You car's muffler is an important part of the engine's exhaust system. Without it the engine would be loud enough to annoy everyone and worse yet, the engine would not run properly. All engines are designed to run their best with a specific amount of back pressure, which is created by the resistance the exhaust gasses enconter on their way to the tailpipe. Exhaust gases and sound waves enter through the center tube. They are then reflected off the back wall of the muffler and are then travel through a hole into the main body of the muffler. Next, they go through a set of holes into yet another chamber, where they turn and exit the last pipe and leave the muffler.
A resonator chamber is connected to the first chamber by a hole. The resonator hols a specific volume of air and has a particular length that is designed to produce a wave that cancels out a specific frequency of sound. When a sound wave encounters the hole, part of it continues into the chamber and part of it is reflected back. The wave goes through the chamber, hits the back wall of the muffler and bounces back out of the hole. The length of this chamber is calculated to ensure that the wave exits the resonator chamber immediately after the next wave reflects off the outside of the chamber. The designer's goal is to have the high-pressure part of the wave that came from the chamber line up with the low-pressure part of the wave that was just reflected off the outside of the chamber wall. when everything is working properly, the waves will cancel each other out. In actual usage, the sounds coming from the engine are a mix of many different frequencies. Many of those frequencies are altered by the engine speed, so the sound is almost never at precisely the right frequency for this to happen. Resonator chambers are designed to work best in the frequency range where the engine makes the loudest noise, but even if the frequency is not exactly what the designer expected, it will still produce some noise reduction.
Many cars, especially high-end luxury vehicles, are engineered for quiet operation, and have another, separate component that looks like a muffler, but is referred to as a "resonator". This unit functions very much like the resonator chamber inside the muffler, in that the dimensions are calculated so that the waves reflected inside the resonator work to cancel out certain frequencies of exhaust noise. For example, a Mercedes-Benz E550 produces well over 400 horsepower and can go from 0-60 mph in less than six seconds, but when standing next to one with the motor idling, you can't hear a sound.
If your muffler is noisy or you just aren't getting the same power you're used to, bring your car in and our technicians will diagnose the problem and have you back on the road.
We also install custom exhaust systems and replace catalytic converters!
Golden State Transmission and Muffler 10792 Olson Dr., Rancho Cordova, California 95670 916.853.1788