmholtz chamber (named after Hermann von Helmholtz).

Put simply, the Helmholtz chamber creates an area of vibration and resonance, resulting in altering the tone of the exhaust sound.

Turbo mufflers are the most effective mufflers out there when it comes to noise reduction.

As a result, turbo mufflers are the most popular mufflers and are widely used in cars.

Pros:

Best in noise reduction.

Cons:

Complex and heavy design. Suitable only for heavy automobiles like cars.

Which muffler type is the best?

Muffler

In terms of performance, turbo mufflers are the best kind of mufflers. Their noise reduction is far superior to the other types of mufflers available.

As a result, most cars use turbo mufflers in them. Turbo mufflers are the most popular muffler type in cars.

But, there is a flip side too. Turbo mufflers are complex in design and are bulky and heavy.

This makes them suitable for only heavy automobiles like cars and above.

For motorcycles, the turbo mufflers will be too bulky and too heavyweight.

That’s why straight-through mufflers work the best for motorcycles. Most motorcycles use straight-through mufflers.

This has also to do with the noise reduction necessity. Motorcycle engine noise is nowhere as noisy as cars. Cars have multiple engines and hence, the noise will be proportionately higher than that of motorcycles.

In the end, cars become quieter. And motorcycles end up louder than cars.

So, a straight-through muffler which although not the best in noise reduction works perfectly fine for motorcycles due to its simple design and low weight.

Conclusion

  • The purpose of a muffler in a motorcycle or a car is to help in managing the engine’s exhaust sound levels at lower decibels.
  • A good muffler will have these characteristics: (i) minimal restriction on the flow of exhaust gases; (ii) reduce the sound waves.
  • There are 3 main types of mufflers: (i) Straight-through muffler (absorption type); (ii) Chambered muffler (reflection type); (iii) Turbo muffler (combined type).
  • Straight-through or absorption mufflers moderate noise by absorbing it into a soft material.
  • Chambered mufflers, or reflection mufflers, reduce the noise by reflecting and canceling out the sound waves.
  • Turbo mufflers reduce the engine noise by both reflecting and canceling the waves as well as absorbing the sound waves.
  • In terms of performance, turbo mufflers are the best kind of mufflers. Their noise reduction is far superior to the other types of mufflers available.
  • Turbo mufflers are the most popular muffler type in cars.
  • For motorcycles, the turbo mufflers will be too bulky and too heavyweight. That’s why straight-through mufflers work the best for motorcycles. So, most motorcycles use straight-through mufflers.