Will any of us ever hear a Napier Sabre in our lifetime? Its distant diesel cousin, the Deltic, made a wonderful racket in the eponymous railway locomotives.
Otherwise it has to be the Merlin, or a Griffon when taxying past -- that dot-and-carry-one rhythm is unmistakeable. Or perhaps the RB211s in a 747 spooling up to take you home after a wearisome business trip.