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Safe Dual Exhaust Routing

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bpiccioni, Nov 1, 2003.

  1. bpiccioni

    bpiccioni 1/2 ton status

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    Yes, another dual exhaust routing post...I did the search, but havent found a post w/ answers to my particular dilemma.

    I'm looking to replace my stock, single exhaust on my /forums/images/graemlins/burb.gif, 87 TBI350, with headers and dual exhaust - probably gonna opt for Dynomax Standard Series Headers and their dual kit as well - mainly due to price. If possible, I'll see if a local Dynomax dealer can install an AIR hole for me, in addition to welding on an O2 sensor bung - that way I'll be able to run their coated headers, which arent much more expensive at JEGS and come w/ a lifetime warranty. Clearly, that warranty might be voided w/ custom AIR and O2 bungs, but at least I would get the better heat and flow characteristics of the coated headers. For the difference in price between the standard series and coated series, I could hardly buy enough wrap to cover them.

    One of my biggest concerns is the safe routing of a muffler and exhaust on the passenger side, specifically where it runs along the frame rail, wherein sits my fuel filter and lines.

    Has anyone else encountered this in running dual exhaust? I 've thought about installing some custom heat shield along the frame rail, and maybe also moving the passenger side exhaust further towards the center of the /forums/images/graemlins/burb.gif. Pics? Solutions?
     
  2. Derf00

    Derf00 1/2 ton status

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    [​IMG]

    I opted to use the y-pipe(slightly modified), but as you can see it could run on out the back without any problems, and I don't have any problems with heat and the fuel filter.
     
  3. jjlaughner

    jjlaughner 3/4 ton status

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    If your going to use the dynomax headers, they have a collector with O2 bung already welded in threw jegs (I think they are about 30$). I dont think welding in your own bung will void any warrenties /forums/images/graemlins/thinking.gif I'm going to weld in my own /forums/images/graemlins/smirk.gif

    I have a set of dynomax headers with AIR and it has air tube bungs welded at each hole (like a corvette style air setup /forums/images/graemlins/confused.gif).
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Welding in a bung will probably void the warranty of ANY coated headers if thats what these are)...you'll burn the coating off.

    I talked to hedman about this, and they told me to call one of their reps about it for clarification, but I didn't bother. I can't blame them for not honoring a warranty on a part that was modified by me, which I know full well will ruin the coating in that location.
     
  5. bpiccioni

    bpiccioni 1/2 ton status

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    I might be willing to void the warranty and have AIR and O2 bungs welded on the coated Dynomax headers, assuming I could get the local dynomax dealer to do it, and at least assume some responsibility for good, airtight welds.
     
  6. bpiccioni

    bpiccioni 1/2 ton status

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    I'm not familiar w/ that type of AIR setup. In my /forums/images/graemlins/burb.gif, I have an AIR tube bung on the 1st cylinder exhaust tube of my stock manifolds. Do you mean that you have AIR tube bungs on EVERY cylinder exhaust tube?

    On second thought, do you have a picture? I havent been able to find any on the net specifically for TBI 350's w/ AIR.
     
  7. NetBlazer

    NetBlazer Registered Member

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    Got a part number for those headers? That's EXACTLY what I need for my '88. It has the AIR connections at each exhaust port, and I'm looking for headers that will work with that setup and still pass a visual inspection.

    Thanks!
     
  8. jjlaughner

    jjlaughner 3/4 ton status

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    [ QUOTE ]
    I'm not familiar w/ that type of AIR setup. In my /forums/images/graemlins/burb.gif, I have an AIR tube bung on the 1st cylinder exhaust tube of my stock manifolds. Do you mean that you have AIR tube bungs on EVERY cylinder exhaust tube?

    On second thought, do you have a picture? I havent been able to find any on the net specifically for TBI 350's w/ AIR.

    [/ QUOTE ]

    Yep,looks like a corvette style AIR setup to me. I guess its for 88 year blazers /forums/images/graemlins/confused.gif
    It has a bung welded in at the top of each down tube. I dont have any pics my computer is STILL down till Friday when the new power suppy is going to be delivered! /forums/images/graemlins/tongue.gif
     
  9. jjlaughner

    jjlaughner 3/4 ton status

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    [ QUOTE ]
    Got a part number for those headers? That's EXACTLY what I need for my '88. It has the AIR connections at each exhaust port, and I'm looking for headers that will work with that setup and still pass a visual inspection.

    Thanks!

    [/ QUOTE ]

    85503 is the Part number
    PICS PICS /forums/images/graemlins/thumb.gif
     
  10. NetBlazer

    NetBlazer Registered Member

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    OK, I'm an idiot.... /forums/images/graemlins/tongue.gif
    Took the digicam out to snap pics of the AIR setup and realized that it does NOT have ports on each exhaust port, just the first one, and mount points to the manifold on the other ports. Why yes, I would like some salt for that foot......
    /forums/images/graemlins/crazy.gif

    Never really looked that closely before. I really need to spend more time wrenching under the hood on this thing to familarize myself with it better. Sorry I couldn't clear up the mystery of the multiple port AIR system.


    Sean
     
  11. jjlaughner

    jjlaughner 3/4 ton status

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    No prob, I'm going to do some hunting and find a VET pic with that setup though
    Here's a crappy pic, not of my headers, but you can see the way the air tubes would hook in

    [​IMG]
    On mine they just have the bungs no tubes, they also sweep backmore like a header not like a stock manifold shown, and they are the black kind.... BUT the air setup looks like this^

    UPDATE heres my headers 85503 dynomax
    [​IMG]
     
  12. skratch

    skratch 1/2 ton status

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    One other option is to use the Edelbrock TES headers. They will go back to a single pipe into you cat and then you can dual it behind that. Not sure what kind of emissions requirements you have to meet, but this should keep you legal.

    This is the set up I'm putting on my '87 TBI 350 Suburban, I'll let you all know how it works when it's done. /forums/images/graemlins/thumb.gif /forums/images/graemlins/burb.gif
     
  13. bigjohnintexas

    bigjohnintexas Registered Member

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    I don't know how picky they are in OR about inspections, but I ordered the ceramic coated Dynomax headers without the AIR fitting and scrapped the whole damn mess. Take the vacuum pump off and don't forget to plug the MAPP sensor inlets. I was in Seattle, WA for 2 years and never had any problems getting inspected. The emissions test proved my truck cleaner after I did this than before with the stock system.

    A couple of things to think about:
    1. When you remove the AIR tube from your manifold, be prepared with a Sawzall on hand. The tubes will not give up easily.
    2. With a 6-10" piece of wire spliced into your factory "one wire" O2 sensor, the wire will easily reach the collector included in the kit which are NOT coated. They make a great O2 mount and will save you warranty issues.
    3. The factory ceramic coating WILL eventually fail, however, I would still buy them because of the heat issues and they look damn good. I have not tried to warranty mine yet.
    4. And lastly, unless you have to have dual exhaust or you have a thumpin' motor, I would do a Y-pipe like the one previously posted. I have a setup almost exactly like that, and have had no problems. The collectors that come with the dynomax kit are 3" to 2.5"- run your 2.5" Y-pipes to a single 3" system and you will have more than enough flow. I decided to upgrade to a high flow 3" Cat and muffler instead of spending the money on the second muffler and tailpipe.

    Just somethings to consider. Good luck! /forums/images/graemlins/wink.gif
     
  14. BurbinOR

    BurbinOR 3/4 ton status

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    Hey Fred,

    Even with that mongo motor you run, have you found any reason to NOT do a 2 into 1 exhaust? I'm still contemplating my Burb's new exhaust, and as a cost savings want to keep it to one cat. Figure if you are happy with one cat, I sure would be with my stock 350. /forums/images/graemlins/laugh.gif
     
  15. Derf00

    Derf00 1/2 ton status

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    In general, no. When the 383 first went in, I had the cat on there, but hated the y-pipe, and the way it hung down by the front drive shaft. Based upon the size of the original cat, the performance was not affected by the cat, at least in the normal rpm range.

    Between the y-pipe and shock relocation I ended up with what you see above, and presently does not have the cat installed. The first and most noticable difference is how loud it is, definately to loud for a family vehicle. Secondly, at some point the exhaust needs to be extendend to the rear corners, to many fumes being dumped underneath.

    Your Burb is looking good. /forums/images/graemlins/thumb.gif
     
  16. bpiccioni

    bpiccioni 1/2 ton status

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    I just checked out your pics, and I have to say I'm a little concerned - I went back and forth via email w/ Dave Casto, a Dynomax CSR (contacted via website) and he gave me the part #'s I would need for a COMPLETE dynomax exhaust system.

    1st email from Dave
    [ QUOTE ]
    Thank you for your inquiry for Dynomax Exhaust. We appreciate your
    interest in our products.
    Ben, we do not offer the Ceramic coated headers for your 1987 Chevrolet
    Suburban w/5.7L at this time.



    For your nearest Dynomax dealer you can check our website at
    www.dynomax.com. If you have any further questions,
    please feel free to contact us again either via E-mail at our website or
    phone 1-734-384-7806 M-F 8:30 am to 5:30 pm.
    Thank You,

    Dave Casto
    Dave Casto
    Dynomax Performance Exhaust
    Installation Technician


    [/ QUOTE ]

    2nd email from Dave
    [ QUOTE ]
    Thank you for your inquiry for Dynomax Exhaust. We appreciate your
    interest in our products.
    Ben, the black painted headers have a manufactures warranty only.
    You will need header # 85503, air conditioning bracket # 88304, oxygen
    sensor reducer # 88314, header dual kit # 89004. Mufflers are not
    included in kit. We offer the Dynomax Ultra Flo mufflers # 17217 or the
    Dynomax Super Turbo mufflers # 17731 designed for the dual kit. The
    reducer # 88313 fits the 2 1/2'' collector, header # 85503 has a 3''
    collector, therefor you do not need the # 88313. Also, we do not sell
    direct so I do not have prices on the universal H - Pipes.



    For your nearest Dynomax dealer you can check our website at
    www.dynomax.com. If you have any further questions,
    please feel free to contact us again either via E-mail at our website or
    phone 1-734-384-7806 M-F 8:30 am to 5:30 pm.
    Thank You,

    Dave Casto
    Dave Casto
    Dynomax Performance Exhaust
    Installation Technician


    [/ QUOTE ]

    On my 87 /forums/images/graemlins/burb.gif setup, I only have one AIR fitting on the #1 exhaust pipe. How would I use the 85503 headers, which appear to have AIR fittings at EVERY exhaust pipe? I plan to email Dave again and see what he has to say - I'll post that up when I get it, but I dont expect it til monday at the earliest. Anyone else have any ideas, asside from trying to junkyard additional AIR fittings from a newer model GM?
     
  17. bpiccioni

    bpiccioni 1/2 ton status

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    Im in Eugene, and we currently have no inspection, although I dont want to modify the /forums/images/graemlins/burb.gif to the point that I cant take it anywhere else. It doesnt have a CAT right now, and didnt when I got it - I dont know that it ever had one, although I posted about this and Dorian and others seemed pretty sure it would have come stock w/ a CAT.

    I am not sure that I 'HAVE' to have a dual exhaust, but I have a buddy w/ a later 90's 1/2T 4x4 /forums/images/graemlins/truck.gif that sounds really good w/ duals. I figure I might be willing to spring for the 2nd muffler and higher kit price to have true dual exhaust, although I also plan to run an H-Pipe, which is another cost to consider. I havent figured in the cost of installing CAT's yet - I figure I could do that later when necessary.

    Im still thinking about the idea of scrapping the AIR system entirely - I figured I could just remove the AIR belt (it's installed now) and plug the AIR outlet if I installed headers. However, this would seem a lot less likely to pass an inspection than NO AIR system at all. To be completely honest, I dont even know what the AIR system does, aside from supposedly pump air into the exhaust.
     
  18. jjlaughner

    jjlaughner 3/4 ton status

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    [ QUOTE ]
    On my 87 setup, I only have one AIR fitting on the #1 exhaust pipe. How would I use the 85503 headers, which appear to have AIR fittings at EVERY exhaust pipe? I plan to email Dave again and see what he has to say - I'll post that up when I get it, but I dont expect it til monday at the earliest. Anyone else have any ideas, asside from trying to junkyard additional AIR fittings from a newer model GM?

    [/ QUOTE ]

    No you could just buy the header kit and use whatever else you wanted (might still need the AC bracket though). I dont know why these headers have the air at each port, thats the problem I'm runninginto right now. I still say I have seen these air tubes on a vet at some time. /forums/images/graemlins/thinking.gif


    [ QUOTE ]
    Im still thinking about the idea of scrapping the AIR system entirely - I figured I could just remove the AIR belt (it's installed now) and plug the AIR outlet if I installed headers. However, this would seem a lot less likely to pass an inspection than NO AIR system at all. To be completely honest, I dont even know what the AIR system does, aside from supposedly pump air into the exhaust.

    [/ QUOTE ]

    Just order the headers without air if you planning on not using the air lines and removing the pump. /forums/images/graemlins/thumb.gif
    You can get the ceramic ones without air also


    As far as the duals, my orginal plans was to have a y-pipe into a 3" cat, into a 3" in and dual 2.5" out flowmaster 50, with the dual look
    Otherwise i'm going to do these headers (the 4point air tubes), into dual 2.5" cats, into dual 50series 2.5" flowmasters.
    I would have to get an h-pipe setup in there somewhere to even out the back pressures though
     
  19. bpiccioni

    bpiccioni 1/2 ton status

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    I noticed something the other night when checking out the Dynomax headers available on Summit's website. They had a much more elaborate website than Jegs, and I was able to see some pics and read some technical descriptions of the available headers.

    Summit seems to have Dynomax Ceramic Coated Headers for 88-91 trucks which seem promising. I checked out the PDF Dynomax offers for their headers, and noticed #78, which gave me hope that they might possibly work on my 87 /forums/images/graemlins/burb.gif

    <ul type="square">[*]4 - Modification to stock exhaust required to retain catalytic converter system.
    [*]63 - New style chassis.
    [*]78 - Single A.I.R. fitting on front tube of each header and oxygen fittings on driver’s side header.
    [*]91 - Will fit DART Sportsman II angle plug heads. End wrench may be required for spark plugs.
    [/list]
    Summit's Dynomax Ceramic Coated Header Page

    Dynomax 86097 Headers

    It seems that these headers use the same gaskets as headers made for 87 models, so one might deduce that they have similarly shaped flanges and would fit on 87 motors. Thoughts?

    The endnotes mention that they are made for the 'new chassis'. I havent got any experience w/ the new chassis - would this prevent them from fitting on my 87 chassis? I know that Chevy trucks went IFS in 88, but I just cant imagine than headers designed to fit around IFS would take up more space than headers designed to work w/ a solid axle. Maybe an articulation issue?

    I am still waiting on my reply from Dynomax about their 85503 headers having AIR tubes on the top of every exhaust tube, whereas my 87 only has the single AIR tubes. I will pose this question of them when I get my reply to said question.
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    I would never consider buying a set of headers that weren't made for my exact application unless someone I knew or trusted had done the same. You can't even get headers that are SUPPOSED to fit your application without having some problems, a different chassis throws in all sorts of additional variables. That "only fits new chassis" note is a big time warning IMO.

    If dynomax is such a pain to deal with, why not Edelbrock or Hedman? My hedmans fit with just a minor bit of tweaking, have better flanges than the dynomaxes, and can be had as a "kit" for the '87+ trucks too.

    FWIW, Chev cars of all shapes and sizes had AIR going into the manifold above each exhaust port (as opposed to the odd truck system of one AIR injector), so it's not unusual to see them.
     

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