[HiFlow5 0]

I copied this from a thread posted a while back, hope it clears some things up for ya.

"The torque converter in an AOD is analogous to the clutch in a T-5...it links the engine to the tranny. Also, the same way you can "slip the clutch" while launching, the torque converter "slips" to allow rpms to rise. In other words, at the track, you would launch anywhere from off idle to 5000 rpms with a five speed to get the best launch. Similarly, whey you go WOT on an AOD from a standstill, the engine will be able to quickly rise to the stall speed of the converter and give you a better launch.

In most basic terms, the torque converter uses fluid dynamics and some big impellers to multiply torque from the engine to the tranny. The converter is designed so that there is a given amount of slip in it, or in other words, the engine is allowed to rev faster than it is turning the tranny. This allows the engine to reach its power band more quickly and thus make maximum power more quickly. The stall speed is basically the point where the converter will no longer slip and the engine is linked directly to the tranny.

On a stock AOD, the stall speed is somewhere around 1500 rpm. This is too low for the torquey 302 which makes it power somewhere around 2000-2500 rpm. A converter stalling around 2800 rpm is ideal for a midly to moderately modified mustang, however the stall speed of a given converter is not an absolute. It all depends on the amount of power and torque your engine is making."