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Thread: resonator delete = loss of torque?

  1. #1
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    Exclamation resonator delete = loss of torque?

    so i had some magnaflows put on yesterday and they sounded pretty good but i wanted it a little louder so i had the resonator taken out and installed 2 magnaflow resonators now it sounds great but i could swear i have lost some torque of the line has anyone had an issue like this?

  2. #2
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    yessir...since you removed the resonators you lost some back pressure which in turn resulted in you losing torque...happened to me too and boy you can feel the difference

  3. #3
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    I removed my resonator, and have noticed no loss of torque. Perhaps it's because I still have stock mufflers

  4. #4
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    Quote Originally Posted by farhod View Post
    yessir...since you removed the resonators you lost some back pressure which in turn resulted in you losing torque...happened to me too and boy you can feel the difference
    Myth.

    Modern BMWs don't have to worry about the effects of reduced backpressure, because the DME (car's computer) that controls the engine will detect that the engine is burning leaner than before, and will adjust fuel injection to compensate. So, in effect, reducing backpressure really does two good things: The engine can use work otherwise spent pushing exhaust gas out the tailpipe to propel the car forward, and the engine breathes better. Of course, the DME's ability to adjust fuel injection is limited by the physical parameters of the injection system (such as injector maximum flow rate and fuel system pressure), but with exhaust backpressure reduction, these limits won't be reached.

    Older cars with carburators, could run lean due to reduced backpressure, and without adjustment, could lead to bruned valves in some cases, but outside of that, the slightly reduced backpressure of removing resonators or mufflers from an otherwise full length exhaust does NOT reduce torque, even a little bit. IN fact, it can often INCREASE power and torque, due to less restriction and better exhaust flow. If reducing backpressure reduced torque, then no reputable engine builder would build or install free flowing cat-back exhaust systems or higher flow exhuast headers.

    http://www.remusexhaustshop.com/back...orque-a-6.html

  5. #5
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    i apprecate the info but i can tell you that today i went down to the bmw dealer and talked to the shop foreman and he has seen this happen many times at lower rpm's 1500 to 2000 when you remove the resonator... and i noticed the difference as well he suggested having the shop that did the work install an h pipe if i wanted to run with the magnaflow resonators and mufflers...so im waiting for the call to tell me the car is done i'll let you know how it turns out

  6. #6
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    Quote Originally Posted by cyim4u View Post
    i apprecate the info but i can tell you that today i went down to the bmw dealer and talked to the shop foreman and he has seen this happen many times at lower rpm's 1500 to 2000 when you remove the resonator... and i noticed the difference as well he suggested having the shop that did the work install an h pipe if i wanted to run with the magnaflow resonators and mufflers...so im waiting for the call to tell me the car is done i'll let you know how it turns out
    *shrug* Engines are engines, and work the same. My '98 didn't have any resonators on it to start with. And I saw no loss in power after removing my stock mufflers and going to high flow cats and straight pipes with no mufflers or resonators. If removing resonators and reducing backpressure behind the cats reduced torque, then no V8 tuners, domestic or foreign would use them. BMWs aren't special cases, especially the V8s.

    Simply put, the "remove backpressure, reduce torque" thing is an old school myth, that modern engine builders have debunked many times over. And after 30 years of building race cars and performance cars, I trust guys who specialize in making engines make more power, and spend a lot of time on the dyno, over a dealer tech that specializes in making the car back to stock.

  7. #7
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    Has anyone experimented with installing an x-pipe???



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  8. #8
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    Quote Originally Posted by cyim4u View Post
    i apprecate the info but i can tell you that today i went down to the bmw dealer and talked to the shop foreman and he has seen this happen many times at lower rpm's 1500 to 2000 when you remove the resonator... and i noticed the difference as well he suggested having the shop that did the work install an h pipe if i wanted to run with the magnaflow resonators and mufflers...so im waiting for the call to tell me the car is done i'll let you know how it turns out
    Are you loaded with money or something? Otherwise that's like putting your wallet into a toilet and flushing it

    Shop foreman at a BMW dealer? That's the wrong guy to talk to, unless you are loaded with money and don't really care
    Last edited by dophineh; 04-09-2009 at 09:40 PM.


  9. #9
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    Quote Originally Posted by dophineh View Post
    Are you loaded with money or something? Otherwise that's like putting your wallet into a toilet and flushing it

    Shop foreman at a BMW dealer? That's the wrong guy to talk to, unless you are loaded with money and don't really care
    Very ture!!!!!!
    Bad idea
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  10. #10
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    X or H pipe would it make any difference? Meaning the actual pipe itself, in regards to the torque issue. Can they be used in conjunction with the resonator or in place of the resonator

  11. #11
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    Quote Originally Posted by rdw3 View Post
    X or H pipe would it make any difference? Meaning the actual pipe itself, in regards to the torque issue. Can they be used in conjunction with the resonator or in place of the resonator
    I would think an X pipe would do a bit of torque increasing, as the left and right banks aren't connected, stock. And locating it about where the resonators are might work great. It might calm down the sound, too.

  12. #12
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    had the h pipe put in and car is much better i didnt think it would make that much of a difference but it did it also got rid of the blat sound i am quite happy with it sounds really good

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