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Novak Headers And Exhaust Pipe Sizing

Discussion in 'Early CJ5 and CJ6 Tech' started by Norcal69, Jul 17, 2021.

  1. Jul 17, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

    Northern California
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    My rusted out old fenderwell headers have finally bit the dust. They were 20yrs old when I bought the jeep and I have hated them from day one. I have welded them up numerous times, patched them.... ect...
    This last Rubicon run popped the thermometer on that turkey.......
    I just pulled the trigger on a set of Novak Buick v6 headers. I am trying to decide what diameter pipe I should use to route the exhaust. I am looking at 16 ga stainless tube.....

    I am trying to decide what route to go.....
    2" from header flange into y pipe and 2.25" into muffler
    2.25" into y pipe and 2.25" into muffler
    2.25" into y pipe and 2.5" into muffler

    I am looking for a breathable yet quiet exhaust system. I plan to run the biggest muffler I can fit under the floor board. Tail pipe will exit out one rear side and will be either 2.25" or 2.5" diameter.
     
  2. Jul 17, 2021
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    Do the headers come with collectors? What size are they?
     
  3. Jul 18, 2021
    45es

    45es Member 2021 Sponsor 2020 Sponsor

    Naches, WA
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    What is the sizing of the system now?
     
  4. Jul 18, 2021
    supertrooper

    supertrooper Member

    moreno valley, ca
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    I did 2" from the collectors to the y then 2 1/4" for the rest
     
    Norcal69 likes this.
  5. Jul 18, 2021
    jeepdaddy2000

    jeepdaddy2000 Member

    Eagle Point oregon
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    The collector is 2.5". Why not simply stay with that diameter throughout the system instead of necking the pipes down pre Y, then opening them back up?
    Depending on where you have your crossover, I would recommend at lest one more flange in the system. The best place is usually just after the Y. This will allow you to disassemble the system so it can be removed/installed in sections, add access to the starter, well as ease of access to the transmission/t case.
     
  6. Jul 18, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

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    definitely.
     
  7. Jul 19, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

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    The headers are 2.5" at the collector.
     
  8. Jul 19, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

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    Right now I have fenderwell headers with 2.5" into mufflers and 2" piping out the back on each side.
     
  9. Jul 19, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

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    There will be a couple V band clamps in the system to allow easy install and removal.
     
  10. Jul 19, 2021
    Keys5a

    Keys5a Sponsor

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    The Dauntless is not exactly a high performance engine. It will breathe fine with dual 2" exhausts. Larger wouldn't hurt, but not really necessary unless your turning high rpm, like 4500+.
    -Donny
     
  11. Jul 19, 2021
    45es

    45es Member 2021 Sponsor 2020 Sponsor

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    If I read your post correctly, it appears you are wanting to go from dual exhaust to a single exhaust out the back. With that, I believe 2" run from the headers into a wye pipe and then into the muffler will work. After the muffler, a 2 1/4" tail pipe should be adequate.

    This Website may be of some help to you.

    How To Calculate Muffler Size and Exhaust Pipe Diameter | Exhaust Videos
     
  12. Jul 19, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

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    I am thinking 2" from the headers into a y pipe, exit the y pipe with 2.25" and go into the muffler, exit muffler 2.25" and out the back.
     
    Fireball likes this.
  13. Jul 19, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

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    That's what I'm thinking
     
  14. Jul 19, 2021
    jzeber

    jzeber Well-Known Member 2021 Sponsor 2020 Sponsor

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    On my 71' I couldn't find a good way to cross over where it wouldn't get crushed. I ended up going around the front of the oil pan from passenger to driver. Everything was tucked up out of the way.
     
  15. Jul 19, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

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    That is the route I am going to try to go.
    Any chance you have some old pics of your setup?
     
  16. Jul 19, 2021
    jzeber

    jzeber Well-Known Member 2021 Sponsor 2020 Sponsor

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    I do, let me dig them up. May be a thread on here somewhere also. I used a bunch of pipe and bends from Summit.
     
  17. Jul 19, 2021
    jzeber

    jzeber Well-Known Member 2021 Sponsor 2020 Sponsor

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    Did a search on my exhaust thread and got the dreaded 404 error. Here is 1 pic of how it went around the oil and and caught the collector. I will get the rest off my portable hard drive. Should I email them to you?
     

    Attached Files:

  18. Jul 19, 2021
    jzeber

    jzeber Well-Known Member 2021 Sponsor 2020 Sponsor

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    A few more, still searching for all of them.
     

    Attached Files:

  19. Jul 19, 2021
    Norcal69

    Norcal69 Out of the box thinker 2021 Sponsor 2020 Sponsor

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    I'd love to see them if you have time! Do you still have my Email?
     
  20. Jul 19, 2021
    Mr Vaughan

    Mr Vaughan Fly by the seat of your pants

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    what's this Ehaust you speak of?
     

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