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Thread: Another muffler exhaust question.

  1. #1
    Junior Member
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    Another muffler exhaust question.

    I enjoy the sound of my stock exhaust but would like to update the design or clean up the engine compartment. Clearly all the newer aftermarket systems out there do this very nicely. The only problem I find with this new systems are they are bit noisy or drone. Does anyone have experience with an aftermarket quiet exhaust. Honestly if there was replacement headers that mounted to the stock exhaust , that would be the perfect solution for me. I have a test pipe and this was all the extra sound I enjoy. Also what is the deal with the wrap around exhaust design, seems a bit complex for an exhaust system. Thanks in advance

  2. #2
    Not a DeLorean Guru
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    Yes.
    -Mike
    1981 DeLorean, Carb LS4 swap completed
    1999 Corvette, cam/headers/intake manifold, 400 rwhp
    2005 Elise, stock
    2016 Chevy Cruze

  3. #3
    Senior Member Josh's Avatar
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    If you want quiet, stick with the stock exhaust.

  4. #4
    Junior Member
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    Quote Originally Posted by Josh View Post
    If you want quiet, stick with the stock exhaust.
    yep, I saw that coming . Was just checking if someone out there had a aftermarket exhaust system that was close to stock.

  5. #5
    Senior Member
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    Yeah, it seems that the aftermarket version of "quiet" is a lot different than what people who actually want a quiet exhaust think it is. I have an almost-finished 3.0L conversion with DPI headers running through Magnaflow CARB-compliant cats and into a dual in/dual out Borla Pro XS muffler. The Borla is supposedly "quiet", but that seems to be relative to all the other free-flow aftermarket mufflers. It still seems pretty loud to me.

    Now, so far I've only run it in a garage, which is making it extra loud. Once I'm back on the road, I'm going to take measurements outside at 50 and 100 feet using a sound meter. About a month after that I'll be installing two three-disc Car Chemistry silencers in the pipes between the cats and the mufflers with stainless steel wool packed between them and measuring the sound again. In theory they'll cut 3-10 dB of noise out (where every 10 db is approximately halving the sound level). However, this will reduce the performance. Which I'm fine with, because I'll sacrifice power for quiet. I have a second set of inserts I want to install after the muffler as well; these will be less effective, but I want to see what they do to the noise level.

    Also, the crossover inside the muffler should reduce droning (like what x-pipes do, or so I'm led to believe by Google). I originally had a grand plan to install two cats, then have the pipes go up at a 45 degree angle, though some resonators, into an X-pupe, then down to separate mufflers before exiting out the tailpipes. There is nowhere near enough room for that. My next idea was to run the pipes forward under the transaxles and out the sides, but there's no room for that under the car, and it would just be silly anyway.

    I'll report back when I've actually done the sound tests. If all goes well, I'll be driving the car this or next weekend, assuming no unexpected issues crop up (it's been about 5 years, so this wouldn't surprise me, but I'm hopeful everything will go well).

    -- Joe

  6. #6
    '82 T3 Turbo FABombjoy's Avatar
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    The stock crossover contributes to the quietness of the system, as does the stock pipe diameter and cork.. er "muffler".

    Rear engine means short path for tubing which makes it a challenge to bring out the pleasing lower-tones. Consider the tonal differences between a trumpet and a tuba: both have the same mouthpiece but the tuba has 2-3x more tubing length.

    This is the OEM system from a Carrera. Gargantuan mufflers, twin cats, and a fair amount of pipe:
    https://cdn4.pelicanparts.com/techar...mall/pic01.jpg

    Compare to the king of shortness:
    https://www.deloreanautoparts.com/de...ader-kit-2.jpg

    With a crossover muffler design like DPI or DMCH at least you get a larger muffler body and additional pipe length. You can try to kill drone with resonators or cats or other such devices but I haven't seen much success with that strategy. The muffler should be doing the heavy lifting.

    Philosophically I feel very strongly that best muffler is a turbocharger
    Luke S :: 10270 :: 82 Grey 5-Speed :: Single Watercooled T3 .60/.48 :: Borla Exhaust :: MSD Ignition :: MS3X Fully SFI Odd-fire EFI :: DevilsOwn Methanol Injection

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  7. #7
    Sometimes Owner louielouie2000's Avatar
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    Someone asked this exact question last year. Josh at DPI offered to cut open one of his Spec I mufflers to see if any additional stainless steel wool packing material could be added. I'm not sure if the owner actually had Josh do that, though. There are also debates regarding the merits of muffler packing materials, be it steel wool or fiberglass. I believe fiberglass is quieter, but won't hold up to high temps as well. Which I suspect is definitely an issue with the aftermarket DeLorean systems, seeing how the headers, cats, and mufflers all feed immediately into each other with no chance of heat dissipation.

    I know this is going to be Teitelbaum obvious, but retaining the catalytic converters on any of the aftermarket kits definitely helps cut down on the noise vs replacing them with "test pipes." Regardless, all the aftermarket systems are louder than stock. I believe the modern DMC-Texas systems are probably the quietest of the aftermarket lot, though.
    Louie Golden

  8. #8
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    I'm impressed by how convoluted that Carerra exhaust is.

    You could probably do the dual-mufflers routed past each other, but you'd need a way to bend the pipes to pull it off, and that's out of the scope of most DIY people (I stuck with pre-bent pipes and slip joints, mostly). Maybe you could use a series of 45 and 90 degree pre-bent pipes, but you'd either have to weld them or leave a lot of space for clamps. An even then, it might just BARELY fit, car-width-wise. I doubt you could also fit resonators under the mufflers. That would be more ideal but probably too tight.

    My Borla Pro XS install is really not much different from the DPI or DMC setup, but less elegant (they have nicely bent pipes), configuration-wise. It was more a learning exercise and allowed me to experiment more easily, and I can swap out individual parts to try out different configurations if I want, especially since everything is only clamped together. I also used 2.5" pipe; using smaller pipe would have reduced noise as well, as will the silencers that I plan to put in (they're basically corks).

    -- Joe

  9. #9
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    Quote Originally Posted by louielouie2000 View Post
    Someone asked this exact question last year. Josh at DPI offered to cut open one of his Spec I mufflers to see if any additional stainless steel wool packing material could be added. I'm not sure if the owner actually had Josh do that, though.
    I am said owner. I sent the exhaust to DPI at the end of July 2015 (everything but the headers). I heard back in December 2015 that it was ready to test, and they wanted to match it to an engine similar to what I had (3.0L) to see how it sounded. In November 2016 I got an email saying that it was ready to ship, and they just needed to know where to send it. I sent the info, but I never heard back. I sent a few more emails and left some voicemails, but by the middle of 2017 I just gave up and built my own exhaust using the DPI headers as a base. I'm not out any money or anything (just time), and I wasn't going to use the DPI muffler anymore if it wasn't silenced anyway, so it's not a huge loss to me.

    Point is, I don't know if the silenced SPEC I works or not.

    -- Joe
    Last edited by jangell; 08-09-2018 at 01:17 PM.

  10. #10
    President, DeLorean Industries
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    Joe, I was unaware we didn't send you a test muffler back. This fell through the cracks apparently. Let us know what we can do to make it right even though you made your own.

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