resonator

[big barney]

Hey guys. What exactly is a resonator? The reason I'm asking is I just yanked off my stock resonator and muffler and installed a straight through. The whistle on the upshifts is driving me batty. Will replacing the resonator take care of this problem? Is the resonator just a little muffler? Thanks for your help.

 

[Jones]

Hey Big,
Most all resonators are basically a straight through steel-pack (as opposed to glass-pack)
muffler. I'm told they act like an expansion chamber and take out high freq. noise like that nasal rattle you hear with cheep muffler systems or in your case turbo whistle. Maybe thats why you can hear the turbo better now, although I'd think removing the muffler is more the culprit. Putting the resonator back on will dampen it some but I don't know if it will cut it out completely. . 02cents.
Jones

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Jones
'84 Ramcharger w/CTD, non-gated 12, torqflite, NP205, Dana 60 and 70 w/ 3. 07s. Straight piped 3" to x-member 4" the rest of the way.

 

[big barney]

Thanks Jones.
The noise doesn't bother me so much when I'm cruising at highway speeds, or when I'm accelerating. It's only when I upshift do you get this annoying whistle. I just want to get rid of this whistle on the upshifts I would be happy with it.

 

[big barney]

Mick
I have a 1999. I think your right about the wastegate. I was told at the muffler shop that the stock resonator went from 3" inlet to 2 1/2 inside diameter to 4" outlet. Nice design.

Thanks
Curt

 

[TowPro]

Do you have your silencer ring out?

I had mine out, then bought a K&N and the high pitched whine drove me crazy towing my RV up long hills, so I put the ring back in.

Much better now

 

[big barney]

Towpro
I still have my silencer ring in. I yanked off my air snorkle which made the turbo a little louder but not much.
Do any of you guys with the 4" systems have this turbo whistle on the upshifts?

[This message has been edited by big barney (edited 03-19-2001). ]

 

[Mick2500]

Barney,

What year truck? I know they changed them a little in 2001. 5 and there was an Oxidation Catalyst and a muffler in my system before I went to the Banks 4" SS system. I dug around a little on the dodge site before I found out what it was.
A resonator is just a small muffler, this thing actually makes the exhaust a little cleaner. It is NOT a catalytic convertor and it is not inspected (at least in AZ it isn't).
It wouldn't hut to put it back on but you will cause a little restriction. You mihgt be hearing the wastegate opening on upshifts.

Mick

 

[illflem]

Another chamber, called a resonator, is connected to the first chamber by a hole. The resonator contains a specific volume of air, and has a specific length that is calculated to produce a wave that cancels out a certain frequency of sound. How does this happen? When a wave hits the hole part of it continues into the chamber and part of it is reflected. The wave travels through the chamber, hits the back wall of the muffler and bounces back out of the hole. The length of this chamber is calculated so that this wave leaves the resonator chamber just after the next wave reflects off the outside of the chamber. Ideally the high pressure part of the wave that came from the chamber will line up with the low pressure part of the wave that was reflected off the outside of the chamber wall, and the two waves cancel each other out. The animation below shows how the resonator works in a simplified muffler.

Couldn't copy the animation click here to see it

 

[big barney]

Illflem

Thanks for the link. Some pretty interesting reading. Do you think if I reinstalled my resonator it would eliminate most the the whistle sound that I'm hearing now?

Thanks
Curt

 

[illflem]

Curt, from what I understand about a resonator I would say yes. Resonators work best with steady limited frequency sounds, which is what you describe.
You can also try loosening the clamp behind the turbo,reposition it a little then retorque it. It may have lost it's seal when you were taking the exhaust system apart. Also try reinstalling the snorkel and see what that does.

 

[big barney]

Illflem
I'm going to put my air snorkle in this morning. Thanks for the advise.

 

[big barney]

I put the snorkle back in. No improvement. Next I put the stock resonator in I made it a little quieter no much. I'm getting rid of the walker muffler. Is there any other muffler out there that will work with our trucks?