Originally Posted by mdosu
Porsche does not have an adjustable center diff. I believe it's a simple mechanical unit, like a viscous coupler, again, I'm not 100% sure.
To this point, most AWD cars do not allow for user adjustments. and even if it allows it, it generally doesn't allow for power distribution adjustments. The ones I'm aware of are the ones in the STi which allows some type of power distribution adjustment, though I'm not sure how it works or to what extent it works. The system in the EVO 8/9 was to simply delay when the center diff moves the power around the car, so an aggressive sporty setting would delay the movement by a second or two and that would allow the driver to pull off spectacular drift before the center diff distributions the power to the other wheels and corrects the slippage (by locking up the center diff).
DCCD explained. Just a means to distribute torque (not power) between the front and rear wheels. Most drivers just leave it in the AUTO setting.