Schools Training

Power vs. Noise: Know Your Muffler

11 OCT 2012
Career Path : Automotive

When it comes to an automobile’s muffler, some people take it as a general rule that more noise equals more power. We know this when we hear a high-performance car approaching loudly, even before we see it appear and disappear. But the muffler’s main purpose isn’t to warn pedestrians and other motorists that a speed-demon is quickly approaching, but is rather part of the more complex exhaust system. This system is responsible for several functions of the engine, like emitting heat away from the engine, regulating the amount of noxious fumes coming from the engine, controlling and limiting engine noise, and reducing exhaust emissions.


The muffler’s role is not directly related to the exhaust system but is rather sort of an add-on. This means that it does nothing regarding the fumes, and has especially nothing to do with the engine’s performance. It is primarily serving the function of reducing noise. However, if the muffler obstructs the flow of exhaust gases in its attempt to reduce noise, it can have some negative effects on the performance of the car. Obstructed fumes can possible be pressured back into the engine which will reduce the engine’s power to some degree. It is because of this, that the concept of “more noise equals more power” exists. But it is not as simple as that. The assumption is that a noisy exhaust system has minimal obstructions, thus minimizing back pressure. But this isn’t a rule so much as an effect of poorly-functioning mufflers. A well-functioning muffler reduces noise and should cause little to no obstruction.


Specializing in exhaust systems and specifically on mufflers is an important part of a mechanic program. In such a program one will learn the three major systems of mufflers: absorption, restriction, and reflection.



This is a relatively simple system whereby the exhaust is passed through a tube that has many holes in it. This tube is placed in a larger tube, or can, that is then stuffed with a packaging material. This is one of the most effective methods for passing exhaust, but conversely, the least effective method for reducing noise.



This is the simplest form of muffler, because it consists of not much more than a pipe which lets the exhaust emissions out with little or no restriction. It could be noisy, but unlike the ‘noise-power’ myth, not necessarily better for reducing back pressure. It is the cheapest kind of muffler.



This is the most complex form of muffler. It utilizes sound engineering principles by reflecting the engine’s sound waves back into a chamber which are then canceled out by being combined with other sound waves of the opposite noise frequencies from the engine. It is the most effective in noise-reduction.


Every aspect of the car’s performance is equally important, and students of mechanic colleges should take care to learn just as much about the muffler as every other part of the engine and structure of a car.


Visit Automotive Training Centre for more information on mechanic courses.