So the ceramic heater is 48W at 24V 12ohm
You’re about right, I’ve hit a bottleneck at around 35mm³/s on with CHT nozzle on the Bambu cloned hotend
As I was printing a speed flow rate tower, the flow kept increasing but around 35 the temperature kept decreasing, after 3minutes of being off the printer gave me a temp runaway error and stopped print, it was almost 20C under set printing temp because the cool filament was flowing too fast and actively cooling the hotend faster than the heater / PID was doing its job.
But some other user mentioned that with this hotend and CHT nozzle he did not have this temperature / heater issue, so I think this need much more tests
So… I’ve wired 2 ceramic heaters in parallel and put the second one on the other flat side of the hotend. This is not recommended at all and it might damage some electrical components, but it works for me, it heats faster and allows to bypass the previously mentioned bottleneck. I have a ticket with Bambu Lab, they do not recommend this but they recognize this might work as well, so do what you want with that
I can now reach above 40mm³/s with PETG
I am also about to design an external electrical circuit to allow 4 ceramic heaters on all sides of the hotend for super fast heating and no more heating issues