quiet exhaust with a nice rumble a pipe dream?

[cutty collector]

I have 2 3.4 liter cutlass supreme's .One has an oe type walker exhaust The other has a set of walker performance mufflers the latter sounds nice at idle and when you pull away it has a nice throaty rumble but at highway speeds with the tcc locked up they both exhibit a drone at 1500 to2200 rpm. In the car with the performance mufflers it is almost unbearable to drive .The cars are both convertibles and this likely makes it worse.they both have resonators again aftermarket .Is there anything out there resonator wise that will stop the drone.I think the walker resonators are junk surely there must be a resonator out there that takes the drone away?

[55trucker]

Seeing as you're not too far away from me (Ontario being a rust-belt), are the original pipes still under the car? Do you still have the original resonator alongside the fuel tank in place?

 

I know precisely what you're putting up with, the 1st time I redid the exhaust I chose regular Magnaflows, ( I replaced the cat with a 2 1/2' in 2 1/2" out, had all the pipe back to the split redone in 2 1/2", no resonator ), it was just god awful, I like to hear myself think & keep the radio volume down.

 

Off came the Magnaflows & on went a pair of (then available) Maremont OEM replacement mufflers & a Dynomax bullet resonator to replace the original piece that sat alongside the fuel tank. I had to cut the new piping to fit the res in there. The car has a throaty rasp when it first fires up but quickly settles down to a deep rumble that is not loud at all.  The car has been this way for 14 years now, the piping is all aluminized but seeing as it doesn't see winter use the pipes have held up (oh, and the back half is all coated with black plasti-dip)

 

 

Maremont no longer exists, they were purchased up by IP exhaust 8 years ago and quickly shut down, IP was then purchased up by AP exhaust, so now you have to choose between Walker's Quiet-flow's (fiber filled roving) or AP's chambered original designs.

[RobertISaar]

I'm not entirely sure where you would fit it, but a 1/4 wave resonator is voodoo for exhaust drone.

[Nas Escobar]

I'm not entirely sure where you would fit it, but a 1/4 wave resonator is voodoo for exhaust drone.

Any brands in particular you recommend?

[55trucker]

^ you make them, every exhaust system is different, the resonator has to be tuned to the particular frequency that the drone occurs at & the number of cylinders the engine has.

 

As Robert stated.... where does one find the room under these cars for one?

 

 

http://i59.tinypic.com/53pdmf.jpg

 

https://www.stangnet.com/mustang-forums/attachments/dsc01818-jpg.143396/

[Imp558]

There has to be some math to determine what the length of the branch should be. Perhaps the clue "1/4 wave" ? It may be as simple as determining what the Frequency roughly is of the Drone and looking to see how long that wavelength is and making the branch one quarter of that length?

[Imp558]

I'd call the drone from her L67 SSEI 50HZ with the Thrush muffler on it. The lenth of a 50HZ wave is 24' on the first chart I saw online, so if the 1/4 wave branch actually measures 1/4 of a wave then 6' of branch. Yeah where the hell WOULD that live under there?

[55trucker]

There has to be some math to determine what the length of the branch should be. Perhaps the clue "1/4 wave" ? It may be as simple as determining what the Frequency roughly is of the Drone and looking to see how long that wavelength is and making the branch one quarter of that length?

There is a formula....this is for a v8 engine (they fire 4 times (90 degrees) per revolution, a 6 would fire 3 times (120 degrees) per revolution)

 

Things you need to know to build the resonator:

 

-RPM that drone occurs at

 

-Number of engine cylinders

 

 

You will also need to know the speed of sound. It varies with temperature, but is generally accepted to be 343m/s.

 

 

Say your V8 resonates at 2000rpms, right at cruising speed. You'll need to find the frequency of the drone. Units here are pulses per second, or Hertz.

 

 

f = RPM * pulses/rev * (1/60)

 

 

f = 2000 rev/min * 4 pulses/rev * (1/60)

 

 

f = 133.34 pulses/second = 133.34Hz

 

 

At 2000rpms, your V8 fires 4 times per revolution. RPM is in minutes, so divide by 60 to reduce to seconds. Now you need to find the length of the wave at the frequency you just calculated. Wavelength is denoted by lambda (λ), units are meters.

 

 

λ = v/f = speed of sound / frequency

 

 

λ = (343m/s)/(133.34Hz)

 

 

λ = 2.572 meters

 

 

1/4 wave = 2.572 divided by 4 = 0.643m

 

 

The idea here is to reintroduce a sound wave into the exhaust that is 180° out of phase with your drone frequency. To do this, you build your resonator tube at exactly one-fourth the length of the resonant wave.

[Imp558]

https://m.summitracing.com/parts/pye-hvc10?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-pypes-performance-exhaust&gclid=CjwKCAjwranNBRBhEiwASu908Cyof2MBU5VFtWGK9L3SO2rCEjyYZYlmcePivVd75jxpPx-lQHWS2BoCqLkQAvD_BwE

 

 

 

I'm thinking about making an adjustable one, imagine how a trombone slide works

[cutty collector]

Is there no parts I can just buy and install to cure this?