Quite exhaust ideas??
11-11-2017, 09:46 AM
#1
TECH Regular
Thread Starter
Quite exhaust ideas?? I'm building a street rod with an LS3. I'm looking for some ideas on how to make it sound stock OEM quite. Why? Well..... Ive had drag cars and I'm old 
. My wife and I will take long trips and I want to be able to talk at highway speeds and listen to music, etc. I don't want any highway drone. Also not concerned about killing a little hp. I haven't stumbled on any aftermarket mufflers that even come close to stock, SO I've been looking at take off mufflers such as Camaro, Corvette, and Mustang. I'm noticing the OEM folks also usually use catalytic convertors and sometimes resonators along with a good size muffler/mufflers. Anybody been down this road that can shed some light on this subject? Many thanks! Kharp
. My wife and I will take long trips and I want to be able to talk at highway speeds and listen to music, etc. I don't want any highway drone. Also not concerned about killing a little hp. I haven't stumbled on any aftermarket mufflers that even come close to stock, SO I've been looking at take off mufflers such as Camaro, Corvette, and Mustang. I'm noticing the OEM folks also usually use catalytic convertors and sometimes resonators along with a good size muffler/mufflers. Anybody been down this road that can shed some light on this subject? Many thanks! Kharp Last edited by Kharp; 11-12-2017 at 07:43 AM.
11-11-2017, 10:09 AM
#2
I used a turbo, a long resonator, and a typical off the shelf "turbo" muffler, to get it fairly quiet. Helps to conserve fuel if you know what I mean (less output from the engine). It sounds like a van or something, because now its so quiet I can hear the subtle transmission's whine, so it reminds me like a big chevy van.
If you want it to open back up use a cut-out.
Some notes on output:
a naturally aspirated engine would need individual exhaust tubes (a header) in any performance application. One of the things that annoyed me was the two sides of exhaust to deal with; I really didn't want to have to Y-pipe it, or make some difficult extensive dual exhaust under the vehicle to deal with (I prefer things that are simple and easy to deal with, and a Twin exhaust with an X-pipe and multiple sections/hangers custom welded seemed tedious). Furthermore, if you screw up the design under the car, the output will suffer, sometimes dramatically.
I threw all of that worry in the trash by going turbo. Now, I have just one single downpipe to deal with, and it doesn't matter how "restrictive" or "wrong shapes" it is because the engine has an atmosphere dial (boost controller) as opposed to depending on and requiring a 'perfect exhaust mated' to an engine which requires it.
If you want it to open back up use a cut-out.
Some notes on output:
a naturally aspirated engine would need individual exhaust tubes (a header) in any performance application. One of the things that annoyed me was the two sides of exhaust to deal with; I really didn't want to have to Y-pipe it, or make some difficult extensive dual exhaust under the vehicle to deal with (I prefer things that are simple and easy to deal with, and a Twin exhaust with an X-pipe and multiple sections/hangers custom welded seemed tedious). Furthermore, if you screw up the design under the car, the output will suffer, sometimes dramatically.
I threw all of that worry in the trash by going turbo. Now, I have just one single downpipe to deal with, and it doesn't matter how "restrictive" or "wrong shapes" it is because the engine has an atmosphere dial (boost controller) as opposed to depending on and requiring a 'perfect exhaust mated' to an engine which requires it.
11-11-2017, 10:20 AM
#3
Good luck! Definitely run the exhaust all the way out the back, make sure you don't do like I did and not leave enough room to snake the tailpipes over the axle. 
Other than that, just get the biggest muffler you can fit under the car. You are pretty much stuck with where you can put them, so there's not really any way to move them towards the rear, which helps, so there really isn't a lot of options. Other than that, the wind noise will probably drown out some of it, I know on my car it does. Driving a car meant to usually go 45mph at 85mph down the freeway tends to be a little loud! 
Other than that, just get the biggest muffler you can fit under the car. You are pretty much stuck with where you can put them, so there's not really any way to move them towards the rear, which helps, so there really isn't a lot of options. Other than that, the wind noise will probably drown out some of it, I know on my car it does. Driving a car meant to usually go 45mph at 85mph down the freeway tends to be a little loud!
11-11-2017, 10:29 AM
#4
Back in the day (1986) I ran two of the largest bodied truck mufflers I could find (Kmart Auto service .LOL) with down spouts. Even without tailpipes, it was dead quiet.
If quiet is the goal, I do the same thing today, but with tailpipes.
If quiet is the goal, I do the same thing today, but with tailpipes.
11-11-2017, 03:36 PM
#5
Add a short round bullet as a resonator early after the header/manifold then add a turbo muffler where it fits under the car. Tail pipes out the back.
That will do the trick
That will do the trick
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11-12-2017, 08:12 AM
#8
Quiet exhaust We must be in the same age group! I have a '39 Chevy and wanted quiet also so I went with large Magnaflows. Routing the exhaust wasn't easy. Driver side had to dip under the engine/trans gap, over to pass. side then back over to driver side under the trans tailshaft. Not enough room to go over the rear end so had to go under but I've had no problems with that. Cruising into a show is a problem because they don't hear me coming! If I get on it, there is a bark and at highway speeds there is a little rumble but not something I can't live without.
11-12-2017, 02:56 PM
#9
TECH Senior Member
IMHO, stealth is good! Don't show your hand until necessary.... lol
11-14-2017, 06:46 AM
#11
Been chasing this for almost 20 years with my car. For my old ears, anything aftermarket is just too loud. And much of it with drone on top of that. Tried Bassani, Borla, Magnaflow, Spintech, Flowmaster -- various configs and sizes -- all too loud. Finally realized that OEM was the way to go for me. My car works best with a single transverse muffler at the rear - so I used an OEM replica Boss 429 transverse. Dual inlet/outlet - pic below. Nice and quiet, but flow restrictive. Eventually, packing burned out and it got too loud. Plus I knew more HP was coming with the LS conversion (previously an old pushrod 5.0L V8) so I needed quiet with more flow. So I fabbed up a single big transverse muffler (32"L x 9" x 12"W) using 2 Mustang 5.0L Coyote mufflers. No drone, quiet but a good tone when you're on the gas hard. Big - but it takes big mufflers if you want it quiet and not too restrictive.
Old Boss 429 set up ---
Now - turned these ---
Into this ---
All that to say -- you're on the right track if you want high performance AND quiet -- no one does that like the OEM's.
Old Boss 429 set up ---
Now - turned these ---
Into this ---
All that to say -- you're on the right track if you want high performance AND quiet -- no one does that like the OEM's.
11-14-2017, 01:17 PM
#17
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I always run glasspacks before the mufflers. I have a set of 24" glasspacks in front of Flowmaster mufflers on my Chevelle Wagon with LS1 and I think it sounds great. About as loud as a stock corvette. Idle and light throttle is quiet, and when you get on it has a nice tone. No Drone on the Highway.
Resonators may have the same result.
Resonators may have the same result.
11-14-2017, 01:44 PM
#18
TECH Addict
I am evidentially in the old fart class as well, just swapped out the spin-tech on my Jeep for a Magnaflow-XL, its a hybrid stock style turbo with a slightly different baffle setup, its much quieter but does have a small drone at 3000 rpm.. I'm trying to figure out a way to fit a small resonators in there somewhere to kill the hum on the freeway.. its not my DD but I typically am doing long trips in it..
11-14-2017, 02:08 PM
#19
I am evidentially in the old fart class as well, just swapped out the spin-tech on my Jeep for a Magnaflow-XL, its a hybrid stock style turbo with a slightly different baffle setup, its much quieter but does have a small drone at 3000 rpm.. I'm trying to figure out a way to fit a small resonators in there somewhere to kill the hum on the freeway.. its not my DD but I typically am doing long trips in it..
11-14-2017, 06:00 PM
#20
Part of the challenge here is that terms like "too quiet", "too loud", "not too loud", "a little drone" are all subjective. They're really only meaningful to the person doing the listening. Two different people can listen to the same car/system - one loves it and one hates it. Further confounding things -- trying to compare sound clips is useless. Different phones, mics, speakers, etc. - reproduction can sound far different than the car does in person. Further - it can sound very different inside the car vs. outside. And - intake noise adds a tremendous amount to the sound the car makes when run hard - both inside and outside the car. So -- things are complex.
I believe the best anyone can do is experiment until they find something THEY like on THEIR car. Sounds like 64 sleeper has stumbled onto an approach that works for him, as have I. So to the OP -- good luck! About the only useful piece I think I can add was alluded to up above: If you want it to both flow well and be quiet, it almost always takes a big muffler to do that. And no one does big mufflers like the OEM's.
I believe the best anyone can do is experiment until they find something THEY like on THEIR car. Sounds like 64 sleeper has stumbled onto an approach that works for him, as have I. So to the OP -- good luck! About the only useful piece I think I can add was alluded to up above: If you want it to both flow well and be quiet, it almost always takes a big muffler to do that. And no one does big mufflers like the OEM's.