Fixed My Exhaust Drone

[Charlie Brown]

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.

This is the original system.

The mocking up of the new system

Temporary adjustable length pipe

Finished product. I left the band clamps on instead of welding just in case I want to fine tune the system.

 

[Don Frelier]

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.

 

[YY1]

Interesting.

 

[70 sublime]

How did you know how long to make the dead end pipes ?

 

[6PKRTSE]

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.

 

[snakeoil24]

This is pretty cool what makes more sense the cherry bombs or the dead ends???

 

[MarPar]

 

[68 Sport Satellite]

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?

 

[68 Sport Satellite]

Here’s the j-pipes on my car. Looks crazy but works.

 

[snakeoil24]

Here’s the j-pipes on my car. Looks crazy but works.

View attachment 1649329

View attachment 1649330

how long did you make them???

 

[68 Sport Satellite]

how long did you make them???

28 inches sticks in my brain, but the photo looks longer. Car is not at my house right now. Will need to confirm later.

 

[68 Sport Satellite]

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.

The frequency table is purely the math of a v8 firing 4X per revolution of the engine, thererfore the number of pulses per minute.

 

[Charlie Brown]

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

 

[Charlie Brown]

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.

 

[Cranky]

Total length is about 30 inches - which includes the "J" bend

I'm thinking the dead pipe gets just as hot as the regular exhaust does?

 

[Charlie Brown]

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.

 

[Charlie Brown]

This is pretty cool what makes more sense the cherry bombs or the dead ends???

My system WILL work. Cherry bombs or other mufflers MAY work.

 

[Charlie Brown]

I'm thinking the dead pipe gets just as hot as the regular exhaust does?

You're probably right, although there is no direct exhaust flow through these pipes.

 

[eldubb440]

 

[68 Sport Satellite]

You're probably right, although there is no direct exhaust flow through these pipes.

plus, they're directly next to the regular pipes, so they'll get pretty warm. Never IR gun temp measured them though.