Quiet, mellow mufflers?
 

I need some help from those more experienced then me on muffler selection. This is for my '56 Chev pickup with a hot cam LS-3 and a 6L80E. I bought it with a horrendously noisy exhaust system. It had terrible harmonics, and it was torture to sit in the truck at idle.
I just had the entire system replaced with mandrel bent 2-1/2" stainless pipes, H-pipe, and Magnaflow 18" long mufflers. As the truck has a C-4 IRS suspension, there is no reasonable way to exit it at the rear. The exit is out the sides, ahead of the rear tires. The old system had turn downs, but it was blowing dirt all over the rear wheels, so the new system has straight out square tips.
I "auditioned" the Magnaflows, but the shop was in a metal high-roof building and what I thought I heard inside is not what I ended up with.
The new system is at least as loud as the old system, and with any reasonable throttle, it is way noisier. The harmonics issue is gone, but I don't think I can live with this. I have the Camaro with Flowmasters as the in-your-face vehicle, this one needs to be a quieter, mellower hot rod.
So I am looking for recommendations for a QUIET muffler. Performance is a secondary consideration.
Thanks in advance for sharing your experience!

Bill

I've only tried Magnaflow on my daily Yukon. Their cat-back system. A little too much sound for me on a daily and had a terrible highway drone. Flowmaster has several different styles of mufflers and they are rated by sound, I swapped just the muffler on my Magna system over to a flowmaster an have been very pleased... something I noticed though, usually the quieter the muffler, the bigger the muffler... pay attention to the sizes.


Jef-

Thanks, Jef. Do you know which model Flowmasters?

I've tried several types of mufflers and the one I felt was the best for power/ flow and mellow quiet cruising was the Dynomax turbos. They're decently deep toned and quiet when cruising and come alive fairly well when you lay into it. As with other turbos they have internal flow direction changes but they have bends inside the muffler that direct and keep the flow moving smoothly instead of just dumping into a chamber and then moving through another tube, if that makes sense.

I grew up in the 80s and have always loved the sound of Flowmasters, but every vehicle I had them on from a street strip Nova to my 76 Suburban to my G-body wagon the drone was a little annoying. Their larger truck mufflers are said to cut down on that drone.

50 series Delta Flow is what I used on my Yukon...

You could try adding resonators up stream of the mufflers if you have room.

Borla XS. Run your pipe/pipes (mine is 3" single) under the C4 pumpkin. Mount muffler(s) at end of vehicle, not under the middle. This is the best muffler I have ever had in my 20+ years of doing stupid hotrod things (and I am so old that I now hate loud exhaust).

Is it an 18" case length or 18" overall? The biggest they make is 4x9, 24" overall (18" case) and is fairly quiet. I installed a pair on an LSX 454 and they was too quiet

Have you researched side branch resonator / Helmholtz chambers / "J" pipes? It may be a less expensive way to "tune" your exhaust.

http://penn.freeservers.com/jeep/wj/qfrexhaust/

https://ls1tech.com/forums/cadillac-...ltz-tubes.html

I know it's not a muffler, but it may be worth looking into.

Also, you may want to look at:



:cheers:

I ran the Borla XS and it was pretty quiet..it also depends on muffler size.

I ran Billy Boats on my Mustang that were 20" long and even with full 3" exhaust and a fairly hot motor it was quiet compared to most to run 90DB at Laguna.

Borla.

I ended up with the Dyno Max Turbos on my convertible Cutlass running a stock 350, manifolds and a 2-1/2” kit to the bumper. I tried the cheaper Borla which I belive are the XS, Magnaflow & Flowmaster and all had a untalerable amount of drone between 30-40MPH.

I’ve had a chance to hear the exhaust of several of the Stielow builds. I think in the older builds he’s used Stainless Works & Borla XR1’s. I was shocked how quite the XR1’s were at idle and at cruising speeds but at WOT they screamed.

I've got Flowmaster Super 44's, with full-length tailpipes, on my 70. They sound tinny, are really loud, have lots of resonance/drone, and the overall sound quality just sucks. I've outgrown the need for racecar sound levels so a pair of 20" Dynomax Super Turbos are probably going on the car, soon.

I want something quiet enough I can carry on a decent conversation with my passenger or enjoy the car's audio system.

Thank you all for your input.
As usual, ask 10 people, you'll get 10 answers. Nothing wrong with that....everyone has different experiences and perceptions and hence, opinions.
I was told almost 50 years ago when I was looking for my first set of home stereo speakers, confounded by the 40 or 50 choices, "you pay your nickel, and you see the show." In other words, you'll won't know how any of these speakers sound in YOUR house until you get them home. That is one of the most universal pieces of advise I have ever been offered.
There is another shop in my area that will cut off my old (new) mufflers & tack on several types to compare. My hope is they have 3 or 4 of the above suggestions.
This time, I will make sure we back the truck outside and check the sound more than at idle.:headspin:

Thanks again for all the suggestions!!

It is not difficult to run the exhaust pipes under the pumpkin of an IRS. This is my '67 Camaro.

Dynomax 17749
 

http://www.pontiacstreetperformance....p/exhaust.html

YW

That is a SWEET setup! But it is more involved (expensive) than I want to put in the truck at this time. But I certainly will keep this type of routing in mind if I take this thing to another level...

Great article! A lot of interesting info.
I have an appointment on the 10th to "audition" the Flowmaster 50's, Dynomax Super turbo, and 1 or 2 others. We'll see what my ears think...

Thanks for the info!

IMHO hard to beat flow master rumble. Adjust pipe size and number of chambers to your liking.

I dropped 13db at idle by going from the traditional straight through 14" case mufflers (think Magnaflow, Borla, Pypes) to the Dynomax Turbos.

There are only so many designs when it comes to mufflers... go for the Turbo style where the exhaust pulses actually have to change directions and add an X-pipe if you want something quieter and liveable.

The bigger/longer the muffler case the quieter they will be... 3" race style mufflers sound cool unless you actually want to drive and enjoy the car!

I'm a mod on the Team Chevelle site and there have been many discussions about mufflers, over the years. Dynomax seems to be the leading muffler of choice, when it comes to quiet performance.

FWIW, I am leaning towards the Dynomax Turbo or Flowmaster 50 series, but hoping my "audition" will clarify the decision. I also would strongly prefer a stainless muffler as my entire system is now stainless. That limits the Dynomax choice to an offset/ offset muffler, which is a change from the current center/offset setup. Not sure how easily that will be to change. I am hoping to keep the pipes relatively as-is.

Any updates?

I am in the same boat..... I want my cake and eat it too walk softly and carry a big stick!!!!

Stan

My exhaust guy talked me out of changing the mufflers UNTIL I get the LS3 tuned, which needs to be done because the previous owner put a Holley hi ram manifold on it. That really messed with the cold and low end tuning. It only makes sense to wait until the engine is running perfectly.

My tuning appointment is in a couple weeks. I will post an update when it happens. Should be in the next few weeks.

I agree. Here's a test of various mufflers. In this test, the Dynomax Turbo 17740 has the best balance of performance and noise level.

https://s8.postimg.cc/w68uurqtd/Muffler_Comparison.jpg

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THIS


3" is definitely a sound increaser... went with 2 1/2" on the '40 -- engine builder (Don Hardy) said that was plenty for 550hp. I was pushing for 3" and they talked me out of it. BUT ------ I did have them put in electric cutouts for the rumble thru a parking lot show. Damn kids...... LOL

WHY? Just because.

I went with Walker Quiet Flows. Similar to the Dynomax super turbos which I was running before. When the super turbos finally needed to be replaced, I decided to try for something a little quieter. The quiet flows are in fact a little quieter, and very quiet overall. My system consists also of cats and resonators too.

I need to check those out, as I've never heard of them, before.

Any updates?

Stan

I've decided to live with the Magnaflows for the time being. This is for a few reasons...
A. The engine tuning I had done mostly eliminated the exhaust popping and gurgling on decel. That helped the sound issue a bunch. So the sound is growing on me, or more accurately, is annoying me less. My friends tell me they like the sound from the outside. But it is still pretty obnoxious at high throttle.
B. I have more important issues at hand, #1 is getting the trans to work properly. Thought it was simply a programming issue, but now thinking it may be mechanical. Really need to get that sorted out first.
C. Still undecided if I'm going to keep this truck or just sell it.

What is your transmission issue?

How much time you got? :headspin:
It is a 6L80 that is supposed to be brand new. By the looks of it, I think it is new.
The main issue is it gets "lost" at light throttle, usually after decel, like when slowing for a railroad track or approaching a red light. Then when you lightly accelerate, it goes to downshift, then mid-downshift decides it needs to go back to upshift and bangs into the gear it just downshifted from. Goes back & forth...up/ down/ up/ down....I call it "lost". This continues til you accelerate enough to "forcefully" make it downshift with more throttle.
Took it to a tuner who found some upshift & downshift points that were set at the same speed. SO it appeared when he adjusted those points it would be cured. But all that did was change the speeds that it happens from the 30-40 mph range to the 50-60 mph range.
My tuner questioned whether there is a mechanical issue with the trans. I took it to a reputable trans shop in my area (owned by a street rodder). He scanned it (found no codes), and we went for a ride. It did the lost thing once during the test ride, but after it got really warm (over 180) it stopped doing it & I couldn't induce the issue. He thinks it is fine mechanically and it is a programming issue.
After I dropped him back at the shop, it did it again on my way home.
So it does this every time I drive it, mostly during warmup, but not always so.

Another issue is it has a very tight convertor in it...I'm guessing 1500 stall speed or so. The engine idles at 870-880 and is tugging at the convertor. So it is constantly trying to move the truck at idle. It will drive the truck at 7-8 mph at idle. It takes high brake pedal effort to hold it at a stop light and makes it tricky to pull into my garage with Racedeck matting.
GMPP recommends a 3200-3400 rpm convertor for the LS-3/ 480 hp. for auto trans applications.
I have a 3000-3200 convertor on order that should help this issue.
Once the convertor is installed, I think my next approach is to find someone who can simply install a stock ZL-1 program into my trans. and see where that takes us.
Thanks for asking. Always looking for someone who can steer me in the right direction.

I like my Borla XSPro’s on my Chevelle. I’m thinking about going with some Tesla mufflers however to quiet it down some.

I looked at a set of Tesla Turbos, but their range is too short for long cruises, and there aren't many superchargers around here.:headspin:

Do you have a stand alone controller for the trans? What brand?

No, the 6L80's have an internal TCU. Part of the valve body I'm told. There is a 15-ish wire harness going from the trans to the GM ECU so the engine & trans can communicate. That's about all I know about it at the time being.

I have/had something similar in my combo, coyote with 4R70w and simple shift command ecu. Trans builder said it’s the ecu the ecu company said it’s the trans. The trans builder back probed the w/h going from ecu to the trans ( where the shift signal comes from ) and proved that it shifts (at the screwy times) due to the ecu telling it to do so. The question then became why is the ecu telling it to shift. Right now I am leaning towards too narrow of a canbus signal from my gas pedal making inputs to the ecu way to sensative