My two cents:
Cent #1: Acura's system isn't all that new - I had its one-axle progenitor on my 1997 Prelude SH. It does not work like an LSD, by the way. An LSD keeps the inside drive wheel from spinning too much in a turn compared to the outside wheel, since the spinning wheel decreases the amount of torque going to the outside wheel in a conventional differential. The SH system actively transfers torque to the outside drive wheel to get it turning faster than the inside wheel so that neither of them spins, and you get extra turning help when you need it (that's where the yaw sensor comes in). To illustrate the differences numerically, consider these three cases:
a) a regular differential in a hard turn under power with poor traction under the wheels: the inside drive wheel will spin, so up to 100% of the torque will go to the spinning wheel, and 0% torque will be delivered to the ground.
b) a limited slip differential in the same conditions: the inside wheel will start spinning, but the LSD will only allow it to spin a certain amount compared to the outside wheel. With the 40% LSD on my other car, the outside wheel will get something like 50% of the torque, the inside wheel will get 40% of that (20%), and the rest (30%) is lost to spinning the inside wheel, resulting in only 70% of the torque getting transferred to the ground (these numbers are for illustration purposes only! I have no idea how to calculate the actual values, which probably involve differential equations, the friction coefficient of the road surface, etc.)
c) the front-axle SH system in the same conditions: the system will sense the slippage and yaw rates and apportion torque to the outside wheel so that neither wheel spins, and the car goes where the tires are aiming. Let's say that amounts to 80% to the outside wheel and 20% to the inside wheel, resulting in transfer of 100% of the available torque to the ground.
It's a great system - another example of Honda engineers cheating physics (the much-copied V-TEC valve train being another good example). I beat on my SH system for 145,000 miles and it never gave me any problems. In the SH-AWD system, I think they are using the same principle to apportion torque not just left-right but also front-back.
Cent #2: The Isuzu TOD system works pretty well, except that it doesn't hold the engagement of the front axle long enough when driving on snow. When starting from a dead stop on a snow-covered road, it senses slip in the rear, it engages the front, then sees that there is no speed differential between the axles, and disengages the front 0.1 seconds later. Of course, the rear axle starts spinning again, it engages the front for a tenth of a second, sense no speed difference, etc... It would be great if after fully engaging the front axle, it held it there for a couple of seconds before gradually decreasing torque to the front axle. It operates much better on dirt, though, I'll give you that.
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