The 917’s debut was even more unusual, because Porsche had already committed to its 908. Under uber-competitive racing director, Ferdinand Piëch (Ferry Porsche’s nephew), Porsche AG had been introducing one completely new racecar each year. They’d never before campaigned a large-displacement model, but anticipating competition from Ferrari and McLaren, giant-killer Porsche had stepped up decisively.

Hans Mezger and his engineering group were responsible for the design. Although it wasn’t publicized (and at first, it was denied), Volkswagen AG helped finance the 917 effort. After all, the success of air-cooled racing cars surely benefitted VW. Air-cooled engines were potentially not as powerful as liquid-cooled competition, but the Porsches weighed less without radiators and that was significant.

Writing in Porsche – Excellence Was Expected, premier Porsche historian, Karl Ludvigsen, quoted Ferdinand Piëch as saying that his uncle Ferry “…let me carry on because our racing pleased him. He himself would never have done it but…he happily tolerated the 917.”

Like Porsche’s road cars, the 917’s engine would be air-cooled and horizontally-opposed. A flat-12 made sense, as it was simply four cylinders more than the 908. Dr. Ferdinand Porsche had developed a similarly configured engine for Cisitalia in 1948. A pair of connecting rods shared each crankshaft journal, so the new flat-12 could be built nearly as compactly as a V-8. After experiments found a point on the crankshaft that was nearly vibration-free, Mezger and his team elected to drive all the engine accessories from the center of the crankshaft, including the big glass-reinforced plastic (grp) cooling fan.

Engine cooling was further aided by a 5.25-gallon, remote tank that supplied a large oil cooler. Tiny jets squirted oil at the undersides of the piston crowns. Initial tests soon found the flat-12 was producing 580-hp @ 8400 rpm. The first engines weighed just 530-lbs, making this the first Porsche engine to develop more than 1-hp per pound of weight.The chassis was aluminum, saving even more. Whatever could be lightened was drilled. The shift knob was made of birch.

The 917 showed its potential at the 1969 Le Mans trials where Rolf Stommelen turned the fastest times of the weekend at 142.999 mph. The car was available with both long and short tails for low and high-speed circuits. The long-tailed versions were scarily unstable, especially so at the car’s next outing at Spa. Jo Siffert set the fastest lap in the short tail car. The long tail 917’s quirky handling still baffled both drivers and engineers. This was complicated by the fact that after several F1 incidents, the FIA banned elevons (small movable wings which helped with downforce). Porsche engineers had thought the 917’s light chassis was flexing. As they later discovered, the problem was with the car’s initial aerodynamics.

Determined Porsche competition manager Rico Steinemann brought three 917’s to Le Mans and convinced the organizers that the car had to compete with movable wings — or Porsche would withdraw all its entries, including the 908’s. Reprieved, Vic Elford and Richard Attwood drove one of the 917’s in the race. Even with the elevons, Vic noted “it was virtually undrivable. That said, “Quick Vic” bravely set the fastest lap before the car retired.

In 1970, England’s John Wyer (JW Racing) was retained as Porsche’s competition manager. By observing that dead gnats were not flattened on the 917’s low rear spoilers, Wyer’s brilliant team manager John Horsman realized the airflow was barely touching the car’s tail. To the chagrin of the German engineers, Horsman and his team modified the 917’s aerodynamics, hastily fabricating a completely new design based on the Spyder version’s shorter tail. Dr. Piëch had been obsessed with having a low coefficient of drag, to the exclusion of effective air management. Horsman later wrote, “…it was obvious to me, that if the whole body surface was in the airstream, it would be able to exert some downforce.” Coupled with a revised front end, that wizardry solved the 917’s high-speed instability issues. Brian Redman, who tested the new modifications exclaimed, “That’s it; now it’s a racing car!”

But as it turned out, John Wyer’s biggest challenge was not the 917’s aerodynamics. Ferrari announced its new 5-liter 512, with its own display of 25 cars, but Wyer’s toughest competition would come from the Austrian team, Porsche Konstruktionen, better known as Porsche Salzburg — a team fielded by Mrs. Louise Piëch, Ferry Porsche’s sister, and Ferdinand Piëch’s mother! Close family ties ensured Porsche Salzburg received new 917 development parts as soon as, and sometimes before, John Wyer’s official factory team.

In 1970, with the 917 finally sorted out, Porsche Salzburg won Le Mans — a first for Porsche – with Hans Herrmann and Richard Attwood driving, but JW’s Gulf Wyer Porsches won every other major race that year, except the Sebring 12-Hours, when a hastily-developed 917 front wheel hub bearing failed and the new Ferrari 512S was victorious. This car, 917-019, raced for Porsche Salzburg in 1970. The following year, 019 competed with the Martini Racing Team, which Louise Piëch had renamed after a sponsorship deal with Martini & Rossi. For the second consecutive time, the Piëch/Martini team won Le Mans, this time with Helmut Marko and Gijs van Lennep. And the JW Gulf Porsche factory team won everywhere else, capturing the 1971 Sports Car Championship.

Marko and van Lennep raced 019 three times in 1971, but results at Daytona, Monza and Spa (the car’s last race) were marred by three mechanical failures. Remarkably preserved, this 917K retains its 1971 configuration. It’s actually quite conservative given that one Martini 917 was painted in bold psychedelic colors and for Le Mans, Porsche’s Styling Department painted an experimental 917/20 in pink, with dotted lines representing various cuts of meat available from swine.

With its nine variants, the Porsche 917 remains one of the fastest, most iconic sports prototype racecars of all time. When the rules changed, Porsche built the turbocharged 917/10 and 917/30 spyders that won the CanAm Championship. The 917 starred in Steve McQueen’s epic film, “Le Mans.” With 1,580-hp available for qualifying, the 917/30 was one of the most powerful sports cars ever raced. Mark Donohue set a 221.160-mph closed course FIA speed record in 1976 in a 917/30 at Talladega Speedway.

This year is the 50th Anniversary of the 917’s first win at Le Mans. In the panoply of Porsches, the 917 will always have a special place. Miles Collier kindly consented to describe what it’s like to drive:

“Walking up to a 917K makes you feel like a Jehovah’s Witness approaching a strange front door with a pit bull snoozing on the porch. This thing could hurt you.

“While it seems to be a big, hefty car, once you climb in, you fit like a gorilla in a phone booth. It is claustrophobic. The crudely built gray-painted interior smells of fiberglass resin. The right-side driving position is very reclined, almost supine. Your feet are way out there in front of you in what feels like a tunnel at the end of which are the pedals and a left footrest.

“The shifter is also on the right. Instruments: a 10,000 RPM tachometer; oil pressure and oil temperature gauges occupy a binnacle. They lurk at the bottom along with three idiot lights; an ignition switch with a key, no less, albeit permanently epoxied in the slot; the starter button; four CD ignition circuit switches; and a fuel pump switch are to the driver’s left on the felt-covered, passenger-side dash.

“Startup is simple – ignition key on; CD circuit switches in; fuel pumps in; press gas down a bit; push the starter button and – whoom – it’s running with a breathy fan whine and spitting from the injectors behind your head. The 5-liter, flat-12 is not that loud, just very busy. There are a zillion oily bits whirling around and you can hear every one of them.

“The engine idles like, well, a big 911. The shifter linked to the four-speed tranny clunks into first gear. Remarkably, the clutch isn’t particularly heavy probably because its throw is generous. Engagement feels like a road car, and the engine even pulls away happily at 1800 RPM.

“Accelerate down pit lane at 5,000 or 6,000 revs, pull the gear-stick back for second and push down on the gas … an enormous electric motor seems to be powering this thing. It firmly pushes you back in the seat as you struggle to depress the long, long travel accelerator. Immediately, you’re at 8,000 RPM. Firmly push the stick forward and outboard for third, and the Niagara Falls of acceleration just keeps coming.

“The forward view is between two massive fenders so you see apexes way out, but not near the car. Brakes require only modest pressure. Turning is precise and quite comfortable with no kick-back despite the tire size and … wow, this thing gets up a head of steam without much fanfare.

Acceleration is intoxicating. Infinite power seems to flow out of that long pedal travel, all the better to feed in nuances of power when driven at the razor edge of control by a Vic Elford, or Pedro Rodriguez. At 80 per cent effort, your granny could drive this thing – provided she’s okay with hitting 150 miles per hour at the braking marker.

“Within a few laps, the cockpit, surrounded as it is with oil tank, oil-filled chassis tubes, oil radiator the size of a twin bed, and that whirring, snorting 12-cylinder engine behind you, becomes, not warm, but hot. G-loads drag at your head. Shifts, with the fully synchromesh gearbox need to be thought about. Any residual pressure on the gas pedal will cause engine revs to skyrocket instantly and a mis-shift would be catastrophic. These engines are safe to 8,200 RPM; they explode at 8,500. Limiting the red-line to 7,500 seems prudent.

“What can we say about the 917? If you don’t twist its tail, it’s a helluva fun thing to drive with its intoxicating, seamless and apparently unlimited acceleration. At 8/10ths, you can experience the full sensuousness of G-loading. But try to drive this thing fast – Brian Redman fast – and, like that pit bull on the porch, it might hurt you.”