I need a small but quiet muffler

2drx4

Greasemonkey
May 28, 2022
121
43
The middle of BC, Canada
So not exactly G-Body, but the 4x4 scene doesn't know so I figured I'd ask here. It's for my Jeep, but yeah, exhaust is exhaust.

I'm running a Pypes 2.5" inlet/outlet 4" OD 14" long straight through muffler. Seen here: https://www.summitracing.com/parts/PYE-MVR200S

It was cheap, stainless, and it fit, so it's what I bought. However, it's loud. Really loud. And it drones badly. My hearing is damaged already, some of it occupational, some of it recreational. I'd rather not make it dramatically worse.

So is there anything of a similar size/form factor that isn't actually straight though? Or will actually reduce the noise level significantly?

The Borla 40842S looked promising: https://www.summitracing.com/parts/bor-40842s

But I'm not sure if it's actually baffled in the sense that it isn't a straight through design.

What sort of tight clearance muffler do you have? Are any of the round body mufflers actually not a straight through design? Is there straight through designs that are actually significantly quieter without being huge?

The other suggestion was to add a cat, but I don't think I can from a heat management standpoint. Oh, and somebody suggested a turbo. :rofl:
 

melloelky

Comic Book Super Hero
Oct 22, 2017
3,714
113
mass
Any straight through muffler is gonna be loud by default,let alone a shorter one. The chambered style mufflers (ones without Fiberglass packing or matting) are on the louder side of things too. A lot of times the drone with the chambered style comes from placement also. Most vehicles you don't have a lot of choice where the mufflers gonna go So it is what it is. I'd look for a Turbo style muffler.that style that has the fiberglass and the matting inside are quieter than the chambered.they're the quieter design.
 
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2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
Any straight through muffler is gonna be loud by default,let alone a shorter one. The chambered style mufflers (ones without Fiberglass packing or matting) are on the louder side of things too. A lot of times the drone with the chambered style comes from placement also. Most vehicles you don't have a lot of choice where the mufflers gonna go So it is what it is. I'd look for a Turbo style muffler.that style that has the fiberglass and the matting inside are quieter than the chambered.they're the quieter design.
Is there any round "turbo" mufflers out there? Packaging is very tight.
 

ck80

Comic Book Super Hero
Feb 18, 2014
4,420
113
Another question is if you have room elsewhere to allow for a resonator somewhere with more clearance
 
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2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
Another question is if you have room elsewhere to allow for a resonator somewhere with more clearance
Probably not. Just snaking the 2.5" pipe through was quite difficult. Maybe a very small one. How much difference would it make? I know nothing about exhaust tech, normally I just throw whatever is cheap and fits on things, but this build is the worst as far as lack of space goes.
 

Bonnewagon

Geezer
Sep 18, 2009
8,753
113
Queens, NY
Dynomax.
 
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ck80

Comic Book Super Hero
Feb 18, 2014
4,420
113
It can make a huge difference. Resonators can be at the very end of the system, no need for more than a couple inches of tailpipe.

They can remove or reduce harshness, sharp sound, volume, vibration, etc.

So if at the very rear of the body you can find an area it makes a world of difference.

your results may vary, but, the exhaust rotted clean away on my 77 squarebody that lived in a field for years before I got it. I took an empty hollow pancake gm converter, attached it as a resonator directly to the crossover pipe, and it runs quieter than most of the full factory exhaust system trucks and cars in the driveway.

Google and read up on a resonator for a few minutes, and, peek under the very rear of your project to see if you can stick sometjing there.

an easy test before cutting is just add the resonator onto the end of your tailpipe in garage, and give a Rev test parked in place. If you notice an effect you like, that tells you something
Probably not. Just snaking the 2.5" pipe through was quite difficult. Maybe a very small one. How much difference would it make? I know nothing about exhaust tech, normally I just throw whatever is cheap and fits on things, but this build is the worst as far as lack of space goes.
 

2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
Unfortunately I'm typing this from work and the Jeep is sitting in my driveway at home (but I did drive my Cutlass to work, so give me some credit) so I can't just walk out and take a bunch of pictures of how this all fits.

The best file picture I had of the exhaust exit is poor... But eh.

8rfhg3oh.jpg


Basically it does a U over the top of the axle to allow for uptravel, and the muffler is in upward part in front of the axle. There is no space under the belly anywhere. Then from the U over the axle I just turned it out a bit so it dumps just past the front edge of the gas tank skid. There isn't much space between the leaf spring and the gas tank skid. I think if I take some 3" pipe and flatten it a bit, or even 2.5", and turn it into an oval I can get between the side of the tank skid plate and at least out to around the spring shackle and turn it down. I'd have to add a small section of bend to it as well to turn it back towards the rear. I'm thinking part of my problem is there isn't that much pipe past the muffler at all, and that the exhaust pulses are still hitting the floor above the end of the pipe quite hard.

I'm also now considering how much I've been heating my gas/gas tank with the current setup. Some soot builds up on it, but the majority of the exhaust is blown past it.

Here's a high tech photoshop of what I think I'll try first:
8rfhg3oh21.jpg


Do I need to turn it down at the end? Or just go straight out? Would it make any difference to how the driver perceives the sound?

I guess I also could make a resonator to go there by really flattening a piece of 4" down.
 

Rt Jam

Master Mechanic
Mar 30, 2020
251
43
Ontario Canada
I've been through this a dozen times. There is a large misconception, sound comes from muffler. It's only part of the equation.

95 Thunderbird 4.6L. Remove resonator, still super quiet, 2 Magnaflows, Still pretty quiet. Conclusion, 4.6L Modulars are quiet engines.
08 Allure Super 5.3L. Remove resonator, same. Change from stock to 2 Flowmasters. Pretty loud but nice at full throttle.
97 Silverado 1500 5.7L. Change from stock muffler to biggest Flowmaster single muffler. Almost no change.
02 Silverado 1500HD 6.0L. Single tiny Flowmaster 10. Sounds like clapping at full throttle and crap accelerating, only nice rumble at idle. Had to replace catalytics with Magnaflow cats. Even louder so changed to a SAME single biggest Flowmaster 50 series big block that was on my 97 Silverado. Same muffler but so loud and drones. Switched duals to 2 big Flowmaster 50 deltaflows. Not as loud as b4 but louder than stock with no drone. Conclusion, 6L with aftermarket cat is loud, no matter the muffler.
72 Dart with stock 383, even with open headers, not that loud. Changed camshaft and heads, higher compression. Same 383 was now super super loud. Even with 2 3" Flowmaster 40's you could hear this car a kilometer away.

So 2drx, alot of noise comes from engine, not just mufflers. Catalytic converters take alot of noise away, especially stock ones. Thick pipes, bends, tails and long systems will reduce sound. More sound is thin wall headers, straight systems like axle dump and straight through mufflers.

There is no muffler = this much sound chart. It depends on combination.
 
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2drx4

Greasemonkey
Thread starter
May 28, 2022
121
43
The middle of BC, Canada
I've been through this a dozen times. There is a large misconception, sound comes from muffler. It's only part of the equation.

95 Thunderbird 4.6L. Remove resonator, still super quiet, 2 Magnaflows, Still pretty quiet. Conclusion, 4.6L Modulars are quiet engines.
08 Allure Super 5.3L. Remove resonator, same. Change from stock to 2 Flowmasters. Pretty loud but nice at full throttle.
97 Silverado 1500 5.7L. Change from stock muffler to biggest Flowmaster single muffler. Almost no change.
02 Silverado 1500HD 6.0L. Single tiny Flowmaster 10. Sounds like clapping at full throttle and crap accelerating, only nice rumble at idle. Had to replace catalytics with Magnaflow cats. Even louder so changed to a SAME single biggest Flowmaster 50 series big block that was on my 97 Silverado. Same muffler but so loud and drones. Switched duals to 2 big Flowmaster 50 deltaflows. Not as loud as b4 but louder than stock with no drone. Conclusion, 6L with aftermarket cat is loud, no matter the muffler.
72 Dart with stock 383, even with open headers, not that loud. Changed camshaft and heads, higher compression. Same 383 was now super super loud. Even with 2 3" Flowmaster 40's you could hear this car a kilometer away.

So 2drx, alot of noise comes from engine, not just mufflers. Catalytic converters take alot of noise away, especially stock ones. Thick pipes, bends, tails and long systems will reduce sound. More sound is thin wall headers, straight systems like axle dump and straight through mufflers.

There is no muffler = this much sound chart. It depends on combination.
I get that, but clearly the straight through muffler I have isn't working. And clearly there will be muffler designs that work better than others. I can extend the tailpipe, maybe put a small resonator in, a cat is basically out unless maybe I cut the floor out to make enough space for one and even then the heat management issue will still be there, and there's no real option for a different header. So basically the muffler would be the main thing I can do. I doubt extending the tailpipe will make enough difference that I'm going to be happy with it, but maybe.

I'm looking for a small muffler that isn't straight through because I think that has the best chance of actually dampening the exhaust pulses enough to not be so loud. Or at least it's worth a try I think.
 

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