Porsche 993 GT1 chassis #109 was one of just nine customer racing Porsche 911 GT1s built between 1996 and 1998. The 911 GT1 became the Grand Touring Meister when it triumphed in the 1998 Le Mans 24 Hours, but its route to success was not an easy one and at one point, the whole GT1 project looked in jeopardy.
How did the 911 GT1 come about
Porsche is accustomed to adapting its models and technology to suit various race or class regulations. Looking back through their history, they achieved this with the extremely successful 934 and 935 models, the 924 GTP, the 959/961, and in the mid-90s with the Dauer 962LM GT. But it was through an intimate knowledge of the model and its performance potential, that led in each case to the creation of a highly successful racing car through an astute application of the rules, all correct and above board.
Porsche engineer, Norbert Singer, is deservedly credited as the man behind the famous 935 ‘Moby Dick’ as well as the most successful prototype that ever raced, the 956/962 model. It should then come as no surprise, that when Singer spotted the Dauer 962 Le Mans GT at the 1993 Frankfurt Motor Show, that the cogs of creativity began to turn in his mind. At this time, Porsche only had the 911 Carrera RSR 3.8 as a contender in the GT racing class, but the Dauer 962 offered the possibility of an overall win at Le Mans. It is a matter of historical record that the LMGT1 class #36 Dauer 962 LM beat the Toyota LM prototype, the Japanese car being chased home by the #35 Dauer sister car, the second- and third-placed cars being just a lap down on the winner. Porsche therefore won the 1994 Le Mans 24 Hour race which gave the Stuttgart manufacturer its fifteenth victory in this classic French endurance race. But the focus of the FIA was shifting towards GT cars, and so Porsche needed to pull another race-winning rabbit out of the hat, if they hoped to add to that tally of wins.
“The Le Mans people didn’t really like the Dauer car, but it was to the letter of the regulations, and out of this we developed the GT1 car. The idea was to have it as close to the road car as possible, and so for the 1996 and 1997 season we took the steel body shell of the 911, cut it behind the driver seat and made a mid-engined car out of it,” Norbert Singer revealed.
It was clear to the Porsche engineers, with all the experience they had gathered over the years with the 911, that the rear engine gave them very good traction and some advantage on braking. On the downside though, it provided the engineers with problems, especially in cornering. However, with lessons learned, Singer and his team felt confident that should the regulations allow it, they could make a mid-engined car. Singer explains, “So we took the front part of the road car, the steel body, and made up a frame on the back of this, then we turned the engine and gearbox around and we had a mid-engined car.”
The Porsche Board required that the GT1 should resemble the 911, and so under the watchful eye of Singer and Horst Reitter, the concept based around a mid-engine layout using a standard 911 body shell of the day, began to take shape. Tony Hatter, a Scottish designer working in the Porsche design studios, was given the task in early July ’95 of penning the shape which had to meet all the necessary safety criteria for motor sport as well as road use. The car was to be 1100 mm high, 1960 mm wide and with a wheelbase of 2500 mm, and had to be instantly recognisable as a 911. Later that same month the Porsche Board gave its approval for the project to proceed, which it did at considerable speed, and by November the design and all dimensions were finalised. Two months later, in January ’96, the first chassis for the roadgoing car arrived, and this was followed by two racing chassis in March.
The GT1 was subjected to extensive testing throughout the first half of the ’96 season, with its first competitive race being the Le Mans 24-Hours that year. Porsche could not really have wished for a better debut for the GT1, as the two works cars came home first and second in the Le Mans GT-1 class, finishing second and third overall behind the TWR-Joest Porsche WSC95.
Our feature car, 993-GT1 chassis #109, was built in early 1997 and was sold new to Konrad Motorsport. It made eleven appearances during that season, the first three outings in May of that year being the Le Mans test weekend, and the Silverstone and Helsinki rounds of the FIA GT Championships in which it finished twelfth and seventh respectively. The car failed to finish in the 24 Hours of Le Mans due to an accident, and wearing its green/blue Giesse/Warsteiner livery, 109 recorded another DNF in the Spa round of the FIA series on 20 July. The regular drivers for Konrad Motorsport were the owner, Franz Konrad, and ex-Formula 1 pilot, Mauro Baldi.
The 1997 Porsche 911 GT1 Evo rolls out with a totally modified body as well as a new undercarriage under the front of the car. These measures result in improved downforce. The front axle is also new and features a wider track. Many details are improved with a view to becoming more service-friendly. On 7 March 1997, the GT1 Evo rolls out of the workshop and with Bob Wollek at the wheel laps Porsche’s own proving circuit in Weissach for the first time.
(Extract from official Porsche press release…)
The GT1 Evo version was introduced for the 1997 season, the engineers at Weissach having worked over the winter months of ‘96/97 on developing the GT1 still further. Improvements included a wider track with a reworked suspension, with the most distinguishable exterior feature being the new front end. Here the Evo model was fitted with a 996-look nose with the familiar teardrop headlamps which was a clear attempt by Porsche to link their endurance racer with their roadgoing models. The GT1 Evo also boasted another innovation, the 6-speed sequential gearbox actuation mechanism which had been developed by Porsche.
At the end of July, the chassis #109 returned to Porsche where it was converted to the new Evo spec whereupon it was sold to the French team, JB Racing. Now wearing the 996-nose, and finished in the Marlboro colours of their sponsors, 109 finished eleventh in the Suzuka 1000 km at the end of August. This was followed by a disappointing DNF in the Mugello 4-Hour, and a ninth place in the Sebring 3-Hour and a thirteenth place in the 3-hour race at Laguna Seca rounded off the 1997 season. JB Racing’s regular drivers included Mauro Baldi and the French driver, Emmanuel Collard.
Chassis #109 ended the ’97 season in America where it attracted the attention of Larbre Competition owner and founder, Jack Leconte, who subsequently purchased the car from JB Racing. Prior to the 1998 Le Mans race, a new lightweight clutch was fitted to the car at the Porsche factory, but this component unfortunately broke on its first lap during qualifying, and the team did not have sufficient time in which to repair the unit and for the drivers to post a qualifying time. As a result, 109 was not allowed to participate in the Le Mans race that year. The car raced in a number of other races that year, and amongst its drivers was the highly talented Frenchman, Bob Wollek, but at the end of the 1998 season, 109 was retired and stored by Larbre for a customer who did not compete with the car.
Engine and Gearbox
The GT1’s engine (Type M96/80) used a 911 six-cylinder aluminium crankcase with aluminium cylinder heads. The block and heads are all water-cooled as Porsche had been doing for many years with its racing machinery. The valve train consisted of four valves per cylinder, two inlet and two exhaust valves, which used rigid bucket tappets with valve play compensation. The 3.2-litre engine was fitted with two KKK K27.2 exhaust gas turbos with 35.7mm air restrictors (1996 models). Engine lubrication was by means of a dry sump. Fuel injection was of the Multipoint, sequential type with Lambda control, with single plug ignition. When the GT1 was introduced, it was fitted with the TAG 3.8 engine management system.
Mated to the engine was a bespoke Porsche racing gearbox (Type and number: G96/80-105). This was a 6-speed gearbox in a conventional H-pattern layout with a single-disc sinter metal racing clutch and a locking differential. Additional lubrication is by means of an oil pump with an oil-to-water heat exchanger.
Body and Chassis
The body was fabricated from carbon fibre by Zakspeed and was built up using a Type 993 front end structure, which ended at the car’s B-pillar. The cockpit section was reinforced with a roll cage, and a bulkhead stretching the full-width and height of the body was fixed behind the driver. To the bulkhead was attached the frame that carried the engine and gearbox, and the suspension mounting.
The body of the GT1 was extremely sleek and aerodynamic. The air inlet for the turbocharger was located on the roof which directed an airstream into the airbox sitting above the engine. Air passing over the car then flows over the adjustable rear wing, which on the early cars was reasonably small, the Evo model having a much bigger rear wing with side plates reaching almost down to the rear bodywork of the car. On the 1996 GT1, the bodywork around the front was quite smooth with a small chin spoiler, while the Evo model boasted a more aggressive chin spoiler with front dive planes. The Evo also let more air out of the back of the wheel well, and the shape of the rear bodywork had a more pronounced lip which the earlier car did not have.
Centrally located on the front bonnet is an air scoop which directs cool air into the cockpit. Low down on the car’s nose is a large radiator opening which feeds air to the centrally mounted flat radiator for engine cooling, the air from this exits through two large vents on the bonnet. On each side, but still within the radiator opening, are two ducts which channel cool air to the front hubs and brake callipers. A fairly substantial air scoop just behind the door, guides cool air down to the rear hubs and brake callipers. Located lower down on the rocker panel, and just ahead of the rear wheel, is a NACA duct which feeds air to cool the turbos.
Suspension, Wheels and Brakes
Because the track of the GT1 was both wider with wider wheels than the 911, the original McPherson struts would not have allowed sufficient space for adjustments to the suspension. As a result, the front suspension was replaced with a double wishbone setup. At the rear, the double wishbone suspension setup was attached to a sturdy collar or frame that sat between the engine and gearbox. As one technician put it, from this suspension mounting rearwards, it was ‘all prototype,’ and consisted of the suspension components including an adjustable anti-roll bar, and the racing gearbox. The suspension consisted of upper and lower A-arms with a pushrod actuated spring/damper setup, a completely new configuration that was not used on any other Porsche model at the time. Both front and rear dampers were each attached to their own reservoir to ensure that the pressure within each damper remained optimal.
The works GT1 cars were fitted with centre-lock BBS wheels, courtesy of a sponsorship deal the Porsche had with the wheel supplier. The three-piece BBS wheels were comparatively heavy on the factory cars, which led some of the privateer teams to opt for the lighter monoblock OZ Racing wheels.
Chassis #109 Rebuild
In 2005, the car was sold to a customer in the UK, its new owner having had plans to use it for tracks days but soon realised that it was a car for a professional racing driver. It was subsequently sold to its current owner, Mark Sumpter of Paragon Porsche in 2007. Unfortunately, the engine had picked up a misfire while in the hands of one its previous owners, and being an expert on Porsche sports and race cars, Sumpter bought the car with the aim of rebuilding it.
The task of 109’s rebuild began in the Paragon workshop, but having just closed down their own race team, the workshop staff were required for the maintenance and repair of customer cars, and so 109 was given to Paul Knapton of X-Tec to complete. At first it was just the engine that was going to be done, but Sumpter soon realised that this was a golden opportunity to restore the whole car. Sumpter explained, “I didn’t know the extent of the engine damage when I bought it, but just assumed the worst. I have been around enough racing cars to know that it wasn’t going to be an easy fix.”
Dismantling the engine revealed damage to the crankshaft which meant all the internal parts needed to be replaced in a race car of this stature. A new crankshaft was sourced from Porsche, along with Mahle pistons and liners, Mahle titanium con rods, chains, valves, valve springs, resulting in a comprehensive rebuild. “All components came with Porsche part numbers on, as many of the parts are derived from a 996,” Paul Knapton said.
The racing cams provide 385/1000 of an inch lift on both inlet and exhaust valves. Inlet valves are 37 mm in diameter while the exhaust valves are 32 mm, with both having a 6 mm stem diameter. Inlet cam timing is 105º ATDC with the exhaust cam timing is 107º ATDC. Following the engine rebuild, Paul Knapton puts the current output at 650 bhp at 7600 rpm.
The GT1 received a new wiring loom during the rebuild, and although the GT1 was fitted with a TAG engine management system, this was replaced with a MoTeC unit. “Updating the electronics wasn’t done so much as a performance issue, it was just to make it more user friendly. If anything, we have simplified it, because we can access the data logging a lot more easily so we can keep on top of any potential problems before they crop up,” Knapton added.
The body was given to Normandale Refinishing in Daventry, UK, a company with vast experience in carbon fibre body restoration. In taking the paint down to bare carbon fibre, they found evidence of the Marlboro livery, but Sumpter wanted the car to be finished in its PlayStation livery. “That is the way I remember the car. People talk about the PlayStation generation, and I just think it is quite an iconic car. The other thing is that with [Marlboro] cigarette advertising, in years to come it will possibly become harder and harder to run those cars. Although the Marlboro colours are cool, it is still cigarette advertising, and I just prefer the PlayStation livery,” Sumpter explained.
New brake callipers were sourced which were still available, but the carbon discs had to be fabricated. “We still have the original discs and they looked fine, but they were just old, and it is better to fit new ones than to risk using the almost 20-year-old carbon discs,” Sumpter added.
Driving and Maintenance
The GT1 starts with a traditional key, but 109 has not raced competitively since it has been in Mark Sumpter’s ownership, it has only done the odd track day and demonstration run. Even so, when preparing the car for an outing, it must still be checked over thoroughly, as Knapton explains, “Apart from the basic spanner checking, it has got carbon brakes on it so we keep an eye on the brake wear, but other than that, to be fair it’s a very reliable car. We do basic fluid changes in the engine, but other than that, I must admit that the car is very good.”
It has got the heat exchangers from the water to the engine and to the gearbox, so to warm it up might take ten minutes from cold. After starting it up, it will just be left to run at 1500 rpm for a minute or two, and as the temperature builds up, the revs will be increased to 2000 or 2500 rpm until all temperatures level out at around 75° to 80°. The team ensure that they use a good quality, fully synthetic oil in the engine and gearbox. For the engine, Millers 10/64 is used while 90/140 is used in the gearbox.
GT1 chassis 109 has proved extremely reliable, but as Knapton admits, “We had a breather pipe split from the oil tank and that’s about the only thing. It made a bit of a mess, but apart from that, we’ve had no mechanical issues with the car at all.”
One small modification was made to the car during the rebuild, and that was to fit a passenger seat. “I have got no plans to race the car at the moment and I don’t want to customise it, but we added the extra seat by moving the position of the battery. This was done subtly without affecting the car’s provenance, and it has been good to let other people have a ride in it,” Sumpter added.
Two years back Sumpter took the car down to Paul Ricard circuit, in the south of France. “It is a very open circuit and you can really push on a bit without risking anything. The car is very different from the 962, it has a lot less aero but that actually makes the car feel faster strangely, even though it has slightly less horsepower than the 962. With less aero and a 6-speed ‘box and bigger brakes, it is quite a busy car to drive. It is easy to drive, but there is a lot to do, and it is very exciting to drive because with all the power, you are forever changing gear, but it feels so much more modern than the 962.
“It is much more user-friendly, and with the seating position, you have a lot of space in the car. The gear stick feels like it goes straight into the top of the gearbox, they really have sorted out the linkage problems. It just clicks in and out, you couldn’t get a gear wrong, it is beautiful. We haven’t changed springs and dampers, it just feels like a typical factory built Porsche, it all works properly and it is very well-balanced,” Sumpter admits.
Only recently has the opportunity opened up in Europe for the 911 GT1-109 to compete on the race track once again. This car is now eligible to race in the Peter Auto Endurance Racing Legends and the Masters Endurance Legends series, two exciting race series that have been formed in recent years. The Porsche 911 GT1-109 can also be seen at the Chantilly Arts & Elegance Richard Mille to be held on Sunday 30 June 2019 – it would be a good idea to get yourself over to Northern France to visit this event in the summer.
Technical specifications (as at 28 April 1996)
|Engine||6-cylinder boxer (M96/80)|
|Bore x stroke||95 x 74.4 mm|
|Power output||ca. 600 bhp @ 7200 rpm|
|Torque||650 Nm @ 5500 rpm|
|Valves||4x valve per cylinder|
|Turbos||2x KKK K27.2 exhaust gas turbochargers|
|Restrictors||2x 35.7 mm|
|Intercoolers||2x charge-air intercoolers|
|Engine management||TAG 3.8|
|Fuel supply||Multipoint, sequential fuel injection with Lambda control|
|Clutch||Single-disc sinter metal racing clutch|
|Suspension||Front: double wishbones|
|Rear: double wishbones with pushrods|
|Shock absorbers||Adjustable front and rear|
|Anti-roll bar||Adjustable front and rear|
|Wheels||Front: 11.5 x 18” ET49|
|Rear: 13 x 18” ET66|
|Brakes||Carbon disc brakes front and rear, hydraulic servo unit|
|Discs||Front & rear: 380 x 37 mm|
|Callipers||Front: 8 pistons (fixed)|
|Rear: 4 pistons (fixed)|
|Dimensions||Weight: ca. 1000 kg|
|Length: 4683 mm|
|Width: 1946 mm|
|Height: 1173 mm|
|100-litre fuel tank with integrated catch tank|
Written by: Glen Smale
Images by: Virtual Motorpix/Glen Smale & Porsche Werkfoto