Porsche 917

When David wanted to turn into Goliath

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1970: in the horse's year

The five litre's sunset

Introduction

Till the end of the 60's Porsche had been playing a David's role. Whenever the ground and conditions have permitted, it had inflicted deadly strokes on various Goliaths in turn and, above all, on the Ferrari car. Porsche did it thanks to cars that didn't count on max power and extreme research, but by means of simple cars, light and reliable ones, with small engines keeping a very tight link with the production. In the first twenty years of its history Porsche had collected a remarkable "palmarès" of absolute wins, but above all of first rate. However, it was left far from sensational results on important circuits like Le Mans, where it took much more than those means. A remark that suited no more the top management of the German factory, by that time it was a well known brand that occupied important niches in the GT car world market. With a strong craftsmanship stamp it had become an industry and even its sports ambitions had to be consequently measured according to a new reality. In a certain sense, at the end of that ten-year period, our David suffered from what today is called an identity crisis, having the dream of turning into Goliath: a concentrate of brute force. First step was the 908, also said the "bicycle" because of its frame made of thin tubes. Powered by a boxer air-cooled eight cylinder engine, the Stuttgart car was designed under the regulations for sports cars up to 3000 cu. cm. But from 1970 they would have been starting with the new queen class allowing an extension of the capacity up to 5 litres with a heavy falling back on the engine powers and car sizes. The world of endurance motor races was on the point of being invaded by real monsters that should have beaten all previous records and Porsche, not to be taken by surprise, started off in great advance on its competitors. In the winter between 1968 and 1969 Ferry Porsche started off the 917 design, giving its supervision to his nephew Ferdinand Piech. The engine realization went on with Hans Metzger, who had already worked on the three-litre 908. The choice of its structure brought Porsche to a direct challenge with Ferrari, that made the 12-cylinders a mark of identity like the prancing horse on its bonnet, but the other solutions were tied to the tradition of Stuttgart factory. Therefore, the air-cooling system, permitted by the usual big fan placed on the upper side of the engine and, obviously, its boxerconfiguration. Due to cost matters they decided to obtain the new unit by combining of the two light-alloyed blocks of the six-cylinders mounted on the 2.2 litre 911 R That brought Porsche to don't make the most of the new rules because the total capacity obtained was only 4500 cu cm. The use of updated materials and special alloys allowed reducing the weight of the "monster" to 260 kg: thus the shaft, composed by two forgings, made of light steel, connecting rods, always forged, of titanium and cylinder heads in light alloy of aluminium, while pistons were subject to chromium plating process. The timing layout was made up by two camshafts for each main bearing, moved by a set of gears and operating by means of bucket type tappets on the two-valves of each cylinder. Three electric pumps supplied the mechanic injection Boschsystem, developed by the Porsche needs and particularly complicated by a grid of very thin pipes. Always of the Bosch type, there were two magnetos, each for main bearing, causing the ignition in the cylinders. The new powerful engine could produce 520 hp at 8000 rpm with a torque of 50 kg/m at 6800 rpm. therefore, rather elevated under steady state conditions. From every capacity litre the German engineers had succeeded in squeezing a good 115 hp. As for the gearbox the Porsche engineers chose the longitudinal synchronized shifting with four or five speeds according to the circuits, designed by themselves and homebuilt. Such as for the engine, the cooling was mainly created by air flows generated by the air-intakes on the bonnet and sent on to the box fins by air-ducts, purposely studied. A self-locking differential favoured the engine power performance, while the clutch was a multiple dry-disk type. The chassis utilized a network of thin tubes made of a special alloy kept as a top secret by the Porsche Factory. The construction was particularly complicated on the rear side, where the engine and the gearbox were unable to perform any bearing function. Well, designers stayed away from the charm of the "monocoque" body or from any particular innovative experimentation such as the honeycomb shortly tested by Ford with opposing results. Piech himself explained that the bearing body or "monocoque" didn't yet assure the same values as torsion stiffness and presented a more complex handling. "If you damage a body its maintenance is difficult and expensive in terms of time. If you damage a tubular frame it's sufficient to cut the damaged part off and weld a new tube". Thus, they obtained a light construction (47 kg) with stiffness values equal to 5000 - 6000 Newton/degree. Suspension system was based on a simple wishbonelayout, with Bilstein shock absorbers matched with helical springs. The four-disk brakes were activated by a double circuit to avoid damages of tragic effects. Together with the engine, the strengths of the project should be the accurate streamline study: the body shape, in fibre glass reinforced by polyester, had very soft and harmonious lines. The low nose rose in the middle towards the wheelhouses, while the air was flowing because generated by a generous oval mid-outlet, went out from the bonnet after cooling the big oil radiator. Two "Naca" air intakes had to convey the air to brakes. The back lights were fully integrated in the body work surface thanks to Plexiglas covers. The aggressive side "moustaches" were considered very useful by that time, because they could generate an additional aerodynamic load, but they were dropped in favour of a better designed bonnet. The big widescreen , aeronautic type and strongly convex shaped, was, in case of rain, kept efficient by a complicated pantograph type windscreen wiper. The very low roof line, outdistanced 92 cm from the ground, sloped down to the tail by a transparent rear window, that allowed catching a glimpse of the mechanical parts and eliminated the heat from the engine room through the holes made through Plexiglas. The doors were made to offer the driver a quite easy access to the cramped space of the cockpit, where he was almost sitting in a mid-position. But, above all, it was striking to see that long and tapered tail, featured by the monoplane wing that those who had a slight knowledge of motor races were able to correlate to a unique and legendary event: Le Mans. However, for the French marathon designers were preparing a version, much more extended to the extremes; while some mobile wing elements had been experimenting, which often caused anxiety to the drivers, the real guinea pigs of those tests, and turning up competitors' nose because they represented a borderline rule interpretation. Later on, in that year a new spider version was also studied, however it wasn't followed up by production. Obviously, everything was conceived to favour technicians' intervention as much as possible for the race management and possible emergency repairs: thus the bonnets could be completely opened; chassis had lifting points easily accessible as well as the fillers for refuelling and topping up the engine with oil. Given the employed technology, it was consequently very complicated to make a 917 run and be assisted: you have only to think that the check list of Gulf Porsche team, i.e. at the time when the 917 car had achieved a reasonable reliability, was composed by something like 130 scores. In the 1969 spring, the 917 was displayed at the Geneva Motor Show to have journalists and fans dreaming of it. Its 4290 mm length and 1630 mm width, with 2300 mm wheelbase and front and rear tracks equal to 1488 and 1457 mm respectively, gave a respected stage effect. May be the white with green striped livery wasn't so exciting, but the lines, without compromise, quite clearly explained what Porsche was aiming at with that racing car. Together with the car display, the Stuttgart factory made its programme known: the homologation, which involved the construction of 25 running examples, was envisaged on the 1st May of that year that is in a very short time and with a heavy financial commitment. Most of the production would have then given to private racing teams at a profitable price. The 917 construction cost Porsche 305,000 DM, but the car was sold to customers at 140,000: Piech himself called the operation "the greatest publicity stunt ever made by Porsche". The factory would have run, on its own account, some units, given to reliable crews. Going round Porsche there were some of the best drivers of that time: people like "Seppi" Siffert, Rolf Stommelen, Vic Elford and Hans Hermann. The old "908" became as an additional weapon to the 917, required in certain races like "Targa Florio" or the 1000 Km Nürburgring, where the agility qualities of the "bicycle" were much more useful than the power and top speed featuring the new car. De facto, the 918 was obliged to be playing the role alone and still for several months, waiting for the solution of the 917 early problems and that the calculations, made on paper by engineers, should be also correct on the track. By the end of April, the picture of the 25 examples lined up for the F.I.A delegates' inspection, travelled round the world, but in Maranello neighbourhood it was rumoured that the cars were unfinished and unable to move without the "human drag" help. The direct consequence of that malicious gossip was that federal inspectors didn't do their job well. Unfortunately, motor races lived on names, capitals and the expertise of those who construct racing cars: it was impossible to say no to such a glorious name as Porsche. And some time ago Ferrari had been also favoured by indulgent "carelessness" and discounts from F.I.A. No detail was neglected to develop the car: during the first tests in view of Le Mans they filled the tubular chassis with compressed-air, to highlight any possible cracks. During those first laps on the French circuit, the 917 let Stommelen to take the lead on times list, recording 347 Km/h top speeds on the Hunaudières straights. In spite of his good performance, the German driver wasn't fully persuaded, especially for the strange feeling arousing from the chassis. When Porsche factory decided to enter the car in the 1000 km Spa Francorchamp, Siffert was also less diplomatic: the 917 let him to gain the first row, but he complained much at the car instability both on fast bends and long straights. Moreover, the too external location of the fifth gear caused some trouble to the transmission selector, which often induced drivers engage third gear by mistake, making the engine revolutions jump up to stars. For the competition, Siffert declined the 917 by going back to the old long-tailed 908 that, moreover, allowed him to win the race. Porsche managers, after suffering from their best driver's reject, had to add their disappointment for the retirement caused by the 12 cylinder engine failure. The first race of the 917, driven by the Mitter-Schutz crew, lasted one lap only. On next meeting of the 1000 km Nürburgring, Porsche drivers kept far from the 917, despite the use stiffer springs and shock-absorbers that should partly eliminate the unpleasant feeling caused by high speed. Everybody clung to his 908, also because the car was, objectively, more suited for the 22 km twisty track. Thus the 917 fell into David Piper's and Frank Gardner's hands that didn't finish further on than the tenth place in the qualification and the eighth in the race. For your information, Siffert won the race again at the wheel of the 908. The winning scores served to affix the Porsche mark in advance of the 1969 world championship of makes. At Le Mans everybody expected the 917 to win again; was it or wasn't it conceived to leave broke the 24 hours, race that Porsche wanted to win at all costs? Regenerated by a new and more rigid suspension, a long tail shaped body and with the fuel vaporization problem solved, the 917, in Rolf Stommelen' s hands made the pole easily. The German driver was also the main leader of the first part of the competition, being in the lead till engine and gearbox didn't start failing. It was the beginning of a misfortune suffered by Porsche, the team that, in newspapers' opinion, couldn't fail the target, thanks to the available means, organization and quality of its cars. At the wheel of the 908 Siffert was obliged to retire, Elford, by that time in the lead, was a prey to vaporization problems of the brake fluid and later on definitively betrayed by a clutch spring, under to high tension, that smashed the disk to smithereens. The surviving 908, driven by Hermann-Larrousse, was compelled to suffer for a humiliating fight with the Ickx-Oliver's old Ford GT 40, with the addition of a mocking overtaking few metres before the finishing line. To the sports disaster it was added John Woolfe's dramatic accident at the wheel of his private Porsche 917 that crashed against barriers and set fire. Flames alimented by the recent filled-up tanks devoured wrecks and driver. And after the real flames it was the turn of the false flames appeared on newspapers that accused Porsche factory of having constructed unstable and dangerous racing cars. That the 917 was without any doubt still young and under certain conditions actually unforeseeable, but it was also necessary to consider Woolfe's inexperience, who had been till now driving less powerful vehicles and, suddenly, had, perhaps, decided to make a too challenging step with respect to his ability. Some days before the race, Woolfe had told his friends that he was terrorised by that car and its performance, but his fear wasn't sufficient to make him give up driving. On the occasion of the Watkins Glen race further betterments were introduced to front stabilizers and cockpit ventilation. Also exhausts had a new design that permitted to minimize fuel consumption. The treatment didn't give any considerable results in the American mission, above all because the Porsche drivers went on striking against such a young creature, but on next Zeltweg meeting a smile returned on everybody: in the new Austrian circuit the 917 was led to victory by Siffert-Ahrens: at the beginning the Swiss driver had to run at the wheel of the 908, declining for the umpteenth time to drive the last version, but on Ferdinand Piech' s polite and steady request he had to change his mind : "Mr Siffert, could you drive the 917 as a personal favour, despite all the problems existing now?" It was a triumph and not only for the 917, considering that the eleven cars Porsche were the first 12 places. Only the old Lola with Joackim Bonnier succeeded in worrying the two leading drivers and breaking a classification that appeared to be, on the other hand, a mono-make. Victory didn't convince at all either Porsche or sports papers. The experience on track had helped the Stuttgart racing team to acknowledge the car problems. Much had been done but the aerodynamic problem was still unsolved. How could they give stability to the car at top speed without adding too aerodynamic load? To look but not to see, to be able to solve an equation by a simple operation and, on the contrary, to have been racking one's brains for hours over some complex calculation. It looked like a funny Zen story: a couple of hours of tests on the Austrian track, few days after that victory and some aluminium sheets were, in fact, sufficient to solve all trouble. Valentin Schaffer, the modifications' author and Porsche's expert, with the help and the invaluable suggestions of some engineers from John Wyer Automotive Co., that was, as we see later on, on the point of taking a leading role in the 917 history. The devised solution wasn't a new one, but interpreted in an original way: a wedge-shaped and very short tail that originated the well known version "Kurz". On the basis of Schaffer's experiments, a new bonnet without the big rear window in Plexiglas: wheelhouses were no longer following the rear wheel full arches, but running straight onto the short tail, leaving the chassis lower side and the gearbox in-sight. Moreover the rear section had been increased to house new 15-inch tyres instead of 12-inch ones. Also the front bonnet was modified by the big mid-intake having two smaller intakes on both sides, while the big outlet was left unchanged for the hot air coming from the radiator room. But aerodynamics wasn't the only sector where the improvements had been made: the welding of the frame was sturdier now and, in consequence of tragic Woolfe's accident at Le Mans, a fire-fighting system was installed. The engine got flexible pipe joints that offered major safety in case of accident. However, the most radical change concerned the organization of sports activities: Porsche factory abandoned the direct management of its cars and entrusted the task exclusively to private teams. The priority was given to John Wyer Automotive team, the successful creator of the Ford GT 40 programme in the previous ten-year period. As for the English team management, it was a real fortune to find the German factory sponsorship: after finishing the experience with the American sedan that had still gained a win at Le Mans in 1969, there was only left the prospect of Mirage "Barchetta", home manufactured and powered with the Ford 3000 cc. Despite promising results, it was obvious that Mirage alone couldn't be sufficient to keep the team on the top of endurance racing. The agreement on the management of the Porsche 917 cars permitted also to keep the Gulf oil company as the main sponsor. The Stuttgart racing car was on the point of wearing the light blue and orange livery that made it renowned and recognizable by all fans of racing cars. The second priority team was the Salzburg work team that would have imposed the red and white of the Austrian flag.

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Introduction

The five litre's sunset

1970: in the horse's year

The 1970 season appeared to the fans of racing cars as the year of the struggle between horses: the year, not very significant, represented by Porsche's logo and Ferrari's one, a rampant and black horse in a garish yellow background. At Maranello it was decided to embark on the 5 litre challenge with a forefront project that took up important technical and economic resources: the aerodynamic study was entrusted to Pininfarina. The engine was 60° V12 type that capitalized the recent experience in Can-Am, with 580 hp at 8500 rpm, on paper it was more than the 520 hp declared by Porsche for the 917. Ferrari managers thundered because they wanted to revenge themselves for the 312 flop occurred the year before, but the 512 was 9 months' delay compared with the 917. The season began with the 1000 km Buenos Aires, race that wasn't valid for the championship. Ferrari absent, practices were monopolized by the private 917 driven by Piper-Redman against a 3 litre handful of cars. Despite the overwhelming superiority of their car, the drivers launched into an absurd performance; trying to win a race they had it already to hand. By insisting they went out of track and suspensions were damaged. The winter treatment had clearly improved the 917, now more handling and stable at high speed. The work had been so radically done as to invert the car performance: the aerodynamics of first version and the load of the rear made the car over steered. On the contrary, the Kurz was under steering in the slow curves. Daytona marked the official beginning of the season: there were also 5 brand-new 512S that drew the spectators' attention. Andretti at the wheel of the Maranello racing car made chronometers blow up with a top performance. On that circuit of fast and over elevated curves the Maranello 12 cylinder seemed to overcome the competitor Porsche. During the night, while Ferrari technicians exerted themselves to remedy one trouble and the other, the colleagues of Porsche team were sleeping peacefully, confident in their means. In fact, the competition was a complete nightmare for the 512s that were faced by problems of feeding, brittleness of chassis and body and some mistakes in the set-up. In race the Porsche Gulf driven by Pedro Rodriguez and Leo Kinnunen took the lead before the twin car given to Siffert - Redman that could win if they were not faced by trouble to brakes and electric system. The Porsche leading by 1 to 0 soon turned into a draw in next race, on the Sebring circuit. Parts not previously tested cut off the Gulf Porsche cars and caused both crews to retire. Even if the two cars, entered by Porsche Audi USA and driven by Hermann-Linns and Elford-Ahrens, had got the latest improvements, weren't able to place a winning blow because of the engine failure and the accident that damaged suspensions. Andretti won at the wheel of the 512S. At Maranello they deceived themselves into thinking they had solved all problems relating to their young creature but. as a matter of fact, troubles had still to begin. At Brands Hatch, through a pouring rain, there was the right occasion for Pedro Rodriguez's fantastic solo that left the wheel to his crew mate Kinnunen only for few laps. Behind them the 917s Porsche Salzburg driven by Elford-Hulme and Herman-Atwood were easily placed. On next Monza meeting for the traditional 1000 km race, Porsche introduced the new and more powerful 4,907 cc engine. The major displacement had been obtained by increasing the stroke from 66 mm to 70.2 mm. As a consequence of it, the engine power increased to 580 hp approx, while the torque values were left the same as the preceding version, recording 54 kg/m at 6800 rpm versus previous 50. First time that they experimented the Girling new brake disks, that proved to be more effective than ATF previous ones. The updated engine was used by Siffert only during practice and then put immediately aside because of an oil leakage. That didn't prevent Seppi from the sad retirement when he was at the lead of the race, just betrayed by the engine. Elford and Ahrens also got into trouble after shivering for a puncture when they were driving over 280 km/h. The victory was still gained by Rodriguez-Kinnunen. In view of Targa Florio the Porsche teams decided to renounce the big 5 litre cars, scarcely suited for the twisty Sicilian track. Only the Salzburg team risked entering a 917 for Elfort - Hermannn that however didn't go over the tests. Ferrari entered its 512s, resigning itself to be subject to the more handling 3 litres. In fact, the 908 soon resulted very performing by gaining the pole with Kinnunen and the victory with Siffert-Redman. Next race represented also a celebration: in 1969 the 1000 km Spa had marked the official debut of the 917 that, as told before, was a failure. After one year, in a car which was deeply modified and improved with respect to the original, Pedro Rodriguez set the pole, while usual Siffert, matched with Brian Redman, crossed the finishing line victoriously, allowing the Stuttgart factory to win the world championship of makes much earlier. The race wasn't a piece of cake, because the wet track was the ideal ground for the talent of the man who was by that time considered as the king of rain: Jacky Ickx, on such occasion at the wheel of the 512S. Porsche was favoured by good luck because the Belgian team mate, John Surtees, didn't prove so skilful and Maranello drivers had to be content with the second place ahead of Vic Elfort and Kurt Ahrens's 917. On the occasion of the Nürburgring 1000 km the small 908s re-entered the field; they hadn't difficulty in following the rival 512s more and more put to shame by bad luck, bad management and not always successful technical developments. After Sebring's win, the big Ferrari car had scarcely troubled the Porsche 917s, getting some podiums and various placing, but it didn't succeed in going up the craved top step of podium. Enzo Ferrari might as thunder against and snarl at his men as he liked, but results didn't change. Nino Vaccarella, who experienced both cars, during an interview of some years ago, focused their difference: "the 917 was overall better: a car easier to handle, softer as for its set-up, not asking too much for the tyres, with a decidedly more comfortable driver's seat. As regards the power they were equal in value, but the 512 was too nervous, obliging the drivers to drive constantly at limits. It was a nightmare to be at the wheel of it at the Targa Florio or Nürburgring (editor's note: where Vaccarella gained two third places). Also the Porsche gearbox was more effective and precise." Le Mans was Ferrari's last chance to save the season, while Porsche didn't want absolutely to miss the target that was in the DNA of its racing car: to win the terrible 24 Hours that had been so long denied. The line-up gave shivers: 11 cars "512" against 8 cars "917".The technical and tactic choices made by Porsche were fully illustrated by eng. Piech in an interview given to Autosprint on the eve of the race: "Here at Le Mans we have eight cars of the 917 type with 12 cylinder engine. Five examples are powered with the 4.5 litre engine, while our faster crews, i.e. Siffert-Redman, Rodriguez-Kinnunen and Elford-Ahrens have the 4.9 engine at their disposal." Then the engineer went deeper into the long-tail version created for that year: prepared in April, once tested on the track the new aerodynamic solution had highlighted a great increase of top speeds, to the disadvantage of stability when curving. Besides, the limitation of the warm air outlets brought the mechanical parts to a reliability crisis, while the need to find more aerodynamic load in the mixed parts of the track had obliged the use of a large wing running along the tail width, thus making useless the interesting values of a top speed (they said about 370 km/h on the straights). "John Wyer team preferred short-tail cars, because they were more stable" but the engineer also hesitated to let everybody know that "personally, I'd always rather the "long dress" for Le Mans, because even if on a bend we are a bit slower, we aren't so slow as to made us overtaken by the others, while on straights we are much faster than the others. The top speed of the long-tailed type is so higher than the 917 standard versions that obliged us to equip the cars again with the 5-speed gear box, having been abandoned since the end of the year." The conversation was still more interesting when Piech went on illustrating the 917 consumption: "Here at Le Mans the cars have a high consumption, because engines are running at a top rate. Our 5 litre engines almost eat up 55 litre of fuel every 100 km, that's to say that the 120 litre of fuel supply permitted by the rules will be exhausted in every 45 or 50 minutes." Moreover, the 917 drivers were called for 8200 rpm top rate, quite prudentially in comparison with the top rate of 9000 rpm admitted by Piech. Nevertheless, the engines had been bed testing for 20 hours, according to the quality control standards provided by the Porsche factory, without finding any anomaly. That interview revealed certain reliability on the quality of the available material and a good chance of Porsche's winning. As a matter of fact, the result was much less taken for granted than we could expect, even if in Stuttgart they had already printed celebrating posters. Vaccarella's time was there to show that, at least as an absolute performance, Ferrari was present. "The flying headmaster" stopped the chronometer at 3:20, at the average of 242-442 km/h breaking the preceding record of the 917 driven by Stommelen. In vain, Porsche's drivers tried to be faster than Vaccarella and only Vic Elford in the end succeeded in setting the time of 3:19.8, which won him the pole and spared Ferry Porsche, the race starter, to suffer the humiliation of the race starting to a red Ferrari. The race was another story, with Porsche cars that did their utmost to gain the win and Ferrari cars that did everything not to gain it. After all, at start, out of the 8 cars "917" only two of them saw the finishing line: the red and white car of the Salzburg team, driven by Hans Hermann and Richard Attwood and the other of the Martini Racing team with Larousse- Kauhsen at its wheel. By a twist of fate: Hans Hermann, the winner a year after suffering a defeat in the great duel with the GT 40 driven by Ickx, and what's more with a 917 which had neither further aerodynamic improvements, nor did with the 4907 cc engine. A twist of fate also for the second place gained by the youngest team entered in the 917 management, with that livery a bit loud, all green and blue doodles that someone called "psychedelic Hippie". None of the 917 Gulf crossed the finishing line, even the one entered directly by the factory, made the pole: engine failure and some errors. Perhaps Siffert was the most embittered among Porsche drivers: if the fourth gear didn't slip out when he was just in the lead, causing his 12 flat cylinder engine to scream, how would things have gone? To point out the ninth place gained by a bit particular 908: entered by Solar Production and driven by Herbert Linge and Jonathan Williams, it was equipped with a cine camera to film the race. The clips were then used in the famous film: "24 Hours of Le Mans" with Steve McQueen. It cost a fortune; the film had very little success, causing the Solar Production to go bankrupt with McQueen himself, who was the owner. What about the Ferrari cars? All that was summarized by Marcello Sabbatini in a set of worrying questions coming out in a moment of Italian sadness: why so much exasperated rivalry among Ferrari drivers and so much foolishness from the stands as to permit their cars struggling so close? An oil splash on the windscreen of the first 512 driven by Wissell, a bad joke of Larousse's diabolical car that was ahead, and that's that! Four Ferrari cars curled up all in one go at Maison Blanche, a terrible crash over 200 km/h. What about Ickx, the king of the wet track, who, in the downpour, dashed in a foolish pursuit of Siffert's pilot car, and run into a fatal out of track? It was a fatal event to his win expectations and to a track commissary. If he had been waiting, with patience, for 34 minutes, he would have seen Elford making his exit with "broken pistons". At the end it was Chinetti's NART (North American Racing Team) that saved the face, with the 512 driven by Posey - Buchnum that gained the fourth place, but behind a 3 litre Porsche 908. With the Porsche that had gained the World Championship of Makes and finally hit the mark in the 24 Hours of Le Mans, the interest in the season end seemed fading. But the protagonists of that exciting ride proved that the show wasn't over, and it wouldn't have been finishing as long as the checked flag didn't greet the winner of the last race. At the 6 Hours of Watkins Glen Ferrari found his best driver again, Mario Andretti. It was a fine struggle between his 512 and the 917 cars of Wyer: the Ital-American driver, with a wonderful start flashed past Rodriguez pole man, but his leading race lasted few laps before giving in to Siffert and the Mexican driver. At this point a terrible and fratricidal battle burst out among Porsche drivers, with Rodriguez fiercely in pursuit of Siffert: the Mexican didn't pay him compliments and overtook Seppi on the Big Bend, the very fast bend preceding the box, touching the side of the team mate's car without restraints. Seppi was obliged to give in and drive back to the box to replace a wheel damaged during the contact, moreover without losing his position. It was a real stroke of luck if both of them didn't find themselves off the track among the burning wrecks of their racing cars. Siffert made up on next and last season race in Zeltweg, gaining a bright win on the fast Austrian circuit. Ferrari entered the fray with the 512 umpteenth readjustments, with a complete different aerodynamics, some horse power more under the bonnet and some kilos less in the load. At Maranello they thought they had finally arrived at the end of their suffering, but the engineers' confidence in what was then called 512M was swept away by Enzo Ferrari' s fury, who won't hear of the 5 litre car any longer.

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Introduction

1970: in the horse's year

The five litre's sunset

The 1971 season started with the 1000 km Buenos Aires, for the first time valid for the championship of makes. The five litre class, which came into force with enthusiasm the year before, had its days already numbered. The tables of the automobile associations were like conjurers' top hats: doves and rabbits came out of there in great number and then disappeared with the same swiftness. Only Ferrari and Porsche had launched in the route of the big sports cars, while other constructors had gone on the three litre cars. And now also Ferrari, after the 1970's defeat, was making a rapid back out to start developing the 312 PB. The 512Ms were given to private teams without any extra charge. With regard to that matter Vaccarella reminds: "when I think of it I believe that Ferrari has missed a great opportunity. In 1970 the Porsche 917 was a car better than the 512S, but the 512 M Ferrari had same superiority as to Porsche. Really I never understood why in 1971 Enzo Ferrari decided to schedule a reduced race-card with a 3 litre prototype, when, on the contrary, he could line up two 512Ms and to take his good revenge." To believe in what had to be the queen class there was only Porsche, determined to make the most of its own project potentiality, waiting for the future settlement in the motor races. Two top teams would have still managed the best material: the already tested team of John Wyer and the Martini Racing, replacing the Salzburg one. Inside the Gulf Porsche team, they made some change in crews: Rodriguez lost Kinnunen for Jacky Oliver, the F1 ex-driver, while Siffert was matched with Derek Bell. The struggle for the first grid position saw the 917s competing, but also the surprising 312 PB Ferrari driven by Giunti-Merzario. The Italians succeeded in passing between pole man Rodriguez and Siffert, with Giunti, who from the start had been attempting an escape, immediately stopped by the more powerful German cars. Ignazio didn't succeed in holding out against Siffert and Rodriguez as well as the absurd event waiting for him: at the 39th lap he found the track obstructed by the Matra pushed by Beltoise, on foot. There was an awful crash that left the French driver unhurt by a miracle but the generous Italian driver lost his life. Siffert-Bell won the race before Rodriguez and with his new mate Oliver who turned out as hothead as the Mexican. Behind them an old Porsche acquaintance: Rolf Stommelen at the wheel of the Alfa 33. At the wheel of Alfa also Emerson Fittibaldi had to run, but once demolished the Italian car in practice, the Brazilian "betrayed" willingly to run in the private 917 of Alex Soler Roig, with Carlo Reuteman co-driver, the new entry and local idol. On the next 24 hour of Daytona, Porsche 917s received a tubular reinforced arc behind the cockpit that made the chassis stiffer and offered more safety to drivers in case of accident. Besides, the tail was equipped with large side fins to give stability to the car. At Daytona there were also the 512Ms. It was particularly successful the car managed by the Suneco team of Roger Penske, driven by the talented driver Mark Donohue and David Hobbs, who made the pole position easily. The Americans tried immediately to pull ahead, but they only succeeded in outdistancing Siffert, while the 917 driven by Rodriguez - Oliver was stuck up like a stamp waiting for an opportunity. Their patience was awarded when the alternator of the bleu and yellow Ferrari started playing up, obliging Donohue to go to pits for a hasty repair. Thus the 917 driven by the Mexican and the English ran away, taking a good lead over Siffert-Bell, later on obliged to retirement because of the engine failure. Thus, the second position was inherited by the 512 driven by Bucknum-Adamowicz, who, however, found them very much outdistanced from the lead of the race. Behind a fierce duel was beginning for the third position between the 512 with Donohue and the 917 Martini with Efford, ended by a disastrous off track of the latter owing to a tyre that caught fire. Being fully conscious of the rival's accident, Donohue lifted his foot as a precaution to avoid being involved in the accident. It wasn't like that for a Porsche 911 that crashed into the Ferrari rear axle, obliging the Ferrari car to have another emergency pit stop in order to be repaired. Meanwhile the 917 driven by Rodriguez-Oliver had been keeping the lead for all night, when towards morning a downpour broke on the track. There was a forced stop for tyre changing, with the Mexican's car that started sending smoke from its left exhaust pipe. Once back to the track, the crew tried the difficult compromise to safeguard the car and the lead over the Ferrari driven by Bucknum, who was strongly coming back on the wet track. But it was the transmission to cause the Porsche to lose ground, because it forced the car to stop for a long time to have the gearbox repaired. When a furious Rodriguez set off again, Bucknum was by that time in the lead and the Mexican had to toil away for catching the Ferrari again and take it away the pace setter role. Meanwhile, also the other Ferrari driven by Donohue pushed itself forward and the final of that 24 Hour race was among the most drawn in the history of the famous American race. The 917 succeeded in crossing the finishing line in first position, but it nearly was overcome by the two Ferrari cars. At Sebring there was fear again of the small 3 litre cars, with Ferrari and Alfa competing for pole position. At the race start the following cars took immediately the lead: the Ferrari 512M with Donohue, the 917s with Siffert and Rodriguez, the Ferrari 312PB with Adretti and the 33/3 with Nanni Galli. After one hour, Mario "Piedone" Andretti moved behind Siffert threateningly, when the Swiss driver run out of petrol clamorously. Seppi took it philosophically and parked his racing car at the trackside; a commissary gave him a lift by moped to the pit box, where he recovered a can of petrol. Then, always by moped, he returned to his car that after refuelling began roaring again much more than before, allowing the Swiss driver to race again. The race directors were indifferent to the claims of the other teams and in particular to the ones of Roger Penske, thus allowing Siffert the "filling station attendant" to get out of trouble that could cost him a disqualification. Meanwhile, in the lead of the race there was an interesting small group: Andretti-Ickx in the lead, followed by Donohue-Hobbs and Rodriguez-Oliver, while behind them Elford-Larousse were coming like a shot at the wheel of the other Martini 917. And it was just that car to be favoured by the events following the seventh hour of the race. Andretti left because of engine failure and Rodriguez, after making continuous contact with Donohue to gain the lead, causing both of them to go in search of a panel beater in the pit box. Once these bad fellows disappeared, Elford and Larousse had to get out of the Alfas driven by Galli-Stommelen and De Adamich-Pescarolo that were slyly waiting for the course of events and now making a frantic attack. However, it was nothing to do with the 917 better performances. Also the new 4998 cc engine arrived at Brands Hatch: if to get 4907 cc they had acted on the stroke, this time they increased the bore up to 86.8 mm. Its power was about 630 hp at 8300 rpm with about 65 kg/m torque at 6400 rpm. At first the new unit was exclusively given to John Wyer's only team, to be later on given to other teams for the extra championship races at the end of season. Less substantial was the experiment of two big air scopes, one for main bearing, on the cars of Martini International team, which, in fact, had no future. The important innovations didn't prevent the Porsche drivers' rebellion: with about 600 hp under their bottoms, the 917 crews felt the risk of the small 3 litre cars' attacks. "The car staggers by taking certain bends and it is scarcely handling in braking" Elford complained. For the moment Regazzoni was gaining the pole at the wheel of the 312PB. At the race start the Porsche cars of the Gulf team prevailed in the rain. Then, when they were settling their dominium, frenzy burst out. Rodriguez on foot betrayed by the injection, Siffert stopped in the pits owing to a wheel jammed nut. The Swiss driver managed to be on track again, but only to find himself with a broken gearbox. Thus, the win was handed over to the Alfa 33/3 driven by De Adamich-Pescarolo, before the 312PB with Ickx-Regazzoni. In spring, as usual, first tests were run in view of the 24 Hours of Le Mans. The 917 entered with a very surprising new long-tail aerodynamics. The nose was now more profiled and front air-intakes had been united in a unique great opening, rectangular shaped and more squared one. The fully new rear bonnet was with a tapered and no more cut tail, a great wing profile supported by side-pods and rear wheels streamlined so as to improve aerodynamic penetration. Thanks to that version Jacky Oliver became the fastest man in the world at the wheel of a racing car, stopping chronometers at 3:13 seconds and recording 385 km/h top speed on Hunaudières. "Thanks to the aerodynamics of our cars it isn't necessary to make the 5 litre engine more powerful" Oliver explained. "On that speed the car has confirmed its exceptional stability and road-holding quality. Fancy that, immediately after the straight, I entirely took the half bend". But aerodynamics wasn't the only sector in which Porsche engineers concentrated their efforts, in private practice they also tested a new chassis made of magnesium even lighter than the one in use, but innovation wasn't immediately successful. At the 1000 km of Monza, Porsche proved itself a protagonist and not only owing to the events on track. But, unexpectedly, everybody was stunned by the confirmation that the German company had no longer interest in the championship of makes. It still remained to be defined where they would have concentrated their sports activity; even if it was rumoured that next destination should have been famous CanAm racing. The Brianza circuit seemed to be designed to highlight the power of the German 5 litre cars, having no problem to dominate with Rodriguez-Oliver on the top step of podium and Siffert-Bell at the second place. Same story at Spa where Siffert broke every possible speed record and made pole at the incredible average of 260 km/h. But in race he didn't managed to fight against the driver considered as the king of the Belgian track: Pedro Rodriguez, who gained the victory with a splendid performance. The Florio Targa, on the contrary, turned out a standstill. The 908s didn't keep up with Vaccarella-Hezemans at the wheel of the Alfa 33/3, by that time the nightmare of German cars. The patrol of Porsche's drivers made up on the 22 km Nürburgring, where the Martini 908 won driven by Elford-Larousse. This impudent Porsche "ride" could newly come to a halt at Le Mans, but very few people believed in it, judging by the forecasts widely favourable to the German car. Ferrari 512Ms had no longer been updated and the numerous 3 litres lined up on the field had no possibility to stand out on a fast track that rewarded pure power. The only chance was that the 917 cars shouldn't bear the heavy updating introduced for the classic French marathon. Out of the three "long-tail" chassis built by the factory (917LH), two of them were given to Gulf Wyer team for top crew Rodriguez-Oliver and Siffert-Bell, plus one to Martini Racing team for Larousse-Efford. To this last team was also given the 917/20, a prototype car envisaged for experimenting new solutions in view of the future Can-Am championship: brake disks with radial fins instead of the conventional holes, wider treads, short nose, closed tail and decidedly more rounded shapes which made Stuttgart engineers think of a "pink pig". The car destined to crew Kauhsen-Jost was pink painted and, in a witty way, on its surface some cuts of meat were outlined in a similar way to a butcher's carcass diagram of a pig. Then, both teams lined up, each of them, an example of the old K cars for Marko-Van Lennep (Martini) and Attwood-Muller (Wyer). Moreover, there were one 917 of Zitro and one of the Escuderia Nacional. Funny, the Porsche didn't risk using the 4998 cc engine, too new to risk it in such an exhausting race. The most reliable rivals of the cars were ten 512s lined up by private teams, none of them directly sponsored by the Ferrari Company. There has not been history from the race tests: the 917LH cars reached an appalling top speed along the straights of Hunaudières. Rodriguze gained the pole position in 3:13:9, before Larrousse and Siffert. The first Ferrari was the 512M of NART, given to tested match Donohue-Hobbs, fourth at the time of 3:18:5. At the race start, Rodriguez had to eat his words on the eve of the race: "We will make use of consistency as the basis of our performance. This is an endurance test and not a Grand Prix." In fact, he dashed like a cannonball and in a few laps he had already taken the lead over his direct rivals, Elford and Siffert. After four hours Porsche cars were practically running in a pack, scarcely troubled by Donohue, who struggled as a damned to drive after the 917s. From the fifth hour retired drivers had been starting to reduce the number of the pretenders to the win: Donohue and Hobbs' attempts ended by overheating the engine. Meantime, Larrousse and Vic Elford had also suffered the sad fate of retiring due to overheating problems. At three a.m., Oliver had to inform Rodriguez about a broken hub on their 917. Thus the Mexican and the English saw their leadership vanishing: Pedro was back onto the track after one hour repairing and thanks to his usual impetuosity he succeeded in recovering up to the sixth place, but at that point he found himself in an oil bath owing to a broken oil gallery. The race lead was inherited by the only surviving 917 LH driven by Siffert-Bell, who, however, in their turn had to say goodbye to their dreams of glory for the engine failure. To Helmut Marko and Gijs Van Lennep, in their old 917K of Martini Racing, was unexpectedly given the go-ahead to the win, also thanks to race behaviour wiser than the one of their rivals and mates of make. They achieved success before the other John Wyer's 917K, the one given to Richard Attwood and Herbert Muller. For two years in a row and in spite of being the top team of Porsche, John Wyer had seen, under his nose, taken away the win of the race that counted for one season. The Martini Racing had also won from the organization point of view, by devising a system of refilling based on special inclined tanks that it turned out to be the quickest gaining from 10 to 30 seconds over the other team, for each refill (tyre change and driver included). The race preparation was so detailed as to paint the winner car only in white and not in the usual metallized silver, to save 4-5 kg on the weight. In addition to the joy for the win there was the satisfaction for the record on distance, now set at 5335.313 km run at the average of 222.304 km/h. At the fourth and fifth place the 512M cars driven by Posey-Adamowicz and Craft-Weir, arrived with a gap of 31 and 42 laps from the first ones: practically an abyss. In the after race analysis, Porsche revealed that the trouble suffered by the 917 LH cars was probably due to their excessive speed, that through the generated vibrations caused the mechanical parts crisis. At the 1000 km of Zeltweg, Rodriguez this time with his mate Richard Attwood monopolized qualifications and race. But fate was waiting for Pedro: a few days after his bright performance, he went to Nümberg to drive a Ferrari 512M given to him by a friend. The courageous Mexican, who was hardly able to control his Latin and passionate nature, the driver who had his own way to run generously, the man who didn't spare himself and often neither the cars given to him, fell on the stage of a minor race and in the car that had been his rival for two seasons. The last race valid for the 1971 championship of makes was the 6 Hour Watkins Glen, where the 917s driven by Siffert-Van Lennep and Bell-Attwood had to be content with the line up on the finishing line behind the 3 litre Alfa of De Adamich-Peterson. In a certain sense it was the baton passed from the formula 5 litres that had given two intense seasons with dream cars to the one that should have been the queen class starting from the subsequent season. However, the magic abbreviation 917 wasn't destined to disappear. In spring as already announced at Monza, Porsche would have emigrated to Can-Am and the new car would have been named 917/10K. The reasons due to such a radical breach with the world championship of makes were in the free regulations offered by overseas countries. Less rule restrictions also meant much freedom and creativity in search of the solutions to the problems that every racing car might meet. Solutions that could have been later on adopted in the mass production, last aim of the sports activity for a factory like Porsche. There were also less philosophic explanations to that retirement: the new regulation based on the three litre engines would oblige Porsche to redesign the 908 engine to get the needed power to defeat Ferrari, Matra and Alfa Romeo. The 908 proved to be still excellent at Nürburgring and Targa Florio, but those races were the exception to a panorama of circuits that often favoured full speeds. The problem was that with the design restraints of the air-cooling, they couldn't pass to the four-valve timing for cylinder, because it was impossible to keep under control the temperature of cylinder heads and for space reasons. Without doubling the valves it was very difficult to get the power necessary to counterbalance the engines of Matra, Ferrari and Alfa that have been by now adopting that solution from time. The problem had been already highlighted with the 917 12 boxer, for many it had come to the limit of its development without the possibility of increasing its displacement. To join the Can-Am meant to remove these restraints and allow new ways: after the proposal of the 16-cylinder engine, almost immediately set aside because of size and weight, they opted for the innovative technology of the turbocharger. The 12-cylinder power jumped as if by magic to 1000 hp. Porsche researchers were, however, faced by the notorious turbo lag and the need to combine a light chassis with the obtained great power. The team Suneco of Roger Penske and his lead driver Mark Donohue gave a big hand to solve these problems. After the experience, everything considered, disappointing with Ferrari 512M, the American organization succeeded in gaining the Can-Am management of Porsche cars. Mark Donohue, besides being an excellent driver was also an engineer, moved to Stuttgart and worked together with Porsche engineers to enter the field with an extraordinary car. After all, the 917/10K turned out a "barchetta" completely different from the original 917, which it only kept the engine basis and some experience in common with, but it proved as effective as the 917 by winning the 1972 and 1973 Ca-Am championships, with 16 wins to its credit. Its real strengths were the great lightness of the chassis combined with the superpower which made immediately obsolete the high powered big block engines with rods and rocker arms, up there uncontested rulers over the series. People say that once a journalist asked Donohue whether he shouldn't be afraid of controlling that absurd mass of horse powers. The United States driver answered very simply: "To me there isn't power enough till the wheels aren't skidding at the straights end, when I'm up shifting." By the end of the 73's successful season Porsche left also Can-Am, that, above all, was going through a crisis and should have survived only another year; finally leaving the 917 to history as the one of the highest and perfect form in which the win had ever expressed itself in motor racing.

Stefano Costantino

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Introduction

1970: in the horse's year

The five litre's sunset

I welcome this opportunity to thank the Automobile Museum "Carlo Biscaretti" in Turin, for the usual kindness in putting at my disposal its archive and Marco Zanello who helped me patiently in reconstructing this fabulous story.