How the Porsche 917 Works

Development of the Porsche 917 racecar came about due to a rule change in motorsports. In 1968, the Federation Internationale de l'Automobile, the international racing governing body commonly known as the FIA, announced a new class of racing for sports cars with engines no greater than 5 liters and that weighed at least 1,760 pounds (798.3 kilograms). The decision was made to allow cars with smaller engines to race in the World Sports Car Championship and to attract new companies to the grid [source: Read].

In this new class of racing, only 25 examples of the car had to be built instead of 50, which lowered the cost of entry and production for other manufacturers. Development was headed by an engineer named Ferdinand Piëch, a member of the Porsche family and the chairman of the Volkswagen Group today.

But when FIA officials visited Porsche's factory to inspect the cars for the 1969 racing season, they found only six examples of the 917, although engineers said they had the parts to build the rest. The FIA said "no way," and mandated Porsche have all 25 cars completed in order to race.

So in just three weeks, Porsche rushed the remaining cars into construction, using secretaries and office workers to quickly assemble the cars in time. They succeeded in building all 25 of the cars, and they passed FIA inspection -- although some of them barely ran and later had to be reassembled and rebuilt by Porsche mechanics [source: Porsche].

Once it started racing, success was not immediate. The car only won one race its first season and was plagued with handling issues. It exhibited wheel spin at 200 miles per hour (321.9 kilometers per hour), and its instability on the track resulted in the death of a driver. Fortunately, John Wyer's Gulf Oil team discovered that adding aluminum sheets to the 917's rear end added some much-needed stability and downforce. Suddenly, the car -- now called the 917K -- became a monster on the racetrack [source: Lieberman].

Before we look at the Porsche 917's racing record, let's learn a little more about the car itself. In this next section, we'll learn about its engine, chassis and how it used novel techniques to keep its weight down.

The 917 was designed to race in a class of cars with smaller engines than the Ford GT40, which dominated the World Sports Car Championship for years with its massive V-8 engine. But don't let the word "smaller" fool you -- the 917's engine had a little less displacement, but it was nothing to fool around with.

The car packed a 4.5-liter, air-cooled flat-12-cylinder engine, similar in design to the flat-six or boxer engines used in the Porsche 911 sports car. The 917 engine initially had 520 horsepower, could do the zero to 60 miles per hour (96.6 kilometers per hour) dash in 2.5 seconds and had a top speed of close to 250 miles per hour (402.3 kilometers per hour) [source: Read].

The engine was capable of far more than that. When Porsche began using the 917 to compete in Can-Am racing, which carried far fewer regulations than other events, the engine was tuned and turbocharged to produce anywhere between 1,000 and 1,500 horsepower. Even today it ranks among the most powerful racecars ever to compete.

But an engine is nothing without a body to put it in, and fortunately, the 917 had an impressive one. It featured a lightweight aluminum frame that weighed just over 100 pounds (45.4 kilograms), and included a variety of weight saving measures like a gearshift knob made from balsa wood. The body itself was made of fiberglass [source: Lieberman].

In addition, the car featured interchangeable rear ends. Teams could choose between the "long tail" with low drag for races with lots of straight sections, or the "short tail" for races with curves when downforce is called for. Other iterations of the car included a combination long/short tail, and open-cockpit "Spyder" versions.

The 917 is also famous for coming in a variety of paint schemes, including the famous Gulf Oil colors, as well as a "Pink Pig" version and a psychedelic green-and-purple "Hippie Car" model raced by Martini Racing. Hey, it was the 1970s, after all [source: Porschebahn].

In the next section, we'll look at what made the Porsche 917 so memorable today -- its penchant for winning races.

Ferdinand Piëch's goal for the Porsche 917 left nothing to the imagination: he wanted it "to be the best. Everywhere" [source: Porsche]. However, while the car was unveiled in 1969, it would be a while before it would achieve greatness.

The car's handling was so sloppy in early races that many drivers refused to pilot it. Porsche asked two BMW drivers for a 1969 race on the Nürburgring, but they refused, saying the car was too dangerous. Later on, a driver named John Woolfe was killed in a 917 at the 24 Hours of Le Mans. The car ended up only winning a single race in 1969 [source: Lieberman].

The 1970 racing season proved to be a better year once the Wyer team ironed out the kinks in the 917's handling. The car went on to claim victories at Daytona, Brands Hatch, Monza, Spa, the Nürburgring, the Targa Florio, Watkins Glen and at the Österreichring in Austria. The season's high point came in June when the 917 won the long-desired overall win at the 24 Hours of Le Mans. The car won nine of 10 races that year to secure the World Championship of Makes trophy [source: Porsche].

Footage from the 1970 Le Mans race was used to create the Steve McQueen film "Le Mans," where the 917 featured prominently in the story. The Gulf Oil 917K was driven by McQueen's character Michael Delaney as he battles Ferrari's 512 racecars.

The following year was equally successful. The car defended its world trophy in 1971 by winning eight of 10 races and once again won the 24 Hours of Le Mans. This time, it set a record of 240 miles per hour (386.2 kilometers per hour) on the track's Mulsanne straight, a feat that has yet to be broken today.

The 917 became so dominant that the FIA once again changed their regulations, and the car was no longer eligible to compete. So Porsche brought it North America, where they entered it in the Sports Car Club of America's Canadian American Challenge Cup, better known as CanAm. This form of racing had far fewer regulations than the FIA races, so the car was able to compete with well over 1,000 horsepower. As could be expected, it dominated there as well [source: Porsche].

Only 65 examples of the Porsche 917 were ever built. Seven exist in the Porsche Museum in Stuttgart, Germany, while many others are in the hands of collectors all over the world. They tend to command high premiums at auctions due to their prestigious histories -- and still inspire awe over their power today.