IMSA GTP and The Porsche 962
Another year, another championship for Porsche and driver Jacky Ickx who was solidifying himself as one of the all-time greatest sports car drivers in history. Our favourite international motorsports governing body FIA stepped up mid 1983 with significant new regulation changes, the most prominent of which was a reduction in fuel consumption from 60L/100km to 51L/100km. Porsche was straight to work to develop the 956B with a new fuel injection system. Fast-forward to March of 1984 when they retracted the fuel consumption rule – three months before Le Mans – and there was no question this was a direct insult to Porsche who has put in many man hours to prepare the car as per the new rule. This was blatantly malicious as opposed to their lazy ignorance of modern times, and Rothmans Porsche responded by boycotting the big race. This left the door open to customer 956’s and factory Lancia’s to vie for top spot. The race was won by 117 Joest Racing New Man 956 driven by Henri Pescarolo and Klaus Ludwig; neither of whom strangers to the winners circle at Le Mans.
Insult aside, Porsche had already been busy in the factory working to accommodate for another rule change, but for a different racing organization all together. The International Motor Sports Association (IMSA) created a new class denoted GTP. The class regulations followed those of FIA Group C with some slight modifications, namely an unlimited fuel ration, single turbo configurations, and stricter safety levels for the cockpit. Americans don’t often get the credit they deserve for doing their best to make a motor race a true entertainment event. Derek Bell seemed to agree, quoted as saying “race fans do not come to races to watch an economy run!” I’m no NASCAR fan, but ‘die hard’ Formula One fans seem to sit on a horse that’s a bit too high in my opinion. To compete, Porsche developed the 962, essentially a 956 with all the boxes checked for the IMSA GTP and the American market. They extended the wheelbase by 4.8 inches to bring the drivers feet behind the front axle line, and tuned the flat 6 with a single turbo set up for a sharper torque curve. American tracks were generally shorter and rougher than most European circuits as well, so the 962 was configured with a higher downforce aerodynamics package compared with its 962C version for Group C which debuted a year later.
Additional similarities between the two Porsche racers included the aluminum sheet tub. Keep in mind that the 956 was Porsches first attempt at an all-monocoque chassis design after decades of running spaceframce chassis. Monocoque chassis technology was not a new concept by any stretch – even Jaguar’s 1954 D Type was semi-monocoque – but Porsche stubbornly stuck with spaceframe all the way up to the 936. Updated FIA crash tests for Group C would never allow continuation of the space frame chassis, and it was far less flexible for more advanced aerodynamics. With only limited monocoque chassis experience in CanAm a decade prior, Porsche faced a steep learning curve. Porsche left the emerging honeycomb carbon materials technology that came from aerospace and was starting to find its way into Formula One to third party manufacturers. The engine was also elected not to be a stressed member of the chassis. Porsche engineers while adhering to the safety rules stipulated by IMSA, noted that only volume of crash structure was specified, and not content. They could have filled the spaces with soft cheese if they wanted, but elected for more practical components like radiators and a fuel cell.