Thank You to all!!!
For the engines, I use 2 pf "M" motors each train, but standard batteries discharge was very rapid, so I bought an RC (NO LEGO) Li-ion 11,1v. battery for each train, and now they run perfectly.
The idea of a 10w train was realistic but not so good regarding making curves, so for the next trains i retourned to 8w.
Beautiful trains! They are rather large but look very realistic. I like them very much.
What kind of PF motors did you use? The new train motors or the "technic" M or XL? And as the passenger train is 10w, how many motors are necessary to move this train? It must be quite heavy!