The way the Tuff Stuff tech explained this to me, the internally regulated alternators only produce the amount of amps that the draw on the electrical system requires. Like a generator which will loaf along all day, but needs to "throttle up" when a real load is put on it. So I will pay about 4 hp to get the 140 amps out of it at +/- 1,200 rpm. But when that happens the jeep will be barely moving, (stuck), or not moving at all, (moving a log, or pulling someone else out), so I will have hp to spare. Driving down the road it should cost me less hp than the one I'm replacing, because the amp draw to run the inline 4 is very low and the new alternator is more efficient that the old one. Added bonus: If wired as a "3 wire", the new alternator makes amps as low as 850 rpm, (idle) so the battery amperage used to start the engine is being replaced immediately, leading to less load when I start driving.
