How do i keep my Exhaust from Droning?

[Flip888]

It isnt bad when im on the gas a little but when its just idleing at a stoplight or something, it drones so loud it sounds like your sitting in front of a fog horn.
A friend of mine sayd it was rattling his car at a stop light the otherday it was so loud. Wheather it was or not i dont really know but if gotta get this fixed. Is there anyway of fixing it without replacing my exhaust with another one?

BBK y pipe to flowmaster

 

[Bladez5_0]

Don't think so. Unless you want to change your idle by a significant amount you will have the drone you have right now. You can try putting turn downs on it to get the sound to bounce off the ground. Other than swapping in a different muffler you will probably be stuck with the Flowmaster drone.

 

[HISSIN50]

Are you sure your exhaust is not touching anything (like the DS or frame rail)? That will make a lovely sound.

Good luck.

 

[gt40_2003wes]

thats just part of flowmasters they all have a droan i love it myself took a lil while to get use to but now i like the droan.

 

[HISSIN50]

You guys have drone at idle? That is not right IMHO. I used to get it at ~2K RPM, which is more normal IMHO.

 

[jstang209]

the drone isnt really that bad.. i mean its the quietest part of the mufflers.. i like my 2k drone for when cops are followin me..

 

[Mavrick]

I love the drone...

If your getting it THAT loud at idle, your exhaust may be making contact with the frame of the car. Turn downs will just make more reverberations..

 

[cjman15]

get quieter mufflers

 

[gt40_2003wes]

i dont get droan at idle i get it between 1800-2200 rpms.

 

[vristang]

Any exhaust system is going to have a natural frequency where the noise will become louder. This has to do with how the sound from the exhaust resonates through the chassis and passenger compartment. Mine seems to be around 2k rpm. You can change out exhaust parts to move the resonance to a different rpm or quiet it down, but it will always be there. manufacturers spend a great deal of time and energy fine tuning the exhaust in this way. It's not surprising that a given aftermarket kit does not provide the "ideal" solution for all cars.

As JT suggested though, make sure nothing is hitting the chassis. This too can be more pronounced at a given rpm. Unless you idle at 2k, you should not have the resonance at idle.

jason

 

[Flip888]

thanks for the responses, Ill check tomorrow to make sure its not hitting anything. I bet thats what it is, sometimes with the windows down it actually gets so loud in the car it makes your ears hurt like someone is yelling in them as loud as they can or something.

And what basically happens is, at idle the drone is loud but like you guys were saying, its at its loudest at about 2000 rpm, unless i give it some gas, which makes it go away almost completely. So for example if i floored it from idle, the droning wouldnt be very noticeably at all, although maybe thats because the exhaust sound overpowers the droning sound. I dont know but i guess like you guys were saying, the drone is inherent with the exhaust so maybe its just normal, it is a racing exhaust afterall.

 

[sgarlic]

Get gears so you rarely see 2k

 

[50bomber]

Get unequal length mufflers! That's how ford solved on the stock system or more realistically get Borlas!!:Word:

 

[vristang]

Get unequal length mufflers! That's how ford solved on the stock system or more realistically get Borlas!!:Word:

Unequal length mufflers?

Can you elaborate?

Haven't heard this term before.

 

[HISSIN50]

50 Bomber is spot on! (That is a piece of tech I dont often post and dont see others post too often). The two different length mufflers helped cancel drone (all that stuff with harmonics, nodal/antinodal points, etc).

I have wondered why some manufacturers of aftermarket stuff cant offer systems with two different sized muffs (or an added-on chamber), etc.......

 

[DTT92LX]

I've also heard that offsetting the equal length muffs you have will work. Move one forward or back. Course that means probably cutting some pipe from one end and adding it to the other.

 

[90bronconate]

BBK y pipe to flowmaster

y pipe? is it a sixer? or did you mean to hit "H"?

 

[vristang]

50 Bomber is spot on! (That is a piece of tech I dont often post and dont see others post too often). The two different length mufflers helped cancel drone (all that stuff with harmonics, nodal/antinodal points, etc).

I have wondered why some manufacturers of aftermarket stuff cant offer systems with two different sized muffs (or an added-on chamber), etc.......

I've also heard that offsetting the equal length muffs you have will work. Move one forward or back. Course that means probably cutting some pipe from one end and adding it to the other.

This thread just turned into the best exhaust thread I have ever seen. Never even considered that as a solution, and never heard of it as one either.
I would love to hear from anyone who has tried this, either with or without success.
Cool stuff

 

[50bomber]

I got this from one of the 5.0 Mustang books, I think "How to tune and modify your 5.0 Mustangs" It even has photos of the stock system and by golly, one of the mufflers is like 1" shorter than others, measure it, you'll see. Short of getting custom mufflers, try running like one 2 chamber Flowmaster and one 3 chamber ? Or one Magnaflow and one Dynomax?? i dunno how you feel about automotive cannibalism (?) like that but it may be a solution.
Another one is kind of like manufacturers of other cars have done is to put a "resonator" in the exhaust before the muffler, which basically look like a glasspack muffler, kind of like DynoMax bullet. I just replaced my Civics exhaust so I know what it looks like since it fell apart at that point.
Hope this helps.

 

[tjm73]

Resonators. A friend added 2 to his street rod after the Mac mufflers he has were droning so bad he couldn't talk to his wife on a trip to street rod show (maybe that's a good thing - lol). Worked like a charm. Now has nearly no drone, you can talk inside the truck and it still sounds great under throttle & at idle. His street rod has a 4.6 Ford.