than 110C, maybe closer to 120C; it depends on the coupling coefficient between the VFC and radiator and secondarily. the engine heat radiation.
If your aux fans don't come on until 110C, I'd recommend you change your B10/8 sensor or, if not, purchase a Cool Harness. This will force the ax fans to come on around 95 to 100C depending on the model.
By MB spec, the aux fans are supposed to come on at 100C with AC off or 14bar with AC on. Check the table in Menu#18 about halfway down the page.
3800rpm: I think that about halfway to the speed of light!
If I remember correctly, 3100 is 105mph, so 3800 is very, very fast! MB's choice is certainly up for question.