Here is a 180 amp alt. It only produces about 40 amps at idle.
See how the output drops like a lift with its cable cut near the bottom of its range.
It also depends on how much the alt is over driven. Idle can be as low as 650rpm and on diesels for some reason OEMs use a larger alt pulley. Sometimes giving a alt drive ratio as low as 1 engine rotation to 2 alternator rotations.
Then the problem is can the wiring in the vehicle even handle 80 amps of continuous output?
Not likely.
On my diesel the 100 amp alternator burned the 12gauge wire (2.3mm diameter) off the plug that goes to the alternator.
I rewired the alternator to use the a heavy duty output screw terminal, not the cheap plug and ripped out the 12gauge circuit that failed and replaced it with 6 gauge wire (4.1mm diameter) to the battery.
The largest OE wiring I have found on a normal vehicle appeared to be 8 gauge (3.3mm diameter).
The wire burned out because of the very short drive I had to work, during the winter. The batteries kept discharging deeper and deeper and after each time I started it and with each start the batteries drew more power than the previous time until something failed.