Looks like 5 HP powering a 45 amp -60 amp alternator.
Another site had this information.
I simulated a test with a Summit one-wire, 100 ampere alternator and tested it at several RPMS. I loaded the alternator down with what I thought a fair representation of typical application of 65 DC amperes output at 13.65VDC. At 4500RPMs the alternator averaged over the 4 tests a measily 1.28 hp loss. It was really consistent with the high being 1.29 and the low 1.26 over the testing pulls.
