LOL, you don't need to explain what star and delta are in alternator configuration. IF the alternator is of a three-phase design, yes, you get ~1.85x the current and ~0.58x the voltage at the same RPM. It may be sufficient at idle, or it may be not.
Note the IF statement. I found one P38A 120-amp unit that is of four-phase design, with the rectifier having 8 diodes. Another, a D1 100-amp unit, had rectifier with empty holes for two diodes, also indicating that four-phase design is not uncommon. I need a moment to consider a four-phase delta-equivalent connection - because nobody does it.