Stall speed
Senior Member
Joined: Mar 2000
Posts: 1,985
Likes: 1
From: Cincinnati, OH
This is kind of technical, but it's the best answer about K factor, (It was written some time ago, but still relevent)
Stall speed is a made up number really, it varies widely under different conditions, but the 4R70W 5.4 I think stalls at about 2,000, it has a 130K factor
In general, there are two basic equations used to describe the behavior of toque converters with respect to diameter, input torque and input speed. The first equation relates to th Diameter (D) and input speed (Ni) to the input torque (Ti)
Ti = C Ni^2 D^5
Factor C is a function of geometric design, fluid density and viscosity. This equation points out that a change in capacity can be reached through a small change in diameter. When the variable C and the diameter D are condensed into a new variable K, or K factor.
K = Ni/ Square root of Ti
( I ain't even gonna ask how to type a square root symbol)
This relationship holds over the full range of converter operation. The value of K is not constant, it increases with increased output speed and speed ratio. When K is used to identify a converter, it is referring to the value of K at stall, which is in most cases the lowest K Factor value. Converter efficiency is represented by the following relationship
Eff = T out/T in x N out/ T in = Torque Ratio x speed ratio
Engine stall speeds are noticeably higher with smaller converters which also have higher K values. Converter diameter is inversely proportional to stall K value. Smaller diameter converters extend torque multiplication and coupling point (lockup) engine speed for better performance but sacrifice effeciency. Larger diameter converters give better fuel economy. I understand that in a diesel, some peolple think that lower stall is better, so larger diameter would be better if you're so inclined, all other things being equal.
If I didn't lose you, I hope that helps, but it's not an easy thing to explain, and the lack of proper superscript type doesn't help.
Stall speed is a made up number really, it varies widely under different conditions, but the 4R70W 5.4 I think stalls at about 2,000, it has a 130K factor
In general, there are two basic equations used to describe the behavior of toque converters with respect to diameter, input torque and input speed. The first equation relates to th Diameter (D) and input speed (Ni) to the input torque (Ti)
Ti = C Ni^2 D^5
Factor C is a function of geometric design, fluid density and viscosity. This equation points out that a change in capacity can be reached through a small change in diameter. When the variable C and the diameter D are condensed into a new variable K, or K factor.
K = Ni/ Square root of Ti
( I ain't even gonna ask how to type a square root symbol)
This relationship holds over the full range of converter operation. The value of K is not constant, it increases with increased output speed and speed ratio. When K is used to identify a converter, it is referring to the value of K at stall, which is in most cases the lowest K Factor value. Converter efficiency is represented by the following relationship
Eff = T out/T in x N out/ T in = Torque Ratio x speed ratio
Engine stall speeds are noticeably higher with smaller converters which also have higher K values. Converter diameter is inversely proportional to stall K value. Smaller diameter converters extend torque multiplication and coupling point (lockup) engine speed for better performance but sacrifice effeciency. Larger diameter converters give better fuel economy. I understand that in a diesel, some peolple think that lower stall is better, so larger diameter would be better if you're so inclined, all other things being equal.
If I didn't lose you, I hope that helps, but it's not an easy thing to explain, and the lack of proper superscript type doesn't help.
Technical Article Contributor
Joined: Oct 2003
Posts: 1,490
Likes: 0
From: Topeka Kansas
I dont know what the factory setting is but you might like this link...
http://www.bankspower.com/Tech_understandstallspeed.cfm
Larry
http://www.bankspower.com/Tech_understandstallspeed.cfm
Larry
Senior Member
Joined: Jul 2001
Posts: 1,109
Likes: 1
From: Nu Joizey
