Porsche 917: flat-out flat-12

| 1 May 2022
Classic & Sports Car - Flat-out Flat-12: Porsche 917

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No car manufacturer has been more successful at Le Mans than Porsche, with its record 19 wins, and next year the famous German marque will return to the Circuit de la Sarthe in a bid to add to that tally under new LMDh rules.

But trace the marque’s legacy back to its origins and you arrive at the 917, a fearsome racing car that made its debut in 1969 and went on to become the most iconic endurance racer of all time.

Capable of a still astonishing 246mph, at a time when aerodynamics was not yet fully understood, the 917 was a flat-12-powered brute that even the best struggled to tame.

The 917 won Le Mans twice, taking back-to-back victories in 1970 and 1971 before a rule change led to it departing for Can-Am in North America, a series it also dominated.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
A Porsche 917K which starred in Steve McQueen’s film ‘Le Mans’ (1971) was valued at more than $16 million in a 2021 auction

That historic first Le Mans victory was taken on 14 June 1970 by Richard Attwood and Hans Herrmann.

Jump forward to today and, like some surreal dream, the sprightly octogenarian Attwood is watching me climb into the cockpit of a 917 at a damp Sonoma Raceway some 30 miles north of San Francisco, California, calmly offering a few tips ahead of my first-ever drive of this legendary machine.

‘Unbelievably privileged’ barely covers it. Likewise ‘unbelievably nervous’.

The 917’s feathery glassfibre dihedral door hinges up and forwards (taking a chunk of roof with it), and you slot down into the driver’s seat, with an improbably small second chair alongside to cheekily meet the two-seater regulations.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
The dashboard switchgear’s labels remain period-correct

I’m almost lying down, my legs stretching right out towards pedals that leave my feet alarmingly in line with the headlights, yet still it’s a claustrophobic squeeze for my 6ft 1in frame due to the 917’s wind-cheating, low-set shape.

Even with the padding removed from the glassfibre seat (yes, it’s uncomfortable and unsupportive) there is about one centimetre of headroom so for most of my laps I opt not to wear a helmet, otherwise it’s like driving in a neck brace.

The windscreen is goldfish-bowl domed, with the curves of the front wheelarches peaking above my shoulder height.

The steering wheel is a perfect, small, black three-spoker, warning lights seem to be marked with Tipp-Ex (Alt, Oil), there’s a ‘Wischer’ label for the wipers and the rev counter is tilted to put the 8000rpm redline at the top, bang in a busy driver’s line of sight.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
The Porsche 917K’s interior is uncomfortably cramped

If it’s incredibly evocative, it also feels a little improvised – not a word you necessarily want to associate with a 200mph-plus racer.

Conceived for the FIA’s then-new sports prototype regulations that required only 25 examples to be produced, the 917 was a development of the eight-cylinder 908 competition machine, in which Attwood began his relationship with Porsche.

While the 917 was Ferdinand Piëch’s baby, chief engineer Hans Mezger was in charge of development: his death aged 90 in June 2020 lent extra poignancy to the 50th anniversary of the 917’s win that year.

“The 908 was probably good enough to win all the races through 1969,” says Attwood. “But Ferdinand Piëch wanted something bigger and faster, particularly with Le Mans in mind.”

Classic & Sports Car - Flat-out Flat-12: Porsche 917
This Porsche 917K is equipped with a 5.0-litre flat-12 engine which makes around 620bhp

So while both 908 and 917 had lightweight spaceframe chassis, the 917 was fitted with that flat-12 engine, Porsche’s largest ever, with six throttles lined up on either side of a central cooling fan and exposed through the top of the rear bodywork like vertebrae.

Various configurations were available, from 4.5 to 4.9 and 5 litres, and with either four or five speeds. The one we’re driving has the largest motor and produces around 620bhp in a car weighing only 800kg: 775bhp per tonne remains a terrifying figure half a century on.

Conceived when aerodynamics in motorsport was still in its infancy, the 917 was capable of 235mph at first (and later 246mph). 

It wasn’t fully sorted when the car made its debut in 1969 and Attwood shared with Vic Elford – the former driving it for the first time in practice, having previously been highly reluctant to do so.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
Richard Attwood (pictured) first drove the Porsche 917 at Le Mans in 1969 and it was a handful, but a year later he returned to win in the short-tail car

“Vic said he liked the 917, I don’t know if it was bravado or something, but as soon as I drove the car it was wandering horrendously,” says Attwood.

He follows: “The testing had been done on an airstrip, and I don’t believe they were getting to the terminal velocity, maybe 185mph, but it would do 235mph.

"There was a clue something wasn’t right: if you looked in the mirror in the pits you got a very good view behind, but on the Mulsanne Straight you couldn’t see anything.”

Confirming Attwood’s fears, 917 privateer John Woolfe was killed on the opening lap, and Attwood remembers vividly his gruelling double stints: the continual corrections to steering that felt unnaturally light because the nose was lifting, the unbearable noise from the exhausts, and how he would rest his head against the bulkhead.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
The Porsche 917K’s tailpipes hang off the rear of the transmission

“I was in a lot of pain after not even two hours,” Attwood grimaces. “Fortunately the race was dry, because in the wet I honestly believe we would have retired.”

Somehow the two drivers wrestled the car through the night, finding themselves with a six-lap lead after 21 hours.

Only gearbox failure forced retirement: “The factory thought I was disappointed at retiring, but I was just utterly drained and actually relieved,” he laughs.

The 917 was tamed the following year, with the introduction of the 917K (for Kurzheck, or Short-tail) body, while new Langheck (Long-tail) bodywork was also developed.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
The shorter Porsche 917K sacrificed some straight-line speed for significant improvements to handling

“The Short-tail wasn’t as fast in a straight line, but you had the stability,” recalls Attwood. “It was like a completely different car: we had to slow for the kink at the end of the straight the year before; now it was flat, a piece of p*ss.”

It was the Short-tail with which Attwood and Herrmann won Le Mans, and that’s the variant we’re driving today – not the winning car in Team Salzburg colours, but its iconic Gulf livery couldn’t be more appropriate.

This is chassis number 15 of a total of 35, run by British team JW Automotive Engineering in the 1971 World Sportscar Championship.

The JW stands for John Wyer (and co-founder John Willment), who had previously overseen Aston Martin and Ford racing successes, and had been responsible (courtesy of inventive engineer John Horsman) for finessing the aerodynamics.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
This Porsche 917 was campaigned by Pedro Rodríguez and Jackie Oliver in period

This very car won the Spa round of the 1971 championship with Pedro Rodríguez and Jackie Oliver driving, finished second in Buenos Aires and third in the season finale at Watkins Glen.

After one more race in the US in July 1971 it was retired, but it didn’t lie idle: from 1972 to ’79 it was used as a ‘race taxi’ at Porsche’s Weissach team headquarters (hopefully with a more accommodating passenger seat) and has been tucked away in the Porsche Museum since 2009.

The bare cabin amplifies every movement with the engine dormant, and the ignition key seems tiny for a car so intimidating. But with one twist the flat-12 explodes into life behind your head with an air-cooled chatter and thrum.

The way the revs flick up with such a lack of inertia is an early indicator of just how responsive this engine is with its titanium conrods, quad cams and Bosch fuel injection.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
Cut slick tyres on a damp track make for a challenging drive in this iconic Porsche 917

Unfortunately, the 917 has been shipped to Sonoma on cut slicks and there are no spares, so really quick laps are out of the question. But it’s still a thrill to slot the famous balsa-wood gearknob to your right up into first (oddly, unlike in the contemporary Porsche 911 there’s no dogleg here) and ease up a clutch that’s heavy and tremors with tension as it bites in a narrow window at the top of its travel.

With Attwood looking on it’s a relief I don’t stall, and soon I’m trickling down Sonoma’s pitlane in a Porsche 917. Bloody hell.

The speeds are quite modest, but the 917 is such a distinctive thing to drive that it reveals its character very easily. It feels very much as if you’re perched over the front of the car, able to place it perfectly on the apex, while the steering is surprisingly light and feelsome, as if you could jab in some emergency lock, no problem.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
A free-revving flat-12 engine and light steering imbue the Porsche 917K with a sense of agility

This all lends a wieldiness and agility to the 917’s dynamics, and you can feel the tyres arcing to that grainy state of near-understeer on the low-grip surface. A quick lift and jab of throttle would surely bring the rear into play, but I’m also aware of the mass and potency of that monster 12-cylinder engine mounted in the middle of this machine. And the value. Always the value…

The Porsche Museum guys told me to keep the revs up, but the flat-12 actually feels quite tractable from low rpm, and the way it shoots this old racer forwards on the lightest throttle opening is quite remarkable.

Hold out and it chomps through revs so rapidly – bassy, with a kind of distorted ‘flat’ sound at low engine speeds, yet deliciously smooth and perfectly balanced as the revs and the treble climb – that soon you’re reaching for that balsa-wood gearknob and praying you don’t mis-shift in the notoriously tricky gearbox.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
The Porsche 917’s gearknob is turned from balsa wood

The change is light enough in its action but needs a confident pull home to engage. Dip the clutch and for a split-second the flat-12 orchestra is replaced by a suck of induction, then the gear engages and you’re straight back on the throttle.

At one point I reach fourth (I don’t even know if ‘our’ car has a fifth, which some do) and the performance is never in doubt, but the brakes are – the pedal’s travel is long and spongey, and the stopping power feels decidedly mediocre.

Given that I can sense the 917 lifting up and feeling skittish over standing water, I’m in no mood to push my luck here, so I just enjoy the experience, driving as hard as I feel comfortable while I soak up this bucket-list moment.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
Crossing the finish line in the Porsche 917K

Rolling back into the pits, Richard Attwood is standing there, waiting to ask what I think, as if this is some fuggy jet-lag fantasy.

I’m just glad to get the 917 back in one piece and to be one of the few to have experienced it.

It’s incredible to think that in similar conditions in 1970, Attwood and Herrmann beat the world.

Images: Marc Urbano

Thanks to: Richard Attwood, Gijs van Lennep, and Porsche AG


A record Le Mans victory remembered

Gijs van Lennep took the second and final win for the Porsche 917 at Le Mans in 1971, driving a 4.9-litre Short-tail in Martini colours with teammate Helmut Marko.

“I did 22 races in the 917, more than anyone – Le Mans, Interserie, two Can-Am races – and it was one of my favourite cars,” van Lennep enthuses.

“I was never afraid of any understeer or oversteer because it was so nicely balanced, and you could drive it on the throttle fantastically because it had a 100% locking limited-slip differential.

“But I was lucky not to drive it in 1969, when they hadn’t sorted the aerodynamics! It felt very good already in 1970, and then in 1971 it improved again with the 5-litre flat-12 instead of the 4.5.”

Classic & Sports Car - Flat-out Flat-12: Porsche 917
Gijs van Lennep shared his Porsche 917K Le Mans victory with Helmut Marko – who is today an advisor to the Red Bull Racing Formula One team © Getty Images

Van Lennep’s Le Mans debut came in 1970 with privateer David Piper, the pairing running second after 10 hours when Piper crashed the 917.

Van Lennep had proved his ability, however, and was promoted to the works-supported Martini team for 1971 alongside Marko. The B-team provided stiff internal competition, just as engineer and 917 driving force Ferdinand Piëch liked it.

“John Wyer had the official factory team, but the Martini team had all the factory Porsche people – Mr Dechent was officially our team boss but he wasn’t really in charge,” van Lennep recalls.

“We had people such as Wolfgang Flegel, Helmuth Bott, all the factory guys. It was a little bit Gulf against Martini.” 

Classic & Sports Car - Flat-out Flat-12: Porsche 917
The Porsche 917’s engine fan was known to be troublesome, and the Gulf cars were set back by breakages at Le Mans

Neither van Lennep nor Marko knew their number 22 car had a new magnesium chassis, which had been prone to failure during testing.

“The welding was difficult and the first car they tested at Weissach broke after three or four hours,” reveals van Lennep.

“Our car had different welding and was tested for 12 hours and didn’t break, but not 24 hours. I didn’t feel angry after finding out it was magnesium, not at all. If Porsche says you have to race, you race.”

Van Lennep and Marko qualified fifth, five seconds adrift of Pedro Rodríguez’s JWA 917 pole time.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
The Porsche 917’s drilled brakes were fragile and faded quickly

After six hours, JWA Porsches ran 1-2-3, but every JWA car suffered setbacks in the night, and both other Martini entries had cooling fan trouble, so number 22 took the lead after 12 hours – partly because the mechanics proactively ensured its fan wouldn’t fail.

“The fan was known to break and that was the end of the engine,” recalls van Lennep.

“So at every pitstop, starting in the evening, they’d change one bolt – there were four – so it was no problem and we could use 8400rpm.” Instead, the brakes proved to be the chink in the 917’s armour.

“It was the old circuit with White House, the quick left-hander,” says van Lennep.

Classic & Sports Car - Flat-out Flat-12: Porsche 917
Gijs van Lennep celebrating his victory after the 1971 24 Hours of Le Mans © Getty Images

He continues: “Six hours before the end we ran out of brakes more or less: they were thinner, so they’d get hot.

“We were two laps in front of the John Wyer car but knew that if we changed discs we wouldn’t win, so we decided to lift early, not to brake so much and hope for the best.

“It was the first time we drove with drilled brakes and you can still see all the little cracks in the discs on the car in the Porsche Museum – it’s just as it was after the race.”

Only 12 finishers were classified in the results, but van Lennep and Marko won Le Mans at a record speed and set a new distance record that would endure for nearly 40 years.


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