What the difference is between locked versus unlocked when dealing with converters, and why does one dyno higher than the other. I'm a little new when dealing with tranny's.

 

Hi first a little converter lesson , A converter in its simplest explanation is two fans facing each other in fliuld one powered one not, When the powered or driven one is forced to turn it moves the fluid this forces the non powered driven fan to begin turning though what is called a fluild coupling. There is also what amounts to fluid based gearing going on (torque multiplication)but Im not going into that in this post ,
As for why the dyno shows higher hp figures locked that is due to loss in the fluid coupling being eliminated by the clutch bypassing this coupling which does give a more accurate assessment to the real HP of the car. However it does not give any real indication of how fast the car will be since the torque multiplier more than makes up for any loss(that fluild gearing torque multiplication I mentioned) Which is why if you put a standard and a auto trans with the proper stall side by side all other things being equal the auto will be faster because of the higher torque curve it can make at lower speeds ,Hope this helps a little