Torque Converter stall ??

Transmission and Drivetrain Tech

  1. 44070dart

    44070dart How the hell did I get this old

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    if you have a 3200 stall converter and are driving on the highway continuously at 2800 rpm's, is the converter slipping until you hit approx. 3200. Doesn't that translate to extra heat for the converter and the trans.
     
  2. RussellSullivan

    RussellSullivan Well-Known Member

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    The stall speed of a converter is a way of rating how many RPM it will take to break the tires loose from a dead stop, with your foot on the brake. This number is approximate, due to differences in engine characteristics, rear gears, transmission, etc.

    The torque converter does continue to slip throughout the gears, unless it is a lockup unit. A lockup converter does exactly what the name implies; it locks up at a certain RPM, creating a 1:1 ratio of engine output RPM and transmission input RPM. It also reduces heat, and provides better fuel mileage.

    Someone can correct me, but this is the way I understand it.
     
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    • RussellSullivan

      RussellSullivan Well-Known Member

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      Usually when choosing a converter, you will want one with a stall speed close to that of your peak torque RPM. This ensures that you "get the most" out of your engine's available power.

      Let's say you have a 2000 stall converter but your torque peaks at 2800. The "loose" 2000 stall converter will launch your car before you reach peak torque, which will have a negative impact on acceleration.

      Forgive me if I seem long-winded, I've been trying to choose my own torque converter lately and have tried to memorize what I've learned.
       
    • roccodart440

      roccodart440 Well-Known Member

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      While there will always be a percentage slippage in any non-lockup converter or a converter under the stall speed, however with a quality converter this is minimal.

      Remember the converter only sees what's in front of it at that time. So if you make 350ft/lbs of torque at 2500RPM, that's what the converter sees. IF you make no sharp movements with the throttle, it will act accordingly. Flash stall is observed when you mash the pedal from a dead stop or mash it when cruising under the flash stall. My convertor is a 10" 3500, I run a GVOD and can't foot brake much past 1200rpm. IT buimps going into gear
       
      Last edited: Nov 20, 2020
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      • 318willrun

        318willrun Utube channel 318willrun

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        A 3200 stall converter "as advertised" is just a blanket statement - trying to get the buyer an "idea" of how loose a converter is. Stall RPM's is measured by "flash stall", or, the sudden mash of the gas and what the converter flashes up to. The engines power will determine what that number is. For instance, a 3200 converter may flash to only 2700 behind a 318 2bbl but 3500 rpm's behind a decent 408. As far as "slippage" at cruise can and will be true if you have a 299.99 off the shelf special. Trust me, GER taught me that years ago :D A "good" converter will respond totally different these days....
         
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        • Kendog 170

          Kendog 170 Let the boy go !

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          I have a 2500 stall behind my 500" stroker and it flashes at around 2700 2800
           
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          • RustyRatRod

            RustyRatRod Lemmie see your b00bs. FABO Gold Member

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            There's no way for us to know that. Whose converter is it? Is it off the shelf or custom? What's the part number?
             
          • Charrlie_S

            Charrlie_S Well-Known Member

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            Change one part on the engine, and you can change the stall speed. I have a 9 1/2 inch converter that will "locked brakes'' stall at 3200 rpm with my 170 slant. That same converter in the same car, but with a 225 engine will stall at 3900 rpm. More cubes = more torque= more stall. This is why, in general, don't pick an "off the shelf" converter, or pick one yourself. Call a reputable converter builder, and give him the info on your engine/car (don't lie), and let him build it. You'll be damn close right off the bat.
             
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