I challenged myself to see how fast I can spin something, why you may ask, its a electro/mechanical challenge. My RC motors are in the 50,000 rpm range. If not interested, please skip to the next thread.

I managed to get to 3.8 million RPM, 63,480 RPS, 1338mph, 2153kph, 24 million G's.
Here is a video of 3.3Mrpm, read the description for more info.