Originally posted by CumminsAholic
Sorry for my ignorance, but I still don't understand the 100% efficiency rating in fluid coupling. How does it unlock? Like at a stop sign, if it's 100% efficient out of lock-up why doesn't the engine die? Or is there a stall built into the converter so under a certian RPM, like idle, it doesn't move(like a drag racing car with a stall converter that doesn't engage til 2500 RPM?)? That car is just an example, if that's how it works, then I understand, otherwise could you please explain it better for me and others to understand. Also, if my truck had a 100% tc instead of say 89% wouldn't it have really bad turbo lag? Also I believe that Bill's TC drops about 200 rpm when it goes into lock-up. If yours is 100% in fluid coupling it should have NO rpm drop into lock-up right? 100% to 100% should be no drop. I can see the 200rpm drop if it's 93%, but can't understand it if it's 100%, please explain. Thanks for the info, I'd call if I had the time, but I don't and when I do, it's late at night when everybody is closed. I'm still looking for a TC, I was going to go with Bill's but I like to keep my options open. I also want the best, Bill has proved that to me. If yours is better then it'll be behind my motor. I guess time will tell. Thanks Again,
Corey
The housing of the torque converter is bolted to the engine, so it turns at whatever speed the engine is running at. The fins that make up pump of the torque converter are attached to the housing, so they also turn at the same speed as the engine. The pump inside a torque converter is a type of centrifugal pump. As it spins, fluid is flung to the outside.
As fluid to the outside, a vacuum is created that draws more fluid in at the center.
The fluid then enters the blades of the turbine, which is connected to the transmission.
The turbine causes the transmission to spin, which basically moves your truck.
The blades of the turbine are curved this means that the fluid, which enters the turbine from the outside, has to change direction before it exits the center of the turbine. It is this directional change that cases the turbine to spin. In order to change the direction of a moving object, you must apply a force to that object—it doesn’t matter if the object is a car or a drop of fluid. And whatever applies the force that causes the object to turn must also feel that force, but in the opposite direction. So as the turbine causes the fluid to change direction, the fluid causes the turbine to spin. The fluid exits the turbine at the center, moving in a different direction than it was when it entered. The fluid exits the turbine moving opposite the direction that the pump (and engine) are turning. If the fluid were to hit the pump, it would slow the engine down, wasting power. This is why a torque converter has a stator. The stator resides in the very center of the torque converter. Its job is redirect the fluid returning from the turbine before it hits the pump again. This dramatically increases the efficiency of the torque converter. The stator has a very aggressive blade design that almost completely reverses the direction of the fluid. A one-way clutch (inside the stator) connects the stator to a fixed shaft in the transmission the direction that the clutch allows the stator to spin. Because of this arrangement, the stator cannot spin with fluid—it can spin only in the opposite direction, forcing the fluid to change direction as it hits the stator blades. Something a little bit tricky happens when the truck gets moving. There is a point, around 40 mph at which both the pump and the turbine are spinning at almost the same speed (the pump always spins faster). At this point, the fluid returns from the turbine, into the pump, already moving in the same direction as the pump, so the stator is not needed. Evan though the turbine changes the direction of the fluid and flings it out the fluid still ends up moving in the direction that the turbine is spinning because the turbine is spinning faster in one direction than the fluid is being pumped in the other direction. At these speeds, the fluid actually strikes the back sides of the stator blades, causing the stator to freewheel on its one-way clutch so it doesn’t hinder the fluid moving through it. In addition to the very important job of allowing your truck to come to a complete stop without stalling the torque converter actually gives your truck more torque when you accelerate out of a stop. Modern torque converters can multiply the torque of the engine by two to three times. This effect only happens when the engine is turning much faster than the transmission. At higher speeds, the transmission catches up to the engine, eventually moving at almost the same speed. Ideally, though the transmission would move at exactly the same speed as the engine, because this difference in speed wastes power. This is part of the reason why trucks with automatic transmissions get worse gas mileage than trucks with manual transmissions. To counter this effect, some trucks have a torque converter with a lockup clutch when the two halves of the torque converter get up to speed, this clutch locks them together eliminating the slippage and improving efficiency.
Hope this helps
Don Ramer ATS/PTC
Attention: TDR Forum Junkies 
Just kidding around w/you. 
. I know a stall and % are different, the stall gets the motor in the powerband, the % makes the weaker motor "have more power" or not be a dog at least that's the way it makes sense to me . Anyways, I just don't understand how their converter can be 100% efficient in fluid coupling and still come to a complete stop without stalling the motor. The explanation is probably an easy one, but I don't get it yet. 
