depends really..."black caapi" seems to mean less and less honestly the more I research ayahuasca. What does that really mean? I have heard of black caapi that was not any stronger than yellow and then I have heard of black caapi that was super super potent..then I have had yellow vine that is like 4x stronger than any other vine I had had...
I think that perhaps "black caapi" may not be banisteriopsis caapi at all and refer to a different species of banisteriopsis or another genus even..or maybe there are many black ayahuascas out there..some stronger..some weaker..
So who really know what one you have..only one way to find out..
I would start with not more than 20-40g just to be safe..then increase the dose as needed.
Long live the unwoke.