So after getting some clarification from "my guys" I see where I was not entirely correct in some of my understanding of some of this, and I don't want to go through life ignorant, nor can I go for a Masters in everything I need to know a little bit about. So, length is important, but there are other considerations.

OP's question was how many amps at 14.5V with 4ga cable.

Again, what length and also what voltage drop can you tolerate?

Using 60A for an alternator line and 150A for a starter - the only things on a race car that would require that heavy of a conductor...

4ga voltage drop at 13.8V...

60A - 5' long - 13.72V
60A - 15' long - 13.57V
150A - 5' long - 13.61V
150A - 15' long - 13.24V

8ga @ 60A goes to 13.61V @ 5' long & 13.23 @ 15' long.
10ga " " " " 13.50v " " " " 12.90 " " "

Conversely, if you want no more than a 2% drop at 60A, maximum lengths are - 18' for 4ga; 11' for 6ga; 7' for 8ga; 4' for 10ga.
at a 5% drop at 60A, maximum lengths are - 46' for 4ga; 29' for 6ga; 18' for 8ga; 11' for 10ga; 7' for 12ga.

Keep in mind, for an alternator rated at 60A output to get close to that, the battery would have to be dead as a stone and/or the electrical load of everything running in the car would have to be near that. Unlikely unless you have a serious sound system. I've used 8ga for an alternator line to the trunk, in carbureted race cars with the typical electronics, with acceptable results. Charging the battery to 100% in between weekends was included.