51 Hours is an unreleased track recorded in mid-April 1992, by Lori Elle (Werner) (as 'Diamond') and Robia LaMorte (as 'Pearl'), at Platinum Studios, Melbourne, Australia (while also on the Diamonds And Pearls Tour, during the same set of sessions as Don't Talk 2 Strangers, Poor Little Bastard, The Rest Of My Life, There Is Lonely, Be My Mirror, Wow, and re-recordings of Make Believe and I'll Do Anything).
The music for the track was written and recorded by Australian techno producer Mark Forrester.
Prince heard the track while working in the studio and added to the track by having his background dancers Lori Elle (Werner) and Robia LaMorte add a rap. Carmen Electra is also believed to appear on the track's vocals. Prince appears only briefly on vocals.
The track was played on a Spanish radio station during the Summer of 1992, and was said to be due for release after the Diamonds And Pearls Tour.
Prince had around 20 copies of an in-house 12" vinyl, 51 Hours, pressed, containing a longer version of the track, but the copies were not officially distributed, and both the single and the track remain unreleased.