In our working lives a new boss usually means a new broom, so it proved at Porsche AG in 1971. The wildly expensive (and successful) racing campaigns involving the Porsche 917 and 908 may have won the German marque the ultimate prize in endurance racing, the Le Mans 24 Hours and all manner of championships and races, but they were not sustainable in the longer term for such a small organization. The arrival of Dr Ernst Fuhrmann to replace the mercurial Ferdinand Piëch that year initiated a reappraisal of all the company's activities, including racing. To continue to challenge for outright victory at the classic long distance races would require a completely new car and engine, financially out of the question was the conclusion that the new boss came to. This decision was blessed with extremely good timing for Porsche in the long term as the Oil Crisis of 1973 would soon engulf the Western economies. So non-essential purchases such as Porsches would endure a drop in sales revenues, not the time to be engaged in a major financially expensive sporting effort.
Competition has always been a major element in the DNA of Porsche so a more modest program would continue focussing on developing the 911 for racing, this having the happy side-effect of being able to sell the results to private teams, creating a supposedly virtuous financial circle. In fact the 911 had been a factor at Le Mans since its début in 1966 but recently efforts from the Werks had been concentrated on the high profile prototypes. Concentrating on "product" would bolster the position of the 911 in a difficult marketplace, a further benefit from this back to basics strategy.
Norbert Singer was put in charge of the modest 911 competition program and spent the last months of 1972 preparing the 911 Carrera RSR for its first event, the 1973 Daytona 24 Hours. As can be seen from this celebratory poster, the Floridian endurance classic lived up to its reputation as a car breaker, the faster prototypes retired leaving Peter Gregg and Hurley Haywood to take outright honours for Porsche.
This fantastic result was followed up by another famous victory, this time in Sicily in what would be the last real Targa Florio. This amazing race had first been run in 1906 but by the 1970's it was considered too dangerous, even by the Italians, for both competitors and spectators alike. The 72 kilometer (44.74 miles) Little Madonie circuit was over closed (for the most part) public roads and the race was watched by a fanatical local populace who lined the whole course.
As with Daytona the faster prototypes, local favorites Alfa Romeo and Ferrari, all struck problems and it was left to Herbert Müller and Gijs van Lennep to give Porsche a record 11th win in what would prove to be the final Targa Florio.
These successes encouraged Porsche to continue with the 911 competition program. Further impetus was given by the announcement from FISA (the governing body of motorsport at the time) that as of 1975 there would be a new formula governing endurance racing with production cars forming the basis of the new racers - this was all the encouragement that Porsche needed. Singer was once again summoned by the boss and told to get on with developing the car in 1974 with serious racing to begin with the implementation of the new rules in 1975.
The first major change was to introduce a turbocharger to the 911. The proposed car would run in the prototype class, meaning a capacity limit of three liters for the engine, in line with the Formula One regulations of the time. The equivalency formula for forced induction engines to those normally aspirated was 1.4 to 1. The maths dictated a capacity of 2,142 cc for the air-cooled Porsche flat-six powerplant and it was claimed that the resultant engine developed between 460 and 490 horsepower, depending on boost pressure.
That boost was provided by a single KKK turbocharger, but this was not the first turbocharged race car from Porsche. The team could draw on the experience of its wildly successful Can-Am campaigns in 1972-73 as the open top 917 was given even more power than the 5-liter flat 12 engine already had. However the flat 6 engine in the 911 Carrera RSR Turbo was Porsche's first production-based turbo unit to go racing, being taken from the road going 930.
(Photos: copyright and courtesy of Porsche AG, and John Brooks)
So power was more or less in line with the prototype opposition but the pure racers from Matra, Alfa Romeo and Gulf Mirage weighed in at around 650 kilos, the Carrera RSR which would form the platform that the new car would be created from was a hefty 930 kilos. A crash diet would be the order of the day. Running in the Prototype Class would afford Herr Singer a great deal of flexibility to change the standard car.