In an effort to reduce the frightening speeds obtained by the largest prototypes at Le Mans, the CSI (technically the FIA) announced in 1967 that Group 6 would allow a maximum of 3 liter engines for 1968. This gave manufacturers less than a year to prepare, to which Ferrari boycotted the race, and Ford (who had already accomplished their goal of winning) closed their Le Mans program altogether.
The rules seemingly handed Le Mans to Porsche. The 908 would have no competition in Group 6 moving forward. To their chagrin, overall victory would come from the Group 4 John Wyer GT40 team, which was still allowed to use 5 liter engines.
The lack of entrants in 1968 scared the FIA into reducing homologation to just 25 vehicles. While continuing the development of the 908, Ferdinand Piëch signed off on production of a Group 4 prototype using a new 4.5 liter flat 12, dubbed the 912.
Starting with a 908 design, the chassis used aluminum instead of steel. To make room for the flat 12 without increasing the wheelbase, the cockpit was moved forward so that the drivers feet were positioned ahead of the front wheels. The bodywork was initially believed to be more aggressive than the 908, with long and short tail versions which were easily detachable. 25 cars were built in just 10 months, in almost complete secrecy. It's a common story that even the Porsche factory drivers were unaware of the project until the first 917 debuted in March 1969 at the Geneva Motor Show. When testing began in April the handling flaws of the car baffled everyone, with the car moving all over the straights at anything over 150 mph. When it was time for the 1000 km of Spa, all of Porsches drivers agreed to use the 908.
When the 917 finally made its debut at the Nürburgring 1000km, only David Piper and Frank Gardner were willing to drive it. The rest of the factory drivers used 908's to score a 1-2-3-4-5 finish, with the hapless 917 finishing 8th.
Piëch persisted that the 917 could win Le Mans, bringing three 917's to compliment a fleet of 908's. On his very first lap, John Woolfe fatally crashed his 917, the car splitting in half in a fiery explosion. Vic Elford and Richard Attwood had much more experience with the car, and were able to not only set fast lap, but led the first 18 hours before the clutch failed. The very same GT40 from the previous year won again, again ahead of a 908.
The unstable 917 did find victory once however, at the 1000km of Zeltweg at the brand new Österreichring, outlasting a 3 liter Mirage M3 for the win.
Determined to fix the handling of the car, Porsche returned to the Österreichring and worked with newly contracted John Wyer Automotive. JW engineer John Horsman famously noted that the rear of the 917 wasn't dirty with dead insects, meaning that air wasn't reaching the rear aerofoils. Overnight the JW team constructed a new tail out of spare sheet metal, and screwed it on over the top of the existing bodywork. The next day a skeptical Brian Redman took to the track for an expected 2 laps. 7 laps later Redman pulled into the pits, telling everyone "Now it's a racing car."
drive.google.com/file/d/10eLV...
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