Porsche flat six

It didn’t take long after the 911 arrived for Porsche to start rallying the 1991cc model, which enjoyed plenty of success as capacity grew to 2195cc. Its focus switched to track with the 210bhp Carrera 2.7 RS, and then Porsche went Group 4 racing with 300bhp. This was followed by the 3.0 RSR racer and then the RSR Turbo in 1974. Out of this came the twin-turbo 3.3-litre Group 5 935, which made up to 845bhp – enough for 70 IMSA wins.