Stall Speed Recommendation

Mopar Racers Forum

  1. Cazbah362

    Cazbah362 Well-Known Member

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    I am rebuilding my 727 putting a new convertor in my 71 Dart (Factory Weight) with a 440/727. The engine Im guessing is about 400-425 (.30 74 truck motor, 915 heads (no work just 2.14's and large exh valves, decked) .540 hydraulic roller cam, M1, HP Ultra HP and MSD ignition locked out and a NOS 100 (for this time). No dyno numbers, so this is a bit of a swag. I take this engine to 5900/6000 (cast crank and factory style cast pistons)

    727 is a reverse manual VB, going with Red Eagle bands and clutches and sprag upgrade, deep pan.

    The rear is 430's with a 295/65/15's. This car is track first, cruiser second. All the other 440's I have dynoed in the past have been a little more beefy than this one and max torque has always been close in the 3800 K range. With that, I am thinking of a 3800 to 4000 K convertor, preferably closer to 4000.

    What are your suggestions. Insights etc. I would like to go to a 200 HP shot once I get the NOS worked out. I get the cast crank/piston issue, but not the scope of what I am looking at this moment.

    I do appreciate the insight
     
  2. bamamopar

    bamamopar Well-Known Member

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    Call PTC! They will build a converter for your motor and car! They are good and price wasn't bad at all!
     
  3. Cazbah362

    Cazbah362 Well-Known Member

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    Bama - thanks, I am working through Eric at JW transmission right now. They are actually re-building my old convertor to the 3800 to 4000 K specs.
     
  4. Rotax

    Rotax Well-Known Member

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    I have a PTC 2800 to 3200 workd great
     
  5. Cazbah362

    Cazbah362 Well-Known Member

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    Rotax - What do you foot brake to?
     
  6. 67 prostreet gt

    67 prostreet gt Well-Known Member

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    Call PTC for an accurate recommendation the stall speed is one of those subjects where u ask 20 people u get 20 opinions I I have a PTC 4000 stall in my dart though granted I'm using a transbrake on a bigger big block with lots of nitrous but still call PTC

    Posted via Topify using iPhone/iPad
     
  7. OldmanRick

    OldmanRick Well-Known Member

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    With your N/A engine combo, I'd think the 4500 range would get you the best et's. If and when you plan on hitting the NOS, and if your applying it off idle, make sure the converter builder knows that.
     
  8. SpareParts

    SpareParts Well-Known Member

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    DO NOT go off of this, way too many variables
     
  9. Cazbah362

    Cazbah362 Well-Known Member

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    All - thank you, I will call PTC too.

    SpareParts - Explain, please keep in mind im learning and its nice to see others views.

    Rick, thanks, I will let them know
     
  10. flyfish

    flyfish C8H18+N2O = :-D

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    More than likely you will have to chose if you want it setup for nitrous or NA. When I talked to PTC for my 8" I was on the fence about if I was going to spray it or not. The motor was fresh and had not been run yet, so I had no idea what it was capable of. They said that I should choose one way or the other for the optimal setup...I chose to have them set it up for NA. A few years later removed the nitrous system from the car because I never used it...the car hit all the ET goals I wanted without N2O.

    My point being, be sure to give them as much info as possible to get a good match on the converter.
     
  11. SpareParts

    SpareParts Well-Known Member

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    Brake rpm can be affected by a ton of things, engine combo is the obvious one. But what if he has better brakes then you? He will be able to stall the converter higher, same situation with his vehicle weight vs yours. If I put my 4700 converter that will foot brake 3200 in my duster into say a 3/4 ton truck with my motor I bet it would act totally different.
    Hope that helps clear things up
     
  12. Cazbah362

    Cazbah362 Well-Known Member

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    Spareparts - Thank you, yes does put a bit of insight on things, and good points
     
  13. D-50394

    D-50394 Well-Known Member

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    The higher the gear ratio in your rear end the more a convertor will footbrake stall and the heavier the car it will stall more.
     
  14. SpareParts

    SpareParts Well-Known Member

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    I had the opposite happen, years ago went from a 3.91 to a 4.56, converter got vise grip tight.
     
  15. D-50394

    D-50394 Well-Known Member

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    Yes that is what I was trying to say. the lower number or higher gear ratio equals more stall.
    I have a 5000+ 8 in PTC convertor. I had 5.14 gears it would stall about 26-2700 rpm . I broke them and put in 3.50 gears and it would go 3000-3100. I only lost a tenth and gained 1 mph, 6.39@ 109.We only run 1/8 mile in the south. I crossed the line in 2nd gear with the 3.50 gears.
     
  16. bad440

    bad440 everything,all the time..

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    Yep.....
     
  17. Cazbah362

    Cazbah362 Well-Known Member

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    All - Thank you very much, took much of your insight and tried to apply it. I purchased a 4500K convertor and rebuilt the trans with a bolt-in sprag and Red Eagle/Kolene items. I had a nice reverse manual VB already, so just re-used it.

    The car is factory weight so a guess would put it @ 3300. Tires are 295's and gears are 430's. I am looking forward to get some track time and test this out. I am not going to use the bottle until I have a few passes and the bugs worked out, once I do, I will fold the nitrous in.
     
  18. ian

    ian Well-Known Member

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    is that 4500 on gas or not , i run 4300 asp 1.37 60 ft on gas on a 275
     
  19. Cazbah362

    Cazbah362 Well-Known Member

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    Ian - gas? Guessing nitrous? will be, not at this time.
     
  20. ian

    ian Well-Known Member

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    that will work good mate ,cheers
     
  21. dustoff440

    dustoff440 Well-Known Member

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    contact some manufacturers they do this all day long
     
  22. Charrlie_S

    Charrlie_S Well-Known Member

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    X-2

    And, yes, you need to tell them if using nitrous or not. I had a new converter built, and told them nitrous. When I first tested the converter, on motor only, I didn't like it. When I turned on the bottle, the converter worked great. It needed the extra torque of the nitrous hit to work correctly.
     
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