Porsche 917/30 Can-Am

Premiere: June 6, 1973 Can-Am Mosport

1973 Can-Am winner

1975 world speed record on closed course


© Porsche

1973 racing engine: 5.4F12 twin-turbo without intercoolers 809 kW
1975 top speed engine: 5.0F12 twin-turbo with intercoolers 904 kW

The final evolution of the 917 was created after Ferdinand Piëch had left the Porsche company in 1972. Two complete 917/30 Can-Am cars with 2500 mm (98.4") wheelbase were made for Roger Penske Enterprises racing team. They were chassis 917/30-002 and 003. The 001 car was not a real 917/30 and was raced in Europe at the Interserie. The Can-Am 917/30 had a 5.4-litre flat 12-cylinder twin-turbo engine which produced so much power that nobody really knew how much. Mark Donohue has said: “It’s the only car I’ve ever driven that can spin the tires at 200 mph.” Comments are excessive.

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Drag coefficient CW and lift CAH dependency on the rear wing attack angle. The wing shape is NACA 63-412, but naturally reversed, to generate downforce (or negative lift as they spoke at the time).© Porsche
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The cut engine shows the crankshaft with 6 necks for 12 connecting rods. This type of flat engine is sometimes refferred to as a 180-degree V, but cannot be reffered to as a boxer. It is not a boxer engine where every connecting rod has its own crankshaft neck which makes the pistons in the left and right side of the engine "box" with each-other. © James Herne
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Kugelfischer high performance fuel injection system © James Herne
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Inlet manifold of a turbocharged 917 © James Herne
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Cylinder heads with inlet and exhaust valves© James Herne
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Camshaft drive was positioned in the middle of the engine to eliminate the possible problems caused by the torsional vibrations of the long shafts© James Herne
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Half of the block © James Herne
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Headers © James Herne
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Twin turbos© James Herne
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Transmission © James Herne

Driver Mark Donohue, who was also the advisor for the 917/30, drove both the chassis 002 and 003 in the 1973 Can-Am races. The cars had the same livery and wore the same racing number.

© Corel Photos
Mark Donohue in Porsche 917/30
Mark Donohue © Porsche
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1973 posters of the races that Donohue won with the 917/30© Porsche

The 917/30 was the most powerful racing sports car ever created and so unbeatable, it is known for having its share in killing the Canadian-American Challenge Cup's popularity. In 1973 Porsche won all the Can-Am races and 6 out of 8 with the 917/30. In October 1973 the oil crisis started resulting in fuel prices going up four times in half a year. Porsche had already created three more chassis for the 1974 season, but the cars were not completed as Porsche didn't participate in the new season. The 1974 Can-Am championship was terminated before the last race of the season.

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The car in the Porsche Museum in Stuttgart has received the SUNOCO, PORSCHE and AUDI logos with incorrect typefaces after overhaul© James Herne
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Note the shape of the headrest © James Herne
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© James Herne
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Porsche type 920 transmission © James Herne
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© James Herne
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© Margus Holland

1975: intercoolers and closed-course speed record

In 1975 the 917/30 was assigned its final task - to brake the closed-course world speed record. When Mark Donohue took the 5.4-litre 917/30 for a series of test drives on the oval at Daytona Beach in January, it became apparent that the engine was not stable enough for flat-out driving. Following discussions with Porsche technicians around engineer Helmut Flegl, the decision was taken to use the more reliable 5.0-litre engine. Despite the smaller engine capacity, thanks to charge-air intercoolers the power was bumped to 1230 hp. Porsche performed 120 second full-throttle test bench inspections before agreeing with Donohue that the company would pay for any material damage that might occur during the record attempt.

In addition to the engine and small aerodynamic modifications, the springs were replaced and the chassis was altered to ensure that the car pulled to the left when driving on the straights. This adjustment done to any oval-circuit racer makes the car more stable at the corners. The record braking car was sponsored by CAM2 motor oils and was painted red instead of earlier Sunoco-blue.

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Porsche 917/30 at Talladega in 1975
Note the different central part of the nose - the brake vents have been deleted for better aerodynamics © Porsche
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Porsche 917/30 at Talladega in 1975
© Porsche

On August 9, 1975, on the Talladega Superspeedway in Alabama Mark Donohue managed to lap the track in 43.3 seconds with average speed of 221 mph/356 km/h. During the attempt, the absolute maximum speed reached was 237 mph/382 km/h.

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Mark Donohue in Porsche 917/30 at Talladega in 1975
© Porsche

It should be mentioned here that in 1975 Donohue was doing his first full season in Formula 1 and died in Austria into head injuries (in addition to killing a marshal) 10 days after he had set the speed record at Talladega.

The top speed record car was later painted back to its dark blue and yellow Can-Am livery.

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2018 Rennsport Reunion VI, 1973 Porsche 917/30, intercoolers
917/30 was the first Porsche fitted with intercoolers. They cool down the air that comes from the red-hot turbochargers before entering the inlet manifolds. The cooler the air is, the more power the engine develops at the same boost level. © Porsche
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2018 Rennsport Reunion VI, 1973 Porsche 917/30, engine and fuel tanks
No scheduled pitstops in the Can-Am races meant all the fuel had to be carried onboard which meant enormous 200+ litre fuel tanks had to fitted on both sides of the 917/30 chassis© Porsche
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2018 Rennsport Reunion VI, 1973 Porsche 917/30, top view
© Porsche
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2018 Rennsport Reunion VI, 1973 Porsche 917/30
© Porsche
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2018 Rennsport Reunion VI, 1973 Porsche 917/30
© Porsche
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2018 Rennsport Reunion VI, 1973 Porsche 917/30, front grille
© Porsche
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2018 Rennsport Reunion VI, 1973 Porsche 917/30, front-end
© Porsche

Article © James Herne / Stuttcars.com


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