- The Porsche 917 was "acclaimed as the greatest
racing car of all time in an expert poll conducted by Motor Sport Magazine
in 1997"
The following is a summary from Porsche 917,
The Winning Formula by Peter Morgan. It is published by
Haynes
Publishing who also publish the Haynes Repair Manuals. I bought
my copy on-line at Classic Motorbooks
but it is also available at Amazon.com
and AutoFanatics.
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| This summary uncovers the principles which undergird the "greatest racing car of all time." |
| Environment | Growing up, Ferdinand Piech was very close to his grandfather, Professor Ferdinand Porsche Senior. He spent his summer vacations helping his uncle Ferry Porsche build the first 356s. |
| Character | Piech was an energetic born achiever who did not accept that there were limitations to anything in life. |
| Vision | When Piech assumed control of the development and test department in the summer of 1965, he immediately let everyone know that they were going to do something very special. |
| Complimentary
Leadership |
Helmut Bott headed the development group and his engineering and reason complimented Piech's inspiration. |
| Inner Core | Piech and Bott would sometimes meet all day in one of their offices discussing their direction before they came to the designers. |
| Organization | Piech built a small, highly talented team around him. He captured the enthusiasm and energy of the young engineers molding them into a highly efficient unit that had no regard for rigid departmental boundaries. |
| Experience | From 1965 to 1968 the team developed several racing cars including the 904, Carrera 6, 910, 907 and 908. The engine size grew from four to six to eight cylinders. |
| Internal
Competition |
Piech promoted internal competition within his department to spur greater performance and to ensure a maximum effort. |
| External
Competition |
In early 1969 when rumors were circulating that Porsche was developing a 12-cylinder car, Ferrari made fun of Porsche. When the rumors turned out to be true, the rivalry heightened and the 24 Hours of Le Mans developed into a big budget contest between the two greatest sports car manufacturers in the world. |
| From Rival to
Teammate |
After driving the Ferrari 512M coupe as the fierce rival to the 917, Mark Donohue came on board the Porsche Can-Am program. |
| Cross-
Functional |
Mark Donohue was a rare combination of a driver and engineer. This enabled him to interact with the Porsche engineers a hugely productive way. |
| Window of
Opportunity |
In 1968 The FIA governing body decided to open up the Sports Car class to allow cars of up to 5 liters and in 1969 the number of production cars required to qualify was reduced from 50 to 25. |
| Make a Case
for Resources |
Piech went to his uncle Ferry Porsche and made his plea for a large amount of money to build the full compliment of 25 5-liter "production" sports cars. |
| First Principles | The development of the Carrera 6 reflected Piech's triple doctrine of low weight, low drag and more power. In its press release, the 917 was linked to the 12-cylinder Auto Union and it was announced that the 917 was a car that Porsche designed completely from first principles. |
| Rapid
Development |
The 917 project was approved in July of 1968 and the first car was delivered to the Geneva Salon car show on March 12, 1969, an eight month design-build. For a few months the team went up to about seven designers, a small size which yielded spectacular results. As with any rapid development project, there was pressure on the engineers and yet it was a dream project. They worked a lot but never felt stressed. It was fun. |
| One-Pass Design
Philosophy |
With such a short development, the full parts inventory for the whole run of 25 cars, including the engines, was ordered off the drawing boards. It was a large risk because this was Porsche's first 12-cylinder engine and there were no prototypes. Orders were placed for several different designs of the same part at the same time. The designers combined the proven with the unproven. The proven designs gave an escape path if the more innovation designs failed. The philosophy worked - the new engine they calculated to make 525 bhp actually produced 540 bhp in the first test runs. |
| Normally
Aspirated 12 Cylinder |
The basic engine design:
|
| A Normally
Aspirated 16-cylinder Experiment |
An air cooled 16-cylinder was also developed after the design work on the 917 coupe was completed. It was a research experiment not intended for the Can-Am car, but it was considered later when they decided to do Can-Am. It was Piech's way of building team confidence and scaring Ferrari. A 7.2 liter version developed 850 bhp normally aspirated. It was put into to a modified 917PA (the original Can-Am car) which was lengthened 10.6 inches. However, the car's weight distribution and handling were completely upset and the power to weight ratio would give Porsche only marginal advantage over the ever-improving McLaren's. Mark Donohue drove it and said "the thing was a monster. You could hear one end (of the engine) start up before the other." Porsche opted to go with turbocharging the 12-cylinder because in the earliest test runs it had developed up to 1500 bhp. |
| Turbocharged
12 Cylinder |
The final version of the Can-Am car was the 917/30. It
was powered by a 5.4 liter 12-cylinder fitted with twin turbochargers and
cockpit adjustable boost. It normally produced 1100 bhp with 1.3
bar boost and up to 1500 bhp with 2.0 boost.
|
| Aerodynamic
Philosophy Advances |
Piech's aerodynamic doctrine of minimum drag for highest top speed was the highest priority on the 917. In development, they focussed on the most "flowing shapes" possible, minimizing body openings and exits and trying to avoid drag inducing add-on shapes. However, they were in a region of the performance envelope that they had never experienced before. Aerodynamics rather than mechanical grip was the dominant influence on the car. On lesser powered cars, the effects of poor aerodynamics are less prominent and could be "trimmed out." But the 917 had a proposed top speed of 236 mph and they were in a region where the problem was obvious. Their philosophy eventually changed to balance drag with downforce and they paid attention to the front/rear downforce distribution. |
| Initial
Low Drag and Instability |
With their interest in streamlining and extensive wind tunnel testing, the first 917 came out with a lower drag coefficient than the Porsche 908. From the first time out on the test track, they knew they had the fastest car in the world. But as expected, the 1969 917 Langheck was difficult to drive. Brian Redman drove one of the cars in practice and recalls that "it was incredibly unstable, using all the road at speed." |
| Aerodynamic
Development at the Test Track |
At the test track the old tail of the car was cut away and an entirely
new "high tail" was molded with aluminum sheet and
taped together. At that point the car began to behave. This
became the very successful 917K coupe.
The Can-Am car developed in a similar way. The original 917PA was quite "smooth" but eventually received trim tabs and spoilers. The next Can-Am version, the 917/10, was fitted with a large rear wing to increase downforce. Influenced by Mark Donohue and Roger Penski, the Porsche team finally accepted the idea that if you go though a corner 5 mph faster, you can carry most of that speed most of the way down the straight. In 1973, the 917/30 was their final Can-Am car. Wind tunnel testing shaped most the body. At the test track, however, Mark Donohue was "unimpressed by the top speed of the car" and challenged them to improvise one of their famous "Porsche Le Mans long-tails." A tail was built up using aluminum sheet, self-tapping screws and tape and the top speed rose from 206 mph to 231 mph. |
| Frame | The 917's were designed with a welded space frame. A 104 lb aluminum frame was in the 917K which had a total weight of 1760 lbs. A 93 lb magnesium alloy space frame was in the 917/30 which had a total weight of 1860 lbs. |
| Endurance
and Speed |
It has been said that, "To finish first, first you have to finish."
In endurance racing, durability has to be as important as sheer speed.
This was the message that Helmut Bott brought to the Porsche team which
had to be reinforced again and again. The factory backed Wyer Gulf
team was seduced by the speed of the 917 long-tail car but did not do any
long distance testing. In the 1971 Le Mans race, it dropped out due
to transmission and driveline overheating associated with the long-tail
section.
|
| Acceleration
and Top Speed |
917K Coupe
|
| Influence | The technology of the 917 was applied to the Porsche production cars. The 911's saw turbocharging, use of lightweight alloys (magnesium alloy crankcase from as early as 1969), cross drilled brakes and the characteristic "whale-tail" wing. Today, the source of Porsche reliability is the commitment to abuse their cars in racing to expose design weaknesses. |
| Personal
Achievement |
Piech rose to the top of the Volkswagen-Audi Group and, at the end of the 1990's, he was believed to be one of the wealthiest men in Europe. With his genius for doing the unexpected, Ferdinand Piech is considered among the century's greatest automobile engineers. |
Ferrari's
most advanced version of its endurance car was the 
