HP exhaust manifold verses Header comparison

Mopar Exhaust Systems

  1. 62440

    62440 Well-Known Member

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    Merry Christmas Everyone, My headers look awful, I've been thinking about getting cast HP manifolds and wonder about the difference in Horse Power. Also would anyone know the weight differences?
    Cheers Everyone
     
  2. Sahara

    Sahara FBBO Gold Member FBBO Gold Member

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    I gotta follow this ‘cause I’d like to run manifolds but don’t want to give up too much power.
     
  3. Beekeeper

    Beekeeper FBBO Gold Member FBBO Gold Member

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    I been researching the same thing and it’s a pretty big restriction with manifolds. Nick’s garage on YouTube does a Dyno comparison on a 440 that will tell you a lot. I think it depends on the build mild vs. wild my builder told me around 20% is the HP loss with manifolds. Guess it all depends on what you doing with the car

     
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    • Beekeeper

      Beekeeper FBBO Gold Member FBBO Gold Member

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      I have really been undecided on running headers or not on my 493 just don’t care for the ground clearance issues and the price tag.
       
    • kramer

      kramer Member

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      The horsepower loss has alot to do with how the engine is built, if its mainly a high rpm race engine with a camshaft with a narrow lobe seperation and very little difference on the amount of duration on the exhaust lobe compared to the intake lobe you will probably notice a good amount of power loss but if the engine is built with a fairly wide lobe seperation and the exhaust has a good amount more of duration on the exhaust compared to the intake with HP manifolds the power loss won't be as noticable escpecially if its mainly street driven.
       
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      • moparedtn

        moparedtn Ed on the Ridge FBBO Gold Member

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        Not to mention, having to fuss with headers fairly often (according to brand, of course).
        I've just had to get under the car and reposition the exhaust, then crank down on the collector bolts
        AGAIN....shiyat gets old, man.
        I'm sure having Hedmans has something to do with it, as does having these ridiculous 3" pipes, but....
        dangit, I've had to tighten most every bolt on both sides, at engine and at collector, more than once
        since the last engine install.
         
      • Turboomni

        Turboomni Well-Known Member

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        I run HP's on my old stock 440 and plan on running HP's on my 505 stroker being built. I went to Mr Porter of Porter Racing Heads and told him what I want and to use HP's. He massaged the Stealth heads and set them up for me to use a roller cam he had ground to his specs for the HP's. For me going to a 505 of any kind is going to be a huge improvement over what I have now and am sure I will be happy. It was also designed from the get go with HP manifolds in mind. But if you have always run headers and then went to HP's all bets are off I would think. Might be ok depending on what you expect. For me I don't know what I am missing with headers but the gains will be huge compared to what I have now. Don't blame you with the headaches that some say are very possible and the cost with headers. For me I just wanted a car that I can go anywhere anytime.
         
        Last edited: Dec 25, 2019
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        • Dennis H

          Dennis H FBBO Gold Member FBBO Gold Member

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          Weight and heat enough reason to go with headers for me.
           
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          • Beekeeper

            Beekeeper FBBO Gold Member FBBO Gold Member

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            My car will be 100% street driven and don’t mind to lose a few horses it’s the torque you feel in the seat of the pants anyhow.
             
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            • Beekeeper

              Beekeeper FBBO Gold Member FBBO Gold Member

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              Where’s @andyf when we need him?
               
            • steve340

              steve340 Well-Known Member

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              I think the use of manifolds is likely to cost 20-30 HP.
              The loss would be more as you revved the engine higher.
               
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              • Robert Schaad

                Robert Schaad Well-Known Member

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                Mopar built their engines for great response. The addition of headers in many applications actually caused more problems then they are worth. The may over heat the starter. The burn thru spark plug cables. So if you are not building a HP motor you may find it is better to stick to Exhaust manifolds. I am not the professional but I have had troubles before and have gone back to Stock Exhaust manifolds.
                 
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                • Robert Schaad

                  Robert Schaad Well-Known Member

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                  I am curious, headers create more heat then factory exhausts. The may burn thru cables if spark plug cables contact them. They cause so much heat that they may cause the starter to over heat if you do not have a cover. They leak easy. They do not give you that much more power then one might think. The cause a lot of problems when working on steering. Just what I have experienced using headers.
                   
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                  • Turboomni

                    Turboomni Well-Known Member

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                    According to Nick's video above HP's lost 22.8 HP and 20.6 torque over 2 inch headers but all runs ended before 6000 rpms. I would guess the headers would shine above that and the HP's would shut down. Since my stroker will never see 6000 rpms I think I will be fine.Torque peak for both headers and manifolds peaked at the same rpms. Horsepower however peaked at 5700 and 4900 rpms with the HP exhaust manifolds..
                     
                    Last edited: Dec 25, 2019
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                    • Beekeeper

                      Beekeeper FBBO Gold Member FBBO Gold Member

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                      That’s me my stroker will never see 6000 rpm I’m thinking I’ll run manifolds and the option is there to run headers if the need ever arises.
                       
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                      • Dennis H

                        Dennis H FBBO Gold Member FBBO Gold Member

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                        Mine has the ceramic coated million dollar TTI’s. Under hood temperatures 100 degrees cooler with them. Weight savings huge.
                         
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                        • Beekeeper

                          Beekeeper FBBO Gold Member FBBO Gold Member

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                          How much ground clearance with the TTI and what diameter tubes?
                           
                        • dadsbee

                          dadsbee FBBO Gold Member FBBO Gold Member

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                          Got headers out of my system when I was 18... almost 40 years later now and this is how it's gonna be until I'm gone, well unless I build a '68 Dart.. LOL

                          beerestoration2018 1264.JPG
                           
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                          • steve340

                            steve340 Well-Known Member

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                            With a larger capacity stroker engine the manifolds could cost you 50 hp.
                            You can get air fuel in but if you cannot get it out the cost will be more as engine size and revs go up.
                             
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                            • Turboomni

                              Turboomni Well-Known Member

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                              Yes I understand that. I believe Mr Porter took that into consideration when he ground the cam for me to make the best of that situation. My car a 69 Fury III 2 door and weights in at 4100 pounds and has a 3.23 rear which I want to keep to blast down highways. What I am looking for is 500 to 600 ft lbs of torque down around 2800 to 5000 rpms to get this beast moving with ease. That is it's sweet spot. Not a drag car. Not a street racer but a real sweet cruiser with some hair on em.
                               
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