Torque converter stall question

[Cooter]

Man this stuff is confusing, I still don't really get it but I'll read up on it just so I can follow threads like these.

I still think that yanking the 727, smooth as it is, and replacing it with a 5 speed will give me a much more pleasant driving experience.  Heck I'd even bolt a GV unit on the auto if I could justify the cost but this 3 speed thing is ridiculous.   

Dino, I'll try and see if I can explain it as I do with some of my customers at the shop when looking into stall Converters....

Think of the inside of a Converter as a Paddle wheel on an old timey mill...Now, a stock converter will have little "vanes" that catch fluid being slung by them at a certain RPM. A Higher Stall converter will still have the vanes, but will be at a Steeper angle...Therefore, catching fluid that passes by takes more and more RPM in order to make the wheel turn...(More force). More force to turn Stator inside converter relates to more heat build up.
As a rule of thumb, if you like those "Bang Screech" shifts with a stock converter (Shift kit), then most times installing a Higher stall converter kinda "Covers up" the harsher shifts due to the extra slipping. however, depending on gear in rearend, this isn't always the case...

[Dino]

Ok I'm starting to get it now.  So by using a higher stall converter you are effectively putting it in the higher rpm range and thus higher hp and torque numbers which is great on the strip, but on the street it will act more like a slipping clutch which may give you the same benefits as on the strip but due to the slipping it generates more heat in the trans.  Am I kinda on the right track here?

So my car with its high rear end gear and (supposedly) stock converter will be good for a cruiser but even if I replace the rear end gear with a lower ratio I will still lose because of the low rpm stall converter?

Thanks for the explanation Cooter, sorry if I still messed up.   

[Cooter]

"Ok I'm starting to get it now.  So by using a higher stall converter you are effectively putting it in the higher rpm range and thus higher hp and torque numbers which is great on the strip, but on the street it will act more like a slipping clutch which may give you the same benefits as on the strip but due to the slipping it generates more heat in the trans.  Am I kinda on the right track here?"

YEP....



No, not at all Dino, in fact, now you know why Most ALL newer cars have a LOCK-UP Torque Converter in OD....

A high stall converter that never really "Stops stalling", or "Tightens up" will definately burn fluid. (Don;t ask me how I know. Something bout a 4500 RPM Converter in my 5.0 Stang, with 3.73:1 gear and trying to cruise it down the highway with a C4)....

Many of the newer trans's use Lock up Stall converters. So, while in the first three forward gears, you have the higher stall, but once in OD, it Locks up and doesn't stall anymore. Acts just like a Clutch in a manual.

[Dino]

"Ok I'm starting to get it now.  So by using a higher stall converter you are effectively putting it in the higher rpm range and thus higher hp and torque numbers which is great on the strip, but on the street it will act more like a slipping clutch which may give you the same benefits as on the strip but due to the slipping it generates more heat in the trans.  Am I kinda on the right track here?"

YEP....



No, not at all Dino, in fact, now you know why Most ALL newer cars have a LOCK-UP Torque Converter in OD....

A high stall converter that never really "Stops stalling", or "Tightens up" will definately burn fluid. (Don;t ask me how I know. Something bout a 4500 RPM Converter in my 5.0 Stang, with 3.73:1 gear and trying to cruise it down the highway with a C4)....

Many of the newer trans's use Lock up Stall converters. So, while in the first three forward gears, you have the higher stall, but once in OD, it Locks up and doesn't stall anymore. Acts just like a Clutch in a manual.

Awesome!  That actually makes sense to my little brain!  Thanks for the explanation Cooter.   

[TUFCAT]

I just re-read this thread from a couple of years ago...and man, there's some good info here!     I figure I'll bump it, in the event it can help someone else answer a question they forgot to ask....but always wanted to know.