Q for Mufflers' Experts for my 8.1 (How to reduce sound resonance?)

[GMCbigblock]

Hello......I need your assistance for my situation. I just bought and fixed the following Muffler on my 8.1 Truck:

"Dynomax® Performance Mufflers: Ultra Flo™ X" (Overall Length= 25 In.), (Shell Diameter= 4 1/4 x 9 3/4 In.), (Inlet & Outlet Diameter= 2 In. each)

While the performance is observed to be 'excellent & fits my off-road application', I findthe tone & sound-resonance is a bit high at our 'legal cruising speeds' (ranging between 75 to 87 MPH- depending on the street-type). Even during the acceleration, the Muffler sounds abnormally high and loud; which attracts the public's attention; especially the Cops

I do like the Muffler & its performance, and love to keep it....but am thinking to add extra 'sound-deadeners' right after the muffler or use 'sound-reducer' or any other good idea that you may offer or have used for a similar case!

For info, the Exhaust Manifold is stock with dual-pipes from top to tip; 3 In. each.

Am looking forward to hearing your valuable-advices and sharing your proven-experiences in reducing the sound while keeping the sound & performance at the peak; legally. Thanks in advance!

 

[dhcomp]

The 70 series Flowmasters are built for big block applications. They are pretty quiet at idle, but still sound good at Wide Open Throttle.

I would not use 2 mufflers in a row. Replace the dynomax.

Flowmaster even has sound clips on their website...although not really that accurate.

 

[GMCbigblock]

The 70 series Flowmasters are built for big block applications. They are pretty quiet at idle, but still sound good at Wide Open Throttle.

I would not use 2 mufflers in a row. Replace the dynomax.

Flowmaster even has sound clips on their website...although not really that accurate.

That was really fast and great.....Thank you.

Do I need to use one for the two pipes (as the case is with the current muffler, 2 in & 2 out), or one muffler per each Pipe?

 

[dhcomp]

That was really fast and great.....Thank you.

Do I need to use one for the two pipes (as the case is with the current muffler, 2 in & 2 out), or one muffler per each Pipe?

Either will work, if they make a 2in 2 out. Single is cheaper, but 2 will probably flow a bit better. Not a big deal either way.

 

[GMCbigblock]

Either will work, if they make a 2in 2 out. Single is cheaper, but 2 will probably flow a bit better. Not a big deal either way.

Noted and I just checked the same in Flowmaster's Website. I found the 70-series and also the 50's. But the 70's seem to better-fit my application. Thank you Darren.

 

[Cruz89K5]

I've got a 70 series dual in dual out on my 6.0. Quiet and no drone, but it's got a weird raspy sound at 3500-4000. Sounds like a V-10. I've got short turndowns and no cats though, might be part of it.

 

[GMCbigblock]

I've got a 70 series dual in dual out on my 6.0. Quiet and no drone, but it's got a weird raspy sound at 3500-4000. Sounds like a V-10. I've got short turndowns and no cats though, might be part of it.

Thank you for the feedback. And your comment sounds right, as it matches with the sound advertized in the YouTube under the title "Flowmaster Exhaust Systems". In that video; I observed the same "comment" (raspy sound)....however, am willing to trade off for sake of getting a quiter muffler (WITH NO DRONE), and yet flows efficiently.

Also, I am considernig going for dual mufflers (one per a pipe) as it will provide a better flow as well as better sound than 2-in-one; especially for Big-Blocks.

 

[Cruz89K5]

Thank you for the feedback. And your comment sounds right, as it matches with the sound advertized in the YouTube under the title "Flowmaster Exhaust Systems". In that video; I observed the same "comment" (raspy sound)....however, am willing to trade off for sake of getting a quiter muffler (WITH NO DRONE), and yet flows efficiently.

Also, I am considernig going for dual mufflers (one per a pipe) as it will provide a better flow as well as better sound than 2-in-one; especially for Big-Blocks.

It is very quiet and has a good sound. There's minimal noise in the cab even at highway speeds. If you want quiet you wont be disappointed. The raspy sound is annoying at first, but I dont notice it anymore.

 

[GMCbigblock]

It is very quiet and has a good sound. There's minimal noise in the cab even at highway speeds. If you want quiet you wont be disappointed. The raspy sound is annoying at first, but I dont notice it anymore.

Rogered that and I truly found the 'discussion outcomes' exchanged in this Thread and the Website really fruitful and do provide great help! Once again, thank you all for your time, info-sharing and value-addition.

Accordingly, I went ahead and just placed the order on 2 No. MF's 70-Series, and now waiting for their arrival and installation....eagerly.

 

[Greg72]

Do some research on resonators too.....

Study most modern cars and trucks and you will notice that the exhaust runs from the engine into a canister (called a resonator) and then continues to the back of the vehicle into the mufflers.

The resonator is a tuned canister that cancels out a lot of the droning noise of an exhaust. I first read about them on the DynoMax website (IIRC). They had some great articles on proper exhaust sizing based on engine size and HP, as well as calculating the size of the resonator for the system. Lots of tables that would allow you to cross-reference your calculations to an actual DynoMax product too...

A lot of young guys want a loud truck. Personally I find it annoying, whether it's on the highway or trying to enjoy some low-rpm wheeling on the trail.

Study up on resonators and I think you will solve your problems.


-G

 

[Deuling]

Once you get them installed, take some videos of how they sound, and maybe some of the terrain you use your blazer on out there!!

 

[dyeager535]

Been doing some research on this myself. I don't want to hear the exhaust at all to be honest. Sick of not being able to hear the phone (on speaker, drive safe! lol) so considering options.

The quietflow SS (stainless steel) series (http://www.walkerexhaust.com/products/mufflers_QFSS.asp) should be a less raspy/droney muffler. Maybe lose some power, maybe not, never seen dyno tests to show it. You may not need the SS, but it's just what I'm intending. Not real keen on potential loss of power vs. more performance oriented mufflers, but if it's far enough back, and large enough, it *probably* won't hurt things too much. I'm running stock mufflers now, so it's not going to change in my case. Yours might be different, but honestly, that far back, I just don't think loss of flow is going to hurt enough to notice, as long as flow is enough.

Along with that, a cat converter (or two) will help both with sound and odor, and as mentioned, a resonator as well. Resonators don't do much for overall sound (something around 4dB is what I saw for most of them) but likely helps more for drone. Interesting that there seems to be little concrete research/videos/whatever on them, but OEM's are using them, so you know there is benefit.

Issue with the K5 of course is that you don't have a ton of length to work with, but I am thinking if I can get the exhaust to crossover far enough forward I can use a single converter, with enough space for the muffler, and if still enough room, a resonator. I believe that is the order recommended, and on the K5,there isn't much room for a muffler to stay well hidden except in the stock location(s).

 

[454Sub]

I used to run my 454 with open headers for years on the road, but I guess I got old. I have basically stock exhaust on it now, but true duals. And it sounds like a stock showroom 350 at idle now. Alot of us went the quiet route after years of straight pipes and open headers. In the summer we have parties, and Im talking 50 to 60 trucks, buggies, cars, 4wheelers, and several trucks built sorta like monster trucks with 64in tractor type tires on them and they are all basically quiet now. So we can do that ALL NIGHT LONG and no one complains. And its so much nicer now that we can have fun at our local mudbog and no cops shut us down.

That being said the 70 series muffler has a good sound to it.

 

[Greg72]

If you like math....(and who doesn't?!) here's an article that might help. Helmholtz resonators...

http://www.performancetrucks.net/fo...xhaust-resonator-tube-eliminate-drone-489463/


-G

 

[GMCbigblock]

If you like math....(and who doesn't?!) here's an article that might help. Helmholtz resonators...

http://www.performancetrucks.net/fo...xhaust-resonator-tube-eliminate-drone-489463/

Thank you for the two adequate-responses, which will surely help me in reducing the loud-sound on my Blazer as well as the Sierra, as both are equipped with 8.1 and are talking "too Loud".

-G

I used to run my 454 with open headers for years on the road, but I guess I got old. I have basically stock exhaust on it now, but true duals. And it sounds like a stock showroom 350 at idle now. Alot of us went the quiet route after years of straight pipes and open headers. In the summer we have parties, and Im talking 50 to 60 trucks, buggies, cars, 4wheelers, and several trucks built sorta like monster trucks with 64in tractor type tires on them and they are all basically quiet now. So we can do that ALL NIGHT LONG and no one complains. And its so much nicer now that we can have fun at our local mudbog and no cops shut us down.

That being said the 70 series muffler has a good sound to it.

I feel you man….and "fun" is such a ‘great thing’ that none of us like to miss in everything we do daily. It’s known to be one of the strong-drivers to achieve results.

As for gatherings, we have similar arrangements in our area like the “Annual Jeep Jamboree”; which is organized by a local Jeep-Dealer. It gathers few hundreds of Jeeps, plus other types of 4X4 cars for 2-day trip in the desert. It is always fun to drive with some distinction, sound, look, drive-style etc…So’ I’ll give it a try with the 70 Series.

Been doing some research on this myself. I don't want to hear the exhaust at all to be honest. Sick of not being able to hear the phone (on speaker, drive safe! lol) so considering options.

The quietflow SS (stainless steel) series (http://www.walkerexhaust.com/products/mufflers_QFSS.asp) should be a less raspy/droney muffler. Maybe lose some power, maybe not, never seen dyno tests to show it. You may not need the SS, but it's just what I'm intending. Not real keen on potential loss of power vs. more performance oriented mufflers, but if it's far enough back, and large enough, it *probably* won't hurt things too much. I'm running stock mufflers now, so it's not going to change in my case. Yours might be different, but honestly, that far back, I just don't think loss of flow is going to hurt enough to notice, as long as flow is enough.

Along with that, a cat converter (or two) will help both with sound and odor, and as mentioned, a resonator as well. Resonators don't do much for overall sound (something around 4dB is what I saw for most of them) but likely helps more for drone. Interesting that there seems to be little concrete research/videos/whatever on them, but OEM's are using them, so you know there is benefit.

Issue with the K5 of course is that you don't have a ton of length to work with, but I am thinking if I can get the exhaust to crossover far enough forward I can use a single converter, with enough space for the muffler, and if still enough room, a resonator. I believe that is the order recommended, and on the K5,there isn't much room for a muffler to stay well hidden except in the stock location(s).

Thank you for the illustration, and in my case I think I will go for the resonators for my Blazer; whereas I will fit the 70-Series in the Sierra; to treat the sound, which is my desire (as I use the Sierra more often than the Blazer, to tow my XP-900 Polaris RZR to the remote deserts).

Generally; whenever am driving any V8 car, I simply cannot live without hearing its rumble (within reasonable tolernaces)…..As for the dyno results, I’ve seen a loss of good 5 to 8 horses when using restricted exhaust mufflers compared to easier-flow ones, and this range is potential to grow depending on the exhaust’s overall setup and engine’s size, configuration etc. Thus, I’ll keep trying to achieve maximum flow with least noise, as much achievable as possible and available. I tried the 'cross-over' in my K5 and it proved to bring better balanced exhaust flow and reduced-tone, and I will repeat the same in the Sierra.

Once you get them installed, take some videos of how they sound, and maybe some of the terrain you use your blazer on out there!!

I’ll do my best, as am not much into voice and photo’s capturing. No worries, will try with a friend of mine, and in case the sound & pictures are captured digitally; I’ll post ‘em right here for you and other interested Members J

Extra-Note:
Sorry to derail from the track of the Thread, but for sake of having a break for change, and to respond to the request, I opted to post herein some photos on the same terrain that I normally pass thru numerous times using my Blazer……


To help shaping quick idea about our terrain, the vast majority of our area is sandy, and the 'external remote deserts' are having series of dunes, soft & lose sands, extreme and deep bowls. The sand-dunes are getting bigger as we head towards the 'Empty-Quarter', the dunes become chained to each other in long series, with some gigantic sand-accumulations (only found in empty-Quarter); which are normally formed due to the build-up of several dunes, one over the other; altogether making a total height of more than 900-Feet.

 

[GMCbigblock]

Here is a good link to stop by and read/see interesting material:


http://www.wellknownplaces.com/2012/09/tal-moreeb-adventure-in-abu-dhabi.html

 

[Cruz89K5]

Man I'd love to come play in those dunes. I cant imagine shipping a quad there would be cheap. Thanks for sharing.

 

[Deuling]

I love sand! Sweeet. Looks like some fantastic wheeling

 

[dyeager535]

As for the dyno results, I’ve seen a loss of good 5 to 8 horses when using restricted exhaust mufflers compared to easier-flow ones, and this range is potential to grow depending on the exhaust’s overall setup and engine’s size, configuration etc. Thus, I’ll keep trying to achieve maximum flow with least noise, as much achievable as possible and available. [/quote]

Yes, lots of variables factor into exhaust. The further back you can place any restriction to exhaust, the better off you are. Single size exhaust from front to rear is actually pointless, as exhaust gases cool they don't need as much space. Getting into exhaust theory, tapering the exhaust down from front to rear would net the best results, but that's obviously impractical for most of us to test for optimum results on every vehicle. It's easier/smarter to go too big than too small if you want to make sure you aren't costing power.

Converters appear to be very powerful in taking drone out of exhaust, if cost isn't too much, they may be more beneficial overall than a resonator IMO, especially since most resonators don't seem to be particularly cheap. I know there is a stigma about converters, but testing of modern high-flow cats shows little if any affect on power. I don't run them now, but plan on changing that when I re-do the exhaust, putting my money where my mouth is, so to speak.

A friend took the muffler off of his late 80's 350 and just left the high-flow cat in place. To me the tone sounded good. Louder, but still deep toned.

 

[GMCbigblock]

Guys, I feel you, and playing serious sand-bashing worth tons of fun. Good luck.

I find the info posted here so far, has exceeded my expectation, and I really find it much useful for resolution of my case as well as knowledge base update.

Many thanks.