Disappointed magnum head flow numbers....

Mopar Performance Issues

  1. yellow rose

    yellow rose Overnight Sensation

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    There is more to making horsepower than cylinder head flow. That can’t be emphasized enough.
     
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    • pishta

      pishta I know I'm right....

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      "...in order to GO, you must FLOW"...where did that come from? I think head flow is the foundation that which all power is built upon.
       
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      • Brooks James

        Brooks James VET, CPT, Huey Medevac Pilot FABO Gold Member

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        Ok, does this mean that mean that my set I will be making around 500 ho ?? Let’s be conservative 450 hp
         
      • Cuda416

        Cuda416 FABO Gold Member FABO Gold Member

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        Depends on the rest of the build.

        The issue is, it doesn't matter how you build the bottom, if the heads won't flow, you're not going to make the power without an adder. If the heads flow but them bottom end isn't built to make power, well, you make more than stock but not full potential.

        The engine needs to move fluids/gasses in and out. That's where the flow comes into play.
         
      • rumblefish360

        rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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        The flip side is how effective you are in;

        1; Making the most power out of what you have.
        2; How effective you are in utilizing that power to go fast.
         
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        • yellow rose

          yellow rose Overnight Sensation

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          Shape is more important than flow. All day long. A quiet port that doesn’t flow well in reverse is better than a noisy port that flows 85% in reverse.
           
        • Brooks James

          Brooks James VET, CPT, Huey Medevac Pilot FABO Gold Member

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          I realize that I need good
          exh flow that is why I put a nitrous grind in it.
          I anticipate around 500 horse on the combo with 150 shot of nitrous I was hoping I could accomplish it on stock heads
          I don’t have the money for aftermarket heads that would definitely do the job
          I jus want an estimate nothing is chiseled in stone
          360 mag
          Stock block/ heads/ crank/rods/ 9:1 pistons
          Edelbrock knock off airgap
          MSD 6al my dizzy accel super coi904 w: 3500 converter
          Massaged 750 dp
          You already the specs on the cam engine is not that far off 380 crate
           
          Last edited: Apr 7, 2021
        • 318willrun

          318willrun Utube channel 318willrun

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          • flow at low lift is important
          • matching the rest of the car to the engine is important
          • having the car "work" in itself is huge.
          My point is, a well sorted out 385 hp powered Duster can beat a 485 hp powered Duster if the 385 mule is in a car that is well sorted out.
           
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          • rumblefish360

            rumblefish360 I have escaped the evil Empire State! FABO Gold Member

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            Bingo dead on.
            Exactly what I was saying above.
             
          • yellow rose

            yellow rose Overnight Sensation

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            Point one is not what my experience says. For more than one reason. I look at the numbers below about .200 lift, but unless something is way wrong I don’t care about that.

            If you can test low lift at say...100 inches of water you’d see why the low lift numbers don’t mean much at 28 inches. Plus, the piston is in the way. Plus, you have to deal with cross flow at overlap. To fix that you have to reduce overlap and that’s a power killer.
             
            Last edited: Apr 8, 2021
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            • 318willrun

              318willrun Utube channel 318willrun

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              I should have said what I meant at low lift. .400
               
            • mgoblue9798

              mgoblue9798 Well-Known Member

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              With a 150 shot 500 hp should not be difficult to hit with magnum heads.
               
            • jos51700

              jos51700 Green Bearing thread connoisseur

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              Listen, comparing flow numbers you found on the internet is like writing food reviews by reading the menu.

              #1 no two flow benches are the same.
              #2 no two operators are the same.
              #3 no two weather conditions are the same, and this matters because flow machines do not suck, they cause atmospheric pressure to blow.

              Notice I didn't even get into heads, valves, cam dynamics, etc. If you're reading flow numbers on the internet trying to decide what heads are best, you're not driving at a level that it will matter.
               
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              • K.O. SWINGER

                K.O. SWINGER Meeting in the alley since 1976

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                Horsepower on a nitrous boosted motor at the kind of power level you're talking about is primarily affected by nitrous jetting. The Magnum head has a decent exhaust side which will help accommodate the nitrous. Head flow becomes a little less critical factor when injecting torque from a bottle. I personally wouldn't spend a lot of time on a set of Magnum heads unless you just love them. if you're going to upgrade then step up. But that being said 500 horse range is definitely achievable with Magnum heads on the juice.
                 
              • Brooks James

                Brooks James VET, CPT, Huey Medevac Pilot FABO Gold Member

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                Thanks, I did a lot of research to set this up. I figured that what I have now is close to the level of hp I could make without spending a lot more and keep from blowing the motor. I will be able to have lots of fun with 500 hp on the
                street, when I get traction set up. Off the juice it will be a 13 sec mild plus engine which my wife can still drive to the grocery store which is exactly what I want. and hopefully in the high 11’s on the juice, which I consider to be a respectable in a daily driver. It will be like what Hirohito said when the japs destroyed Pearl Harbor “I keel as if we have awakend a sleeping giant.”
                 
                Last edited: Apr 11, 2021
              • oldkimmer

                oldkimmer FABO Gold Member FABO Gold Member

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                Just for comparison my 470 stroker Dynoe’d at 655 hp. Heads flow 320 cfm. I believe the formula is 2.06 hp per cfm. Mine is actually pretty dam close. Volumetric efficiency was 108%. I will add that some motors put out beyond expectations while others fall short. I can’t stress cylinder prep enough. Having straight round bores is an absolute must. Kim
                 
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                • Hot Metal

                  Hot Metal '69 440 Cuda

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                  I can give you some track numbers if it helps on my '71 Cuda with stock 340 motor, 2.02 non ported heads that are around 215cfm@best+HS dom intake, 850DP, .590"DC sft cam, 4200stall etc. etc. Motor only made 367fwhp, best mph was 108 NA, according to weight/mph. Added a 250shot but only got actual 158hp from it (525) for other reasons like too rich petrol jet specs back then (110n/110p) and not enough backed off timing but ran 122mph. So you can do it on stock heads, you should be able to get almost 150hp from a 150 shot if you tune it well with todays jettings etc., and your motor is up there with NA hp.
                   
                  Last edited: Jul 24, 2021
                • Brooks James

                  Brooks James VET, CPT, Huey Medevac Pilot FABO Gold Member

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                  OK 220 x 2 is 440 hp normally aspirated
                  How much more. Hp can i expect with a
                  150
                  Shot of gas
                   
                • Brooks James

                  Brooks James VET, CPT, Huey Medevac Pilot FABO Gold Member

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                  What about 220 flow x 2 is 440hp, what about a 150shot of gas added
                   
                • gzig5

                  gzig5 FABO Gold Member FABO Gold Member

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                  Ok, I'll play along.
                  440+150=590
                   
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                  • Brooks James

                    Brooks James VET, CPT, Huey Medevac Pilot FABO Gold Member

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                    OK my build is based on the 360/380 crate, which i have read that regularly dyno at 400 hp, im hoping 530 hp and 500 torque, does that sound reasonable ?
                     
                  • Krooser

                    Krooser Building Chinese Free Engines since 1959...

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                    I doubt it.

                    My 388" 360 based race motor started life with ported w-2 heads flowing 294 cfm intake, 13-1 compression on alky, 750 Holley DP, dizzy locked at 36 degrees, Crower solid lifter cam 580/580 with a 260 degrees duration @ .050... 575 HP @ 6,000 rpm.

                    Now I'm shooting for 625 with my 850 carb, more cubes, lighter valves and a better cam. Still might not make it...
                     
                  • 33IMP

                    33IMP Well-Known Member

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                    I think he is including a 150 shot in those numbers.
                     
                  • Krooser

                    Krooser Building Chinese Free Engines since 1959...

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                    Makes sense...
                     
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