Killing drone by moving mufflers

As noted, the staggering was engineered. Not real easy to shadetree.

A resonance chamber is another option.

My Magnaflows have very very little drone. It's more like a cool cruising growl. You know you're driving something with balls but it won't vibrate your fillings out.

90LX5spd said:

Resonance chamber? As in placing a resonator somewhere else in the system?

Click to expand...

No, using a deadhead chamber to help mitigate the drone. In fluid dynamics it's often called an air chamber. On intakes, it's called an intake resonance chamber.

The piece of pipe (chamber) cancels out NVH in the frequency range for which it's tuned.

It's a long read but it talks about a piece of pipe as HISSIN50 mentioned.


Exhaust Drone is Completely Gone - Corral Forums

LOL.. I was right all along. I KNEW it was mostly the tailpipes causing the drone. Because in reality, it's those tailpipes that give the Flowmaster 40 series it's sound that many of us are so familiar with. The mufflers are enhanced within a specific frequency range, the tailpipes just enhance the noise. I was going to say this a long time ago. I figured this out one day a few years back while messing with the stock tailpipe on my V6 (yes, my 6'er). Had the pipe off and was tapping the end with the palm of my hand. Heard that familiar drone noise while doing so. The drone can be anywhere from 110 HZ to 140 HZ depending on pipe size and diameter. It's noise resonating through the path of the metal piping. I think the axle curve also plays a role. Adding that pipe piece just changes the overall resonant frequency. Either to a much higher tone, or the pipe acts as a damper, dulling out the pipes res. Are these resonators made of real thick tubing? If so, that alone would dampen the sound.

The next part may seem pretty dumb to some of you. I just thought I would post it anyway. It was discovered by accident while I was attempting to straighten a pipe out. It's an optional read...

Try this as a test, just to see for yourself just where the primary resonant frequency lies within a stock tailpipe. If you have a tailpipe laying around not attached to the car, then use that as your test (make sure it is an axle curved pipe that goes to your Stang, and not something off a Honda). Set the pipe on a hard surface away from other objects (cement ). Get a blowtorch, if you can, use a torch that is on a hose (eg.. Bernzomatic hose torch with hi temp swirl flame ). Light the torch and turn it up real high. Put the torch in the inlet side of the tailpipe and insert it until you can't see the whole tip of the torch. Try and keep the torch in the middle so you don't mess with the airflow. If the torch is high enough and the tip is in far enough, the entire pipe will start resonating like a flowmaster.... so friggin loud that your neighbors WILL hear it. Excessive heat and air turbulence at the right location are what's causing the LOUD drone you hear with the torch. The noise you hear, will be the drone frequency of that pipe when it's on the car. WHen your done, remember not to touch the pipe for a little while... hehe