A genetic predisposition also played a role in the origin of the Evo. Once before, in 1973, Porsche turned a victorious vehicle inside out: the 917 became the 917/30. The 917 had racked up fifteen endurance victories by the time it wasn’t allowed to take part in the world championship any longer, and its first evolution happened to continue racing in oversees. North America had become the brand’s largest individual market, and the Canadian-American Challenge Cup, or CanAm for short, became an attractive racing series. In order to be able to compete against the dominant McLarens and their 800 hp V8 engines from Chevrolet, the V12 normally-aspirated engine of the 917 was not enough. Performance improvement by turbocharging was still largely uncharted territory – but one that Porsche now explored.
Among the pioneers was American Mark Donohue, a successful racing driver and engineer, 34 years old at the time. In 1972 the approximately 1,000 hp 917/10 TC Spyder (TC stands for turbocharged; Spyder refers to the now-open cockpit) won six CanAm races and the title. As competition upgraded for the 1973 season, Porsche presented its answer: the 917/30. Donohue’s ideas for improvement didn’t even leave the wheelbase untouched, lengthening it from 2,310 to 2,500 millimetres. An elongated front and a significant extension of the rear wing were also added – aerodynamic measures with which Porsche had not yet had much experience. At Le Mans, aerodynamic drag had to be reduced as much as possible to increase top speed on the long straights. Now downforce was the order of the day to transfer the monumental engine power to the road surface. The V12 now provided the 800-kilogramme Spyder with 1,100 hp and the response behaviour of the turbo was tricky. Meanwhile enlarged to 5.4 litres, the engine released its power late and with tremendous force. Porsche applied several detailed solutions to get to grips with the turbo lag. Sitting in the Spartan cockpit, Donohue could now turn a boost controller to domesticate the V12’s manifold pressure. For the race start he’d turn up the pressure to reduce it later to save the engine and fuel. The V12 was a thirsty one, which was why the gasoline tank of the 917/30 could hold up to 440 litres.
In 1973 Mark Donohue won six out of eight races in the CanAm series and took home the championship title. Then once again regulation changes meant the superior race car was suspended. But on August 9 in 1975, the 917/30 gave one last brilliant performance: on the 4.27-kilometre Talladega Superspeedway in Alabama (USA), Donohue’s average speed of 355.78 km/h (maximum speed 382 km/h) set a world record that stood for eleven years. Thanks to charge-air intercoolers, used here for the first time, the V12 achieved 1,230 hp.
The 917 wasn’t designed for the steep oval and neither was the 919 Hybrid made for the Nordschleife. The parallels stretch from world premier to world record: both cars were presented at the Geneva Motor Show, the only two occasions where Porsche placed a racing car at the centre of its brand profile. Both were the known as the most innovative racing cars of their time and the creation of both took a considerable dose of courage. This applies to Ferdinand Piëch’s determination to build the 25 examples needed for the homologation of the 917 in 1969 – despite financial risks – as well as to the 2014 decision of the Porsche Executive Board to return to Le Mans and the World Endurance Championship with a technologically highly advanced hybrid vehicle.
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