a bit of missunderstanding, or maybe not, it could be the way im explaining! you are the one that knows! I'm the one who's trying to learn 
And my English might be a little bit of a problem!
I've got a 3D printed paddle wheel, cased in a body that lets the water pass trough, and when the water goes trough, it spins the paddle wheel right?
On the paddle wheel is a magnet attached to one paddle/fin.
On the backside off the whole assembly is the sensor
I've measured the pulses, and it's roughly around ~16Hz
And by that ~16Hz it is without any restrictions in the system,
only pump / hose/ sensor / hose
Later on when it will be a massive restriction in the system, due to hose ID change, radiators and so on,
so the value that i have isn't worth that much,
And I'm sorry for not thinking straight, you have absolutely no idea what hardware I've got.
But I'm really starting to think about using a code that's already out there, somewhere.. that use temperature reading instead of flow.
Or I could to try learn by my own and figure something out!