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Killed the DRONE in the Flowmasters

64SF

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As mentioned many times by many members the drone produced with the Flowmaster mufflers can be mind numbing. After an extensive search on the Internet and reading posts here I had installed a version of whats called a Hemholtz Resonator. It's nothing more that a length of pipe installed on each exhaust pipe before the mufflers and capped at the end. It has reduced the drone by at least 95%!....I can now carry on a conversation while cruising at 40-50 MPH! It did have a slight effect on the exit sound but to me it's actually a little less "raspy". Length is about 28".
Drone Killer.jpg
 
Why not just change mufflers? Seems like it will rot out from the inside from all the condensation. Unless they are stainless. Cool idea though.
 
X2 with Krowbar

WOW!
I'm seeing a lot of this lateley.
Cool sounding exhaust at idle and when revved...
But unwanted "harmonics" at 40 mph....

I'm glad you have solved the problem.
 
1) Build black box to receive drone signal

2) Black box feeds the signal into a phase shifter, and amplifies the signal

3) Black box puts out same drone, only 180 degrees out of phase, so drone is cancelled

4) Black box has volume control to match exhaust sound level

Drone cancelled in car, problem solved.:hello2:

ps.. You can get real sophisticated and have it determine the frequency, produce and error/correction signal, fed into a mixer. This will track the received frequency.
 
As mentioned many times by many members the drone produced with the Flowmaster mufflers can be mind numbing. After an extensive search on the Internet and reading posts here I had installed a version of whats called a Hemholtz Resonator. It's nothing more that a length of pipe installed on each exhaust pipe before the mufflers and capped at the end. It has reduced the drone by at least 95%!....I can now carry on a conversation while cruising at 40-50 MPH! It did have a slight effect on the exit sound but to me it's actually a little less "raspy". Length is about 28".

How did you calculate the length? I remember reading about a formula to figure it out based on the rpm's it drones at.
Glad it worked for you, I was thinking of adding resonators in the tailpipes along side the gas tank, it's supposed to help quite a bit, but now I wonder what the better way is.

Why not just change mufflers? Seems like it will rot out from the inside from all the condensation. Unless they are stainless. Cool idea though.

I swapped to super turbos, it helped a bit but I still got a pretty good drone going on, I think it's more in the pipes then the mufflers myself.
 
I've found that just securing the exhaust better really cuts down on the drone, my car really only rumble the interior when coming to a stop which I likey. Very interesting but I guess if I had to do that to get rid of an unwanted noise I'd toss the mufflers.
 
I just took a play from the Hemi engineer's play book and put glasspacks / resonators at the tail pipes works great even get told my car is pretty quite.
 
Some know I run straights and what I do is crimp the pipe. If you run 2 1/2" pipe, install a 3" crimped pipe in place of the muffler. This is kinda what I do but they are not mufflers. The more crimps and the longer the pipe, the quieter it is. Smooth straights can sound good without crimps depending on how radical the engine is and the size of the pipe....
http://www.classicchambered.com/classic/products.html
 
1) Build black box to receive drone signal

2) Black box feeds the signal into a phase shifter, and amplifies the signal

3) Black box puts out same drone, only 180 degrees out of phase, so drone is cancelled

4) Black box has volume control to match exhaust sound level

Drone cancelled in car, problem solved.:hello2:

ps.. You can get real sophisticated and have it determine the frequency, produce and error/correction signal, fed into a mixer. This will track the received frequency.
Huh ?
 
I use Dyno-Max Ultra-Flows since they are straight through and I race through my full exh system. So using them with the 3" X-pipe setup to the rear bumper gives me zero drone. Ron

100_1898_zpsc2099fc2.jpg
 
I use Dyno-Max Ultra-Flows since they are straight through and I race through my full exh system. So using them with the 3" X-pipe setup to the rear bumper gives me zero drone. Ron

100_1898_zpsc2099fc2.jpg

same, no drone just really loud when you stomp it in the big 505. best sounding muffler IMO
 
x2 and x3! I love my dynomax's

[video=youtube;3kq2K1-6y_4]https://www.youtube.com/watch?v=3kq2K1-6y_4[/video]
 
Like bigmanjbmoper said, I added 25" glass packs between the axle and tail-pipe. Problem solved.
Sounds absolutely perfect now.
 
Why not just change mufflers? Seems like it will rot out from the inside from all the condensation. Unless they are stainless. Cool idea though.

If I were to start from scratch knowing what I know now I'd install something other than the Flowmasters to kill the drone. Right now the $75.00 fix is much more affordable.
Will watch the condensation issue.

- - - Updated - - -

X2 with Krowbar

WOW!
I'm seeing a lot of this lateley.
Cool sounding exhaust at idle and when revved...
But unwanted "harmonics" at 40 mph....

I'm glad you have solved the problem.

Interesting point about the increased use of this....at the time they were installing the pipe a 5.0 mustang was having the same thing done.

- - - Updated - - -

1) Build black box to receive drone signal

2) Black box feeds the signal into a phase shifter, and amplifies the signal

3) Black box puts out same drone, only 180 degrees out of phase, so drone is cancelled

4) Black box has volume control to match exhaust sound level

Drone cancelled in car, problem solved.:hello2:

ps.. You can get real sophisticated and have it determine the frequency, produce and error/correction signal, fed into a mixer. This will track the received frequency.

Thanks...

- - - Updated - - -

I've found that just securing the exhaust better really cuts down on the drone, my car really only rumble the interior when coming to a stop which I likey. Very interesting but I guess if I had to do that to get rid of an unwanted noise I'd toss the mufflers.


Interesting...

- - - Updated - - -

same, no drone just really loud when you stomp it in the big 505. best sounding muffler IMO

Definitely look at this next time.

- - - Updated - - -

These pipes should be tipped forward to allow Condensate to drain. Can you post another picture?

Excellent point on condensation...
 
Some know I run straights and what I do is crimp the pipe. If you run 2 1/2" pipe, install a 3" crimped pipe in place of the muffler. This is kinda what I do but they are not mufflers. The more crimps and the longer the pipe, the quieter it is. Smooth straights can sound good without crimps depending on how radical the engine is and the size of the pipe....
http://www.classicchambered.com/classic/products.html

Like GM did with the 67 thru 69 Z/28
Placed the Chambered Exhaust in the trunk when you purchased the car...

- - - Updated - - -

1) Build black box to receive drone signal

2) Black box feeds the signal into a phase shifter, and amplifies the signal

3) Black box puts out same drone, only 180 degrees out of phase, so drone is cancelled

4) Black box has volume control to match exhaust sound level

Drone cancelled in car, problem solved.:hello2:

ps.. You can get real sophisticated and have it determine the frequency, produce and error/correction signal, fed into a mixer. This will track the received frequency.


69Bee...
This is GREAT!
I LOVE IT!


NOTE:
-Black box samples sound thru multiple miniature microphones, fed an "exciter" voltage of 5 volts, via 28 gage wire.
-Signals to miniature microphones are "signal Conditioned" and sent to a digital multiplexer. (Mux)
-Mux places multiple data streams onto a singal "BUS" wire, which in turn is fed directly into a Signal Conditioner.
-Signal conditioners' output is Fed to a Digital Discriminator, whic is in turn fed to a TTC-Ware "overhead" unit, which extrapolates data from initial Black Box, samples data (Simulated Un-desireable sound waves) and produces same sound waves but out of phase by 180 degrees CANCELLING ALL sound waves from exhaust noise produced by said Mopar.
-An audio recording of Don "Big Daddy" Garilit's Original swamp Rat II is played thru audio system, Fed to interior cabin AND heavily amplified by 70dB underneath the rear of vehicle.
-Passenger and rider are happy.
 
Physics at work! Love it! As for water build up you can drill a 3/32" hole at the low point for it to drain.
 
Physics at work! Love it! As for water build up you can drill a 3/32" hole at the low point for it to drain.
We used to do this to the Ford Escorts when I worked at the dealership. Aluminum heads make for a lot of condensation. No noise issues from doing it, but boy would they drip water when cold started.
 
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