Since I've never seen a complete F-1 intake tract it's really just a guess but I can' imagine their normal filering system is designed to do much more than keep anyting smaller than pebbles, tire marbles and birds from gettin into the engine.

In studying proper air filtration systems it's commonly bandied about that the amount of dust required to trash an engine pretty quickly is no more than would fit on an average thumbnail. With the HUGE amounts of air an F-1 engine inhales I'd say they'd have needed to have installed some seriously additional air filters on this ride before lettin it go play in the dirt.

Or, my best guess is they took an engine that had already been raced and was slated for a rebuild already and used it for this exhibition