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Headers on a 6.2L with Stock Muffler/Cat-Back?

Discussion in 'Performance' started by 91RS, Mar 27, 2019.

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  1. ls1frc

    ls1frc Full Access Member

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    Both slip joints are confirmed leaking. Can see the soot as well as the condensation leaking out on cold start.

    With aftermarket cats they have to get hot before they filter enough thus it makes sense that it would go right inside.

    I'll try to seal them up and report back. I just drove the truck tonight and the sound is perfect with headers to stock catback, would suck to have to take them off.
     
    Last edited: Apr 26, 2020
    kbuskill likes this.
  2. ls1frc

    ls1frc Full Access Member

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    Fixed my leaks.

    I had leaks at every single connection. Ball socket, slip fits, and rear ball socket to muffler connection. Used the shop vac in the tailpipe and soapy water technique. Smell is gone after fixing that.

    Only issue I have now is after the lifter swap to Morels (they are LOUD) the headers are amplifying the noise badly in the cabin with the windows up. Any suggestions? I really don't want to have to go back to Manifolds. Love the sound with the windows down, but up and no radio/AC on and it's pretty annoying.
     
  3. avalonandl

    avalonandl Full Access Member

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    The headers are amplifying the Lifter Noise?

    Have you tried putting Dyna Mat on the underside of the engine cover?
     
  4. 91RS

    91RS Full Access Member

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    All LS engines have noisy valve train and the noise is amplified with long tubes. I thought I did something wrong when I did the cam in my SS but its still going strong 25k miles later. I did change to better oil, Redline 5W-30, which made a huge reduction in the noise. I've always used Mobil 1 before and didn't see much reason to use the "boutique" oils but now I use Redline in all of my vehicles.
     
  5. ls1frc

    ls1frc Full Access Member

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    Yeah I've been in the LS game since 2008. Had multiple cammed and header vehicles so I know what to expect.

    This sound I am hearing is just a different resonance than normal. I think it's because the Yukon is so heavy, it's always in this high load area when in low RPM which is where I hear the resonance. With the cars, you don't hit this area at low RPM because they're half the weight.

    It's not a drone, it's hard to explain. Kind of like an air rushing out noise, which makes sense since the collectors are right there at the floorboard.

    It's the same noise this guy complained about in 2013. I may just live with it because the 5.3 is actually fun to drive now with all the mods and I know it'll lose 20-30 hp going to manifolds.

    https://www.performancetrucks.net/f...ce-21/arh-possible-kooks-header-noise-519538/
     
  6. ls1frc

    ls1frc Full Access Member

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    Wondering if the "tinny" resonance has anything to do with feeding these high flowing headers into the stock, restrictive exhaust and there is some back pressure being built up.

    Wonder if swapping that portion out may change the sound at all. Doubt it, but worth a shot maybe since my stock catback is rusted to shit anyway.
     
  7. iamdub

    iamdub Full Access Member

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    At stock/near stock power levels (no boost, nitrous, etc.), the stock exhaust really isn't so restrictive. More accurately, the tubing is sized properly. It's the muffler that's the biggest choke, inherent to its design. It's quite oversized to reduce the choke while still effectively muffling, so even it isn't so bad.

    I've always heard a sort of pinging/sort of ticking/sort of ringing sound from equal-length/long tube headers that was from where the primaries met that open area in the collector, which is also right at the floorboard/lower firewall. Thicker steel, heavy coatings or wrapping reduces the sound. I recently installed some tri-Ys and that sound I was expecting wasn't nearly as prominent. My guess is it's because the tri-Y design separates the pulses so they're already attenuated upstream before they hit the collector. The headers are 14 gauge and supposedly are coated three times on the inside and five times on the outside. With it running, I walked around underneath it to listen for that sound and it seemed to be loudest near the first bend of the Y-pipe, which isn't coated. I may wrap it in the future after I get the rest of the exhaust how I want it.
     
  8. DRKN57

    DRKN57 Member

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    Loud is a matter of opinion, lol


    Sent from my iPhone using Tapatalk
     
  9. ls1frc

    ls1frc Full Access Member

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    Yeah my truck is slow, definitely not a restriction. I think some sound deadening is my only option. Worth a shot before manifolds go back on.

    Truck isn't loud, the sound is just an annoying frequency.
     
  10. ls1frc

    ls1frc Full Access Member

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    I took a video of the noise, it's very clear in the video. Listened to old videos from 2011-2014 of all my header cars I had back then and none had that constant "chirping" noise. They just sounded clean. They all had catbacks too though.



    Basically, less noisy version of what this dude is also dealing with.

     
    Last edited: Jul 5, 2020

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