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#2301510 - 05/08/17 11:00 PM Re: Muffler drone, Please recommend for ones that dont! [Re: Criterion]
Evil Spirit Offline
master

Registered: 01/02/05
Posts: 3653
Loc: Newport, Mi
Originally Posted By Criterion


E) Keep the exhaust the way it is and add a sound deadener if the resonance is from an actual panel, i.e. trunk floor, vibrating.


This. In many cars, especially the ones with full tailpipes, the drone isn't from noise out the tails - it's noise resonating through the body of the muffler, then into the floor pan of the car. Since we tend to try to fit the largest mufflers under the car, and install them as close to the floor as possible, this tends to increase the possibility of an exhaust drone. To over-simplify - sound doesn't pass "through" the muffler body, the noise inside is sound pressure waves that flex the metal body, resulting in sound pressure waves that are created outside the muffler body, and are then transmitted to the floor pans, causing a drone. And yes, sometimes changing or adding mufflers can remove the drone, by changing the sound pressure waves in the system. But I've had better luck removing drone by insulating the body of the muffler than by changing them, or adding a resonator. I usually do a layer of header wrap covering the muffler body sides, a layer of 22 ga stainless sheet, and repeat for a total of 2 layers of each, holding them on with the metal header wrap straps. I've also used old welding fire blankets and hi-temp fiberglass sheet for the sound deadener.

I can't guarantee this will fix every instance of exhaust drone - I'm just offering another method of eliminating it to consider that has worked well for me in the past.
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#2301562 - 05/09/17 12:41 AM Re: Muffler drone, Please recommend for ones that dont! [Re: 451Mopar]
Sunroofcuda Offline
master

Registered: 01/20/03
Posts: 6012
Loc: Highland, MI.
Originally Posted By 451Mopar
Originally Posted By Sunroofcuda
Originally Posted By 451Mopar
Originally Posted By 451Mopar
I put Walker quiet flow SS mufflers on the convertible.

Walker 22154 Quiet-Flow Stainless Steel Muffler, but it really was too long to fit well (29").

The Walker #21498 quiet flow SS (fits a 2004-2006 Chrysler Pacifica) show s to be 2-1/2" in/out, and just $64 from summit racing, just have to cut off the welded on muffler hangers. These are smaller 13" long case mufflers 20" tip to tip. Says they are a turbo style muffler.

Looks like the outlet tube may be angle cut for the exhaust exit? It could be cut straight and swedged to connect to the tial pipes?



Found a picture of the 22154s on the convertible, these are long..


I'm trying to get a print of those mufflers from a buddy. I'm guessing they have 2" internal flow tubes.


When I google the 22154, I don't see anyone carrying it anymore? Maybe it got discontinued? Internally, it might me 2-1/4"? I do think it is larger than 2", and I can still hear the exhaust. I'll have to get a video with sound for these mufflers. Last video of the car was with the Super turbo mufflers that came with the TTI exhaust.


Well, I received the print showing the internals of these today. There are 2 flow tubes internally, both choke down to 2" just like I thought. There is no packing for any noise absorption, & the flow tubes are not perforated. These babies are long - 25" long shells. These are NOT real good-flowing mufflers from the way the print looks, but adequate for a passenger car.
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#2301769 - 05/09/17 12:48 PM Re: Muffler drone, Please recommend for ones that dont! [Re: Sunroofcuda]
dogdays Offline
I Live Here

Registered: 01/20/03
Posts: 15733
I didn't read the three p[ages of comments because the initial assumption is wrong.

Mufflers do not cause drone. The system causes drone. Similar to tuned headers or a tuned intake tract, the exhaust system has resonance and when the engine pulses excite that resonance, you experience drone. I've been in a few Men's rooms where it was easy to excite the resonant frequency by humming the right pitch. One I remember was at my old job, where the room was tuned to low "G".

So if mufflers do not cause drone, why do so many of these solutions work? Because they change the resonant point or else dampen the resonant peak's resonance to the point where it's not objectionable.

I suppose a louder muffler does have more of a tendency to drone, because the sound pressure (energy) is higher and more apt to resonate in an audible way.

Adding a crossover pipe or X-pipe can help too. I'd start there.

Dynomax Super Turbos 17748 and 17749 are my fvorites for 2 1/2" systems, if they fit. They are relatively quiet at idle or at low throttle pressure. With more power they take on more of an aggressive sound. I've received complimentws from strangers who tell me it sounds exactly right Upon startup, I was dismayed at how quite they were, but as the miles went by, they opened up a little.

So remember it's the system, not the mufflers.

R.

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#2301804 - 05/09/17 01:47 PM Re: Muffler drone, Please recommend for ones that dont! [Re: 4mulaS]
70Duster Offline
pro stock

Registered: 01/20/03
Posts: 1374
Loc: PA
Dynomax Ultra-Flows and the only thing better than the Super Turbos to eliminate drone.

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#2383281 - 10/07/17 12:42 AM Re: Muffler drone, Please recommend for ones that dont! [Re: 4mulaS]
4mulaS Offline
super stock

Registered: 01/18/06
Posts: 798
Loc: Alberta
Just as an update, I ended up going with Accurate exhaust hemi repop mufflers, 2.5 in and 2.25 out. Drone MOSTLY gone. The range it used to really bother me in is gone but with the accurate stuff the drone does and can occur at a very low rpm. Thankfully I'm seldom in that range.
On a side note, the sound freekin awesome!!! Sooooo many compliments and I really love it now too. The best part of the sound is at idle, very throaty, when you're on it and giving it full throttle they are respectfully quiet. Not a nuisance muffler.

Happy with the purchase
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#2383358 - 10/07/17 10:18 AM Re: Muffler drone, Please recommend for ones that dont! [Re: 4mulaS]
bonefish Offline
master

Registered: 11/03/04
Posts: 6915
Loc: s.w.fl
if a set of mufflers will keep my wife out of MY! car i,m in for a set. up

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#2383410 - 10/07/17 11:44 AM Re: Muffler drone, Please recommend for ones that dont! [Re: bonefish]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 32530
Loc: Lincoln Nebraska
Sounds like everyone is happy/knows what to do
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#2385776 - 10/11/17 03:56 PM Re: Muffler drone, Please recommend for ones that dont! [Re: 4mulaS]
67SATisfaction Offline
master

Registered: 01/21/03
Posts: 6862
Loc: Albany, NY
Originally Posted By 4mulaS
Just as an update, I ended up going with Accurate exhaust hemi repop mufflers, 2.5 in and 2.25 out. Drone MOSTLY gone. The range it used to really bother me in is gone but with the accurate stuff the drone does and can occur at a very low rpm. Thankfully I'm seldom in that range.
On a side note, the sound freekin awesome!!! Sooooo many compliments and I really love it now too. The best part of the sound is at idle, very throaty, when you're on it and giving it full throttle they are respectfully quiet. Not a nuisance muffler.

Happy with the purchase


Glad to hear - and you've kept the H-pipe, right?

(I've got virtually the same setup as you used to have, 383/4bbl 2in H-pipe and FlowMasters with a wicked drone, but only right at 45mph.. so I just don't stay there much. Now I know what I'll do when it's time for a change.. but I think I'll drop the H-pipe too).

Cheers,
- Art
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1965 Satellite hardtop 361/2bbl, auto, pegleg 2.76
1967 Satellite convert 383/4bbl, auto, pegleg 3.23
1975 Maserati Bora, 4.9L DOHC hemi V8, 5-spd ZF
1982 Alfa Romeo GTV6, 2.5L SOHC hemi V6, 5-spd transaxle
1994 Alfa Romeo 164LS, 3.0L SOHC 24v hemi V6, 4spd auto ZF
2007 Aston Martin DB9, 6.0L DOHC V12, 6spd full manual transaxle

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