You're going to hate this but...how do I quieten the exhaust?

[David Womby]

My car has a 1978 Monaco 360 engine with a Mopar Performance Cam 4452761. It has original cast iron exhaust manifolds and dual 2.5" exhausts. The exhausts had glasspacks but I replaced them with baffle type mufflers. Why? Because despite liking the performance and behavior of the car, I don't like the muscle car sound. I like it in the right car but it just isn't right for my car. The swap out of the glasspacks was an attempt to quieten things down but hasn't done much.

So, although I know most of the questions here are about louder exhausts and power, what else can I do to the exhausts to lessen noise - especially at idle? Some things I've considered are: add an H pipe to even the sound out or add a crossflow type muffler ( like a Dynomax 17553 ) downstream of the existing mufflers, or add small second muffler to each pipe downstream of the existing mufflers.

Any suggestions will be appreciated. Thanks.

David

 

[sam dupont]

Re-pop Hemi mufflers

 

[hunt2elk]

Dynomax Super Turbo's are pretty tame.

 

[RemCharger]

Agree with both these answers. H pipe a good idea, forget the x pipe..

 

[Cranky]

Dynomax Super Turbo's are pretty tame.

And they still flow very well!

 

[MoparLeo]

Install both muffler and resonators. If only mufflers, put them as far to the rear as possible. The further back they are, the quieter your car will be. H 0r X pipes will help even the note.

 

[MIKESPOLARA]

My car has a 1978 Monaco 360 engine with a Mopar Performance Cam 4452761. It has original cast iron exhaust manifolds and dual 2.5" exhausts. The exhausts had glasspacks but I replaced them with baffle type mufflers. Why? Because despite liking the performance and behavior of the car, I don't like the muscle car sound. I like it in the right car but it just isn't right for my car. The swap out of the glasspacks was an attempt to quieten things down but hasn't done much.

So, although I know most of the questions here are about louder exhausts and power, what else can I do to the exhausts to lessen noise - especially at idle? Some things I've considered are: add an H pipe to even the sound out or add a crossflow type muffler ( like a Dynomax 17553 ) downstream of the existing mufflers, or add small second muffler to each pipe downstream of the existing mufflers.

Any suggestions will be appreciated. Thanks.

David

What kind of car is this?

 

[David Womby]

What kind of car is this?

1964 Bristol 408 Had a Canadian built 313 from new but it was replaced in the 90s with the rebuilt ex-Monaco 360.

 

[Ron H]

There’s been more posts I think on reducing the sound, drone, and obtaining a nicer sound…I’ve participated in some. I had FM 50’s on my car that sounded cool; but too loud especially cruising. (I have headers/X pipe.) There are endless selections to be had and you can find video links from some of the suppliers so you can get an idea what they sound like. I opted for the hemi mufflers from accurate exhaust (not cheap) as my idea was getting quieter vs ending up too close to what I had plus several members recommended them. I’m pretty happy with them as they’re notably quieter when cruising with a nice sound. Otherwise if you want quiet go to a standard stock muffler or add resonators to your setup.

 

[MIKESPOLARA]

Most any large muffler shop knows what mufflers are quiet. You don't use aftermarket hot rod stuff

 

[David Womby]

Thanks, gents. I'll take a look at all those again.

David

 

[JoePole]

I had the same problem. I was running HiPo 340 manifolds, 2.5 exh with flowmaster 40's. Couldn't stand the drone and they were pretty loud. Added H-pipe. Not much change. Swapped in Dynomax super turbo's and really quieted things down. I would go this route. For me I needed a little more so I swapped in long tube headers and the sound is perfect for me. More of a muscle car sound. Also added torque.

 

[33 IMP]

Whatever walker quiet flow muffler fits under the car, the larger the better. They flow well and are quiet. If you don't want to change the mufflers, consider adding resonators in the tail pipes. An xpipe would be a monumental waste of money for the sound change, an h pipe might help.

 

[Runcharger]

Fartmasters are for Chebbies. Replace with Walkers, much better.

 

[yella71]

Take out the cam and put a very mild cam in it and change out the mufflers and ad resonators,or just put a smaller weeker engine in place of the 360

 

[David Womby]

Take out the cam and put a very mild cam in it and change out the mufflers and ad resonators,or just put a smaller weeker engine in place of the 360

One day maybe I will change the cam back to something milder but not for now.

David

 

[moparedtn]

H-pipe helps more than folks realize - and yes, the Dynomax Super Turbos (some quiet) or Walker
"stock" type (ALL the quiet) mufflers do the work from there. Resonators not needed for this IMO.

 

[furious70]

If you don't have a subscription to motortrend online get one and watch engine Masters, they've done a bunch of exhaust tests

 

[chtampa]

Add resonators.

 

[CMCE]

The Dynomax advise above is spot-on. The longer the muffler, the quieter. Here are some sound clips:
https://www.classicmusclecarexhaust...y/2-5-Dynomax-Super-Turbo-Mufflers-p231638939