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Question about resonators

Hey everyone,

I know the purpose of a resonator is to control the pitch or type of sound the exhaust makes but my question is:

With a bottle style resonator, what difference does a longer bottle (18”) resonator make compared to a shorter (12”) bottle resonator. Assuming they have the same shape and materials used on the inside, what difference would going from a longer to shorter resonator do?

Would the shorter resonator sound slightly higher pitched and the longer resonator sound slightly lower pitched? What about actual volume wise?

Al else being equal, longer means quieter. The pitch doesn’t change a lot. But that assumes equal design. Change brands and all bets are off. And a resonator is really just a muffler. Lately they get mounted mid-car while in the old days they were at the rear and the muffler was mid-car.

Muffler designs are similar but different. S-path mufflers, straight-thrus, reflection-style, fiberglass or steel wool packed, the perforations in the inner tubes all change the character and tone of the exhaust for a given car. Same for positioning, mid - or rear. Change the car - longer, shorter, ect or the engine and things change yet again.

To get the sound you like best in your car either requires experimentation (which can get expensive) or finding a very similar car with a custom exhaust that sounds good to you. Or do both.

You want a good sound? Put a cutout whistle on it, like my dad had on our 1911 Regal:


A resonator cancels noise.

A muffler reduces sound pressure to reduce sound.


Resonators in the exhaust system can be used to get a certain sound characteristic or to cancel vibrations, but they also aid in assisting the flow of gases and are usually tuned to help achieve optimum performance for a given purpose (such as more lower mid-range torque or higher horsepower), and the exhaust and intake resonances work together. When I started driving in the mid 1980s, I inherited a Renault 5 Le Car that was my mother’s, and the exhaust had a hole where it rotted through at the junction where the resonator joined the pipe between the catalytic converter and the muffler. Getting it fixed not only quieted things down, it also increased the power noticeably, and yes, that thing needed all the help it could get…