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Getting rid or exhaust "drone" #333378
05/30/09 02:31 PM
05/30/09 02:31 PM
Joined: Jul 2003
Posts: 2,344
Cincinnati, OH
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6T6Cuda Offline OP
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Hello,

On the 67 'cuda vert, I have a 300HP 360 crate motor, 340 exhaust manifolds and TTI exhaust going back with the TTI supplied Dynomax turbo mufflers.

Around 2200-3500 it has a real bad "drone" making the car a pain to drive (most of the driving is at these RPMs)

Can anyone suggest a good muffler which will get rid of this?

Re: Getting rid or exhaust "drone" [Re: 6T6Cuda] #333379
05/30/09 02:49 PM
05/30/09 02:49 PM
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Santa Cruz, California
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Lefty Offline
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If you don't have tail pipes that will cause a drone.

Re: Getting rid or exhaust "drone" [Re: Lefty] #333380
05/30/09 06:45 PM
05/30/09 06:45 PM
Joined: Feb 2003
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Manitoba, Canada
DaytonaTurbo Offline
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I've heard two solutions from this problem. One is to put resonators on, I hear a pair of cheapie cherry bombs will do the trick.

Other thing I've heard (not sure if is true) is that staggering the mufflers distance from the headers/manifolds helps as well.

Re: Getting rid or exhaust "drone" [Re: Lefty] #333381
05/30/09 07:36 PM
05/30/09 07:36 PM
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Lincoln Nebraska
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RapidRobert Offline
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Quote:

If you don't have tail pipes that will cause a drone.


I had a 1/2 t pickup w turndowns right after the muffs(about halfway back). It was intolerable. I sold it before I ever dealt with it.


live every 24 hour block of time like it's your last day on earth
Re: Getting rid or exhaust "drone" [Re: RapidRobert] #333382
05/30/09 07:53 PM
05/30/09 07:53 PM
Joined: Jul 2003
Posts: 2,344
Cincinnati, OH
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6T6Cuda Offline OP
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[Quote]
Quote:
If you don't have tail pipes that will cause a drone.

I had a 1/2 t pickup w turndowns right after the muffs(about halfway back). It was intolerable. I sold it before I ever dealt with it.

[/Quote]

Full exhaust all the way out the back...

Re: Getting rid or exhaust "drone" [Re: 6T6Cuda] #333383
05/30/09 08:25 PM
05/30/09 08:25 PM
Joined: Mar 2006
Posts: 253
Orange County, CA
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Mike H Offline
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Orange County, CA
I have the same problem with a 440-6 69 Roadrunner, factory cast iron manifolds, new TTI exhaust system for the rest. The system resonates inside the car so badly you almost cannot drive it. I was told to replace the mufflers with "hemi mufflers", whatever that means. When I restored my Challenger (383, stock), I promised myself to never do the TTI thing again. I used a stock system from Accurate Exhaust. Beautiful. Sounds like it did originally. When I get around to re-doing my Roadrunner, that TTI crap will go in the trash in favor of a stock muffler and resonator system.

Re: Getting rid or exhaust "drone" [Re: Mike H] #333384
05/30/09 09:41 PM
05/30/09 09:41 PM
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Posts: 1,624
qc
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mxbeep Offline
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Quote:

I have the same problem with a 440-6 69 Roadrunner, factory cast iron manifolds, new TTI exhaust system for the rest. The system resonates inside the car so badly you almost cannot drive it. I was told to replace the mufflers with "hemi mufflers", whatever that means. When I restored my Challenger (383, stock), I promised myself to never do the TTI thing again. I used a stock system from Accurate Exhaust. Beautiful. Sounds like it did originally. When I get around to re-doing my Roadrunner, that TTI crap will go in the trash in favor of a stock muffler and resonator system.




I used tti kits on both our b-body 440+6 cars and have no drone whatsoever, 1 car even as headers and mopar 528 cam.

I can barelly ear the exhaust noise from inside the car

Re: Getting rid or exhaust "drone" [Re: mxbeep] #333385
05/30/09 10:05 PM
05/30/09 10:05 PM
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Tampa FL
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hemibeep Offline
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my tti has H pipe, and walker dynomax. sounds fine.

Re: Getting rid or exhaust "drone" [Re: hemibeep] #333386
05/30/09 11:08 PM
05/30/09 11:08 PM
Joined: Aug 2003
Posts: 848
Avondale AZ
Prodart440 Offline
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I had the same problem on my 71 cuda 440. As soon as I took the manifolds off and put the headers on the drone was gone. It was much faster, and much nicer to drive.


Aaron

68 Roadrunner 383/AT
69 Dart GT Conv. 383/AT
05 Dodge Ram 4x4 Cummins
06 GoManGo R/T Daytona #757
68 Coronet 440
Re: Getting rid or exhaust "drone" [Re: Prodart440] #333387
05/31/09 07:19 PM
05/31/09 07:19 PM
Joined: Jun 2004
Posts: 3,380
St. Charles, MO
wingman Offline
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St. Charles, MO
Quote:

I had the same problem on my 71 cuda 440. As soon as I took the manifolds off and put the headers on the drone was gone. It was much faster, and much nicer to drive.




On my b-body I just replaced the factory HP manifolds and an H-pipe with cheapo headers and an x-pipe. Everything from the x-pipe back stayed the same.

My drone went away also!!!

Last edited by wingman; 05/31/09 07:20 PM.

1969 Dodge Coronet Super Bee 383 A4
1970 Plymouth Road Runner 440 FC7 (sold)
Re: Getting rid or exhaust "drone" [Re: wingman] #333388
05/31/09 07:56 PM
05/31/09 07:56 PM
Joined: Jun 2006
Posts: 834
Beavercreek, Ohio
OA5599 Offline
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My 69 Cuda has TTI headers and 3" all of the way back to 3" factory style tips from TTI using Dynomax Ultraflos. I had a drone problem when first fitting the exhaust and taking it for a test drive. Once the tips went on and took the exhaust slightly past the bumper, the drone hasn't seemed to be a problem anymore.


Re: Getting rid or exhaust "drone" [Re: OA5599] #333389
06/01/09 12:35 AM
06/01/09 12:35 AM
Joined: Sep 2004
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IL, Aurora
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ademon Offline
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Most of the problems are when using the factory exhaust manifolds my hand built system with factory manifolds, x pipe, dynomax Hemi mufflers 20" case, flowmasters tailpipes to tips, did the same thing as the original poster describes, i installed magnaflow resonators made of SS with SS packing, now very quiet !!

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Re: Getting rid or exhaust "drone" [Re: ademon] #333390
06/01/09 06:34 AM
06/01/09 06:34 AM
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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exhaust drone is actually a resonance, where the whole system is allowing the sound waves to basically "build up" and create the drone...kinda like blowing air over the top of an empty coke bottle.

and, every car combo is different! only way to figure it out yourself, is to experiment, change the length of the tail piples if you want, change the mufflers, add an H or X pipe, if you already have one, then try it without...


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Re: Getting rid or exhaust "drone" [Re: 70Cuda383] #333391
06/01/09 09:10 AM
06/01/09 09:10 AM
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new berlin wisconsin
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Mr T2U Offline
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on my 72 road runner, 572 hemi TTI big tube headers hooker areo chamber mufflers 3" X pipe exhaust, i had a exhaust drone. i changed the 3" tail pipes to 2 1/2" and now it sounds perfect. i put the car on a chassis dyno to measure hp loss. i lost 2hp with the change, but it was also 10 degrees warmer when i dynoed it the second time, so in my opinion there was no loss of hp with smaller tail pipes.


perception is 90% of reality
Re: Getting rid or exhaust "drone" [Re: 70Cuda383] #333392
06/01/09 11:09 AM
06/01/09 11:09 AM
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Junky Offline
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Quote:

exhaust drone is actually a resonance, where the whole system is allowing the sound waves to basically "build up" and create the drone...kinda like blowing air over the top of an empty coke bottle.

and, every car combo is different! only way to figure it out yourself, is to experiment, change the length of the tail piples if you want, change the mufflers, add an H or X pipe, if you already have one, then try it without...



I had that somewhat even with an H-pipe. Switched to an X-pipe. That fixed it. I like the tone now, too. Can hardly hear the exhaust from within the car at cruise.


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Re: Getting rid or exhaust "drone" [Re: DaytonaTurbo] #333393
06/02/09 11:03 AM
06/02/09 11:03 AM
Joined: Jul 2003
Posts: 2,344
Cincinnati, OH
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6T6Cuda Offline OP
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So does the exhaust drone come from the "sound" or from the "sound" resonating the pipes.

If from the latter then I need to modify the mount points to change the node points, if from the former changing the muffer or something should make a difference.

Anyone know what is the root cause cause of the "drone"??

Re: Getting rid or exhaust "drone" [Re: 6T6Cuda] #333394
06/02/09 11:13 AM
06/02/09 11:13 AM
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Lincoln Nebraska
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RapidRobert Offline
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Quote:

Can anyone suggest a good muffler which will get rid of this?


I would add resonators or glasspacks at the tail end alongside your leafs. The sound is from the ex exiting not the pipes resonating. Not sure exactly what muffs I'd use there but there will be good suggestions for that


live every 24 hour block of time like it's your last day on earth
Re: Getting rid or exhaust "drone" [Re: 6T6Cuda] #333395
06/02/09 01:16 PM
06/02/09 01:16 PM
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Detroit, Michigan, USA!
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Quote:

So does the exhaust drone come from the "sound" or from the "sound" resonating the pipes.

If from the latter then I need to modify the mount points to change the node points, if from the former changing the muffer or something should make a difference.

Anyone know what is the root cause cause of the "drone"??




Please see 70Cuda383's post:
Quote:

exhaust drone is actually a resonance, where the whole system is allowing the sound waves to basically "build up" and create the drone...kinda like blowing air over the top of an empty coke bottle.

and, every car combo is different! only way to figure it out yourself, is to experiment, change the length of the tail piples if you want, change the mufflers, add an H or X pipe, if you already have one, then try it without...




Re: Getting rid or exhaust "drone" [Re: 6T6Cuda] #333396
06/02/09 01:17 PM
06/02/09 01:17 PM
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Posts: 16,123
Grand Haven, MI
patrick Offline
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Quote:

So does the exhaust drone come from the "sound" or from the "sound" resonating the pipes.

If from the latter then I need to modify the mount points to change the node points, if from the former changing the muffer or something should make a difference.

Anyone know what is the root cause cause of the "drone"??




it happens when the exhaust system hits the natural frequency of the car. it's kind of a combination of both. another idea to try is to use muffler clamps to affix weight to the tailpipes. that adds mass damping and should change the resonant frequency of the exhaust.


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Re: Getting rid or exhaust "drone" [Re: patrick] #333397
06/06/09 10:59 AM
06/06/09 10:59 AM
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USA
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avoid tailpipe lengths behind the muffler in the range of 55 to 75 inches, otherwise you have created your own 'church organ pipe' that will resonate

alternatively,
break up these bad lengths with resonators... or use a muffler design with a 'Helmholtz Resonator' section

the noisy resonance depends on the
temperature & pressure of the exhaust gas too
(for geeks: actually the speed of sound for that gas condition)
so the rpm the noise is worst at will change slightly with the weather and with the throttle opening (you will hear this effect going up and down hills at the same rpm)

you can prove this to yourself by adding a two to three foot long section of exhaust pipe temporarily

notice that many imported cars have the muffler at the very end?

the science of this is the same as with
exhaust primary tube length on headers
and with intake manifold runner length

want to be very afraid of this effect?

see the movie
'The Perfect Storm'
where the gigantic "Rogue wave" at sea
is caused by the same resonance effect

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