What is full line pressure?

[94awdcoupe]

how mamy psi is full line pressure? any body measure it with gauge? how much does the pressure change using different fluids?

 

[Marchev]

Im a little lost as to what fluid or line pressure are you talking about?

 

[airmail96]

I think hes talking about in the automatic, but I don't know anything about them.

 

[pacn91]

Most pressure the transmission will see from the TCU is about 125-130psi. I believe with full line pressure unlocked you get close to 300 (will need to verify with pressure gauge, and of course, the adjustment screw will change this as well). That leads me to think that 50% is being conservative on what the TCU gives it. Maybe Dave can chime in more, but I believe the TCU controls both voltage and pulse going to the solenoid. The higher the voltage (0-12v), and the longer the pulse width, the LESS pressure you get.

If you are concerned about part throttle line pressure, you can turn your adjustment screw up, or Dave can change the pulsewidth based on TPS so can basically do what ever you would like. Full line pressure at 50% throttle, or even a gradient taper as TPS increases. You will have to see if it will be the same price as his basic chip though. I'm not sure if he writes his chips by code, or made a GUI for it.

What you said makes since, but it isn't how it works. Instead of intercepting a pressure sensor, you are intercepting the pressure relief valve, and keeping it from getting voltage so it stays closed. The TCU controls the pressure by looking at a table (like a timing or A/F table) that has TPS and transfer drive gear rpm (picked up by your pulse generators) as its axis.....

This was a comment that "Bender" made on another old thread. Seems like I've read a couple of more posts on it, but I cant seem to find them at the moment.

 

[Bud92gsx]

Do you want full line pressure for your auto? Or just asking questions?

 

[TalonSpeed]

This is how it was explained to me. Using fake numbers just to explain.

The valve body is what determines the max pressure, lets say 300psi
The OEM TCU is programmed to cut that down to 50%....150psi
Using a shift BOX or blue wire mod, full line pressure can only go up to the 300psi the valve body can do
Using a shift KIT (springs and balls inside the valve body) raises the max to 400psi

 

[94awdcoupe]

Do you want full line pressure for your auto? Or just asking questions?

I am asking to gain general knoledge of how the trans works and how to make it better for what i want to do.

This is how it was explained to me. Using fake numbers just to explain.

The valve body is what determines the max pressure, lets say 300psi
The OEM TCU is programmed to cut that down to 50%....150psi
Using a shift BOX or blue wire mod, full line pressure can only go up to the 300psi the valve body can do
Using a shift KIT (springs and balls inside the valve body) raises the max to 400psi

From what I understand the spring and valve body kit would raise the 50% shifts points to 200psi in your example. but it leaves max line at 300psi. this is why english racing saw no real gain by installing the valve body kit in a car already was running full line pressure. the valve body kit only really helps on a setup that retains cut down shift line pressures.

 

[TalonSpeed]

From what I understand the spring and valve body kit would raise the 50% shifts points to 200psi in your example. but it leaves max line at 300psi. this is why english racing saw no real gain by installing the valve body kit in a car already was running full line pressure. the valve body kit only really helps on a setup that retains cut down shift line pressures.

This is what Bender told me:

Originally Posted by Bender
Hello, there is a line pressure adjustment screw on the back of the valvebody. You turn it out to increase line pressure. On the front of the valvebody (What you see when you pull the pan) there is another screw. This is your brake pressure, and should be adjusted with the reducing pressure.

The full line pressure from a shift box and the shifting from the ipt valvebody are two different things. The valvebody has stiffer springs (except for reducing pressure spring which is weaker) and the line pressure turned up to increase shifting. The shiftbox disconnects the reducing pressure solenoid which allows the valvebody to run full line pressure. With the TCU, you can only run about half of the pressure the trans is capable of. The valvebody just determines what that pressure is.

For high power builds you need to adjust both the valvebody and unlock full line pressure electronically.
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