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Fixed My Exhaust Drone

Charlie Brown

Well-Known Member
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3:33 PM
Joined
May 23, 2021
Messages
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Location
Vars, Ontario, Canada
Dual exhaust, cross over, 2.5 inch tubing, headers and Magnaflow mufflers. Drone at 1400 - 1800 was irritating. Had a similar issue with my 62 Chrysler. Made these cars no fun to drive. Fixed the Chrysler drone 15 years ago, now it was time to tackle the Polara. 1/4 wave resonator is the key. Took me almost a week to do the job, but now the drone is gone and I still have the muscle car sound. Love it.
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This is the original system.

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The mocking up of the new system

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Temporary adjustable length pipe
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Finished product. I left the band clamps on instead of welding just in case I want to fine tune the system.
 
That's pretty cool.
I found adding tips helped quite a bit.
I have 2-1/4" with a similar setup h-pipe and magna- flows it was really really annoying going up a grade around 35-40 mph.
 
Resonators (cherry bomb or race muffler) type cylindrical mufflers at the tail pipes before the chrome tips is much easier and still sounds great. I have a couple of Dynomax on my cars done this way.

wlk-24215_oh_vz_xl.jpg
 
Dual exhaust, cross over, 2.5 inch tubing, headers and Magnaflow mufflers. Drone at 1400 - 1800 was irritating. Had a similar issue with my 62 Chrysler. Made these cars no fun to drive. Fixed the Chrysler drone 15 years ago, now it was time to tackle the Polara. 1/4 wave resonator is the key. Took me almost a week to do the job, but now the drone is gone and I still have the muscle car sound. Love it.View attachment 1649221
This is the original system.

View attachment 1649235View attachment 1649236
The mocking up of the new system

View attachment 1649237View attachment 1649238View attachment 1649239

Temporary adjustable length pipeView attachment 1649240

View attachment 1649242
Finished product. I left the band clamps on instead of welding just in case I want to fine tune the system.
I did the same thing on my car to cure the drone. The dead ends and the length of those tubes is key to cancel the acoustic wave response. I'll dig up my photos around somewhere. I recall on my install it called for each dead end tube to be 28-inches long. Yours look a lot shorter. What is their length measurement?
 
When I installed this on my car, I found the length guidance on a mustang site. Seems that a lot of those guys are installing these. Here is a chart with various lengths. I didn't have this chart when I did mine and just went off of someone else's online advice and used a fixed length.

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The frequency table is purely the math of a v8 firing 4X per revolution of the engine, thererfore the number of pulses per minute.
 
I did the same thing on my car to cure the drone. The dead ends and the length of those tubes is key to cancel the acoustic wave response. I'll dig up my photos around somewhere. I recall on my install it called for each dead end tube to be 28-inches long. Yours look a lot shorter. What is their length measurement?
Total length is about 30 inches - which includes the "J" bend
 
How did you know how long to make the dead end pipes ?
Doing the internet search thing, it seemed that the lengths were all over the map. Most were between 20 and 40 inches. There are formulas to follow, but there are all sort of variables, so I decided to design my system to be variable via an adjustable sleeve / length of pipe. I test drove the car with the extensions at different lengths and when I found the best fit, I measured the length and cut a pipe the appropriate length and capped the end. Started at 42 inches and finished at about 30 inches, which includes the "J" bend.
 
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Resonators (cherry bomb or race muffler) type cylindrical mufflers at the tail pipes before the chrome tips is much easier and still sounds great. I have a couple of Dynomax on my cars done this way.

View attachment 1649261
I've changed mufflers before, but with limited effect. Seems like each car is different. A person could go through a bunch of mufflers before they find the right fit - and that is expensive.
 
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