Porsche 917

This page is an ovation to the
legendary racingcar Porsche 917.
It all started back in 1968, when CSI allowed
5-liters production cars to pick up the fight
against the 3-liter cars like Ford GT40 and Lola
T70. The companies had to build at least 25
examples of these 5-liter cars before they
could enter Le Mans. Ford had no intentions to
develop their GT40 and when Porsche found
the necessary capital, the 4,5-liter racingcars
was born.
Porsche 917 saw the first light of day at a
motorshow in Geneve March 1969 and Porsche
showed up with the 25 cars.

Actually the 917 was a development of the Porsche 908 3-liter and on paper it looked as the
917 would be miles ahead of the rest of the 3-liters racing cars.
In the beginning the engine in a Porsche 917 would have a capacity of 520 hp at 8000 rpm, but
it was the appearance thast stole the picture. 917 had a short nose, a narrow and long cockpit
and a long tail. In the back it had moveable flaps which was connected to the shock absorber.
This system did that the rear always was in a certain angle, so if the rear of the car lifted, the
flaps moved up to increase the downforce.
Because of the length of the races at this time which normally would be between 6 and 24
hours, it was very difficult for a new racingcar to obtain stability right away, so noone
expected that the 917 would achieve any succes in 1969. In the first couple of races it was
obvious that the 917 had problems with the raodhandling and the aerodynamics, even though
Porsche now had developed long and short tails.
But at Le Mans the opponents like Ferrari, Gulf-Mirage and Alfa Romeo would get a taste of
what to come the following years. The engine was now producing 580 hp at 8400 rpm and had
at topspeed at 236 mph down the Mulsanne straight. Porsche 917 lead the Le Mans race in 20
hours before it had to retire.
At the same race John Woolfe died in anotherPorsche 917 on the first lap, so all the problems
was not yet solved.
The development caried on and Porsche 917 won the Austrian 1000km race and even had a
open version build for the CanAm series which was driven by Jo Siffert.

In 1970 the development of the Porsche 917
was given to John Wyer's JW Automotive and
Porsche-Salzburg and both teams had full
support from the Porsche factory. JW
Automotive which was sponsored by Gulf, did
the biggest improvements of the 917 and one
of the most characteristic improvements was
the short tail which improved the stability and
the roadhandling. Futher more a gearbox with
only four gears was used - but not for the Le
mans race.
And if this wasn't enough, they now had
developed a 4,9 liter engine for the Monza
1000 km race and they now had 600 hp at
8400 rpm.

Porsche 917 had already won at Daytona and at Brands Hatch and a4,5 liter 917 had won at
Monza. And it became victories at Spa, Le Mans, Watkins Glen and Osterreichring as well.

Once again the rules were changed in 1971. Maybe to give others a chance for victory than
Porsche 917, so 1971 would be the last year for the 5-liter engines and in 1972 3-liter engines
would be the limit.
Porsche decided to concentrate on CanAm, but caried on to develope the 917 on a protype
basis. First step was to increase the engine to 4998 ccm, which raised the engines capacity to
630 hp.
Ferrari 512M was obviously faster than the Porsche 917 at the beginning of 1971, but the
durability was bad, so Ferrari choosed to develope a 3-liters racingcar for 1972.
This meant that Porsche 917 had an easy time at Buenos Aires, Daytona, Sebring, Monza, Spa,
Le Mans, Osterreichring and Watkins Glen. The biggest victory was perhaps the one at Spa,
where Pedro Rodriguez and Jack Oliver had a average speed at 154,7 mph. Jo Siffert which
drove together with Derek Bell, came 2nd and performed one lap at 3 min. 14 secs. - or 162
mph in average. And when Siffert and Rodriguez chased each other around the track in their
Gulf-Wyer Porsches all the time, the record might as well could have gone to Rodriguez.

Through 1971 diffirent chassis was tested and
Jack Oliver achieved 240 mph at Le Mans in a
Porsche 917LH.
One of the many Porsches was Big Bertha,
where it was tried to get the best from the
short and the long design. The car was
developed by the experimental department at
Porsche and SERA, a French consult firm and
they decided to paint the car pink and identify
the diffirent areas on the car as parts from a
pig.

In 1971 Porsche 917 went from an endurance racer to a CanAm race car with a magnesium
chassis frame to lower the weight. Then there were build 5-liter open race cars for the CanAm
serie in 1971. And the 5,4 liter engine was developed, but Porsche concentrated full hearted on
CanAm and did some smaller engines with turbo charger.
It was decided to used a double Eberspacher turbo charger on the engine and most of the
development was concentrated to reduce the time before the engine reacted on the turbo
charger. With a turbo charger the turbine had to have a certain speed before the engine would
react and this ws were Porsche did most of the development. A turbo charger 5-liter engine
could perform 900 hp. A new gearbox and aluminium breaks was also developed.
In a few races the Porsche 917 had revolutionized the CanAm serie and had shown enough
engine power to win despite lack of roadhandling and breaks compared with McLaren which
fought hard to keep up with its engine at 700-750 hp.
In 1973 the 917 had a new chassis and a 5,4-liter engine with more than 1000 hp. There was
six turbo charged Porsche 917s and the private McLaren was lucky if they were within 5 secs of
the Porsches laptimes.

So from 1970 to 1973 Porsche dominated
each class it raced in. The early versions
achieved their dominans by Porsche being
able to exploit the rules and build steady
racingcars or enough racingcars to make sure
that at least some would complete the races.
In CanAm Porsche was smart enough to
research the turbo charger without suffering
due to the problems. The development caried
on with an "instant power" button which
would give the driver more power, if the felt
that the opponents came too close.