Sunday, January 23, 2011

The Fly Porsche 917/10 Interserie 1974






The Fly Porsche 917/10K Interserie 1974

General specifications:
Country of origin - Germany
Chassis number - 917/10-007
Numbers built - N/A
Produced in 1972



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The Porsche 917/10K Interserie 1974 Driven By Herbert MuellerEngine
Configuration
912.51 180ยบ V 12
Location
Mid, longitudinally mounted
Construction
magnesium alloy block, aluminium alloy head
Displacement
4.494 liter / 274.2 cu in
Bore / Stroke
85.0 mm (3.3 in) / 66.0 mm (2.6 in)
Compression
6.5:1
Valvetrain
2 valves / cylinder, DOHC
Fuel feed
Bosch Fuel Injection
Aspiration
Twin Turbos



Drivetrain
Chassis/body - body on tubular frame
Suspension (fr/r) -  double wishbones, coil springs, shock absorbers, anti roll bar
Steering- rack-and-pinion
Brakes - ventilated discs, all-round
Gearbox - 4 speed Manual
Drive - Rear wheel drive

Dimensions
Weight - 767 kilo / 1690.9 lbs
Length / Width / H-3740 mm (147.2 in) / 2080 mm (81.9 in) / 1145 mm (45.1 in)
Wheelbase / Track -2316 mm (91.2 in)/1620 mm(63.8 in)/1584 mm (62.4 in)

Performance figures
Power - 1000 bhp / 746 KW @ 7800 rpm Torque - 931 Nm / 687 ft lbs @ 4600 rpm
BHP/Liter - 223 bhp / liter  Power to weight - 1.3 bhp / kg

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At the end of the 1971 season, the coupe bodied Porsche 917 was no longer eligible to race in the world championship, which saw the German manufacturer's focus shift to the Group 7 class. In open form the 917 had been campaigned in this virtually no limits class since 1969, but with little factory support. Two championships were open for the Group 7 cars; the European Interserie and more importantly the North American Can-Am Challenge. Big engines, low weight and a host of different looking vehicles had made Can-Am one of America's premier classes, attracting many spectators.


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Porsche was represented in Can-Am for a number of years by privateers who race 908s or decapitated 917s, until a purpose built Group 7 version of the 917 made its debut in 1971. Dubbed the 917/10, it was technically similar to the coupe 917, but featured a number of lighter components constructed from the latest exotic materials. A larger fuel tank was also fitted to enable the car to complete the 200 mile races without having to refuel. Completely new was the spyder bodywork, which was an adaptation of the contemporary Can-Am design.

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A few races into the 1971 season, the Porsche 917/10 made its debut in the McLaren dominated series. It was immediately obvious that the 5 litre flat 12 was not powerful to take on the might of the all-alloy Chevrolet V8s, but nonetheless valuable points were scored in the car's first season. Back in Germany two options to close the gap with the 800 bhp V8s were considered; a 16 cylinder version of the 917 or fitting Turbochargers to the existing engine. The second option was by far not as easy as it sounds today, but it was expected to offer the best performance so it was fully explored.

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In the preceding fifty years racing cars were either Naturally Aspirated or equipped with a Supercharger driven by the crank; exhaust driven Turbochargers was uncharted territory. Throttle lag was the biggest problem to overcome with Turbos. In order to operate ideally the turbines in the Turbo had to run at a specific speed, but that requires a minimum amount of engine revolutions. When the engine was running under that number, there was considerably less power, and when the Turbos did kick in it was not a gentle affair. Drivers of the Turbocharged 917s needed to have a very delicate right foot and stellar reflexes to cope with the sudden power increases.

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 In five litre form, the Turbocharged flat 12 was good for around 950 bhp; not for the faint of heart. In Mark Donohue and George Follmer Porsche found two drivers brave enough to take on the competition in their 917/10K. Donohue proved to be the faster of the two, but an accident early in the season left him out for most of the remaining races. This paved the way for George Follmer to finally challenge and beat the McLarens and secure the championship.

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 In Europe the 917/10Ks were campaigned in 4.5 litre form, but it was still enough to clinch a one-two in the championship.


Frame up in Porsche Museum, Germany
Although the McLarens were convincingly beaten in 1972, Porsche continued the development and constructed the most powerful racing car ever. Available only for Team Penske's driver Mark Donohue, the 917/30 was bigger in every aspect compared to the 1972 racer.

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The engine's displacement was increased to 5.4 litre, which saw the performance rise to at least 1100 bhp in race trim. A new longer and aerodynamically efficient body was fitted, which increased the top speed considerably. In the 1973 season there was no stopping the 'Turbo Panzer', and Mark Donohue won the championship.

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As a side effect of the Porsche dominance, Can-Am was quickly losing teams and spectators and halfway through the 1974 season the challenge was cancelled. Porsche had also withdrawn at the end of the 1973, but the 917/30 was given one final outing in 1975. Specifically prepared for a high speed run, Donohue lapped the Talladega race track at an average of 221 mph in the 917/30, setting a new world record. A fitting finale for the Porsche 917's magnificent career. Unfortunately it was also the finale of Donohue's career, who fatally crashed ten days later during Formula 1 qualifying in Austria.
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Article by Wouter Melissen
Courtesy of Ultimate Garage Pages



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1 comment:

  1. Enzo's Toy BoxJanuary 23, 2011 at 11:55 AM

    This car is available and is for sale - please email enzo.scuderia@gmail.com for further information.

    ReplyDelete

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