What Does a Torque Converter Do..
01-13-2009, 03:50 AM
#1
What Does a Torque Converter Do.. Alright, I already feel like a dumbass but you gotta learn somehow. I've had my car for half a year now, and this is my first one with a bigger TC. If someone could explain to me in a way I could understand, what does my 3500 TCI converter do exactly? I'd much rather have someone here explaining it to me rather than some wikipedia post 
Thanks guys
Thanks guys
01-13-2009, 04:03 AM
#2
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Just read the stickys in Automatic Transmission... you'll learn most everything you need to know.....
1) Higher RPM Launches. This is self explanitory, but so is the search button so ill explain. You can brake stall to a higher rpm and also flash stall to a higher rpm.
2) Static Torque Ratio. I will leave the explaination of this to the experts at Yank
"The stall torque ratio is the amount of engine torque that the torque converter can multiply at a particular rpm level. By definition, stall torque ratio is when the turbine is at 0 RPMs and the converter is at maximum designed stall. This will produce a positive push on the turbine to increase the torque to the input shaft of the transmission, multiplied by the designed stall torque ratio of the torque converter. For example, a stall torque ratio of 2.0 would multiply 200 lb. ft. of engine torque to 400 lb. ft. of torque at the transmission input-shaft. The misconception of stall torque ratio is that more must be better. This is not always the case. High stall torque ratio applications, typically are for industrial equipment or engines with limited low rpm engine torque. With high stall toque ratio converters, there are important trade-offs. What you take at one end you give up on the other. Typically, a torque converter with a very high stall torque ratio, such as 2.0-2.5, will be much less efficient above its rated stall speed. There is a sacrifice in higher rpm efficiency to achieve high stall torque ratios. That lower efficiency translates into less horsepower transmitted to the tires over an RPM range. The problem with a high stall torque ratio converter is that it is only high while the car is not moving. Maximum stall torque ratio occurs at wide open throttle with no rotation of the transmission input shaft. As the input shaft starts to rotate with vehicle forward movement, the stall torque ratio will become non-existent much sooner than a converter of the same stall, with a lower stall torque ratio." (Yank)
3)Shift Extensions. Pretty much the rpm's wont fall down as much between shifts. This also helps deal with the dead spots between gears (like a 45mph with 3.23's).
4)Weight- Aftermarket convertors weigh less and have less rotation mass.
1) Higher RPM Launches. This is self explanitory, but so is the search button so ill explain. You can brake stall to a higher rpm and also flash stall to a higher rpm.
2) Static Torque Ratio. I will leave the explaination of this to the experts at Yank
"The stall torque ratio is the amount of engine torque that the torque converter can multiply at a particular rpm level. By definition, stall torque ratio is when the turbine is at 0 RPMs and the converter is at maximum designed stall. This will produce a positive push on the turbine to increase the torque to the input shaft of the transmission, multiplied by the designed stall torque ratio of the torque converter. For example, a stall torque ratio of 2.0 would multiply 200 lb. ft. of engine torque to 400 lb. ft. of torque at the transmission input-shaft. The misconception of stall torque ratio is that more must be better. This is not always the case. High stall torque ratio applications, typically are for industrial equipment or engines with limited low rpm engine torque. With high stall toque ratio converters, there are important trade-offs. What you take at one end you give up on the other. Typically, a torque converter with a very high stall torque ratio, such as 2.0-2.5, will be much less efficient above its rated stall speed. There is a sacrifice in higher rpm efficiency to achieve high stall torque ratios. That lower efficiency translates into less horsepower transmitted to the tires over an RPM range. The problem with a high stall torque ratio converter is that it is only high while the car is not moving. Maximum stall torque ratio occurs at wide open throttle with no rotation of the transmission input shaft. As the input shaft starts to rotate with vehicle forward movement, the stall torque ratio will become non-existent much sooner than a converter of the same stall, with a lower stall torque ratio." (Yank)
3)Shift Extensions. Pretty much the rpm's wont fall down as much between shifts. This also helps deal with the dead spots between gears (like a 45mph with 3.23's).
4)Weight- Aftermarket convertors weigh less and have less rotation mass.
01-13-2009, 04:06 PM
#3
So are you supposed to be able to brake stall at a pretty high RPM with one? 'Cuz thats the first thing i looked at when I got the car, and it didn't go very high before the wheels were spinnin'. Thanks for the info though I do understand everything else 
01-13-2009, 04:25 PM
#4
Brake stall can be low even though a performance converter is used. Most converters are rated at their flash stall. IE my Circle D 4C is rated at ~3800 stall. This means it will flash to about 3800 on a WOT take off. It might only footbrake to 2500 though. Here is a link to a pic I made and a decent description.
http://www.circledspecialties.com/Converter%20101.html
Chris
http://www.circledspecialties.com/Converter%20101.html
Chris
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01-15-2009, 04:42 AM
#10
Lol it confuses me too so I understand a little better. I have a TCI 3500, does this mean at WOT the RPMs will instantly flash up to 3500 between gears? (If thats true) i believe that keeps the RPMs in the LS1's best power range right?
01-15-2009, 07:40 AM
#12
Quoting myself from some time ago.
"Actually if anybody is interested in how a Torque Converter works you can see some repudable articles here. They are very hard things to explain, they act as a fluid coupling that based on the rate of flow can multiply TQ for short periods depending on how quickly it exits the strator.
http://www.converter.cc/tech_talk/tech_main.htm
http://www.converter.com/torqueration.htm
http://auto.howstuffworks.com/torque-converter.htm
Typically it's a trade off, Tq multiplication for efficiency. I had a dyno graph somewhere of a tq spike through an unlocked converter, it can jump quite high depending on the converter."
"Yeah just remember a TC is a centrifugal pump, it is never a 1-1 input (like a clutch) until the converter lockup occurs (if it has a lockup clutch). At WOT a converter should never lockup unless you have a multidisk converter which can hold the power your throwing at it.
Maybe a way to explain it is if you spin a bucket of water around, the farther away from your arm (outer diameter) the more kinetic energy is being applied, and it's that momentum of kinetic energy that spins the tranny input harder than the input from the motor. The motor and the converter never spin 1-1 until it locks up. A high stall converter slips for performance reasons because the more power/tq at a higher rpm rule still applies, and in combination with a STR of say 2.5 you are effectively mulitplyng the torque at the given rpm more than twice what the motor is generating.
As an example, say if my car makes 350 rwt at 4000 and I have a 4000 rpm TC w/ a 2.0 STR, at a flash stall on the line the car will lay down approx 700 rwt for only but a few second, then it will gradually tail off as you pass the 1000ft mark. I will ask my tuner for any dyno graphs that he may have showing an unlocked car on the dyno. The spike itself since it is something that happens at low speeds is hard to reproduce on the dyno, but in many real aggressive car's (3 or 2 speed, non-lockup) you can see the TQ line WAY over the HP at the start of the pull and not pan out till the 5200rpm mark."
"Actually if anybody is interested in how a Torque Converter works you can see some repudable articles here. They are very hard things to explain, they act as a fluid coupling that based on the rate of flow can multiply TQ for short periods depending on how quickly it exits the strator.
http://www.converter.cc/tech_talk/tech_main.htm
http://www.converter.com/torqueration.htm
http://auto.howstuffworks.com/torque-converter.htm
Typically it's a trade off, Tq multiplication for efficiency. I had a dyno graph somewhere of a tq spike through an unlocked converter, it can jump quite high depending on the converter."
"Yeah just remember a TC is a centrifugal pump, it is never a 1-1 input (like a clutch) until the converter lockup occurs (if it has a lockup clutch). At WOT a converter should never lockup unless you have a multidisk converter which can hold the power your throwing at it.
Maybe a way to explain it is if you spin a bucket of water around, the farther away from your arm (outer diameter) the more kinetic energy is being applied, and it's that momentum of kinetic energy that spins the tranny input harder than the input from the motor. The motor and the converter never spin 1-1 until it locks up. A high stall converter slips for performance reasons because the more power/tq at a higher rpm rule still applies, and in combination with a STR of say 2.5 you are effectively mulitplyng the torque at the given rpm more than twice what the motor is generating.
As an example, say if my car makes 350 rwt at 4000 and I have a 4000 rpm TC w/ a 2.0 STR, at a flash stall on the line the car will lay down approx 700 rwt for only but a few second, then it will gradually tail off as you pass the 1000ft mark. I will ask my tuner for any dyno graphs that he may have showing an unlocked car on the dyno. The spike itself since it is something that happens at low speeds is hard to reproduce on the dyno, but in many real aggressive car's (3 or 2 speed, non-lockup) you can see the TQ line WAY over the HP at the start of the pull and not pan out till the 5200rpm mark."
