[u2b][/u2b]Haha, I actually work as a machinist and program CNC machines for a living. For boutique turbo impellers, yeah they're probably machined from solid. For production engines however, they're most likely pressure-cast, or finely forged parts. There's just not enough time in the world to machine all the required turbo impellers from solid, for production engines.
There's a running joke among machinists that the only thing that a 5-axis milling machine could be used for is impellers. Not true for 5-axis machines, and not true for impellers. But, they do make for neat demo parts...
How much HP do you think
THIS guy would make??? (Notice how the caption states, that it takes 30 minutes to rough out just one vane... Achieving a fine-finish on the vane surfaces will take
HOURS each...
Here's another good one...
And for the record, these machines cost-in about the same a fleet of new BMW's...