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chstickl

How to get a real whisper quiet exhaust system

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Hi there,

by the time we probably all have aftermarket exhaust systems for our pre-war cars. For my two 37s I purchased the complete system at Waldron´s with mixed experience. The cars got a lot louder than they have been before. Not good for a car that should be nothing but humming.... Looking at the drawing inside the documentation and into the pipe of the muffler, it becomes clear why. These aftermarket things are built up inside a lot simpler and cheaper than what used to be the original according to drawings (less chambers, simpler pipe perforation, no damping material).

Question 1: Are there other sources you can recommend for whisper quiet mufflers?

Question 2: Do you know any DYI instruction, dimensions etc. to try to make one myself?

Thanks as allways for good advice,

Christian

P.S. yes, I know that Waldrons has a "loud" and a normal version of mufflers, but even the normal ones are too loud for me.

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Thanks for putting this out there. I have a made up in the 1970s (whatever was handy) oval muffler which is to be round on my 1925 standard. It is too loud and does need replaced. I would like to replace with a more correct style but would like it to muffle!

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I rebuilt the exhaust system on my 1922 Model 48 from the manifold on back. The reason for this was I made a new cutout for the floorboards mounted exhaust heater. The original cutout was discarded when a new muffler was put on the car sometime in the 1940's. My friend, the late Dave Chambers, told me exactly what the dimensions should be on the muffler and I had the folks at Kepich Exhaust build a new muffler for me using those specs. I have had no problems at all with this muffler and it runs really quiet for an inline six cylinder engine. The thing that really throws a lot of people when they see the car is the twin tailpipes. I told one guy that there was a bored and stroked nailhead V-8 under the hood and he almost fell over. Seriously, with the exhaust heater setup, you have to have a second pipe coming from the heater unit. An it does work good.

Terry Wiegand

South Hutchinson, Kansas

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As an interesting historical aside: Our AACA regional newsletter

has reprinted an old article about first-hand experience with an

1897 Benz, from someone who was there in 1897. That car was

so loud, even with its original muffler, that the owner said it could

be heard a mile or two away! The car's noise took the place of a

warning horn!

But your question is an excellent one, and I too am waiting to hear the answer.

I agree that aftermarket exhausts haven't made cars as quiet as they should be.

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I' too am interested if this info gets out and about. I have a full stainless system on my '41 Roadmaster, for durability. It works fine, but yes, the sound is not how I remember these with an original type.

Keith

Edited by Buicknutty (see edit history)

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Although I am not an acoustical engineer, I did sell multiplex piston pumps that resemble automotive engines (which are basically air pumps). So although you will not get a definitive answer to your individual needs, I will take a stab at explaining the issues.

Multiple pistons mounted on a rotating crankshaft create sinusoidal flow curves that overlap with each other creating louder sounds due to more than one piston discharging into the pipe at the same time. So, 4.6 & 8 cylinder cars sound differently. The pulses also occur at different times and require different muffler construction to cancel out these pulses. Piston displacement also comes into play as larger pistons will create larger flows and louder pulses that require larger openings in the muffler internals (or larger overall muffler size).

Basically, mufflers can be made to direct the pulses against each other like noise cancelling headphones and/or in combination with fiberglass to absorb the sound energy by vibrating the fibers. The spacing geometry and sizing of the holes in the channels within the muffler can be "tuned" to match the pulses from the engine to create the desired effect.

IMO, the problem with buying most aftermarket performance mufflers is that they are designed to create "muscle car" sounds and lower flow resistance rather than the quietest option. In any case, there is no single style that will work best for a variety of cars & trucks.

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Edited by Mark Shaw (see edit history)

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Mr. Nagel mentioned the use of stainless steel being louder because the material is 'harder'. I do not think that I ever heard that before. I have always heard that stainless was used to fight the forces of corrosion associated with the heating and cooling of the system. When I had Kepich build the muffler for the '22, stainless was almost double the cost of the 'aluminized' muffler that I chose. If I was putting 30 or 40 thousand miles a year on the car then stainless would have probably been the route I would have taken. I cannot take any side with what Mark Shaw posted. 'Sounds' good to me Mark - excuse that pun there about the sound. I'm just a lowly tool maker with a penchant for smooth-running OLD Buicks that run soft and sweet.

Terry Wiegand

South Hutchinson, Kansas

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This discussion got me thinking. I looked under my car and I don't know what type of muffler I have but it is clearly not an original. I think my 1937 is quiet but I have never heard one with an original muffler. I happen to have received an original NOS muffler with the car when I bought it. Now I am wondering if I want to install that NOS muffler and see if it is quieter...

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