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Need it as quiet as possible without choking the flow

Discussion in 'General Discussion' started by iamdub, Jun 20, 2020.

  1. Dantheman1540

    Dantheman1540 Full Access Member

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    @iamdub did you ever get this figured out? I'm dumb and backed myself into the same exhaust corner and never realized you had the same 12599. I have 2 different sets of Vibrants I'm considering but wondering what you ended up doing.

    Also do you think the location of the resonator matters in terms of sound? I have room before or after the 12599.
     
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  2. 91RS

    91RS Full Access Member

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    I'm telling you, the Corsa Touring is worth every single penny if you want it quiet but still want it to flow (and it won't look like garbage in a year when the exhaust shop special is all rusty). I don't know how they get a flow through muffler to be so quiet. My 08 with long tubes and Corsa Touring is quieter than my 12 with stock y-pipe and Corsa Sport (with 6.2L).
     
  3. iamdub

    iamdub Full Access Member

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    For the most part!

    I never updated this thread, so this reply will serve as the update. First off: Screw that corkscrew insert! I could feel the sluggishness and, according to my DIC, it cost me at least 1 MPG at 65-70 MPH. I immediately went home and cut it out, rewelded the tailpipe back on and went right back out for another test. The sluggishness was gone and I was getting 1-1.xx MPG more at 65-70 MPH.

    At first, I thought my dual mufflers made barely any difference. It turns out the exhaust valve leaks a lot of air and sound. So, the straightpipe side, that runs parallel to the mufflers but is turned down in front of the axle was creating a lot of noise that reverberated under the cabin. With it plugged off (stuffed towels in it), it's quieter than when I had cats. So, 40" of muffler might be too quiet for you. I'll be merging that straightpipe side back into the pipe leaving the muffler and arching over the axle so whatever sound "leaks" through it will just join the muffled side and go out the back. I think it's gonna sound pretty wild outside and be plenty quiet inside. Of course, I'll be able to electronically switch it so that it'll be primarily flowing through the straightpipe side with a little "leaking" through the muffled side.

    I have the 12259 clone, which is an 18" body with offset/center configuration coupled with a 12579 clone which is a 22" body with center/center configuration. Basically 40" of the same type of muffler with a little offset on one end. Your 12599 is a dual in/dual out configuration with internal X-pipe. It's the same 22" body size as the 12589 and 12579. I'm guessing that because it has two 3" pipes going through it instead of just one, it has a lot less packing to do as much muffling. Based on my experience, you need more muffling to make up for what it's lacking.

    It's hard to say what the resonators will do. Many companies make a small muffler that basically just a much smaller version of the regular muffler and call it a "resonator". These Magnaflows (and their clones) we're discussing are all pretty much just glasspacks but with a lot more body to hold a lot more packing. It's a perforated pipe wrapped in packing and encased in an oval-shaped body. Many "resonators" are the exact same thing, but much smaller. I think an actual resonator is a more calculated design that manipulates the sound waves rather than just absorbs them. The factory resonator at the tail end of the system is an actual resonator. It's a Helmholtz chamber. But, instead of being a pipe that extends off the main pipe, it's like a pipe "rolled over onto the other pipe". It's length, volume and location in the system has been calculated to target a specific frequency.

    If them Vibrants actually have some sort of a hollow chamber in them to reflect and manipulate sound waves, then they are truly resonators. What frequency they'll target is a wild guess. They may just be supplemental mufflers, though. Last I looked inside one, I saw a perforated tube going through a stainless body. No clue what was between the tube and body, though.

    My thoughts on location are that they'd be more effective after the muffler. I see them more as a "clean up" device. The muffler's main job is to absorb to attenuate sound, although some reflecting/manipulating will take place since it is a chamber (just not hollow). So, whatever notes that still make it through the muffler will at least be weaker. The resonator or smaller "after-mufflers" act as a secondary "filter". I think that, due to their size, they'd be much less effective if located ahead of the muffler. It's like using a toothbrush to scrub your entire dash, then using the vacuum to try to clean the crevices versus cleaning the large area with the vacuum and the toothbrush just for the crevices. Also, temperature and air velocity play a role in the sound waves. The temperature and velocity of the exhaust air will be different after the muffler than before, so this will affect what frequencies are left for the resonator and/or supplemental mufflers to act upon, rendering them either more or less effective.
     
  4. iamdub

    iamdub Full Access Member

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    You have cats on them long tubes on your '08? After listening to YouTube vids of the Corsa, I'm thinking that I essentially created a giant, $100 Corsa Touring muffler with my shenanigans.
     
  5. Dantheman1540

    Dantheman1540 Full Access Member

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    I agree most if not nearly all straight through mufflers are just funny shaped glasspacks and likely will not be completely silent ever which is fine performance/efficiency is still top of the list or I would have never cut out the flopro.

    Are you running dual 3" out the back or a single pipe?
    That's nice to know about the cork screw thingy I was googling them half the day haha.

    Do you have an pictures of your setup? Also sound clips? I think I saw some in another thread but I don't remember where. I am still going to work at an all straight through "Quiet-er" dual 3" setup. Probably unobtainable but I like throwing money in the trash. If I end up filling the entire exhaust area with muffler and its to loud then I guess I'll have to get a Borg Warner T6 turbo muffler.
     
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  6. iamdub

    iamdub Full Access Member

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    Single 3" all the way through the mufflers. It tapers down to the factory 2.75" for the factory arch over the axle. I have some bent 3.5" tubing I'll squash to make another arch that should have the same volume as the 3" pipe but not consume any more space so the axle won't hit it (lowered). I have pics in my build thread, starting on Page 78: https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/page-78. I don't believe I have any videos yet since I'm not finished. I've only made a couple 0-60 vids and you can hear the sound from inside, if listening to that would tell you anything. Here's the one from my build thread: https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/page-85#post-1491218

    I'm sure you wouldn't mind yours being a little louder than mine. With cats, that one 18" muffler was perfect. No drone, only loud when I was really gettin' on it (but not obnoxiously loud inside) and just a mild, soothing, distant purr when cruising. Not obtrusive in the least. Now, with 40" of muffler (which is pretty much the most you can squeeze in there), it's quieter than it was with the cats and that 18" muffler. I wanted this since I have that cutout to open 'er up when I want to. So, unless you want it as quiet as possible, you should be fine with a little less muffler than I have.
     
  7. 91RS

    91RS Full Access Member

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    I do have cats on the headers. I don't want it to smell too bad. Let me tell you the Corsa Sport for the 6.2L with the long tubes was LOUD (at WOT)! I loved it but not what I wanted for an Escalade. My friend's 05 RCSB 5.3L with long tubes and Corsa Sport is nowhere near as loud as mine was.
     
  8. Dantheman1540

    Dantheman1540 Full Access Member

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    Looks good and you did that yourself very nice! The over axle section is really tight the dual 3" has been squished a bit and has a few dents from the axle shoving it into the body from before I added appropriately sized bump stops and after the free travel mod.

    I ordered some slip fittings so I can attach each resonator/muffler directly to the tailpipe and record the decibel difference. I also found a set of Dynomax bullets in the very bottom of my parts stash so I have 3 sets of different sized straight through muffler/resonators to test. Looking at the Dynomax specs they claim up to a 4-decibel drop with just a single 6" bullet. So I have hopes that a combination of the 6 will get me where I want to be while all being straight through.
     
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  9. Dantheman1540

    Dantheman1540 Full Access Member

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    I've always heard those Corsa mufflers were ridiculously loud, possibly louder than their price tag.
     
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  10. randeez

    randeez Full Access Member

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    its only money
     

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