Forest Racer 1970 Porsche 911 2.3 S/T Replica

2019 Charles Russell and Drive-My EN/UK

Forest Racer 1970 Porsche 911 2.3 S/T Replica Driving an air-cooled Porsche built for racing is always special. We track down a unique 1970 911 S in Switzerland that was converted in period to S/T specification for FIA Group 4 racing…. Story: Wilhelm Lutjeharms Photography: Charles Russell.

Group 4 racer

The 911 S/T is one of those early 911s lesser known to most enthusiasts in period, but today immediately identifiable. This can partly be attributed to the fact that firstly, these were race cars (the parts were an option from the factory) and secondly, that they were never really called an “ST”. The “ST” moniker was the internal name given to the racing version of 24 factory-built cars based on the 911 S model in 1972.

Forest Racer 1970 Porsche 911 2.3 S/T Replica

Forest Racer 1970 Porsche 911 2.3 S/T Replica

These cars have now reached iconic status in the Porsche world, revered as collectible items. In period a few privateers upgraded their racing cars in Group 4 to the S/T specification after 1972. This car is one of those.

Converting a 911 S to Group 4 S/T specification involved modifications to the body, engine and cabin. Apparently only around two dozen of these lightweight shells were produced straight from the factory. However, as was often the case during this era, racing kits could also be supplied to customers should they want to convert their 911 S to S/T specification themselves. This decision to allow customers to convert their own cars meant that no two cars were likely the same, as not all parts were fitted to all cars. The result is that, for instance, some cars featured the wider arches and some the slimmer body. Tastes differ, but those wider arches seem more fit for purpose and do add some visual drama to a shape that we all adore so much!

Forest Racer 1970 Porsche 911 2.3 S/T Replica

Forest Racer 1970 Porsche 911 2.3 S/T Replica

At the business end, Porsche kept the 2.2-litre engine from the S for rallies (180hp at 6,500rpm), but for the S/T the engine was heavily modified. The cylinder bore was increased by 1mm to 85mm, resulting in a capacity of 2,247cc.

With a raised compression ratio of 10.3:1, the flat-six produced up to 240hp at a much higher 7,800rpm – a notable increase. To be able to reliably deliver this power a number of internal upgrades were done to the engine. This included a crankcase that was pressure die-cast in magnesium alloy, the cylinders had chrome-plated bores and the cylinder heads were made of aluminum alloy. Then, the forged-steel crankshaft ran in eight bearings. Lubrication of the engine was done by a drysumped system featuring a pinion mechanical oil pump.

This 1970 Porsche 911 S 2.2 (chassis number 9110300592) was first driven off the production line in January of that year. Its first owner was Andre Wicky of the Wicky Racing Team, based in Lausanne, Switzerland. Wicky himself was a Swiss racing driver who competed in motorsport for a number of decades. He was very active at Le Mans, his best result being an overall 17th place in 1971, at the wheel of a Porsche 908.

The updates to this car have totally transformed the way it performs…

Shortly after delivery, the car was sent to racer Jo Siffert who at the time had recently opened Jo Siffert Automobiles in Fribourg. Here it was ultimately converted to Group 4 S/T specification. The conversion meant an increase in engine size to 2.4-litres (cylinder bore was increased to 89mm) and featured twin plugs. The FIA technical historical passport reflects the certification of this piece of history being upgraded from an engine capacity of 2,193cc to 2,466cc.

Interestingly, the car’s records show that its second owner was a priest in Fribourg! Apparently, this priest was known for his passion for and love of fast cars. The priest sold the car after a small accident and found the lack of a heater in the car a little too spartan, considering those icy Swiss winters. Over the following years the car had many owners and during this time its original Tangerine colour was changed to Ivory. In the early-2000s this car was restored by respected Porsche racer and restorer Marc de Siebenthal in Lausanne, Switzerland.

Following the restoration (which included the body, interior, drivetrain and suspension) the car participated in numerous European rallies, ranging from Tour Auto and Ollon Villars to Tour d’Espagne and Modena Cento Ore Classic. In 2009 the car won a stage in the Gstaad Rallye in Switzerland, followed by a win at the Coupe des Alpes in 2011.

That all these participation documents and trophies form part of the car’s history folder makes this particular car all the more valuable. Subsequently the car was acquired at auction in 2012 after hefty bidding in a telephone bidding exercise by its current owner, a South African Porsche enthusiast and amateur racer. Before the auction, the car was part of the world famous Milou Porsche collection.

Parked in the forest only metres away from the roads on which we are about to unleash an 8,000rpm flat-six howl, this 911 looks like no other early air-cooled model I’ve driven. This is partly attributable to two quaint-looking additional front lamps (with the number plate attached to the boot lid just below it) and those flared wheel arches front and rear – the rears reminding me of the later RS models. However, those extended front arches especially draw your attention. The wider arches were thanks to racing rules and regulations at the time that allowed for wider wheels. They give the car a zesty, purposeful look and frame the tyres that will likely provide surprising levels of grip in the corners.

I walk to the rear and notice the engine lid features a wide mesh for cooling, while the lid itself is kept in place by two rubber latches (very similar to the ones that keep the front lid in situ). Release the rubber latches, lift the lid and the special 2.5-litre, flat-six engine presents itself, showing off all of its stickers and the finer details of its mechanical fuel injection system. If you are familiar only with road-going 911s, the engine’s odd capacity takes a while to sink in.

Walk past those teardrop-like rear side windows (in this case made from Perspex,) to the driver’s door, and, as you open it, you are greeted by a very focused cabin, successfully blending basic road car architecture with just enough equipment for serious track or rally driving. The period correct Recaro bucket seats, four-point harness, Stilo headsets and roll-cage all vie for your attention while reminding you that this is no ordinary 911.

There is also a fire extinguisher mounted next to the open gate gearshift. The restoration during 2002 and 2003 provided all the correct period rally details, including the Halda trip meter, Halda speedometer, map light, and twin Heuer stopwatches.

Once seated in the comfortable and supportive (from your upper legs all the way up to your shoulders) bucket, it is the 10,000rpm rev counter that grabs my attention, providing a clue to this engine’s capabilities. The steering wheel is slightly thicker and smaller in diameter than other first generation 911 I’ve driven. That being said, it feels perfect in your hands. As with all period 911s, the steering wheel is very close to the dashboard, if you are used to more modern cars it might come as a surprise. However even at six-foot one-inch tall the driving position is good, even though my head is close to the horizontal bar of the roll cage.

Peering through the windscreen and readying myself for the drive ahead, the thick red line through the middle of the car and the view of the back of the spot lights never leave you in any doubt that you’re about to pilot something special. A quick final look around the cabin before we set off reveals the one nod to modernity: a luggage net which kept the owner and his wife’s travel paraphernalia in place during a European trip in 2017.

The 2.2-litre engine from the 911 S is already a free-revving unit that is willing to spin with enthusiasm around the clock. However, the updates to this car to take its motor out to 2.5-litres have totally transformed the way it performs. Not only is there already some poke from just past 2,000rpm, but suddenly the engine feels totally unstressed at 5,000rpm or even 6,000rpm. In a standard S model, you would be approaching the redline at this point but in this 911 you feel as if the engine is just getting into its stride, sounding and feeling like it has so much more to give. That is because there is comfortably another 2,000 to 3,000 of useful rpms before an upshift is required. If you have any mechanical sympathy for cars, you might wonder for a moment if the engine can handle it, but then you put your foot down to watch and experience how eager the needle runs past 6,000 then 7,000 and finally 8,000rpm! The sheer joy of the experience dispelling any mechanical fears. I press the clutch and change gear, and immediately the relentless acceleration continues.

There is a lightness and willingness from the engine to rev that can’t be replicated in today’s heavier, but much more powerful, engines. At these high revs the sound from the engine is not a high-pitch scream like that of modern units, but a rougher mechanical rumble, perhaps illustrating the more basic mechanical state of these engines. Once you’re used to the wonderful engine, you notice that the ride is firm – if any loose items in the car are not firmly secured they will move around. Yet this firmness is to be expected when considering this car’s raison d’être.

I soon realise that the clutch and 915 gearbox compliments a driver with quick foot work. A quick blip before a down change makes the process smoother (and faster). The shifter moves through the gears with ease; don’t try to rush the ‘box though.

Apart from the safety benefits of the roll cage, it contributes to the rigidity of the car, and further encourages you to tackle corners faster and faster trusting the car ever more. This car tips the scales at under a tonne supporting a very convincing ‘less is more’ argument, the car is light on its feet and that allows the engine to provide some proper accelerative force.

Up the mountain ahead there are several corners stitched together by a number of straights. Here I can experience first-hand the needle running excitingly to 8,000rpm a number of times. Stand on the brakes and the speed is quickly and confidently brushed off, accompanied by a solid and positive feel through the brake pedal, the minimal weight of the car adding to the feel. Although it is currently fitted with old rubber, the grip levels for a classic car here are high, while the relatively modest power is just enough to make exiting corners playful and fun. Throttle inputs have an immediate effect on the engine but there is not a moment that the car feels intimidating, or that you feel you can’t make the most of its performance – unlike some modern 911s…

Up front 205/60 tyres are fitted, at the rear slightly wider 225/60 – all on signature 15- inch Fuchs alloys with polished rims. I pull over and open the door by pulling the long leather strap – similar to the later RS specification 911s. I stand back and take a good look at the car. As with any classic 911 the cabin is compact, there is not an abundance of space around you. But, the car counters this by providing you with a feel so integrally part of the experience, especially once you are strapped in and have pulled the harness tight.

As there is no air-conditioning, we don’t have a choice but to drive with the windows open. This contributes to the experience as the aural delights from that special engine now fill the cabin – such a highlight when you pilot it through rural Swiss forests such as these. At the end of the day we travel back through a number of smaller villages, put some fuel in the car and head to our hotel, all the while quietly contemplating this wonderful machine. In my opinion the combination of a lightweight, air-cooled, 911 running a wider track together with a stiffer body and stronger engine, is a perfect mix. It encourages you to string a number of fast corners together to experience a truly thrilling classic Porsche at its best, and to learn the finer dynamic nuances of the car as quickly as possible.

Progress is, of course, necessary, but not always more entertaining, as this 911 S/T convincingly proves. For me the current owner best described this car: “It is simply the most delightful lightweight Porsche I have ever raced. If there is one that I will take with me into another life, this is it.”

You might wonder if the engine can handle it, but then you put your foot down…

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Additional Info
  • Year: 1970
  • Engine: Petrol Flat-6 2.3-litre
  • Power: 240bhp at 7800rpm
  • Torque: 187lb ft at 4900rpm
  • Speed: 160mph
  • 0-60mph: 5.5sec
  • Club:

    {module Porsche 911}