440s and mufflers- too Loud!!!

Sonny · Dec 10, 2020

So in the last 6 months I’ve replaced flow masters with magnaflows (flow thru design) and today went with summit racing welded turbo mufflers. No difference in any of the 3 as they drone my brains out from idle to 50mph. Over 50 they are super quiet. I have stock hp manifolds and 2.5” tubing with an X pipe. The X pipe really helped and smoothed out the sound quality but droning is killing me.

I used boom mat in the trunk, package tray, on the rear seat divider board and under rear seat. What else can I do? Would headers help the droning?

Fran Blacker · Dec 10, 2020

Give me the car, thank you. :thumbsup:

33 IMP · Dec 10, 2020

Google Helmholtz resonators. Welding and math required.
(Tailpipes to the bumper? Maybe add a couple resonators alongside the gas tank, if you have room.)

Stroked438 · Dec 10, 2020

My 68 Sport Satelite Convertible was driving me crazy with the drone when I got it. I have a exhaust shop at my house so changing the exhaust was no big deal. I put on a set of headers, X pipe. big body Dynomax super turbos and used Flowmaster Flow FX mufflers as resonators before the bumper. NO drone what so ever. It is pretty quiet also but that's the way I wanted it. 2 1/2 pipe.

watermelon · Dec 10, 2020

do exhaust tips go all the way back to the bumper?

i recommend some heat/sound insulation on top of the boom mat.

my exhaust tips end before the axle and doubling the insul quieted things tremendously.

watermelon

Sonny · Dec 10, 2020

watermelon said:
do exhaust tips go all the way back to the bumper?

i recommend some heat/sound insulation on top of the boom mat.

my exhaust tips end before the axle and doubling the insul quieted things tremendously.

watermelon

View attachment 1038231 View attachment 1038241

Yes. Just past the bumper

Sonny · Dec 10, 2020

watermelon said:
do exhaust tips go all the way back to the bumper?

i recommend some heat/sound insulation on top of the boom mat.

my exhaust tips end before the axle and doubling the insul quieted things tremendously.

watermelon

View attachment 1038231 View attachment 1038241

Did you do your doors too?

440Coronet500 · Dec 10, 2020

As mentioned, does the exhaust run out all the way out to the rear bumper? If not, you have a large base speaker under your car. Low frequency exhaust pulses will make that baby drown! 440'

Sonny · Dec 10, 2020

440Coronet500 said:
As mentioned, does the exhaust run out all the way out to the rear bumper? If not, you have a large base speaker under your car. Low frequency exhaust pulses will make that baby drown! 440'

Yes it does.

Lionized · Dec 10, 2020

Sonny said:
View attachment 1038268
Yes it does.

That's exactly where you should add your "resonators". I used Thrush glasspacks. From your tips to where the pipe drops over the axel can be sectioned out, weld in the glasspacks. Done.

Don Frelier · Dec 10, 2020

I would suggest hemi mufflers.

Sonny · Dec 10, 2020

Lionized said:
That's exactly where you should add your "resonators". I used Thrush glasspacks. From your tips to where the pipe drops over the axel can be sectioned out, weld in the glasspacks. Done.

Is your car quiet? How’s the tone? Droning?

watermelon · Dec 10, 2020

i did some big patches on interiors of doors and in the interior of area of the rear roll up windows. also did trunk area too. car is carrying probably 100lbs in insulation alone

watermelon

4mulas · Dec 10, 2020

Hi Sonny, how long were the bodies of the mufflers you tried.

I was having the same problem at 2200 rpm with stainless dynomax 20” body (25.5 over all, 2.5 in and 2.5 out), switched to the hemi ‘magnum’ mufflers from accurate exhaust, its better, not as bad but still drones but at 1800 rpm now where the revs are seldom at. Wouldn’t recommend those.

On my other car I’m going to use dymomax 17748’s as per TTI’s recommendation. I had them on a Running engine for a bout 1/2 hour (until the cam lobe wiped!) and they seem pretty quiet so far. Won’t know more until the engine version 2.0 goes in and I drive it though... good luck.

https://www.dynomax.com/super-turbo-centered-offset-641.html

1967coronet · Dec 10, 2020

My brother wanted to quiet his big block down some , headers, 2 1/2" pipe to the bumper.
He found a set of hush thrush mufflers at a swap meet new in the box.
We installed them and he really like them, It did quiet things down , no drone.
Not sure if they are still available new.
One thing I will add is checking all hangers, Some if they are solid or the rubber is just to stiff will cause a drone noise.

Carcinogen · Dec 10, 2020

I also had too much drone at lower engine speeds running 3”with x pipe

Figured the x pipe equalizes the exhaust pulse which then exit pipes at same time

Using a turbo muffler on one side and cherry bomb salute straight through on other side. This has reduced the drone as pulse takes longer path in turbo muffler compared to straight through. now exhaust pulses are offset and Don’t combine pressure (pulse) wave.

still loud but resonance is reduced. longer mufflers and 2.5 would reduce loudness , using 18” long now.

mopar 3 B · Dec 11, 2020

Sitting here reading all this wondering why you all bought Mopars?

Kern Dog · Dec 11, 2020

It seems from what I have read, MOST of the people that deal with D-R-O-N-E problems all have cast iron exhaust manifolds.

moparedtn · Dec 11, 2020

Kern Dog said:
It seems from what I have read, MOST of the people that deal with D-R-O-N-E problems all have ~~cast iron exhaust manifolds.~~Flowmasters.

FTFY.

moparedtn · Dec 11, 2020

mopar 3 B said:
Sitting here reading all this wondering why you all bought Mopars?

Fred's exhaust is LOUD as hell, what with the Buford's Muffler Shop (ask for him by name!) cobbled up 3" duals
and lookalike Flowmasters on it, coming out of those God-awful Hedmans.
There's drone and then there's DROOOOOONNNNNE....
I'd replace it all but there's the $$$ - and the fact the previous neck-of-red owner had it all done in stainless,
so the crap just....won't.....rot away, so it's hard to justify yanking it out.

Well, that and it does sound like the hounds of hell unleashing when I romp on it, so there's that.

Despite my hearing loss and severe tinnitus, I admit it does sound pretty good from outside the car.
Honestly? It's a borderline ear plug affair for sure.

No doubt a cross-over/x-pipe would help, but the mufflers are the thing methinks.
I generally don't like Flowmasters for their industrial sound and Magnaflows are almost as bad, not to
mention they're overpriced and glasspack-filled.
Walker used to make a muffler called the Red Line-Z and since it was them making it, it was good stuff
and sounded at least to me pretty darn good - actually emphasized that Mopar exhaust cadence well.
I often wonder if the DynoMax stuff is similar to that?

440s and mufflers- too Loud!!!

It’s all fun til the rabbit gets the gun.

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It’s all fun til the rabbit gets the gun.

It’s all fun til the rabbit gets the gun.

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It’s all fun til the rabbit gets the gun.

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It’s all fun til the rabbit gets the gun.

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Life is full of turns. Build your car to handle.

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