Quote Originally Posted by Toolmaker51 View Post
Performance test, that's a dynamometer.
https://en.wikipedia.org/wiki/Dynamometer
No, not the original post, but the follow-up that had video of one of those engines starting and running. They joked about having to get folks from the audience to help with whatever they were cranking/pumping back there. Another thought was that they might have been winding up a flywheel used as a mechanical starter.