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Non annoying muffler choices

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wittsend View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wittsend Quote  Post ReplyReply Direct Link To This Post Posted: Jan/11/2023 at 11:41am
Originally posted by BDCVG BDCVG wrote:

... The science of exhaust sound and how mufflers bounce sound waves around and affect flow make most calculus teachers cringe.

I'll agree to that. I have a 318 V-8 Valiant. Two stock cast iron manifolds combined into a 3" pipe with a three chamber (50 series) Flowmaster. The D-R-O-N-E from 1,900-2,600 RPM was utterly unbearable. The drone didn't blend in gradually, it came and went IMMEDIATELY. The military could have used the results for sonic warfare. Using what I had on hand I switched to a 2-1/4" pipe and a Raptor (turbo style) muffler. That only somewhat toned down the drone.

The cast manifolds, the blending the two into one pipe thus the quieting pulse effect of an H or X pipe,  reducing the pipe from 3" to 2-1/4" and swapping the Flowmaster for a Turbo style muffler should have all contributed to avoiding if not significantly dealing with the drone. Yet it made only a marginal difference. The cam (Edelbrock Performer clone) in that motor has  58 degree overlap. I often wonder if that is a contributor to the droning???
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1958 rambler super Quote  Post ReplyReply Direct Link To This Post Posted: Jan/12/2023 at 8:54am
This has been a really good thread I started, gathering lots of info and opinions.
 Why is longer better farna? 


Edited by 1958 rambler super - Jan/12/2023 at 8:58am
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Trader View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jan/12/2023 at 9:59am
That is pretty easy from a design point of view. Think trumpet vs tuba in length vs pitch.
You want lower frequency sound, longer in almost all cases will provide it.
It takes a lot more work to get a lower frequency out of a short muffler without having to restrict flow with multiple chamber passes to get the same relative tube length in a smaller case.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dkrtgood Quote  Post ReplyReply Direct Link To This Post Posted: Jan/12/2023 at 10:28am
I truly hate loud drone, I put a jegs cat back mustang kit with mandrel 2 1/2 tube and it is louder than I would like. I don't like the sound of any stainless exhaust so it's just alumanized steel. I just pulled down front x pipe and put 12" glass packs in ahead of x to see if it quiets it down any. 

390 with free flow manifolds, 2 1/2" full mandrel bend pipe and x pipe all the way out tailpipes.

If this doesn't cure the drone i will just swap mufflers...they were stated as turbo style in the jegs kit..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jan/12/2023 at 11:24am
Typically the only reason SS will sound a little "tinny" vs CS is because it's made from thinner gauge material, all else being equal.
The problem with 68-70 AMX/Javelin with 2-1/2" pipes is that you can only fit a 14"x9" muffler if put in the stock location. Short muffler, "tinny" sound and more drone.
Add to that, an X pipe will sound "tinny" vs an H pipe.
I have the same on my car, changed to turbo from glass pack mufflers and reduced the drone by half, but the next thing would be to put a resonators in front of the X pipes.
Wish I had done the H pipe - live and learn!
IMO, the Walker Quiet Flow SS muffler is one of the best for sound, Flowmaster 50 next. Too bad neither comes in an offset 14"x9" - 2-1/2". 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote dkrtgood Quote  Post ReplyReply Direct Link To This Post Posted: Jan/12/2023 at 11:53am
Originally posted by Trader Trader wrote:

Typically the only reason SS will sound a little "tinny" vs CS is because it's made from thinner gauge material, all else being equal.
The problem with 68-70 AMX/Javelin with 2-1/2" pipes is that you can only fit a 14"x9" muffler if put in the stock location. Short muffler, "tinny" sound and more drone.
Add to that, an X pipe will sound "tinny" vs an H pipe.
I have the same on my car, changed to turbo from glass pack mufflers and reduced the drone by half, but the next thing would be to put a resonators in front of the X pipes.
Wish I had done the H pipe - live and learn!
IMO, the Walker Quiet Flow SS muffler is one of the best for sound, Flowmaster 50 next. Too bad neither comes in an offset 14"x9" - 2-1/2". 


Yeah i'm hoping that adding 12" glass packs ahead of X sort of a resonator squashes it enough. Never cared for the high performance dynomax or flowmasters...I drive my car daily and would want to shoot myself listening to that crap daily
Dave Goodwin
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amxdreamer Quote  Post ReplyReply Direct Link To This Post Posted: Jan/12/2023 at 5:41pm
H pipe and magnaflows on my AMX, duals with magnaflows on the cop car with no H pipe. The cop car has a nice burble at idle and driving but is pretty loud and barks when full throttle compared to the AMX.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mr_Roboto Quote  Post ReplyReply Direct Link To This Post Posted: Jan/13/2023 at 10:03am
Walker Quiet Flow in the biggest case size that fits. SoundFX if you want a bit of volume to it. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 70Xcode Quote  Post ReplyReply Direct Link To This Post Posted: Jan/25/2023 at 9:01pm
I use tractor supply tractor mufflers if what you want is cheap and quiet 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote THE MENACE Quote  Post ReplyReply Direct Link To This Post Posted: Jan/25/2023 at 10:12pm
Yeah, if you put the wrong muffler on a six cylinder it can make your car sound terrible!  

A couple of years ago I replaced the muffler in my daily driver 4.0L Jeep XJ with an AP Exhaust Products muffler. May be different to your needs, but the part number I purchased was #700045 and cost $42.00 on Amazon. It's still on the Jeep and still sounds great. 

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