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Thread: Spec .01 Dual Exhaust

  1. #1

    Spec .01 Dual Exhaust

    I have received an eMail request for info about Spec .01 dual exhaust. Since there doesn't appear to be a thread yet:

    Spec .01 is the only setup I know of that moves exhaust totally outside the engine cradle. This has several advantages:
    1) Reduces engine compartment temperatures
    2) Allows totally unfettered engine access
    3) Does not require tight radius mandrel bent tubing

    It also is the lowest cost dual exhaust option available.

    The setup:

    Adapters are mated to OEM exhaust manifolds (exhaust manifolds need not be removed). I used adapters made from pipe nuts and nipples, but a more popular option now is to use stainless pipe stubs. Note that a pipe stub flange is slightly bigger diameter than space between the manifold mating studs -- use a rat tail file to make two indentations for clearance.

    *STAINLESS* 2" exhaust flex tubing (don't use carbon flex tubing from a parts house) slides over the adapters, is secured with stainless guillotine clamps, then loops around the *OUTSIDE* of the engine cradle:

    exhaustTubing.jpg

    ExhaustMatingLeft.jpg ExhaustMatingRight.jpg

    319530_276402442405013_908504729_n.jpg 319530_276402445738346_399318296_n.jpg

    Mufflers, and catalytic converters if desired (mine are fake) are mounted to the engine cradle and frame extension with ordinary parts house exhaust hangers. I used pins in my rearmost hangers to keep them bent with minimal clearance. My mufflers are generic carbon steel part house models -- still intact more than a decade later. Notice engine side clearance (headers actually make engine side access *MORE* difficult than OEM exhaust):

    MufflerLeft.jpg MufflerRight.jpg

    ExhaustHanger1.jpg ExhaustHanger2.jpg

    Short lengths of 2" stainless tubing carry exhaust out the back of the car using original rear fascia knockouts.

    The biggest advantage of any true dual exhaust setup is elimination of the muffler across the back of the car, which not only makes rear engine access a breeze, but also prevents rear fascia warping:

    432307_340484645996792_40248587_n.jpg

    Spec .01 Exhaust Parts List:
    (2) Stainless 1 1/2 NPT pipe stubs, McMaster Part #45735K295, $15.38 each
    (10 feet) Stainless 2" flex tubing, McMaster Part #5241K61, $80.00 total
    (6) Stainless 2" guillotine clamps (sometimes as cheap as $4 each on eBay)
    (4) Exhaust hangers from Advance, Autozone, O'Reileys, etc
    (2) Mufflers (and catalytic converters): sky's the limit here -- anywhere from $30 each to several hundred dollars each
    (2 feet) stainless 2" exhaust tube (sometimes as cheap $7 per foot on eBay. McMaster Part #8989K408 is $16.82 per foot)

    Bill Robertson
    #5939
    Last edited by Greasy DeLorean Mechanic; 10-04-2013 at 10:21 PM.

  2. #2
    While studying what is left of #2508's exhaust manifold studs (which scream "please snap me off"), I noticed that the manifolds use virgin holes when swapped from one side to the other. Without a crossover pipe to mate up to, there is no reason not to rearrange the manifolds.

    I also noticed that my new manifold gaskets have 5/16" (8mm) holes in them already. I think I will tap #2508's virgin holes to 5/16-24 (virtually identical to 1mm thread pitch), swap the manifolds around, and mount them with Grade 8 studs/ stainless nuts.

    Bill Robertson
    #5939

  3. #3
    Junior Member Spittybug's Avatar
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    Bill, you've had these on a while now I see. Steve too. How's the sound compared to stock? Did you notice any appreciable increase in performance when you did this? Others have said how "dramatic" the benefit has been when they've freed up the exhaust. I'm optimistic, but really, "dramatic"? Your simple design is much more appropriate than the mess they made on the stock setup.

    Have you had any problems with the flex tubing being routed between the axle and the lower link like that? Nothing rubs on bouncy roads or anything?

    The G-lader supercharger install progresses slowly (mainly procrastination and education since I don't want to grenade anything). Not much use cramming more air in unless I make it easier to exit......

    Thanks.
    Still conjuring up something witty.... in the meantime, check out NealVenturesLLC.com

  4. #4
    Uncensored Hypocrite stevedmc's Avatar
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    The only complaint I have about Spec .01 exhaust is that it isn't welded together. You have to make sure you get those clamps super tight otherwise you could have an exhaust leak.

    For years I have been saying I would run Spec .01 exhaust until I could get a good deal on a set of Hervey's headers. Then I realized something. Hervey's headers still block access to the starter.

    The other exhaust options out there might look more elegant, but Spec .01 gives you for better engine access. My vote would be Spec .01 first, Hervey's second, and everything else third.

    I think you biggest performance comes from removing the catalytic converter and installing free flowing exhaust. I'm pretty sure all after market exhaust systems are like this.

    Nothing rubs with the flex tubing as well. My tubing is pretty dang stiff. You just have to make sure it is situated correctly and that you give it a little room for play if you need to move it around. You can always trim it down later if you want to.

    By the way, welcome to the forum sir.
    Rest assured, we have a backup of Farrar's car blog and it will be restored in the near future. (Steve Rice - March 2016)
    Rest assured, we have a backup of Shep's posts and all of them will be restored in the near future. (Steve Rice - March 2017)

  5. #5
    Lack of marks on my axles and links (or the tubing itself) indicates no contact over the past 11 years.

    Stock exhaust forces both sides of the engine into a single 1.5" diameter tube:

    DeLoreanMufflerInside.jpg

    Hardly conducive to performance. It does however do a very good job of melting the rear fascia. And barbequing the belts. And blocking engine access.

    Bill Robertson
    #5939

  6. #6
    Uncensored Hypocrite stevedmc's Avatar
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    Quote Originally Posted by content22207 View Post
    Hardly conducive to performance. It does however do a very good job of melting the rear fascia. And barbequing the belts. And blocking engine access.
    Don't many of the premium aftermarket exhausts do the same thing? With the exception of Hervey's of course.
    Rest assured, we have a backup of Farrar's car blog and it will be restored in the near future. (Steve Rice - March 2016)
    Rest assured, we have a backup of Shep's posts and all of them will be restored in the near future. (Steve Rice - March 2017)

  7. #7
    Quote Originally Posted by stevedmc View Post
    The only complaint I have about Spec .01 exhaust is that it isn't welded together. You have to make sure you get those clamps super tight otherwise you could have an exhaust leak.
    Twist the tubing after sliding it on. Can't remember which direction (I'll check tomorrow in the sunshine), but because it's spiral wound, one direction increases the inside diameter and the other direction decreases it.

    Bill Robertson
    #5939

  8. #8
    Junior Member Spittybug's Avatar
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    Thanks guys. I have a pair of pseudo headers I got a few years ago. I think I got them from Ed in Florida, but I'm not 100% sure... too long ago. I'll post pics tomorrow and see if anyone can identify them.

    I'm looking at the McMaster Carr catalog for the pieces. I think your posted part # for the flex tubing can't be right....5241K61 doesn't show up. Maybe they changed the numbers?

    Listening to Steve's feedback, I wonder if there is benefit to welding the joints?
    Still conjuring up something witty.... in the meantime, check out NealVenturesLLC.com

  9. #9
    Uncensored Hypocrite stevedmc's Avatar
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    If you can get it welded without paying a bunch of cash then go for it. Mine is fine now that I tightened the crap out of it. But I do recommend tightening it up a second or third time after you have driven the car a few days just to be sure.

    I believe the flex tubing came from JC Whitney. I could be wrong though. I'm sure Bill will chime in.
    Rest assured, we have a backup of Farrar's car blog and it will be restored in the near future. (Steve Rice - March 2016)
    Rest assured, we have a backup of Shep's posts and all of them will be restored in the near future. (Steve Rice - March 2017)

  10. #10

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