3 inch exhaust

Mopar Exhaust Systems

  1. Master Gunner

    Master Gunner FBBO Gold Member FBBO Gold Member

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    Does anyone think there's any benefit to running a 3 inch exhaust behind HP manifolds?

    Mark
     
  2. Don Frelier

    Don Frelier FBBO Gold Member FBBO Gold Member

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    I doubt it, @andyf might want to chime in.
    I think your muffler choice and an H-pipe or X pipe would be bigger considerations for backpressure and throughput.
     
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    • dadsbee

      dadsbee FBBO Gold Member FBBO Gold Member

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      No... and pending what engine specs are there's probably no advantage with headers either..
       
    • steve340

      steve340 Well-Known Member

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      No that large a pipe size will probably kill torque and power.
       
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      • Under Pressure

        Under Pressure FBBO Gold Member FBBO Gold Member

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        3060D1E2-A531-46A1-8B13-4B51ADC79D67.jpeg Not really sure on a benefit, but I put on my 70 behind stock manifolds with Dyna Max’s and it sure sounds good
         
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        • Ron H

          Ron H FBBO Gold Member FBBO Gold Member

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          I think 3" is for huge output motors maybe 450-500 horse...I got talked into 3" on my built poly. Waste a money.
           
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          • Kern Dog

            Kern Dog FBBO Gold Member FBBO Gold Member

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            :poke:

            There are always advantages to headers.
            Whether those advantages are negated by their drawbacks is up to debate.
             
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            • dadsbee

              dadsbee FBBO Gold Member FBBO Gold Member

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              Headers wasn't the question... 3" exhaust was.. IE no advantage to 3" pipes with headers either.. pending his engine build..
               
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              • diesel_lv

                diesel_lv Well-Known Member

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                I run 3" w H-pipe n headers on my 496 w 610 crank hp, but I never turn more than 5,500 rpm. Way too much. 2-1/2" would have been more than enough.
                 
              • Master Gunner

                Master Gunner FBBO Gold Member FBBO Gold Member

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                Cool, didn't think there would be.
                Engine specs are: 440 .030 over with KB step top pistons, 10.3 static 8.6 dynamic CR, Hughes Engines 228/232 -110ºLSA cam, mildly ported 346 heads.

                Mark
                 
              • Kern Dog

                Kern Dog FBBO Gold Member FBBO Gold Member

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                YOUR response had the word HEADERS in it....
                 
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                • dadsbee

                  dadsbee FBBO Gold Member FBBO Gold Member

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                  LOL Greg. guess you have to read the entire context to make it work. And it's NO to 3" pipes, manifolds or headers..
                   
                • Don Frelier

                  Don Frelier FBBO Gold Member FBBO Gold Member

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                  • Charged440

                    Charged440 Well-Known Member

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                    • 69a100

                      69a100 Well-Known Member

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                      The only benefit you'll get is that it will sound like shit! Good Luck
                       
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                      • Master Gunner

                        Master Gunner FBBO Gold Member FBBO Gold Member

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                        Factory was 2.5, and that is what I was going with, but I saw that 3 inch was only $14 more for head pipes and the same for the H pipe. Really didn't think it would do anything with my build and manifolds, but thought I'd throw it out for the experts.
                         
                      • 66 Sat

                        66 Sat Well-Known Member

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                        Yeah, but the original question was relating to 3" exhaust behind HP manifolds, so the response was " no advantage behind HP manifolds, nor behind headers". Nothing to do with headers not being advantageous.
                         
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                        • Kern Dog

                          Kern Dog FBBO Gold Member FBBO Gold Member

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                          I don't spend money because my pockets get too full nor do I make changes that have zero benefit.
                          Stock exhaust manifolds are great for a stock engine with a 4500 rpm HP peak. Yes, a 440 Magnum did peak below 5000 rpms, look it up. They would still benefit with headers. I have read that a 400 HP point is where a 2 1/2" system becomes a bottleneck.
                          Headers allow engines to make more power. To argue that is to ignore thousands of examples from the past and present.
                          The F.A.S.T. and Pure Stock drag racers use manifolds only because of the rules in the class. They run fast despite the use of iron manifolds, not because of them.
                          I do understand the support of manifolds. Some don't want to deal with the fitment issues. I agree, headers can be expensive, fit poorly, rattle and have other problems.
                          Also, it is believed that as the exhaust travels to the ultimate exit point, it cools dramatically and as it does, the pipe size can be progressively smaller with no loss of power. The tailpipes can be 1/4" to 1/2" smaller than the intermediate pipes which is great since fitment around the axle and gas tank can be difficult.
                           
                        • 4mulas

                          4mulas Well-Known Member

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                          Weren’t most factory duals 2.25” ?
                           
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                          • Master Gunner

                            Master Gunner FBBO Gold Member FBBO Gold Member

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                            440 cars used 2.5" pipes, at least on the runners and chargers in 73.
                             
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