Guide: Porsche 961
Background
For 1982, the FIA introduced new regulations for motor sport.
At the top of the tree was Group C, a category for out-and-out Prototypes with no minimum production requirement.
The next rung of the ladder was Group B which required a production run of 200 cars built in a twelve month period. Group B was conceived as the premier class for rallying and a junior category for sports cars.
Group A machinery was eligible for rallying and touring car racing. 5000 units were required for homologation.
In the spring of 1983, Porsche started work on a Group B car to complement their Group C 956. The original plan was for a mid-engined, four-wheel drive model with PDK dual-clutch transmission and twin turbocharged Flat 6 engine. However, this ambitious specification was quickly scaled back; the four-wheel drive and twin turbos were retained but a manual gearbox would be used and the car was developed from a standard rear-engined 911 monocoque.
The Porsche Gruppe B concept was unveiled in non-running form at the Frankfurt Motor Show in September 1983. Production was scheduled to get underway in early 1985 and Porsche planned to offer racing cars to customers as per their successful Group C programme.
Porsche’s four-wheel drive system was publicly trialled in the 911-based 953, three of which contested the 1984 Paris-Dakar Rally. That year, Rene Metge and Dominique Lemoyne took a famous debut win in the Rothmans-backed 953.
Porsche returned for the 1985 event with a trio of 959 prototypes running normally aspirated 911 Carrera engines. On this occasion, none of the cars finished: two crashed out and one suffered a mechanical failure.
During the course of 1985, it became apparent that Group B circuit racing was unlikely to take off and, owing to delays with the engine, Porsche were not going to have the 959 ready for production on time.
Despite these setbacks, development continued on a pair of very different 959-based motor sport variants.
First to arrive were the trio of fully fledged 959s for the 1986 Paris-Dakar on which Porsche had their best result yet; Metge / Lemoyne took the marque’s second win while Ickx / Brasseur were runners up. Kussmaul / Unger finished sixth.
Next to break cover was a unique circuit racer, the 961, which was effectively a 959 Evolution.
Group B rules stipulated that one batch of 20 Evolution variants was permitted every twelve months. It was these Evolution models that manufacturers typically used for competition.
Like the Paris-Dakar cars, the 961 would serve as a useful rolling laboratory, particularly with regard to four-wheel drive. It would also garner some publicity for the forthcoming release of what was going to be Porsche’s most expensive road car ever.
Chassis
The 961 was built on a standard 959 monocoque with chassis number WPOZZZ93ZFS010016.
For the production 959, Porsche had developed an electronic suspension system that enabled the driver to choose soft, medium or hard settings. This was discarded on the 961 in favour of a fully adjustable manual set-up that, in addition to having been lighter, was also expected to be more reliable.
Double wishbones, coil springs and dual Bilstein gas-filled dampers were fitted all round along with anti-roll bars at either end.
The brake system comprised cross-drilled and ventilated discs imported from the 962 along with the 959’s unique aluminium four-piston calipers.
The 961 was also equipped with the Westinghouse Wabco anti-lock brake system that was soon to appear on Hans Stuck’s works Supercup 962. Unlike the Bosch and Teves systems, the Wabco software did not send pulses back through the brake pedal.
Speedline wheels were shod with Dunlop Denloc tyres. The rims measured 17 x 10.25-inches at the front and 17 x 11-inches at the rear.
A 120-litre IMSA-spec. fuel tank was originally fitted but this was reduced to 100-litres for Le Mans as per the regulations.
Engine & Gearbox
In the engine bay was a Type 961/70 power unit instead of the 959/50 variant that would be used by production cars. It was another all-alloy DOHC Flat 6 with four valves per cylinder and retained the air-cooled block of the standard model together with air-to-water intercoolers for the heads.
Group B regulations limited engines to four-litres and applied a 1.4 equivalence for turbocharged motors. This meant any forced induction engine had to displace less than 2857cc.
Like the 959, capacity was kept at 2847cc thanks to a bore and stroke of 95mm and 67mm respectively.
Fuel-injection was courtesy of the latest Bosch Motronic.
Each cylinder bank was fitted with an uprated KKK turbo and big output gains were found by increasing the boost from 0.9 to 1.3 bar. The compression ratio was similarly raised: from 8.3:1 to 9.1:1.
As a result, peak power went from 450bhp at 6500rpm to 680bhp at 7800rpm. The torque rating was 484lb-ft at 5000rpm as opposed to 369lb-ft at 5000rpm.
For endurance races (anything over 1000km), the engine was de-tuned to 640bhp.
Although the Porsche Doppelkupplungsgetriebe (PDK) dual clutch transmission was used in a couple of 962s in 1986, the 961 retained a standard six-speed manual gearbox with electronically controlled multi-plate clutch that varied the torque split from front to rear.
The 959’s variable four-wheel drive system was retained but modified to feed more power to the rear wheels.
Bodywork
Cosmetically, the 961 resembled a 959 on steroids. Its extensively modified body was 120mm longer, 50mm wider and 20mm lower than the production model. It also featured a reworked undertray with massive rear venturi.
The standard body including the roof was replaced with new super lightweight composite panels in a mix of aluminium, fibreglass and Kevlar. The regular windows were deleted in favour of plastic or (in the case of the windscreen) thinner glass.
All four fenders were dramatically widened, deep side skirts were added and the new adjustable rear spoiler was much taller than before.
The front apron was reprofiled; the primary intake directed air to a radiator which then exited through vents on the front lid. Myriad cooling solutions were added all around the car and particularly at the rear where the bodywork now lifted up as a single panel.
Interior
Inside, every piece of superfluous trim was discarded.
A single bucket seat upholstered in fire-resistant fabric was installed together with a racing harness.
The basic dash shape was retained but the instrumentation and switchgear was extensively modified.
On the passenger side of the cockpit was an exposed fuseboard and fire extinguishing system.
Cockpit access was made more difficult by the presence of a built-in roll cage.
Weight / Performance
Porsche homologated the 961 as an IMSA GTX machine and, as such, chassis 10016 was built up to the class minimum of 1150kg.
Although Porsche’s PR department optimistically claimed a maximum speed of 248mph, the technical department anticipated something in the region of 212mph.
1986 Le Mans Test
The 961 first appeared on May 9th 1986 at the Le Mans Test day (the first time the event had taken place since 1974).
The Automobiles Club de l’Ouest laid on four hours of practice which was divided by a couple of sprint races to try and drum up spectator interest.
Porsche took 10016 to France for Rene Metge and Claude Ballot-Lena along with a solitary 962 for Bob Wollek, Jochen Mass and Al Holbert.
Metge took the wheel of the 961 for the first session but found its straightline speed slower than expected. The car also proved nervous through the turns as a result of the front / rear bias of the electronically controlled four-wheel drive system.
The torque split was eventually adjusted to 15% front / 85% rear and much time was spent blanking off the front radiator intake to gain a few extra miles per hour.
Metge eventually got the 961 up to 192.6mph which compared to 221mph for fastest car (a TWR Jaguar XJR-6).
Unfortunately, Ballot-Lena did not get to drive; during the first sprint race, a bolt in the clutch mechanism sheared while Metge was travelling down the Mulsanne Straight.
10016 was parked up for the rest of the day having posted tenth fastest time of the 17 runners.
1986 Le Mans 24 Hours
The 961 then became the first four-wheel drive car to race at the Le Mans 24 Hours which took place over the weekend of May 31st and June 1st.
French pairing Metge and Ballot-Lena were partnered together again; they qualified 26th and ran most of the event with a 20 / 80 torque split front-to-rear. Top speed had risen to 207mph thanks to a couple of minor aero tweaks.
Aside from a driveshaft failure on Saturday evening, 10016 climbed steadily through the field. It had broken into the top 20 by midnight and at 2am was lying 15th.
However, at 2:10am, the race was overshadowed by the death of Jo Gartner who was was driving a brand new Kremer 962.
Gartner was travelling through the right-hand sweeper that led onto the Mulsanne Straight when his car suffered a mechanical failure at around 160mph. The Porsche pitched into the barrier at a 45° angle, somersaulted down the road and caught fire.
It ended up on the opposing side of the track straddling the barrier with just the rear wheels and wing trackside. Poor Jo Gartner died of a broken neck on the initial impact.
100 metres of guardrail had to be replaced. The rest of the field toured eerily around for 2.5 hours while the repairs took place and the wreckage was removed.
Shortly after 5am, Metge and Ballot-Lena broke into the top ten.
They ultimately finished seventh overall in a year of total domination by Porsche.
The Rothmans 962 of Hans Stuck, Derek Bell and Al Holbert took outright victory. Nine of the top ten finishers were built in Stuttgart.
1986 Daytona 3 Hour Finale
By late 1986, Porsche still harboured an aspiration to sell customer 961s.
As the car would be eligible for the IMSA GTO class once 200 standard 959s had been completed (expected around October 1987), chassis 10016 was taken out to Florida to demonstrate its prowess at the 1986 IMSA season finale (a three hour race for Prototypes and GTO machinery at Daytona on October 26th).
On this occasion, the 961 was allocated to Gunther Steckkonig and Kees Nierop.
10016 was entered for the GT Prototype class (GTP); it qualified 29th out of 64 starters. However, the steep Daytona banking proved unsuitable for the 961’s tyres which were being loaded beyond their rating.
To try and solve the problem, Porsche switched from the Dunlops they had used in practice to Goodyears for the race.
It made little difference.
At high speeds the tyres would buckle on the banking; it was undetectable by the driver until the tyre suddenly blew. After 10016 suffered two spectacular tyre failures, it was forced to run at a more conservative pace. Steckkonig and Nierop finished 24th overall (eleventh in the GTP class).
Victory went to the Group 44 Jaguar XJR-7 of Bob Tullius and Chip Robinson. Porsche 962s finished second through sixth.
Soon afterwards, Porsche abandoned their plans to sell customer replicas but the 961 was wheeled out twice more in 1987.
1987 Le Mans Test
Its first appearance of the year came at the Le Mans Test on May 17th.
Now resplendent in the colours of Rothmans cigarettes (to match the works 962s), Claude Haldi and Gunther Steckkonig posted 16th fastest time overall. They were the only IMSA class representative in attendance.
1987 Le Manss 24 Hours
Four weeks later, Haldi and Metge were back at la Sarthe for the 24 hour race which took place over the weekend of June 13th and 14th. They were joined by Kees Nierop who had driven the 961 at Daytona back in October.
Nierop was added to the driver roster after the works 962 he was scheduled to drive was damaged beyond repair by team-mate Price Cobb in practice.
For 1987, the 961 had competition in the IMSA class from a brace of works Mazda 757s that were effectively pure prototypes. The Mazdas qualified 27th and 28th while the Porsche lined up 31st.
By the end of the first hour, 10016 had risen to 22nd and with three hours gone, it was up to twelfth.
For the first couple of hours of Sunday morning, the 961 lay tenth before it dropped back a couple of positions until dawn broke.
Shortly after 9am on Sunday, 10016 was eleventh with Kees Nierop at the wheel when the car’s race came to a spectacular end.
The Canadian was approaching Indianapolis at around 180mph when he inadvertently dropped from sixth to second gear instead of fourth. The 961’s rear wheels locked up which span the car around and it glanced the barrier at both ends.
Nierop tried to get the 961 back to the pits, however, its bodywork was flapping around and some of the flailing body came into contact with the red hot turbo which caused 10016 to ignite. This was unbeknown to Nierop who was told to abandon over the radio.
After briefly having been engulfed in flame, 10016 was extinguished by the marshals.
The 1987 Le Mans still turned out well for Porsche. Driving a works 962 Hans Stuck, Derek Bell and Al Holbert went on to take their second successive win.
10016 was subsequently sent back to the factory and restored in its 1987 Rothmans livery. Today the car is on display at the Porsche Museum in Stuttgart.
Text copyright: Supercar Nostalgia
Photo copyright: Porsche - https://www.porsche.com
