Power Meters / Powermeters (SRM, Powertap, Quarq, Ergomo, Vector, Stages, power2max, P2M, 4iii, InPower, Cinch)

You can't derive FTP from an 8 minute test.
it's a specific 2 X 8 mins test. Seemed popular. I have no idea though. Just trying to monitor improvement, and get a rough idea of how long certain rides should take.

BTW having a decent FTP doesn't win races, if that's what you're aiming for.
Not going to win much at 3.2 anyway. But it seems as good a guide anything else.