Quiet muffler choices

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bbab3

bbab3

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I have gotten to the point of building the exhaust system for my '67 fb Barracuda. It has a 372/340 with a 833 trans. For exhaust I have Doug's headers, Summit 2.5" X-pipe kit and Flowmaster 15826 tailpipes. My problem trying to find flow numbers for the Walker Quiet Flow mufflers 21548 and 21856. The other mufflers I am considering are the Dynomax Super Turbo mufflers 17749 and 17662 which both flow 700 SCFM. From what I have read on on FABO and else ware the Quiet Flows are quieter but reduce to 1 7/8" internally which means the are not going to flow as much as the Super Turbos. My question is how much do they flow? A number of people recommend the Quiet Flows including VOETOM because they are quieter then the Super Turbos. I just want to do things right the first time. Thanks
 
Sorry about he title misspell
 
Not a direct answer, but worth a read:
Auto Exhaust Science

Short version is: look at modern OEM systems for clues. Lots and lots of volume is required to get 'OEM quiet'. The smaller the body of the muffler, regardless of pipe diameters, will mean more noise. The larger the body, the less noise.

In order to come up with solutions, you need a detailed description of your goal. So, how quiet do you want to be?
 
I think with the pair that far back it may not be as large of a restriction since the gasses have cooled some. I have the Super Turbos and they sound good but mine drone at around 2k.

Is offset/offset correct for your set up? Stock is center/offset.
 
Walker offers a step up from a stock replacement. It IS a stock replacement, but it's like a factory high flow. It's not the Dynomax.

Look at the Walker 18230.
 
I love the Flowmaster Delta Flow Muffler 40 series. The standard 40 series are to loud, but the Delta Flow don't have the drone and sound better than the Super Turbos
 
Your 372, is a hot build up?
I’m not sure what you’d looking for. The Quietest muffler, the muffler case should be as long as possible to Absorb the most sound. This however can lead to less than optimum power output.
These were super quite.
Cut away of a Dyno Max muffler #18381

Also, click on the links within that thread.
 
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Where are you? I have some 17748 Dynomaxes that are nice. And they are offset in, center out like you need BUT they are 2" longer than the stock 18" body so you would need to be creative when you try to install them.
 
VOETOM has forgotten more about mufflers than i will ever know, but i know that if you want quiet, and good flow, get a large enough pipe, and the biggest, longest muffler you can get under the car. And quiet will usually be a triple pass.
I do have some 3 1/2 in/out flowmasters that i consider quiet(you might not), but they are a HUGE case, 5x12, 24"long.
 
Thanks for the link Auto Exhaust Science. The Walker 21856 are spec'd for 500ci Caddy that is one the main reasons I considering it.

The possible drone with the Super Turbos my main concern with them.

I will ad the Walker 18230 to the list.

The 372 I built is "mild". Eddy heads, ld340 manifold, 625 Street Avenger carb, a cam from Racer Brown .450 lift int/ex adv duration 264. Gearing for the rear axle is 3.00 9" Furd, and 26" tires. From what I have read the 19" case length is max that will fit. The Dynomax/Walker replacement muffler 18339 is 19" long and has the right offsets.

I live on the northern end of the Olympic peninsula in Washington. Thanks, a long ways away.

This article is what has me the most interested in the Super Turbos.
Exhaust (pontiacstreetperformance.com)
 
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Not sure if this helps at all but Engine Masters did a $40 muffler shootout. I cannot find the full episode but here is the clip of the chambered mufflers. Full episode is out there somewhere. They also tested straight through and welded. Dynomax was not included but they did have Walker turbos. No info on drone.

 
My Hardtop with 500 stroker had straight thru racing mufflers. I go to work at 5am so I through 3" suburban mufflers on it lol . Sorry poor quality.
 
doug 371 said:
I have those on my truck and to me they seem WAY louder than a dyno max
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To be honest I’ve never had a set of Dyno Max and I can’t say either way on them. I’ll just have to take your word on that because you have. I would definitely recommend he get together with others that have mufflers that he’s interested in and listen to them and take a good ride to hear them in order to make the best decision for him.
 
Kendog 170 said:
Do they drone on the hyway ?
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To me they don’t. But you may have more sensitive hearing than I do. If you have the ability to get together with others that have mufflers that you’re interested in so you can listen to and take a good ride with to hear them so you can make a great decision for your car.
 
I called Walker's technical service line this morning and asked about the flow numbers for the Quiet flow 3 mufflers. He told me that they don't have those numbers listed with the spec's for that line of mufflers. But, that they typically flow 290-320 SCFM. After talking to him more about my concern regarding a restrictive muffler and sound he suggested using their Bullet muffler 24215 as a resonator upstream of a Super Turbo muffler. The Bullet is short glass pack, removes the drone associated to the Turbos. Once I get the tail pipes I can see exactly what size and offset mufflers will fit and go that route.

The link above Auto Exhaust Science, discusses the formula of HP X 2.2 = flow. If my motor makes 350hp it needs 770SCFM of flow. So it will need more flow than what the Quiet Flow 3's will give.
 
IMO these muffler companies should have 4/6/8 test mills and list dyno and sound numbers. The Pypes video says they have been working on that muffler for 12 years.
 
bbab3 said:
I called Walker's technical service line this morning and asked about the flow numbers for the Quiet flow 3 mufflers. He told me that they don't have those numbers listed with the spec's for that line of mufflers. But, that they typically flow 290-320 SCFM.
Click to expand...
Good call on making the phone call. That is enough cfm for a good hot rod. (Twin mufflers of course.)
After talking to him more about my concern ....
suggested using their Bullet muffler 24215 as a resonator upstream of a Super Turbo muffler. The Bullet is short glass pack, removes the drone associated to the Turbos.
Click to expand...
This is accurate. I have done that myself. The sound does change a tiny bit. The glass pack gives a flat (Bugs Bunny, Elmore) fudd fudd fudd sound. The longer the glass pack, the more quite it will be.
The link above Auto Exhaust Science, discusses the formula of HP X 2.2 = flow. If my motor makes 350hp it needs 770SCFM of flow. So it will need more flow than what the Quiet Flow 3's will give.
Click to expand...
A 350 hp engine needs 770 cfm. Check!
Dual Quite Flows will indeed be short of cfm flow. However!
The power will lack once the flow limits of the muffler(s) occurs & will be noticed (if at all) on the top end. The low end to mid rpm power levels will feel good and be good. It depends on where and/or when the engine is moving more air than the mufflers can handle. This is an interesting and variable point I think, depending on the engines build and C.I.D.

Things that make you go;
Hmmmmmm
(Arsenio Hall, LOL!)
:lol:
 
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