There are cars built to be tamed―and cars built to tame drivers. The Porsche 917/10 that arrives in early March 2018 with the ‘Porsche Legends Pack’ will bring you face-to-face with one of the most terrifying and wildest sportscars Zuffenhausen ever built

At the end of the 1971 season, with two consecutive Le Mans wins and Sportscar Championships under its belt, the Porsche 917 (think Steve McQueen in the movie “Le Mans”) with its 4.5-litre hell-and-brimstone flat-12 was made redundant by the new Group 5 rules that mandated engines of only under 3-litres were welcomed to race in 1972.

Porsche, in response, pulled the works program from the World Sportscar Championship and turned its focus west—to North America and the Can-Am Series, then in all its splendor and pomp.

The Group 7 rules that governed Can-Am were attractive to Porsche as it was ostensibly a free formula―pass a basic safety test, have two seats, have all four wheels covered, and you were all cleared to race. Any engine capacity, any aero, you raced what you brought. Of course, if you brought anything under 700hp and heavier than 800KGs, you were going to get eaten alive by the 7-litre V8 Chevys in the all-dominant McLarens, and the virtuoso aerodynamic genius of Jim Hall over at Chaparral.

​Can-Am was the scene of some of the fastest, fiercest race cars the world has ever seen―and looking back almost 50 years, it’s probably safe to assume we’ll never see their likes again. The money running around the series―US dollar prizes―meant the cars were driven by global superstar drivers, too―Andretti, McLaren, Stewart, Surtees, you name your ’70s star, and he’d have been driving stints at Can-Am events in Canada and the US. Can-Am in its glory years―1967-1973―was wild, loud, and popular―an electric mix of speed, noise, and danger that transfixed the fans who flocked into classic venues such as Watkins Glen, and long-forgotten ones such as the Stardust International Raceway (in Las Vegas.

Porsche had been dabbling in Can-Am since ’70 in the guise of Jo Siffert’s semi-works 908 Spyder, a car that proved woefully too heavy to be a serious challenger to the McLaren M8D and its monstrous 7-litre V8 Chevy lump. The hastily created and decapitated 917 Spyder for Siffert for the ’71 season ended the same way―gobbled up by McLaren’s new M8F.

With the death of the 917’s native series, though, and North America proving an attractive market for sales of production cars, Porsche decided to get serious about its Can-Am program for ’72.

Porsche had two initial plans. Plan A was to continue with Siffert, whose star was very much on the ascendancy after his Formula One win at the Austrian Grand Prix, but when ‘Seppi’ lost his life at a non-championship event at Brands on a cold day in October ’71, Porsche’s Plan B suddenly became their only plan. Plan B had begun back at Le Mans in ’71 when Porsche had sounded out a small US team then running a Ferrari 512 for the 24 Hour classic.

With Siffert’s death, that tentative sounding out was strengthened when Porsche focused on the newly-formed Penske team and their driver-cum-engineer Mark Donohue. Aside from their reputation, Penske, like Porsche, had also been pottering about in Can-Am for a few years without much success before settling in nicely in Trans-Am (then the world’s most dominant touring car series) where the Penske-Donohue pair were winning and battling for championships with the Sunoco Camaro that you can race in Project CARS 2. It would take a lot to get Penske to drop his priority with the Trans-Am program, but Porsche’s offer—big budget and full-factory backing—proved too enticing to reject.

Penske Racing Porsche and the Turbo Panzer

In the autumn of ’71, the Penske-Porsche crew gave some thought to using a 7.2-litre 16-cylinder monster of an engine for the ’72 Can Am season. That engine was so long that you could hear one end start up before the other. There was a brief discussion about turbocharging it, too, with a projected output of 2,000hp, but it took little time for Donohue to reject the engine as far too heavy and cumbersome for the narrow, tight circuits that were the mainstay of Can-Am tracks.

Porsche themselves had never really considered the 7.2-litre for Can Am. Instead, they had been testing their Le Mans-spec’ and bulletproof 4.5-litre flat-12 throughout the summer of ’71, an engine that had been upped to 5-litres … and then turbocharged.

Back in ’71, that technology―turbocharging―was very much a high-wire walk into the unknown.

With a few notable exceptions through the years (including the turbo Offenhauser that was being run in the late ’60s in the US and with which Donohue was familiar), engines were either naturally aspirated or crank-driven superchargers. The exhaust-driven turbo, which needs turbines to spin at a defined rate (beneath which the engine lacks power), is usable on an oval, but the massive delay between when the throttle is squeezed and when the power comes―from nothing to ‘Holy Mother of God!’―made its use on road circuits impractical.

On the other hand, the raw power from turbocharging made finding a solution to the resultant lag something Porsche were keen on engineering through. Not surprising, of course, from the results of attaching two enormous―they were taken from industrial diesel parts―Eberspacher turbos (one per bank, so that the spool of the turbo would happen faster, and therefore aid throttle response) on the 5-litre Le Mans engine.

When it was paired to the re-engineered 917/10 (weighing less than 750KGs), power was an astonishing 900hp, with 60mph rushing by at two seconds, 100mph in under four, and 200 mph in 13.4s. Early testing by Porsche test-driver Willy Kauhsen reported burn-outs in top gear at 200mph.

Sadly, by the late summer, Kauhsen was also declaring the engine undrivable: massive dollops of turbo lag through most of the rev’-range followed by mayhem when the turbos spooled in.

By early ’72, when Porsche finally sent the turbo-engine to the US, where Penske had been testing the chassis of the 917/10 throughout that winter fitted with the Le-Mans-winning normally aspirated lump and a new, massive rear-wing, there had been little progress in its drivability.

Driver and engineer Mark Donohue got his first taste of the turbo on a cold day in early February in Florida. “I tried to drive it for a few laps and discovered that the throttle worked like an ignition switch—it was either wide-open power, or off,” Donohue would recall. “After a banzai effort I got down to about the same lap time as the non-turbo engine with about 300 more horsepower. Towards the end of the test the blower failed, scattering parts into a cylinder and ruining the engine. We sent it back to Germany with a long dissertation on the problem and possible solutions they could try.”

Mark Donohue’s abilities were well-known in US motorsports by the early-’70s, with his “Unfair Advantage”-school of thinking having delivered Penske’s Trans Am Camaros domination against factory-backed efforts from Ford, but back in Germany, his insights went ignored.

Through the winter of ’72 Donohue continued testing new evolutions of the turbo flown into the US, and while it was clear the power was there, drivability wasn’t being improved at all. It was time for Donohue to hop on a plane and fly to Germany himself. At Porsche’s test-track at Weissach, Donohue attempted to demonstrate the problem he was experiencing with throttle response, but it soon became clear there was a disconnect between what he was saying and what the Porsche engineers were hearing. With Donohue at a dead-end, “the Captain” Penske himself came flying into Germany and delivered his opinion―with that engine, he told a shocked delegation from Porsche, they were going to get smoked in Can-Am. It would be better, he said, if they missed the first races of the season and kept working on the engine.

Porsche, alarmed, sprang into action and delivered a new engine in a week. It felt even worse. Donohue, exasperated, asked them to dump the engine onto the dyno.

“I looked at their dyno output curves,” Donohue recalled in his autobiography “The Unfair Advantage”. “They had all the necessary data―torque, rpm, boost pressure, and so on―except the curves started at 5000rpm. I said, ‘Why are there no curves up to that point?’ They said, ‘The motor does not run there.’ I thought, ‘That’s what I’ve been trying to tell you for a month!’ I couldn’t believe it was that simple. I couldn’t believe they had simply calibrated the fuel injection for wide-open throttle with full boost and had totally ignored any part-throttle operation.”

With Porsche’s engine man Flegl, Donohue worked at getting a complete map of the engine across the entire rev-range with fuel-maps aligned to various boost pressures. A week later, they ran the car again, and Donohue immediately cut the lap record by over a second on his first flying laps.

That’s when Donohue sent Penske the now famed telex that ended with: PLEASE INFORM CAPTAIN OF MAJOR BREAK THRU.


With the engine sorted, it was time to get back to the US to tune the handling. With an extra 400hp, the old test-mule 917/10 was a bit of a beast that needed taming, and who else was capable of doing so than Donohue?
Or so everyone thought.

As it turned out, the new beast from Zuffenhausen was not for taming. At Road Atlanta during a test session, at over 240kmh, the rear-end bodywork ripped away from Donohue’s car and, a second later, Donohue and the 917/10 went airborne. The car came down nose-first and barrel-rolled away into the scenery. By the time the car had come to rest in a cloud of debris and dust, Donohue was sitting strapped in his racing seat with his broken legs dangling in the air where once the front of the car had been.

Donohue’s season was done: testing and racing were turned over to a hastily recruited George Follmer. “It just doesn’t feel right,” Donohue said while watching Follmer from the sidelines. “Seeing another man driving your car, a car you know so well.”

If that was hard to watch, Donohue must have been even more disconsolate by the end of the year when the 917/10 ended five consecutive years of McLaren dominance. The Can-Am Championship that year featured nine races: the Penske-Porsche car with Follmer at the wheel won six races, McLaren two, and Jackie Stewart’s protégé, François Cevert, scraped a well-earned win at Brainerd International Raceway for the ‘Young Americans Racing Team’.

​Porsche had not only wrested away Can-Am dominance from McLaren, they had ripped a hole into the future of motorsport with their turbo.

Blowing The Future

The following year, the 917/10’s successor, the 917/30―developing a reputed 1,600hp―blitzkrieged everything in its wake with Donohue at the wheel. It started the season as the ‘Turbo Panzer’ and ended the season as the ‘Can-Am Killer’―Porsche’s dominance was such that McLaren walked away from Can Am, before the series itself would endure just one more season before shutting the doors.

Having eviscerated the field, Porsche left Can-Am with titles, glory, and their turbo technology a generation ahead of everyone else. They also left the US with a speed record when Donohue took the 917/30 to Talladega and clocked 241mph (388kmh).

Back in Europe, Porsche extended their turbo program to their early test-mule, the Carrera RSR, which led to their first-ever 911 Turbo road-car in ’75. Buoyed by the reliability of the RSR, Porsche returned to sportscar racing in ’76 with the 936 in Group 6, and the 935 in Group 5―both available in Project CARS 2―and dominated sportscar racing for a decade. Then they stuck their turbo into the ground-effects 956/962―also available with your copy of Project CARS 2―and pulverized everyone.

And what of Mark Donohue?

Donohue retired from racing after the all-winning 1973 season (he’d picked up an Indy 500 win the year previously with Penske), but when Penske decided to enter Formula 1 at the tail-end of’74, Donohue was persuaded to return to the cockpit. Penske’s purpose-built PC1 for ’75 turned out to be a dud, though, and by the Austrian Grand Prix, they’d reverted back to the March 751. During practice, Donohue lost control and, some days later, his life in a hospital in Graz.

It brought an end to the man who, behind the scenes, had done so much to evolve the turbo in motorsport.

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