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Thread: 3.0L even fire dual exhaust

  1. #1
    Owner since 2007 Farrar's Avatar
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    3.0L even fire dual exhaust

    For anyone interested. I did my best to capture the best sound I could, using headphones to monitor. This was made for someone who was interested in the mufflers I used.

    DeLorean status: Whatever.

  2. #2
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    Just curious, but how loud is it? Iím guessing itís not exactly quiet, but itís really hard to tell from a video with no other sounds or a dB meter for reference.

    ó Joe

  3. #3
    Owner since 2007 Farrar's Avatar
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    When I bought the car in 2007, it had Houston's 2004 "Performance Exhaust" on it. I'd say this setup is comparable in terms of volume.

    I have a pretty good field recording kit, but I don't have an SPL meter.
    DeLorean status: Whatever.

  4. #4
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    Thanks! Those mufflers do seem to put out a nice sound.

    Iíve almost finally got my 3.0L on the road with cats and a Borla Pro XS in a slightly odd configuration, plus some Car Chemistry silencers in an attempt to make a sort of quieter exhaust, but thereís really no space to put any real silencing measures in their óin my (not even remotely tuned) tests, it doesnít sound quiet at all. Not much to be done as long as itís a gas engine, I guess.

    ó Joe

  5. #5
    Owner since 2007 Farrar's Avatar
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    Sounds like an interesting setup. That's the same muffler I used, but as you can see I used two of them.

    I wanted to use some resonators to quiet things down, but I couldn't find enough space to mount them. C'est la vie, I suppose.
    DeLorean status: Whatever.

  6. #6
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    Ah yes, right at the beginning of your video you say that, and I somehow overlooked it.

    Some Googling suggested the Borla Pro XS is the "quietest", although this is a relative term -- the test setup was on a Mustang in a garage without cats and it was around 80 dB idling. The problem with finding quieting solutions is that anything aftermarket seems to assume you want power and noise. Probably because stock exhausts are already pretty quiet in most cars, and ours are a bit of an exception.

    I had plans of using cats, then a 45 degree up-angle to some Vibrant Ultra Quiet Resonators into an X pipe, then back down to mufflers on each side before exiting the tail pipe. That went out the door once I simply placed the resonator at the 45 degree angle -- it'll either poke out of the engine bay or go well below the bumper. And there wasn't enough room to fit the single in/single out mufflers below it either. I also considered some convoluted plan where I'd run the pipes forwards, but I doubt there's room for that. I looked at Porsche exhaust setups, but they seem to have a lot more room to work with.

    The one I'm using is the dual in/dual out design, positioned about where the original muffler would be. This isn't really a muffler like the DMC one (it's designed to run to the engine from the same side, not opposite sides), so I am running the driver's side from the engine and into the "top" chamber, then out the top again to the tail pipe. The passenger side uses the bottom. The interesting bit will be the hole between the chambers that links them; the small amount of gasses going the opposite direction shouldn't be a real problem, but I'm pretty much making this up as I go along. . The muffler sits a little low, but I'm limited by the odd run of the pipes.

    The Car Chemistry silencers are the three-disc variety, plus I welded on both caps and put stuffed the discs with a conservative amount of stainless steel wool. I got one per side, and riveted them in the pipes between the cats and the mufflers. For headers, I have the ones from a DPI.

    Even this setup just barely fits, with millimeters between the back of the subframe and the muffler. Mostly this is because I clamped the bulk of the exhaust instead of welding it, and am using 2.5" pipes and 90 degree bends (since I have no means to bend pipes) with the tightest bends available (2.5"), and even the smallest 50 state cats I could readily find (Walkers) just barely fit. Once the engine is running reliably I'll have to check for exhaust leaks around the clamped areas, which wouldn't surprise me at all.

    -- Joe

  7. #7
    Owner since 2007 Farrar's Avatar
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    Quote Originally Posted by jangell View Post
    Some Googling suggested the Borla Pro XS is the "quietest",
    That's exactly why I chose them. (Also they're stainless steel.) Then I installed them and, well ... I was surprised. Apparently "quiet" on a muscle car forum doesn't mean much. I like to listen to the radio. On the highway in a three-speed DeLorean, I might as well shut the radio off. :\ Now I know why some people end up insulating their DeLoreans from the inside!

    I'm not familiar with your car, so I am curious whether you are using a catalyst to retain the oxygen sensor, or because Massachusetts requires it. It does complicate things, but it sounds like you've got it in hand. With the crossover in the muffler I am sure it will sound nice, too.
    DeLorean status: Whatever.

  8. #8
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    I'm using cats just because it felt like I should, so not for any particular reason. California is strict about emissions control (mid-1970s or later cars need, I think), but MA doesn't do emissions testing unless your car has OBD-II. Also, cats should theoretically reduce a bit of the noise by adding an extra restriction. I'm hoping it'll be more like diesel truck levels of noise by the time I'm out of the garage, but I'm not sure I can get to that.

    I'm using all stainless steel hardware except the pipe from the headers to the cat, because I had to weld the flange on and I've gotten the impression that oxyfuel welding stainless is hard without some insert gases and such.

    I actually do have the O2 sensor for MegaSquirt, but it's mounted in the DPI headers, not in the cats, so if I do remove the cats I can retain it. If I thought I could fit a resonator in place of the cats and it would lower the noise level, I'd probably do it. I might try to install a second set of silencers in the pipes from the muffler to the tailpipes, but that'll probably only drop about 3 dB, and it's every 10 dB that halves (or doubles) the amount of sound.

    The X-pipe (and, by extension, the crossover muffler) supposedly reduces some droning sounds, but since I've never experienced it I won't know if it's helping with that.

    I have covered the back wall and parcel shelf with Dynamat, as well as the floors, but soundproofing is like sealing for water -- any gap and it all leaks in. It has to be completely sealed up, and you can only do so much due seams, glass, holes for wires and hoses, etc.

    I wish I knew more about how modern car exhausts work in production vehicles to make them so quiet. The sheer length of most cars exhaust systems help a lot, I imagine. It's seems to be very hard to find any information on this subject.

    In another decade or so maybe there'll be enough junked electric cars, good enough batteries and accessible conversion hardware that I can have a truly quiet car.

    -- Joe

  9. #9
    '82 T3 Turbo FABombjoy's Avatar
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    Team Borla XS checking in!

    If you want to quiet it down, I highly recommend one of these Garrett pre-mufflers:

    IMAG0418.jpg

    But seriously, the XS may be the quietest for Borla but I don't know that it'll ever be quiet on a non-turbo DeLorean. It's built like a (quality) big fat glasspack with modest sound absorption. Dropping from 2.5 to 2" might help a little but in the end you'd need an OEM-style overly chambered muffler. With a twin 3 cylinder config, straight-through perf mufflers, and a rear engine car I'm not sure you can get enough pipe to lower the less-desirable tones.

    If you look at exhaust configurations of other rear engine cars you can see some fairly impressive examples of plumbing and packaging to get just the right sound.
    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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  10. #10
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    Yeah, the Borla is still sold as a free-flow performance muffler. The silencers I installed also talk about being free flow and how they minimally sacrifice power. I'm happy to sacrifice power at this point, but no one seems to sell an overly-chambered aftermarket muffler. I wonder if something like a Walker Quiet Flow would help with noise (assuming they're any good, and they make a dual in/dual out variant; they seem to be mostly for OEM replacements).

    Looks like a pre-muffler won't help me due to my cats, but hopefully it will help Farrar. I mean, I'm not above installing it in addition to the cat, if if there was room...

    -- Joe

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