Register now to get rid of these ads!

Hot Rods Technical question on stall converters ?

Discussion in 'The Hokey Ass Message Board' started by blazedogs, May 14, 2020.

  1. blazedogs
    Joined: Sep 22, 2014
    Posts: 470

    blazedogs
    Member

    Excuse my dumb question on torque converters. Ok ,so you have say a 1800-2000 RPM torque converter. That means that it will engage at 1800 -2000 rpms from a dead stop putting the car in motion. My question if that,s the case if you are driving down the hwy at 60 mph and the rpm at that point is only 1500 rpms then the converter is still not locked in, for not a better word ,is still slipping ? Explain this to me.. Gene
     
  2. Ldjr003
    Joined: May 8, 2019
    Posts: 20

    Ldjr003

     
  3. Ldjr003
    Joined: May 8, 2019
    Posts: 20

    Ldjr003

    The convertor will act pretty much like a stock convertor when you pull away from a stop. It will hit that rated rpm when you mash the throttle or power brake your vehicle. As far as slippage at speed, ALL convertors slip some, until it locks up, IF you have a lock up convertor. For a convertor you are describing, in normal everyday driving, you'll probably never notice the difference from a stock convertor. Don't expect to run a 5,0000 rpm race convertor on the street. That would not last very long, also a looser convertor allows a wilder cam without the motor trying to stall everytime you come to a stop. Hope that clears things up a little.
     
    olscrounger likes this.
  4. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,025

    Boneyard51
    Member

    The “ stall” of a converter is dependent on power and load. The numbers are just a reference to compare convertors. There is no way that convertor knows how much horsepower you have and how much load it has to pull.

    The same convertor will “ stall” at different speeds with a high horsepower, car than with a low horsepower car.






    Bones
     
    X38, dana barlow and Blues4U like this.

  5. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,692

    Blues4U
    Member
    from So Cal

    The actual stall speed will vary by vehicle, but yes, if the converter stalls at 1800 - 2000 rpm, then when cruising at 1500 rpm the converter will be slipping. This can/will generate heat, so you'll want to run a trans cooler (in addition to the cooler in the radiator). Ultimately, you want to match the stall speed to the gearing so the engine rpms are above the stall speed at hwy speed.
     
    Boneyard51 likes this.
  6. blazedogs
    Joined: Sep 22, 2014
    Posts: 470

    blazedogs
    Member

    Still not clear I understand about from a dead stop the delay, as you step on the foot feed and it reaches its rpm. But my question is when you are going down the hwy at at say 60 mph ( below) the designed stall speed, is the stall converter still trying to match what it was designed to do . Sorry maybe I,m not making myself clear
     
    Boneyard51 likes this.
  7. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,025

    Boneyard51
    Member

    Yes you are making yourself clear and a very good question. That’s the trade off on a high stall converter, they are still “ stalling” somewhat at lower speeds. They are making better converters today to combat that. But a high stall converter will still slip more at low speeds than a low stall.

    Check the specs on the converter that you are looking at. Back in the old days, the high stall converters slipped a lot at highway speeds. The newer technologies are making them work better. But remember all non lock up converters slip going down the high way. That’s why they invented the look up converter!






    Bones
     
  8. blazedogs
    Joined: Sep 22, 2014
    Posts: 470

    blazedogs
    Member

     
  9. blazedogs
    Joined: Sep 22, 2014
    Posts: 470

    blazedogs
    Member

    Ok Boneyard you answered my question ... I,m too old to want to go fast anymore or being able to jump off the line.. I have some other issues ,the reason I,m asking. My driving now is cruising at hwy speed and enjoying life. So if the convertor I ( maybe) select should be based on my rpm at ( crusing speed )) & no I don,t want to have to have a trans cooler... Thanks much ! Gene in Mn
     
    Boneyard51 likes this.
  10. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,025

    Boneyard51
    Member

    If you have a Crusier! , if you want a hot rod to just play around town, you can increase the stall speed..... at the expense of highway speeds! Lol








    Bones
     
  11. squirrel
    Joined: Sep 23, 2004
    Posts: 49,276

    squirrel
    Member

    The "stall speed" is just that---the maximum RPM the converter will slip to, under full power. When you are just cruising, the converter will not slip nearly so much. With a stock converter (which is generally rated at about 1500 rpm stall speed) you probably see up to 200 rpm slip at cruising speed, with a 2000 rpm stall converter, you'll probably see 200 to 250 rpm slip at cruising speed.

    When you get up to 3000 or so rated stall speed, is when you start having issues with the converter slipping noticeably at cruising speed.
     
    olscrounger likes this.
  12. jaracer
    Joined: Oct 4, 2008
    Posts: 1,112

    jaracer
    Member

    I think you are a bit confused. The 1800-2000 rpm stall speed indicates the maximum rpm the engine will obtain with the transmission input shaft not turning. It is connected to the turbine in the converter. All non-lockup converter's (those without an internal clutch) have some degree of "slip" at light load cruise. With the converter in question, you would have the same amount of "slip" if your cruise rpm were 1500 rpm or 2500 rpm. If you add enough load, such as a big hill, the turbine will begin to slow down and the stator will lock up giving you torque multiplication. At maximum load, the difference between the turbine speed and the pump speed (engine) would be 1800-2000 rpm and you would have somewhere around 2:1 torque multiplication. This will create quite a bit of heat. The most likely way for this to happen at any speed above say 30 mph would be towing a heavy trailer up a big incline.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.