Originally Posted by RogerHewson

That isn't quite right on how the Torsen diffs work. The Torsen stands for TORque SENsing. What the diff does is actively transfer power between the left and right, or front and rear depending on which side has traction. The differential senses load. As the traction goes away from one axle, the load lessens and the diff progressively transfers power AWAY from that side to where the load is increasing,( the opposite side with more traction.) If the side the diff is transfering power to begins to loose traction, the diff takes power away from it and gives it to the other side. It's constantly optimising traction between the two wheels, or axles to make the best of what is available. The down side to the TORSEN style diffs is if the wheel comes off the ground, the diff shoots all the power to that diff like an open differential. Torsens tend to only work good when you can keep all the wheels on the ground. Which is why they are really popular on smooth tracks. They tend to handle a little odd on really bumpy tracks because the diffs are constantly unloading and loosing traction, then slapping the ground and throwing power around. A standard diff with oil in it is going to be much more consistant in the same situation because its not trying to react to the situation in so many different ways. but on a smoother track the Torsen should handle better because it's actively looking for traction under acceleration. Gear driven diffs like the Torsen are more complex then that, there are bias ratios, setup changes, etc. but in the right setting they work, and work well. It's one of the reasons cars like the Integra Type R handle so well because of the trick Torsen style diffs they had.

Roger