Cure for lazy Magnum...Has anyone built a Magnum for 7k+ revs?

Magnum Engine Swaps

  1. toolmanmike

    toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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    Sorry, your "stock Magnum 300" label threw me for a loop.
     
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    • MRGTX

      MRGTX Well-Known Member

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      Mopar is guilty of recycling that name too many times.
      I still like these...

      350px-Magnum1.jpg
       
    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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      The only problem I see with a high rpm SBM engine in a streeter,is gearing it to work in your chassis.
      Mostly, a cam to do that will trade away all your low-rpm torque, so the first thing you will need is a hi-stall tc so you can actually get moving.
      Next comes the gearing; It is impossible to make this into a proper 2-gears to 60 mph streeter, And if it only goes thru the power peak once on the way to 60, you lose.
      And the third thing is this ; with the 3000TC and the 4.30 gears and a regular torqueflite trans, it's gonna spin the tires right thru first gear and most if not all of second gear...... so yur gonna have to spend a wheelbarrow full of cash to try to do something about that.
      And fourthly is cruising with 4.30s sucks.
      And Fifth is all the friggin shifting; never a break from shifting.
      Making her rev to 7000 is the easy part. Making it do that more than once only costs a bit more. Making it work in your combo, and living with it, well; that will take cash and dedication.
      No matter what; yur gonna need an overdrive. Cuz hitting 7000 in first gear with 3.55s is not an option most would chose, mostly the tires just smoke all the way to 60/65 mph.

      And for me the worst part is filling the gas tank every couple of hours.

      For a streeter, what you really need is to go thru the power peak twice on the way to 60/65
       
      Last edited: Sep 26, 2019
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      • rumblefish360

        rumblefish360 So close, yet so far away FABO Gold Member

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        AJ! You didn’t write a novel!

        CONGRATULATIONS

        Now, why such an bummer and a nay sayer, your such a bummer!

        “All I see are problems!” Maybe for you!!!!!

        Hey! I’ll count my blessings that you did t write a eye bleeding novel on how your 224@050 cam revs to 7K and gets 24 mpg’s!
         
      • rumblefish360

        rumblefish360 So close, yet so far away FABO Gold Member

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        Yep, get me one of those too. I was working on it about a 1/2 hour ago....

        image.jpg

        I just (Re) dropped in my ‘00, 5.9.
         
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        • AJ/FormS

          AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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          To the guy who gets panties all bunched up when someone misquotes him;I said
          Because I have 4 different types of A833s plus a GVOD, and at one time had a nearly full selection of ready to go pumpkins; I can tell you with great experience, that gearing is where it's at.
          Just cuz you can't make 24 mpgs, doesn't make it impossible.
           
          Last edited: Sep 26, 2019
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          • rumblefish360

            rumblefish360 So close, yet so far away FABO Gold Member

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            You forgot to leave a space after “him; & I said”

            :lol:
             
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            • AJ/FormS

              AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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              For a streeter it's all about two things;
              traction,and average power to the road over a certain speed range.
              From zero to 60mph; even a slightly worked 318 can post a great ET with the right gear package.
              The difference is that a bigger engine just makes a lot more smoke and noise to go a wee bit quicker.
              The bigger engines can hit more bases with less gear, but there comes a point that traction is so severely hampered that it becomes increasingly expensive to carry on.

              Say you had two identical cars; except for the engines and rear gears. Both with the same rear suspension/tires.
              Say one had a stock Magnum 5.2 with a peak of just 230 hp and you ran it thru two gears to hit 60mph revved out on the power-peak. This would take ~4.30s with a regular TorqueFlite.
              and; Say your buddy had a stock Magnum 5.9 ,and it also is stuck with the 727/904 ratios, that forced a shift into second at say 50 mph ( this being 3.23s), and then the rpm fell to 59% or say 3100rpm. That 5.9 with 3.23s will hit 60@~3700;at the very bottom of the power curve. So, whatever average power this 5.9 posted in first gear, that number is now gonna get dragged LOWER until the power comes back up.
              I wonder who would get to 60 first.
              Well stop wondering;
              those 4.30s are making the 5.2 seem 33% more powerful than it would with 3.23s, so it will accelerate accordingly, leaving the 5.9 in the dust. My math says the 5.9 would need more than 300hp to stay even.And the 5.9 will need it at 3700rpm. Yeah that's a pricey build right there.
              But if these examples do nothing but spin the tires,then it's anybodies guess who will ET quicker.
              Like phaith without works; power without traction ...... is dead.
              But is sure is fun.

              Consider the turbocharged Subaru Impreza full-time AWD, 5 speed. Or it's ilk. If it didn't have all-wheel-drive, or if it did but lost the turbo,it would be just another also-ran 4-banger. But as designed, it has the two key ingredients,namely; traction, and average power to the road.
               
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              • rumblefish360

                rumblefish360 So close, yet so far away FABO Gold Member

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                Freakin A! AJ! Freakin A!
                 
              • MRGTX

                MRGTX Well-Known Member

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                Excellent points. There are other variables that matter here but ultimately, that all makes sense to me.

                As someone who owns a turbo Subaru as a daily driver I can confirm that it's still just an also-ran-4-banger. It's as quick as the Dart (similar weight, similar power, way better traction, 3 more gears) and much quicker off the line (for obvious reasons) but it's absolutely sterile and boring compared to the Dodge. The power rarely seems to be available when you want it. There's no joy from the sound or feel of the engine. But it handles great, keeps the Dart out of the snow/rain, and gets 30mpg if I'm driving like a sane person. :)
                 
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