Mid-muffler delete??

Discussion in 'All Wheel Drive Chargers' started by BigHoss, Apr 12, 2017.

  1. BigHoss

    BigHoss New Member

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    Thinking of doing a mid-muffler delete on my 09 r/t AWD. Will doing this hurt the engine in anyway? I'm concerned about losing back pressure and hurting the engine and losing my warranty.
     
  2. Stevens12

    Stevens12 Active Member

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    Nope, won't hurt a thing and when I did it on my 2012 r/t, I noticed no loss of power from it. Remove it and enjoy the new exhaust sound.
     
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  3. Skidz

    Skidz New Member

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    I concur with Steven. Best inexpensive mod I've ever made on a car.
     
  4. BigHoss

    BigHoss New Member

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    how bad is the drone??
     
  5. egoods

    egoods New Member

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    At least on my 2014 there is a slight drone at highway speeds when the MDS kicks in, this is due to the gearing in the AWD vehicles, it just so happens to put the RPM right in the sweet spot to drone. I used a tuner to disable MDS (lost about 2-3mpg in fuel economy), when I was researching the issue a while back I stumbled across a few posts that stated you could put it into manual shift mode once at highway speed and it would handle shifting for you... those posts were from a while ago and unfortunately for me that's not the case (downshifts like normal, but it holds the gear when accelerating up to an obnoxious RPM).

    Many people aren't bothered by the drone, and to be fair it's not deafening (I've had to point it out to people riding in my car) but it was getting on my nerves. Otherwise I love the muffler delete, it's the way these cars should've sounded from the factory.
     
  6. BigHoss

    BigHoss New Member

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    Egoods thanks for the info.
     
  7. SolApathy

    SolApathy ... Moderator Site Supporter Level 5

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    Deleting the mufflers is not going to cause any drone. Deleting the resonators will increase drone significantly, as their function is to reduce drone.
     
  8. egoods

    egoods New Member

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    I'd be happy to re-enable MDS and record the drone that my car (which has a muffler delete, but retains the resonators) has on my way to lunch today... The 3.06 rear gearing in the AWD Chargers put the RPM right into that sweet spot at about 75-80 with MDS engaged. Your statement is true of the RWD Chargers which have 2.65 rear gearing. Not trying to be argumentative, just want to provide good info, as it's something I wish I was aware of before I removed my mufflers.

    Edit: Also, the purpose of resonators is to alter the resonance frequency of the exhaust to a frequency outside of what the exhaust system is capable of producing. In this case, they're not sufficient in altering the resonance of the exhaust system. You could certainly eliminate the drone by using different length/design resonators or altering other exhaust characteristics. It's akin to a musical instrument, it must be properly tuned to sound right. I will agree that running without resonators would most certainly create an unbearable drone, but simply having them doesn't eliminate the possibility.
     
    Last edited: May 17, 2017
  9. egoods

    egoods New Member

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    I'm going to reply again, since it occurred to me that I didn't directly address OP's concern very well. You won't do any damage to your engine whatsoever, and if any dealership gives you issues with a warranty claim they're crazy people (it'd be pretty much unheard of). But, yes the muffler delete will reduce exhaust back pressure, which hypothetically could cause a decrease in engine torque. I don't notice any difference, and without a dyno/more info on how restrictive the mufflers are, I can only speculate... but in my experience large displacement naturally aspirated engines tend to have little issue with a reduction in backpressure, and in some cases it even improves performance numbers. Also, you may notice a slight "wobble" in your RPM at idle for a few days after the delete (it's hardly noticeable unless you're watching your rev counter), but the ECU will adjust to it's new "conditions" and smooth out.
     
  10. Skidz

    Skidz New Member

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    I'm curious. Why would reduced back pressure cause a decrease of torque? It seems counter intuitive. The whole point of the internal combustion engine is it's basically an air pump. Suck the air in (mixed with fuel), burn it, push the burnt product out. Lower back pressure means more efficient scavenging of the cylinder during the exhaust stroke allowing more air/fuel mixture back into the cylinder during the intake stroke. Isn't that what aftermarket exhaust headers and performance exhaust systems are made to do, decrease back pressure to create a more efficient running engine?
     
  11. JCE

    JCE Member

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    The mid muffler delete doesn't reduce any power what-so-ever. I'm still doing consistent 0-60's in 5.1~5.2 seconds before and after this mod. The mid mufflers are a pass-through design as is the straight pipes put on in their place. It also doesn't really drone at all cruising along with 4cyl mode or otherwise on my '16 R/T since I left the rear resonators on. You'll get a little drone when you are under medium or heavy throttle but cruising along you get almost zero.
     
  12. SolApathy

    SolApathy ... Moderator Site Supporter Level 5

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    Back pressure is not what causes the low end torque loss, it is the exhaust velocity. Exhaust is a unique type of plumbing system, as it operates in pulses. When a pulse of exhaust gas runs through the pipes, a collection of exhaust gases flows out, and as it as it passes through the system it has a little area of vacuum behind it that assists in "pulling" out the next pulse. Just like a NASCAR car running around the track, the pulse generates a little bit of a vacuum behind it. In NASCAR, a driver can take advantage of another driver's vacuum by getting right behind him and driving in it. The wind resistance is drastically reduced. This is called drafting, in the exhaust world it is referred to as scavenging.


    At lower RPM's you have a pulsed system, but as RPM's increase the flow becomes more consistent, reducing the vacuum effect that draws out the next "pulse" - which lowers the amount of effort required to "push" out the exhaust gases. This is why at lower RPM's the exhaust velocity can affect the low RPM torque range. I think a lot of people get back pressure confused with gas velocity.

    I hope this helps to explain it a bit
     
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  13. Skidz

    Skidz New Member

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    ^^ Thank you ^^

    This makes a lot more sense. Since my early gear head days, I've heard people make different claims about back pressure and none of them seemed quite right to me.
     
  14. gotzaRT

    gotzaRT Member

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    This right here.

    On a side note, I'm so sick and tired of this "back pressure BS. This post I quoted should be a sticky on every forum and FB page.
     

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