Quietest muffler for my P-15 - SOLVED

[Mr.P-15]

Hi All:

I have had a rather nasty time of finding a good QUIET muffler for my P-15's. A muffler from an old Mopar parts supplier produced a loud, obnoxious "pipe organ" scream at  40 MPH that would make conversation impossible. A replacement did the same. One from a muffler shop was just plain loud. Moving the muffler to the rear just caused the "pipe organ" to occur at 35 rather than 40 MPH. 

I like my cars to be quiet. No, I'm not interested in trying to pretend that I am still 18. I admire the guy on this forum who said "it is on" when his insurance agent asked him to start it up. Or the guy who could "sneak up on" folks at car shows with his Mopar. I want to be able to talk or listen to the radio. No screams, braps or blub-blubs.

That said, looking over the forum I discovered folks referring to Walker 17827's and Smitty 30 (inch) mufflers as quiet. In fact, the Smitty 30 is said to be so quiet as to be "for grandma". Yup, if that is so, that's the one I want.

My question is: "is it really (for grandma") and which of the two is quieter? The fact that the Smitty is a glas-pak gives me pause.

 

Thanks.

[Bryan G]

The muffler that was on my New Yorker wasn't an original equipment type, but was QUIET. I had a bad backfire and the thing swelled up like a balloon, but you couldn't tell it by listening. I had a mechanic friend weld up a small leak elsewhere in the system and, without asking, he replaced the muffler. I was nervous...but there was no change in sound. I'm not sure what he used, but it looks like, well, just a plain muffler. Probably a generic Walker or something similar? Not sure I could find any markings on it to ID it. Either way, I'm sure it was something the local Federated or NAPA had in stock. People do tell me all the time how quiet the car is. There are times when I wish I could throw a switch and really hear what that engine has to say, but overall I'm happy with this setup. 

[Loren]

I have to admit I am watching this thread.

I am not particularly happy with my new muffler. It seems louder than my first 49 Plymouth.

So when some one comes up with a better replacement, I’m in too.

[MarcDeSoto]

Chrysler sixes and eights are known for being "sewing machines" at idle.  I bought my muffler from Andy Bernbaum around 1991, but I haven't started my engine yet.  Finally, I am getting close.  New radiator, new fuel line, rebuilt carburetor, new exhaust system,  new spark plugs, cables, rotor and condenser, new coil, etc.  Hope my muffler is a good one.  I'll report back after I start it which should be in the week or so.  

[Dan Hiebert]

FWIW, I bought the muffler on our D24 from AB as well, when we were first working on the car 30 or so years ago, so I don't remember the manufacturer.  (Yeah, that doesn't help much, I know.)  Not quite "grandma quiet", I'd call it "grandpa quiet", has a nice burble to it, but not loud at all.  I like my older cars to be quiet, too, if they're stock, and I've had no inclination to swap out the muffler on our D24 for something quieter.

 

 

[Sniper]

Youtube has videos of mufflers and the noises they make, that might help.

 

Myself?  I am a dirty neck hot rodder and like Dynomax Super Turbos.

 

Some have used glasspacks as a sort of resonator towards the end of the tailpipe as well to control noise. 

[greg g]

I have a dyno max turbo flow on mine.  It cost me 35 bucks at pep boys.  Dont know if they still make it. It talks a bit at wide open throttle but at cruise from 35 to 65 its quiet.  No drone, no closed throttle crackle pop. System was custom bent 2 inch id, muffler in stock position. It has 50 k miles and 17 years and still doing its job.  Check their web site to see if there is something similar.  Failing that  something stock for a later slant six full size car or pickup truck or van might fit the bill.

Edited November 25, 2022 by greg g

[JohnS48plm]

I got my muffler for my 48 coupe at Waldron Exhaust in Centerville Michigan. They make oem style exhaust systems for classic cars. The muffler I got from them was quiet. 

[Bryan G]

Not sure how helpful these are, but this is what mine looks like. Maybe that number embossed on the bottom will lead to it? (couldn't blow it up enough on my phone.)

[Matt Wilson]

A brief mention was made of this above, but I'll repeat the idea of using a resonator.  However, I have say that I don't have any personal experience with resonators.  I only mention it because Tom Langdon recommended that I use one when I spoke to him once about exhaust systems.  He said that inline sixes tend to produce an increased volume at around 2500 rpm, give or take a few hundred rpm, which can be annoying for many people.  He said the way to quiet it down is with a resonator.  I haven't gotten to that stage in my project yet, so I can't comment personally about it yet.

[allbizz49]

The muffler on my 53 looks exactly like one pictured above. Just a stock looking oval. It's the quietest car I've ever owned. Unless you're standing directly behind it, you can't hear it running.

[soth122003]

Just had my entire exhaust systems replaced this past Tuesday. The muffler pictured here looks just like the one on my car now. The new system is really quiet until you get to about 45 mph or so then it gets a bit louder but not unbearable rumble and engine noise. Right now I don't have the under carpet padding/insulation installed. The nose I did hear at speeds above 50 was the tires and a bit of the engine. A little more sound proofing and I might be lulled to sleep by the light rumble of the road noise.

 

Joe Lee

[Mr.P-15]

Hi All:

Update: Am checking out a few possibilities. So far, there is one I can rule out, (if you are looking for super quiet) and that is the Smitty. "Grandma" must be a little hard of hearing, since this one would be far too noisy. I got this straight form the folks at Smittys; (can you actually believe that I could speak to them in this "press 1, press 2" age?)  they advised me that  glas-paks are not what I am looking for (for those who don't know, glas-paks are all they make). I will give them a double thumbs up, however because they are available, straightforward and honest. I can see why they have the good reputation that they do.

More as the saga continues....

Edited November 30, 2022 by Mr.P-15
more information

[SteveR]

Here is my Glass Pack I believe it is from the late 60s to early 70s. The end of the exhaust is just behind the front seat. My wife loves the noise, I wish it were quieter.

[Sniper]

Found a couple of Mopar flathead muffler videos.

 

Dual Smithy's

 

Dual Cherry booms, on a truck, sounds like a truck

 

 

Duals, no mention of what muffler though

 

Straight pipes (I like this one best, lol)

 

 

Open pipes

 

 

 

[Sniper]

Here's a clip of the Dynomax Super Turbos on a sound test setup

 

 

[greg g]

The first engine in the above pics was put together and documented on this forum by Pete "Blueskies" Andersen.  Pete and Don Coatney were building their cars at about the same time. Their progress was documented with nearly daily updates on these pages.  Their contributions inspired a good many members to continue or start work on several project vehicles.

 

I believe that content is still available here via member name content search.  Those two guys made the p15-d24.com site a daily must visit for about two years.

[iowa51]

2 of the muffler/exhaust systems I have for my old cars ('51 Plymouth and '59 Chevy) came from my local Midas. Just asked for a stock/original style system. No problem with exhaust noise on either car and both can barely be heard when idling.

 

Something else to consider is the noise coming from another source besides the muffler? My dad had a 1969 Buick Wildcat convertible and, despite having a new top, at 40-50mph there would be an unbearable "howling" noise inside the car. Never did find the cause. Could your problem be wind noise and not muffler noise?

 

An interesting side note about the muffler I got at Midas for the '59. The store manager was getting ready to order the new muffler when one of the long time employees came up to the desk. He said "we got one of them in stock". The manager said "nothing showed up on the computer". The employee said that it is the "old, old stock" and went to get it. He came back with a very dusty box and pulled out a new muffler. The label said "Full size Chevrolet 1959-72". After the installation the store manager gave me the warranty card which was the old style punch card. He said despite how old the muffler was it still had the lifetime warranty on it.

[Bryan G]

A guy I know has a barn full of...everything. When I was between jobs about 10 years back I was selling some NOS parts for him on eBay (among other things, some 20's carburetors, a bunch of rebuilt starter solenoids and voltage regulators from the 30s-40s. I remember on a shelf he had a NOS muffler for a Dodge, I think in the 48-52 range. Thing is probably still sitting there, I just don't have the time to try and grab it from him. (Very interesting guy, belongs on "American Pickers") but difficult to get him to stand still long enough to ask him a question.

[Mr.P-15]

18 December 2022

Hi All:

First of all, thanks to SteveR, Sniper, greg g, Iowa51 and Bryan G for all the cool and interesting video and information. As per Iowa 51's suggestion, the noise seems most definitely exhaust system related.

At any rate, last Saturday when I came home, a brand-new Walker "Quiet Flow" muffler was sitting on the front porch, (the first one they sent didn't look like a good fit, so they exchanged it) and this week it will go in. The folks at Walker seemed confident it would work. Well......

This muffler does not quite look like "originals" I've seen, it is a bit wider and shorter (only about 58 cm long as I remember). They did have one that looked right, but alas, it was centre in, offset out as opposed to the offset in, centre out configuration that p-15's want. Yes, I asked. It is NOT reversible.

I am going to make sure that there is as much "free space" as possible, just in case a resonator or auxiliary muffler needs to be installed.

Well, that's all for now, stay tuned for the next exciting episode, which should be in a few days.

[Sniper]

video the noise for us.  If you don't have a youtube account to put it on I can put it on mine

[Marcel Backs]

I picked up my muffler at NAPA and when I had the car running on initial start up, I could not believe how quiet it ran even when revving it a wee bit. I will see if I can get an audio clip when I fire it up again  after the holidays. The loudest exhaust I had in my young hooligan days was a set of supertrapps on my 68 Mustang fastback's 289. That and AC/DC concerts have probably contributed to the decline in my hearing LOL!

[Adam H P15 D30]

I used a stock muffler off an early 2000s Mustang GT.  Single 2.25 exhaust exiting in front of the right rear tire.

May be a little louder than you're looking for, but if you run it out the back it will quiet it down some.

Windows were down during these drives.

 

 

[Mr.P-15]

Hi All:

PROBLEM SOLVED! All you need is a Walker "Quiet Flow-3" model 21353. It's great! No brap, no blub-blub and no loud, irritating pipe organ drone. The car sounds just the way it should sound, the way they always did sound.

I must admit that I was a bit skeptical when I opened the box. Being only 58 CM long, it looked a bit stubby, and not at all like pictures of the original. Looking inside with a flashlight was not reassuring. I could see all the way to the end; how could this possibly work? "Lets leave as much space as possible just in case a resonator is needed!" I was mentally preparing myself for another disappointment, but the second the engine came to life I could hear the difference; and a road test proved it out. Perfect! Don't waste your time even thinking of a resonator!

This muffler is of the proper configuration: offset in, centre out. Both inlet and outlet are 5.1 CM  (2 inches). Yes, they do have another model that looks a lot more like the original, but it is centre in and offset out and not available the other way around. The folks at Walker (very helpful, I might add) told me that the "muffle-ability" specifications are identical, so, no matter anyway.

If you are looking for a nice, quiet you-can-have-a-conversation-in-the-car original sound, as I was, this is the one you are looking for.

Now that I am the proud owner of a nice, quiet P-15, I'm going to call Grandma and ask her for a date...

 

P.S. Loren: this is the one you want.

[Loren]

Got one on the way, THANKS!