[Alan Roehrich]

You need approximately 300 psi to make it really work, because you need to have more than enough pressure to make the pressure regulator work all the time. You do not need a lot of volume, since you are not filling the converter constantly, what you are doing is cooling the internals (but most of the heat comes from the converter, which you no longer have) applying the clutches and bands, and lubricating what moves.