By 1981, the Porsche 911 just wasn't a particularly competitive rally car. It had a lot of power, but rough stages made it extremely hard work.
The great Walter Röhrl, however, did manage to get victory within his sights in this SC at the Italian (pavement-heavy) round of the '81 World Rally Championship, but it broke a driveshaft and Michele Mouton won the even in a Quattro.
You can watch him go by at the start of these two clips of the event.
Röhrl might not have won, but he may well have had the best-sounding car at the event.