Does Beta define the max amperage small frame alternator that can be installed on a Beta 25? My beta was delivered in 2019 with a 60A Mitsubishi alternator and 4-groove serpentine belt system. It was supposed to be delivered with a 75A Mahle, but the Mitsubishi was installed due to a lack of Mahle inventory at the time. I do a good bit of offshore distance sail racing and it would very helpful reduce charge time per day with an alternator that could sustain a higher amperage. My battery bank can accept substantially higher amperage than the 60A alternator can sustain. 

In prior discussions, I was told I could not upgrade to 6-groove serpentine belt and pulleys. As I understand, there is a physical difference between Beta 25 engines delivered with the 125A alternator and those delivered with a 75A or less alternator and my engine could not be upgraded. Apparently the increase lever arm force of the 6-groove engine drive pulley would put excessive wear and possible premature failure on my engine. So it looks like I must stick with the 4PK serpentine belt system.

So the question is, how high of alternator amperage can I install with my current system? Most automotive sources state a max of around 100A with the 4PK serpentine belt. Is a 100A alternator acceptable? Clearly 75A is acceptable since that's what my engine was originally supposed to be delivered with. Is an additional 0.6HP alternator load increase (1.7HP to 2.3HP for a 70% efficient alternator) acceptable? There appear to be Kubota small frame alternators in 80-100HP range in a similar case size to the Mitsubishi that should fit. I could really use the resulting 25% to 40% reduction in charging time and the associated fuel savings. On a 2-week ocean race, it makes a difference.