Exhaust help needed - Headers or HP Manifolds?

1971 - 1974 Mopars

  1. Lazerwolf

    Lazerwolf Well-Known Member

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    I have a 1974 Dodge Charger SE with the factory dual exhaust that needs work. It appears the gasket is leaking between the pipe and right manifold, but can see it's been replaced before. Also, tail pipe is bent and hitting on left side above axle. Both pipes have been butchered by current turbo mufflers and have 3 different sizes (2 1/4", 2 1/2" and 3"). Just going to remove it all and replace it.

    The engine is the 400 HP. It now has Edelbrock E-Street aluminum heads, Performer intake and Performer Carb. Auto tranny has a B&M shift kit according to previous owner. It has a mild aftermarket cam, but I don't know what since it was replaced before I bought car. Car runs fine and is a street driver built to perform between idle and 5500 rpm. When I bought the car, there was a brand new set of Hedman headers (78030) in the trunk he planned on installing but never did.

    I have decided on going with a TTI 2.5" exhaust with H-pipe. The current manifolds are the 74 (only) HP manifolds 3751068 and 3751071, which do not have a heat riser in them.

    I am far from an exhaust tuning expert. Question is should I replace the HP manifolds with the headers, since I already have them? Or keep the HP manifolds on since I already have them? I don't plan on changing much with engine and am currently guessing it has 400 HP or less. It will be a daily summer street driver so no interest in building a high HP race car out of it.

    Thanks in advance for your input.
     
  2. cryplydog

    cryplydog FBBO Gold Member FBBO Gold Member

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    lazer, I personally would use the headers, and particularly so due to the tti exhaust. you will get a good/big surprise. you will probably have to "ding or pein" a area or two for spark plug clearance. last and not least will be a considerable weight reduction that is always good. there are pro's and con's to both headers and mans. but I like the power and being able to tune in more power. good luck.
     
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    • hsorman

      hsorman FBBO Gold Member FBBO Gold Member

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      In Short: headers for power - exhaust manifolds for convenience and/or a stock look.
       
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      • Lazerwolf

        Lazerwolf Well-Known Member

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        Thanks for the input cryplydog and hsorman. As I stated, I'm not an exhaust guy. Surfing the net, depending on where you look, I've found claims of manifolds same HP to headers making up to 80+ more HP on same build. Crazy! Definitely leaning towards headers now.

        -Todd
         
      • acudanut

        acudanut Member

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        I strongly recommend the Factory the HP manifolds. Headers only cause future headaches.
         
      • Nacho-RT74

        Nacho-RT74 FBBO Gold Member FBBO Gold Member

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        :eek:ccasion14:
         
      • gtx1of1

        gtx1of1 Well-Known Member

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        correction gold member.
        its been proven stock manifolds were designed to flow just as good as headers.
        watch last weeks grave yard card.
        mark repeated what I've been saying for years.
         
      • hsorman

        hsorman FBBO Gold Member FBBO Gold Member

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        Oh boy, here we go again.... :violent-smiley-100:

        Look, there are several published tests (with dyno results) that have tested HP manifolds against headers and headers have won every time. On a mild engine the power increases from headers may not be very large compared to the HP manifolds but they are still better.

        There is a reason why headers have equal length tubes and minimal sharp angles that allow for unrestricted flow. Just follow the air flow from each cylinder in HP manifolds vs. headers. If the HP manifolds were so amazing EVERYONE would run them and NO ONE would run headers. Headers are a pain in the arse with fit and limited room, not to mention issues with starters. If the HP manifolds with none of those problems gave me the same power I would run them, and so would everyone else.

        Believe what you want...
         
      • mopar12372

        mopar12372 Well-Known Member

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        headers definately make more horse power proven at the track . if exhaust manifolds made more power all the stock eliminator cars would use them . long collecter 1 7/8 or 2 in
         
      • Dennis H

        Dennis H FBBO Gold Member FBBO Gold Member

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        Headers. Lighter. Cooler if ceramic coated.
         
      • Bruzilla

        Bruzilla Well-Known Member

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        I'm using these Hedman 78070 headers on my 74 Roadrunner. They are easier to install and prevent issues with the starter.

        hed-78070_ml.jpg
         
      • pentahead

        pentahead Well-Known Member

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        I am going to run HP manifolds on a street 440....have headers on my 383 now and they leak, bottom out, ect. I want to hear the moan of my Thermo-quad and the rumble of my exhaust behind me.

        my 2 cents....
         
      • Car Nut

        Car Nut Well-Known Member

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        I had headers 35 years ago, too loud up front, man I must be getting old.

        Stock HP manifolds here, makes the car sound like a muscle car and not a race car.

        Did Chrysler use headers?
         
      • tallhair

        tallhair Rufus "Mod-hair" Firefly Staff Member

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        As some have said .. it depend on how much power your are building and what your goals are. Stockish HP and not going racin' you are probably better off with HP manifolds and will be happy I imagine. The closer to stock you are the closer to output the two setups would have on the same engine.

         
      • Longroof

        Longroof Well-Known Member

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        The only reason to keep manifolds IMO is if it is a numbers matching car that will be restored. Otherwise get a good quality header with a thick flange and enjoy. Headers get a bad reputation because of the cheapo ones that don't fit well and develop leaks.
         
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        • tallhair

          tallhair Rufus "Mod-hair" Firefly Staff Member

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          There are more reason's and absolutes are frequently wrong

          Some people like them for the look, total cost of a pair of magnums (esp if you have some) and exhaust vs a "quality header", not looking for maximum performance but rather appreciate original looking under hood, ease of maintenance over some headers, easier to install and remove if necessary or to pull engine, and other reasons. There's room for both headers and original manifolds in peoples projects. For resto type performance applications most are not pursuing that extra ~25 or so HP over manifolds for the cost and that may be all you're getting for a stock engine and if are not pushing it all the time it's not worth the bang for the buck for many.

          There is no "right" answer and no one should feel bad for choosing either over the other.
           
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          • Nacho-RT74

            Nacho-RT74 FBBO Gold Member FBBO Gold Member

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            weeeeell:

            [​IMG]
             
          • fratzog lover

            fratzog lover Well-Known Member

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          • Dennis H

            Dennis H FBBO Gold Member FBBO Gold Member

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            Even without the confirmed HP gains, the weight and reduced temp with coated headers are a plus.
             
          • tallhair

            tallhair Rufus "Mod-hair" Firefly Staff Member

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            You have reduced temps if you coated the Manifolds too right?
             
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