The History Of Porsche’s Immortal 917
By Bill Oursler for 962group.com
The Porsche 917 was, without doubt, the most significant competition car ever produced by Zuffenhausen, transforming the company from a class winner into the dominant player on the sports car stage. While today, the 917 may appear crude, for its time it achieved a level of performance that few if any of its rivals could match. Moreover, its successes spanned not just the traditional long distance international arena, but the very different, high horsepower universe of North American Can-Am sprint racing as well.
The roots of this 12-cylinder classic can be found, as can so many other
things in the politics of the Federation Internationale de L'Automobile,
the governing body for world-wide motorsport. Unfortunately, in spite
its title, the FIA has long been an European-oriented organization, interested
in protecting the values of the "Old World" in general, and
the French in particular.
When Ford in the mid 1960's pushed the Europeans aside at Le Mans, winning the Sarthe 24-Hour classic in both 1966 and 1967, the FIA had enough of what they preceived as the colonial "interlopers." To stem the American tide the FIA changed the regulations for its World Manufacturers Championship, of which Le Mans was then a part, on extremely short notice by adopting a three-liter engine displacement cap for its prototype category starting with the 1968 season.
With the big 427 cubic Fords and their equally large Chevrolet powered
Chaparral rivals legislated into enforced retirement, the FIA had cleared
the way for a European return to stardom, the Europeans of course being
much more interested in high revving, small displacement, sophisticated
engines by nature than the Americans, whose cheap gasoline supplies had
encouraged the large displacement NASCAR-type V-8's which had overrun
their Continental-bred counterparts.
Although the traditional order might have been restored by the FIA's decision, there was the problem of timing, in that the short six-month period between the decision and implementation of the new rules brought about fears there would not be enough of the three-liter cars to fill the grids. Thus, the FIA decided to allow "production" sports cars, of which 50 examples had to have been made, and whose engines did not exceed five liters in displacement, to likewise to compete as "field fillers."
What the FIA had in mind were the cars such as the original Ford GT40s and the Lola T-70 coupes whose reliability, if not outright performance had kept them at least somewhat competitive. In March, 1968, after being approached by several smaller British race car manufacturers, the FIA cut the production numbers in half, making 25 the new minimum to qualify for "production" status. It was at the time an innocent, seemingly insignificant change. However, it would, in fact, have a profound and lasting effect on both the sport and Porsche.
In large measure, this was due to the ambitions of a young engineer at
Porsche, Ferdinand Piech, the nephew of company head Dr. Ferry Porsche
and the grandson of family patriarch Ferdinand Porsche. For years there
had been on-going tensions between the Piechs, led by Ferry's sister,
Louise who had co-founded Porsche AG with her brother, and the Porsches,
the two branches each owning half of the firm. By most measurements, even
ifit was an uneasy association, it was one which worked reasonably well,
at least until Ferdinand Piech arrived on the scene in 1964.
At the age of 28, Piech might have been young, but he was a brilliant engineer who knew what he wanted. And, what he wanted was to make a name and a place for himself in automotive history, much the same way his grandfather had. With Porsche just having committed its then new 911 to production, there wasn't much Piech could do in terms of street technology. However, motorsport was something else again.
A highly visible activity, competition seemed the perfect place to make
his reputation, and Piech wasted little time in seizing the opportunity,
this coming in early 1965 when he was appointed head of Research and Development,
which included responsibility for all of the factory's motorsport programs.
Over the next several years, Piech would push his engineers to their limits
in his search for intellectual immortality .
As soon as one race car would appear it would be made obsolete by its successor, Piech's team churning out no less than four new competition models; the 906, the 910, the 907 and the 908 between January, 1966 and March, 1968. Each was an evolution of what had gone before, the totality of development taking Porsche ever closer to the forefront of the sport. Indeed, with the latter two cars, particularly the three-liter, eight-cylinder 908, many thought Porsche had arrived as a headliner. Piech, though, had other ideas.
Those centered around the FIA's unintended largess in cutting the numbers needed to qualify for the Five-Liter Production Sports Car category. At time, Porsche's policy was to use a race vehicle just once before selling it to a customer and replacing it with a new example. As a result, the factory annually produced upwards of 30 to 40 race cars a year, meaning that in Piech's eyes, building a batch of 25 Five-liter machines was not much of a burden.
Futher, the German government, for whom Porsche did work, was interested
in exploring the possibilities of creating a large displacement air-cooled
12-cylinder powerplant that could be utilized as the basis for a new tank
engine. With that money available, and with the capacity to construct
the needed number of cars, Piech pushed forward. What had never occurred
to the FIA was about to happen: someone was about to produce 25 racing
prototypes as a single group in order to race them in a series essentially
dedicated to three-liter prototypes. It was to be a slaughter, and its
instrument would be called the 917.
In truth, the 917 was not that radical a departure for Porsche, using as it did the 908 as its base. The 917's chassis, body and running car were mainly beefed up, modified 908 components with the cockpit moved slightly forward in order to accommodate the new, longer 12-cylinder powerplant. As for that, while much of its layout, including its central power pickup shaft to reduce torsional stresses on the crankshaft was new, there was much retained from the 908, the basic head design, as well as the bore and stroke from the eight cylinder being carried over to the new 12.
For a car that would turn the racing world on its ear, the 917 was, in
fact, quite a conservative design. Nevertheless, when the first example
appeared on the Porsche's Geneva Motor Show display stand in March, 1969,
the biggest emotion experienced by onlookers was one of shock. Porsche
had done the unthinkable. Indeed, it had done the impossible, and now
the FIA and its rivals would reap the whirlwind.
Such was the FIA's reaction that it refused to homologate, or approve the 917 as a production sports car until it had actually seen all 25 in person, this leading to the famous line up of the new 12 cylinder racers in Porsche's courtyard that April. (Always before the FIA had taken a manufacturer's word that the correct number had been produced, and in fact, when it approved Ferrari's 917 rival, the 512, not all the required 25 had been fully assembled.)
Still, Piech's surprise package had a few surprises of its own for its makers, mostly unpleasant ones. The biggest problem was the car's instability at high speed, the 917 being fully capable of reaching over 230 miles an hour, 40 to 50 MPH more than the 908, which itself was less than a totally stable vehicle at speed. In fact, the root of the problem could be traced to Piech's insistence on low drag figures, a necessity given the limited amount of power that previous competition Porsches possessed.
In fact, the 917 in its initial 4.5-liter form (the use of the 908's bore and stroke giving it that capacity) pumped out 560 HP, 210 more than the 908. By the end of its endurance career in 1971, in full five-liter form that had jumped to 630 HP, when the 12-cylinder was turbocharged for the Can-Am, it produced no less than 850 HP, and 1100 HP in 5.4-liter trim. (Flash readings of up 1500HP were seen during dyno testing of that latter unit - making it one of the most powerful racing engines ever built.)
Even though in theory the 917 could have traded off its low drag figures
for a higher drag body, featuring better downforce without any sacrifice
in overall lap times, it wasn't until the fall of 1969 when John Wyer's
Gulf Oil sponsored team, which was to run the car for the factory in 1970,
got involved that such a trade off was explored. Before then, Porsche's
engineers merely "nibbled" at the stability problem, revising
the suspension geometry to reduce the car's anti-drive and anti-squat
A measure of just how serious things were could be seen in the reluctance of Piech's chief deputy, Helmuth Bott to take the car to Le Mans for the 1969 24-Hours. "He really didn't want to enter the car there, but I did because I thought I could win with it," said Vic Elford two decades later. In fact, had it not been for a leaking main seal which destroyed the clutch three hours before the finish, Elford might have achieved his goal, having led for a good part of the race
Despite the potential of success, Elford was quite aware of the 917's shortcomings. "Bott was absolutely right in his concerns over the 917's handling. Entering the kink on the Mulsanne straight, where you were near the car's maximum of around 230 miles an hour, you had to be very careful getting off the throttle and on the brakes, or otherwise the back might well start to steer the front. It is a measure of Porsche's engineering that when I went back to Le Mans in 1970 with next generation long tail, I could go flat out through the kink - at night - in the rain."
Getting from here to there for Porsche wasn't easy. Or perhaps it was,
if you knew what areas to explore. Even though the 917 had garnered its
first Makes triumph in Austria during August, the aerodynamic problems
remained when Porsche returned with two cars for the Wyer team to test
There would be a solution, though, this coming in the form of an open-topped 917, the prototype of the spyder Jo Siffert was then running in the Can-Am for Volkswagen of America, which was also brought along for comparison. Although mechanically the 917 spyder remained virtually unchanged from its coupe sibling, its bodywork was quite different, featuring a flat top whose shape rose towards its tail, much in the manner of the Can-Am cars of the day.
Memories about what happened in the test session vary depending on who is or isn't talking, but the fact of the matter is that when Wyer's mechanics revised the coupe's rearward sloping bodywork to match the profile of its open-topped counterpart, the four-second per lap advantage the spyder had enjoyed over the coupes disappeared completely. Ugly though the "ad hoc" modifications might have appeared, they worked. The coupe was transformed into a stable winner.
Interestingly, Piech chose to skip the session. If he had attended, one
has to wonder whether or not he would have permitted the revisions to
have been applied to the cars. However, once the modifications proved
themselves, Piech adopted them wholeheartedly, even going so far as to
fully develop the tail's final shape in the wind tunnel.
What emerged in December was the basic definitive wedge-shaped short tail 917K (for Kurtz) featuring a "valley" down the revised decklid's center axis to provide rear vision for the driver. Also modified was the nose, the air and brake into being changed, as were the fenders whose lower surfaces were made thicker and beefier to eliminate the need for the previously used "tack-on" front dive planes which had proved so vulnerable during 1969. The only other modification made was to get rid of the side exiting exhausts, all the headers now leading to a pair of rear mounted collector pipes.
During 1970-71 there would be further "tinkering with the aerodynamics, the Gulf cars mounting a small winglet at the rear of the decklid's central valley, while Porsche itself would produce a tail that was somewhat shallower at the rear in its upward sweep, this incorporating a pair of large side fins. Mechanically Porsche increased the engine' displacement, producing first a 4.9-liter version in the spring of 1970, and then a full five-liter variant after that. Additionally, the Gulf-sponsored Wyer entries came to utlize Girling brakes rather than the ATE units normally employed. Beyond this, the 917K, with the exception of the Martini-backed 1971 Le Mans winner, which was built up around a magnesium frame, remained pretty much "set pieces" for the rest of their careers.
As for the 917's record, it was near perfect during the two seasons it ran, the only loss in 1970 coming at the hands of Ferrari whose 512S won at Sebring after the 917 brigade suffered a series of mechanical woes, (A Ferrari 512M likewise defeated Porsche in the non-championship Nine-Hour Kylami event at the end of the year in South Africa as well.) In 1971, the 917 was defeated twice, once at Brands Hatch and again at Watkins Glen, both times by Alfa Romeo.
For the record it should be noted that the majority of the 917's victories were posted by Wyer's Gulf organization, the exceptions being Le Mans, where, in 1970, Porsche Salzburg, the team operated by Piech's mother, took the honors, Martini following suit the next year. Similarly, it was a Martini entry which captured the 12 Hours of Sebring in 1971. Other than that it was all the light blue and orange of the Gulf team which appeared at the top of the podium.
Interestingly, while it was the short tail design which prevailed both times at Le Mans, the factory was not content to leave that critically important race just to its standard cars. Instead it developed special long tail or "langhecks" versions specifically for the Sarthe. These 917LHs proved quick at Le Mans, reaching nearly 250 MPH on the course's three and a half mile Mulsanne straight, but showed little endurance, only one of the five entered in the two editions of the 24 Hours making it to the finish. That latter was the Martini entry which crawled home second in 1970 with misfiring, water logged 4.5-liter engine.
The only truly "one-off" 917 was the 917/20, a wide body, short tail vehicle designed by Charles Deutch's SERA corporation in Paris which was intended to see if one could combine the aerodynamic advtanges of a long tail in a short tail body. Dubbed "The Pink Pig" because it was painted that color and decorated in the lines denoting cuts of Pork, it was one of the least attractive of the 917 coupes. As for its record, that too was less than memorable, the car running just once, at Le Mans in 1971 where it retired with accident damage before the finish.
With the 1971 Le Mans race consigned to history, the Can-Am beckoned.
Indeed, even though he had tentatively enlisted Roger Penske and Mark
Donohue as partners in a proposed Can-Am effort, it wasn't until the FIA
decreed that the 917 would be unwelcome to return to the Makes tour in
1972 that Piech began to listen, although it would take to the late summer
of 1971 before Penske and Donohue were officially brought on board as
the designated hitters for Porsche in the sprint series. Even that decision
wasn't easy, internal politics at Porsche delaying things for some time.
Initially, Piech and Porsche had thought in terms of a two-team effort, the second Can-Am operation being headed by Siffert. In fact, it was the Swiss driver who debuted the new Porsche Can-Am spyder, the 917/10 at Watkins Glen in 1971 in the lurid day-glo red colors of the STP corporation. The Siffert spyder was a product of a redeisgn by Helmut Flegl, one of the original engineers assigned to the 917 endurance project. Flegl and his team had simplified the frame, while increasing its torsional rigidity by adding sheet aluminum to its lower sides.
As for the 917/10's body , it resembled that fitted to the 908/3 spyders, with a flat top and slab sides, The tail was short and open with a pair of side fins, while the nose featured the traditional center mounted oil cooler flanked by less traditional cutdown front fenders. Although Siffert's example was fitted with a non-turbo five-liter unit, the plans were to run the factory supported entries with turbocharged powerplants in 1972, the cars Porsche hoped to sell its customers using non-boosted 5.4-liter engines instead.
Surprisingly, Siffert, who had finished fourth in the Can-Am standings
in 1969, dud so again, scoring one second place in the process. Tragically,
however, he didn't finish the '71 season, being killed in October at Brands
Hatch in a non-points Formula One event. This left Penske and company
as "the only game in town" for Porsche, Donohue and his engineer
Don Cox beginning to work with Flegl and his people to develop the 917/10
to its full potential for 1972 shortly after Siffert's death.
Again the problems of aerodynamics, in this case aerodynamic balance, soon made themselves known. While a rear wing, hung out over the tail of the car on a pair of sponsons, provided adequate downforce at the back, nothing seemed to work at the front. Eventually Flegl and Donohue compromised by cutting back the front fenders around the oil cooler, much in the same way as had been the case with the Siffert spyder the year before. While not perfect, with the addition of a front lip, or "splitter," the nose then generated enough downforce to balance out the back.
Far more frustrating, but easier solved was the question of the engine. From the start, when the first turbocharged 12-cylinder was dropped into a 9127/10 in the spring of 1971, until it appeared in the Penske test mule at Road Atlanta the following March, the boosted powerplant had proved impossible to drive, either putting out maximum power or none at all. Such was the level of frustration that at one point Penske himself suggested postponing the car's debut until the problem was fixed.
With that motivation pushing them along, Donohue and the Porsche engineers
soon discovered that the source of the difficulty was a miscalibrated
fuel injection pump. Once that had been recalibrated, the engine was perfect,
and the program ready to go. Given that the Porsche had a power advantage
and as least as good handling as the then dominant McLarens, the Can-Am
should have been a pushover. It turned out to be anything but.
After losing the season opener to the McLarens at Mosport, after Donohue was forced to stop and fix a stuck butterfly valve in the induction system, the Penske driver then proceeded to seriously injure himself in a testing accident at Road Atlanta which destroyed his primary, magnesium-framed race car. Out for nine weeks while he recovered from knee surgery, Donohue watched as substitute George Follmer took his place in the back-up car, the revitalized test mule.
While Follmer won Road Atlanta, he lost before Porsche's top management at Weatkins Glen. At that point there were crisis meetings about what to do. However, in the end Penske stayed with Follmer, who with the help of Donohue's coaching, and some timely modifications to the car, won at Mid Ohio, which followed the Glen, and again at Road America on Labor Day weekend. At Brainerd, the next race up, Donohue was back in a replacement chassis, partnering the now points leading Follmer. Unfortunately neither finished, Donohue going off the road and retiring with a damaged suspension and Follmer running out of fuel on the last lap.
After that, though, it was all Porsche, Donohue winning at Edmonton, and Follmer at Laguna Seca and Riverside, to claim the drivers honors. For McLaren, whose cars previously had dominated the Can-Am, earning the title every year since 1967, the loss to Porsche was enough to send the team packing. Never again would the orange cars be seen in the series. However, Porsche enthusiasts didn't seem to care.
In 1972 there had been two private 917/10s, Peter Gregg's Brumos entry and Vasek Polak's car driven by Milt Minyer. For 1973 the number of 917/10s would increase, Gregg's car being taken over by Hurley Haywood, while Polak would put future World Champion Jody Scheckter in a new 917/10. In addition Polak would field his old 917/10 for Swiss Hans Weidmer in the opening rounds, later entering the much modified 1969 Siffert 917 sypder, now brought up to 917/10s, for Brian Redman.
In addition, Atlanta area resident Bobby Rinzler had purchased Penske's
two L&M sponsored factory cars, running them with RC Cola backing
for Follmer and Charlie Kemp. All Porsche entrants, including Penske,
would have 5.4-liter turbos. However, none would be able to match what
Penske man Donohue would have at his disposal for the year.
About the only he and his rivals would share would be the bigger engine, Otherwise Donohue's new Sunoco-blue 917/30 was unique, featuring an extended wheelbase, a new, more aerodynamic nose from SERA, and the extended rear deck from the 917 longtail Le Mans coupe. It might not have been perfect, but it suited Donohue perfectly. Yet, surprisingly, the start of the 1973 season wasn't much better for Donohue than 1972 had been.
The troubles began once more at Mosport where Donohue tagged a backmarker, and finished out of the running, the victory going to Kemp in the Rinzler RC Cola entry. Then a leaking fuel tank forced Donohue to settle for second at Road Atlanta behind Follmer in the other Rinzler 917. And, as if all this weren't bad enough, Donohue was forced to use his backup car at Watkins Glen when he damaged his primary machine in a practice mishap.
But, that was it. Donohue recovered to win the Glen, and never looked
back, taking the remainder of the races going away (only at Mid Ohio did
Follmer mount a serious challenge, but was unable to overcome Donohue's
"unfair advantage" ). Such was the domination of Porsche in
general, and Donohue in particular, that the Sports Car Club of America
forced Porsche to quit the series for 1974 by cutting the 917's fuel capacity
to a point where the car was uncompetitve. Only in the European Interserie,
the Continental counterpart to the Can-Am, where the 917 had dominated
since 1970, did the turbo live on, Herbert Muller winning in 1974 and
1975 with the first of the 917/30's now in Martini Livery.
Back in America, Brian Redman was called in by Penske, after Donohue decided to take 1974 off from the sport, to make a special appearance with the 917/30 on a rain soaked Mid Ohio track. There Redman finished a surprising second, and might have even won had not he made a wrong tire choice. But, it was all a sideshow. The 917 did not return after that and the series came to a premature halt following Road America from a lack of fan interest.
Still, Donohue and his 917/30 would be reunited in 1975, when, ten days
before his death while practicing for the Austrian Grand Prix, Donohue
used the car to set a new closed course speed record of more than 220
miles an hour at the high banked Talladega NASCAR tri-oval. That should
have been the end. But it wasn't - note quite.
In 1981, under a loophole in the World Manufacturers rules for that year, the Kremer Brothers built and raced a replica 917 coupe, not that much different from those seen ten years earlier. While the reconstituted Porsche, based on a plans drawn from one of the original chassis restored by the Kremers, didn't win, it proved quite competitive, and ironically set the stage for the entrance of the Group C 956 the following season,
By any measure then, the 917 was a remarkable vehicle, which to this day has retained its mystique. Had it never existed, one has to wonder if Porsche would be the same company, with same reputation it enjoys now. Clearly more than three decades after its conception, the 917 continues to be awe inspiring, and there can be no better tribute to a car than that.
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