BORN IN THE USA
The magnificent 962 sports prototype.
In the previous issue of Classic Porsche, we delved into the design and development of the 956 racer’s flat-six engine, tracing its origins from the 1972 911 Carrera RSR Turbo, through the 935 and 936 — and even a stillborn Indianapolis 500 motorsport machine — to the Group C monster’s extraordinary 1-2-3 finish at the 1982 24 Hours of Le Mans, a feat achieved during the model’s debut season. Porsche had intended to use the 956 for competition both in Europe’s FIA World Sportscar Championship and in the USA’S International Motor Sports Association (IMSA) GT series, pitching under GTP regulations, but the 956 would never compete in North America.
IMSA deemed the 956 unsuitable and unsafe for several reasons. The car’s fuel tank, for example, designed to hold a hundred litres, was twenty litres too small for GTP regulations, while the roll cage was manufactured from aluminium (as opposed to steel), which IMSA took issue with. These might sound like easily rectifiable problems, but as far as ‘red lines’ were concerned, one IMSA concern trumped them all: the fact a 956 driver’s legs were ahead of the front axle was deemed completely unacceptable and effectively ended any conversation regarding the 956 competing in Uncle Sam’s back yard.
North America has been a massively important market for Porsche ever since New York importer, Max Hoffman, sports car began fans in supplying the 1950s. 356s It was to Stateside inconceivable European the company would give up on competing at the highest level in such an important sales territory, especially when there was such a lucrative customer racing scene to tap into. Enter the 962. In short, Porsche took the 956’s proven chassis as the starting point, with its folded, bonded and riveted aluminium tub and rear spaceframe. For the 962, however, a steel roll cage was introduced and the wheelbase was extended by moving the front suspension assembly forward twelve centimetres, mounted to the new tub. The driver’s seating position was retained, ensuring the pedal box was behind the front axle centreline.
STREET TO CIRCUIT
In its original form, the 962 is identifiable by its short front overhang, a feature born as a consequence of the overall length of the newer prototype unchanged from the model it was based on. And yes, the 962 was powered by a flat-six boxer from the start, but it wasn’t the partially water-cooled 2.6-litre unit that had propelled the 956 to great success — IMSA GTP directives dictated the engine of competing cars had to be based on a powerplant used in a then current production car. By this stage, a huge amount of development work had taken place at Porsche on the advancement of purely
air-cooled, turbocharged flat-six race engines. Consequently, factory engineers dug into their experience with the 935 project and created a 2.9-litre (2,869cc) flat-six with the same 70.4mm bore deployed in the engine powering the 930 (911 Turbo) road car. IMSA was satisfied, but not with the suggestion of utilising twin turbochargers (a configuration Porsche used to such great effect elsewhere), which is why a single KKK turbocharger was utilised for the 962’s first year of competition in the USA. There, the 962’s engine initially developed 671bhp and 487lb-ft of torque. An air-to-air intercooler was located on each side of the car and the requisite oversized cooling fan was mounted horizontally atop the engine.
STRONG START
The the off, 962 taking was quick pole and from leading 1984 24 its Hours first of race Daytona) (the until retirement with transmission issues. That car, chassis number 962001, was to be the only works 962 built to GTP rules for the US market. Porsche then focused on racing the 962 as the 962C in Europe. It was effectively the same car, but built specifically to satisfy World Sportscar Championship rules. The 962’s introduction as a factory car in Europe occurred in 1985, Meanwhile, where in it North raced America, alongside customer its predecessor, teams took the 956. the lead on the 962’s development for the IMSA GTP series. In fact, many had taken the initiative before the 962 turned a wheel in Daytona. We need to take a step back a few years to understand the progression.
In 1975, Arnold Wagner, Dieter Inzenhofer and Alwin Springer, co-workers at a Californian Porsche dealership, established ANDIAL (taking letters from the starts of each of their first names), their new tuning and motorsport company dedicated to Porsche engine development. The trio built up considerable expertise in developing the 935’s engine and even won the 1983 24 Hours of Daytona with their own version, raced under Henn’s Swap Shop colours by Preston Henn, Bob Wollek, Claude Ballot-lena and Anthony Foyt Jr. A year earlier, March Engineering worked with ANDIAL on a 935-derived engine for its own IMSA GTP racer, the March 83G, an impressive single seater making use of a lone turbocharger and Kugelfischer mechanical fuel injection. Not only did ANDIAL’S engine power the 83G to take the aforementioned top honours at Daytona International Speedway in 1983, it powered the Kreepy Krauly 83G (83G-4, to be precise, a chassis formerly raced by Al Holbert’s team) to the same achievement in 1984, the very race that saw the debut of the 962 and featured the father-and-son duo of Mario and Michael Andretti at the controls of the works team’s ill-fated entry.
ANDIAL took the lead on further 962 engine development for the IMSA GTP class. The original 2.9litre unit was designed with fuel economy in mind, but this wasn’t a major consideration for the IMSA GTP series, which is why the company set about increasing
THE REV LIMIT WAS RAISED TO 7,500RPM, PARTIALLY MADE POSSIBLE BY THE FITMENT OF NEW TITANIUM RODS
the engine’s capacity in the search for more torque. Bore was increased by two millimetres (taking it to 95mm), while stroke was lengthened to 74.4mm, resulting in 3,164cc displacement. This change necessitated reprogramming of the 962’s adopted Bosch Motronic engine control electronics and, after an IMSA rule change, twin spark plugs per cylinder were also incorporated, further improving combustion.
ALTERED AIRFLOW
Next up for alteration was the intercooler setup and its and associated pipework. From factory, the 962 initially incorporated a relatively compact intercooler on each side of the car, but this design resulted in a long pathway for compressed air to travel from the turbocharger (via the intercoolers) to the inlet ports. ANDIAL constructed a single large intercooler instead, mounting it horizontally above the bellhousing of the gearbox toward the rear of the engine. This revision dramatically cut the distance intake air travelled, to the benefit of throttle response and drivability, though the position of the new intercooler required changes to the exhaust and, more disruptively, the 962’s bodywork. This wasn’t as much of a big deal as it might sound, but it’s worth noting a considerable amount of the 962’s aerodynamic development was carried out by customer teams, which explains why there are so many derivatives of the car. Indeed, there were several unique chassis designs through the years, each intended to improve upon the original 962’s lack of rigidity. All variants were fitted with myriad official Porsche components.
Back at ANDIAL, the rev limit of the engine was raised to 7,500rpm, partially made possible by the fitment of new (lighter) titanium connecting rods. It was difficult to increase engine speed further because extra friction caused by higher operating speeds results in a requirement to remove significantly more heat, already a challenge for this larger capacity engine.
ANDIAL did, however, find an advantage over the stock Porsche engine by replacing the KKK turbocharger with an alternative manufactured by Garrett, a company which had worked closely with ANDIAL, resulting in the ability for 962 customer teams to alter turbocharger components to suit the nature of a given circuit, balancing throttle response and outright power as required. The host engine, labelled 962/71, raced in the IMSA GTP series from 1985 to 1987 and is quoted as making 720bhp at 7,300rpm, with up to 531lb-ft of torque. Anecdotal evidence suggests this same unit may have made as much as 800bhp in qualifying trim.
In Europe, the 962 adopted the 956’s 2.6-litre flat-six, complete with its water-cooled cylinder heads. For the 1987 season, the engine was upgraded to three litres (2,994cc) of displacement, with a 95mm bore and 70.4mm stroke. It’s worth reminding ourselves that the European car also used double overhead camshafts per head and four valves per cylinder, whereas IMSA GTP 962s made do with a single overhead camshaft on each bank and two valves per cylinder. The European 962’s engine also was allowed to run a duo of turbochargers. Official performance data for this unit is scant, but it’s widely accepted the engine produced at least 780bhp at 8,200rpm thanks to a freer-breathing cylinder head and combustion chamber design. This incarnation of the 962’s beating heart also debuted a much more advanced engine management system in the form of Bosch’s impressive Motronic 1.7.
Even so, the FIA introduced lower octane fuel in 1987, which penalised turbocharged engines, in the process giving naturally aspirated rivals — such as the Jaguar XJR-8 with its seven-litre V12 — an advantage. Consequently, other than its welcome victory at Le Mans, season, the this 962 despite wasn’t the a winner prolific in number Europe of during examples the 1987 campaigned by various customer teams. Indeed, focus on fuel economy from there on — thanks to a reduction in the amount of fuel that could be used in a race — considerably altered endurance racing, where outright power was only of use in qualifying.
TALKING HEADS
Around the same time, IMSA stipulated a three-litre capacity limit for turbocharged engines, with the added penalty of air inlet restrictors. Even with a higher compression ratio and a raised rev limit, the 962’s powerplant struggled to top 700bhp, though when ANDIAL got its hands on the Bosch Motronic 1.7 system in 1989, the firm managed to improve performance markedly. IMSA also relaxed its rules on twin turbocharging and even on allowing watercooled cylinder heads, recognising the Porsche engine becoming less competitive against newer entrants. By
now, the 962 wasn’t as dominating as it was at the start of its career, but the model remained a huge commercial success for Porsche’s motorsport division: some ninetyone examples were made and, of those, less than twenty were factory cars.
The car pictured here was originally ordered by Brun Motorsport as chassis 962-107 to race under World Sportscar Championship rules in 1985. Powered by the original 2.65-litre flat-six, the car managed a thirdplace finish in its first outing (the 1985 1,000km of Mugello, ending the race behind the secondplace Kremer 962 and the winner, a Rothmansliveried 962 driven by Jochen Mass and Jacky Ickx) before crashing at Le Mans. A replacement chassis (962-117) was sourced and the car went on to deliver respectable performances in 1986. A new engine with electronic fuel injection was fitted halfway through the season, helping achieve victory at that year’s 1,000km of Spa ahead of the Jaguar XJR-6 driven by Jan Lammers and Derek Warwick. From 1986 until its 1989 retirement, this special 962 participated in no fewer than thirty-six races, coining two victories and a further twenty-three top-ten finishes. A testament to the original design and engineering of the 962 and its various engines is that the sportsprototype was still competing a decade after its inception, taking the fight to far more modern machinery. It may not have been reaching the dizzy heights of its early success, but it did manage one last fling with Le Mans. Dauer was a well-known name in motorsport and had campaigned 962s in Europe and North America. Recognising the model’s racing career was tailing off, Dauer Racing was established with the express purpose of producing a road-legal version of the 962. Launched as the Dauer 962 Le Mans, the car was remarkably close to the racer in its final form, using the same core chassis and even a 730bhp variant of the three-litre flat-six.
In 1993, the same year the Dauer 962 road car was revealed, the Automobile Club de l’ouest (ACO) changed regulations to allow production car-based GT racers to compete in the 24 Hours of Le Mans, though the organisation neglected to put in place a minimum production number for homologation purposes. Porsche immediately saw an opportunity to revitalise the 962’s
PORSCHE WORKED WITH THE JOEST RACING TEAM TO BRING TWO DAUER 962 LE MANS MACHINES TO SARTHE
fortunes in the shape of the Dauer 962 Le Mans. The campaigned car had to run relatively narrow tyres and was forced to carry engine air restrictors, but the latter weren’t as small as those stipulated for Group C.
Porsche worked with the Joest racing team to bring two Dauer 962 Le Mans machines to Sarthe in 1994. Entered into the GT1 category, these loophole-exploiting race cars benefited from bigger fuel tanks, Porsche rightly calculating that, usefully, fewer pit stops would be needed than teams fielding faster cars. Ultimately, the Dauer 962 Le Mans driven by Yannick Dalmas, Hurley Haywood and Mauro Baldi won the race outright, ahead of the Toyota 94C-V LMP1/C90 driven by Eddie Irvine, Mauro Martini and Jeff Krosnoff, and in front of the third-place Dauer 962 Le Mans piloted by Hans-joachim Stuck, Danny Sullivan and Thierry Boutsen. This eyepopping performance saw Dauer go on to build a total of thirteen 962 Le Mans street cars.
A short while later, working alongside IMSA to further align each organisation’s regulations, ACO changed its rulebook in readiness for the 1995 season. Le Mans GT1 cars could still be based on a one-off model, as per the Porsche team’s controversial Dauer entry but, even so, the writing had been on the wall for the 962’s viability as a race winner for some time — ACO’S extended changes effectively cancelled any further action for the model. Nevertheless, the 1994 All Japan Grand Touring Car Championship round at Fuji Speedway saw a more or less original-specification 962 take the model’s final victory, marking the end of an extraordinarily triumphant ten years of motorsport success and an ambitious programme of flat-six engine development.