Porsche 911 turbo racers: blown away

By Neil Winn

| 7 Jun 2024

Classic & Sports Car – Porsche 911 turbo racers: blown away

Racing improves the breed… Technology transfer… Win on Sunday, sell on Monday… While all of these phrases have gradually evolved into well-worn marketing clichés since they were first coined in the mid-20th century, their significance still holds a unique resonance when applied to Porsche.

No other automotive manufacturer has so consistently exemplified the advantages of maintaining a robust connection between its motorsport endeavours and the technological advancements in its road cars.

And nowhere is that enduring relationship more evident than in the evolution of the turbocharged 911.

The 1974 Porsche 911 Carrera RSR 2.1 turbo with its outrageous wing

To help tell that story, the Porsche Museum has rounded up three of its most significant turbocharged 911 racers, dropped them off at Goodwood, and generously lent us the keys.

It’s the stuff of dreams, but before trying to get my head around the fact that there is a combined 1880bhp waiting in the paddock, let’s dive into the origins of the very first turbocharged 911 racer: the Carrera RSR 2.1 turbo.

Ironically, its very existence can be traced back to a rule change designed to slow down endurance racers, rather than increase their performance.

The 1978 Porsche 911 935/78 was designed for the long straights of Le Mans

By the end of the 1971 season, the Commission Sportive Internationale (CSI) was faced with the not-inconsiderable problem of prototypes such as the Porsche 917 hitting 240mph down the Mulsanne Straight.

In an attempt to reduce these speeds, a 3-litre engine capacity limit was introduced, effectively banning the 917 from competition.

But anyone who thought the model’s career was finished was in for a surprise.

Undeterred, Porsche shifted its focus to North America, reimagining the 917 for Can-Am by embracing the dark art of turbocharging.

The 1998 Porsche 911 GT1 was the ultimate incarnation of the marque’s turbocharged racers

Its progress was astonishing, and by 1973 the 917/30 was producing 1135bhp from its turbocharged 5.4-litre flat-12, almost twice as much power as the original, naturally aspirated 4.5-litre 917 was making in 1969.

And while the wick could have been turned up even further, this simply wasn’t required because the 917/10 dominated the first two rounds of the championship and the 917/30 the remaining six.

Fearing back-to-back defeats for teams powered by big-block American V8s, this time it was the Can-Am organisers who outlawed the 917.

Herbert Müller navigates the Esses in his Porsche 911 Carrera RSR 2.1 turbo at Le Mans in 1974; car 22 took a remarkable second overall

All was not lost, however.

Turbocharging had proved its worth to the suits in Zuffenhausen, who immediately set about applying the lessons learned on the tracks of North America to improving the 911 on the road.

The first to arrive was a turbocharged 2.7-litre, narrow-bodied development mule gifted to Ferdinand Porsche’s daughter Louise Pïech in ’74, before the 930 was unveiled at that year’s Paris Salon.

The concept immediately piqued the interest of enthusiasts the world over, but, Porsche being Porsche, it was eager to validate the capability of a turbocharged 911 in competition ahead of the production car hitting the dealers in 1975.

The Porsche 911 Carrera RSR 2.1 turbo’s flat-six engine has a magnesium-alloy crankcase and sodium-filled valves

Enter stage right, the Carrera RSR 2.1 turbo.

Crafted to comply with the FIA’s Group 5 rules, the RSR turbo would be going head-to-head with bespoke sports-prototypes from the likes of Matra and Gulf-Mirage, yet Porsche Manager Ernst Fuhrmann was adamant that the racer had to be closely related to the much-anticipated production model.

Because, while the RSR turbo used a G-series 911 chassis as its foundation, like its naturally aspirated 3.0 RSR predecessor, almost every other element underwent a substantial change or modification.

‘The pièce de résistance was surely the 2142cc flat-six engine, with its massive KKK turbocharger slung out the back’

We’re talking light glassfibre panels, a centrally positioned fuel tank for improved weight distribution, a massively increased rear track and a sizeable ‘whale-tail’ rear spoiler to enhance high-speed stability (painted black to appear less imposing).

But the pièce de résistance was surely the 2142cc flat-six engine, with its massive KKK turbocharger slung out the back.

Although you might assume that displacement was arbitrary, Group 5 regulations mandated a maximum capacity of 3 litres.

Taking into account the equivalency factor of 1.4 for turbocharged cars, Porsche achieved a figure of just over 2.1 litres by reducing the bore diameter with Nikasil cylinder liners and shortening the stroke using the same crankshaft design as the 2-litre 911.

The Porsche 911 Carrera RSR 2.1 turbo’s wild bodykit includes swollen wheelarches to house fat racing rubber

Like the RSR 3.0, the RSR turbo’s engine boasted a magnesium-alloy crankcase, titanium conrods and sodium-filled valves.

The result was just over 490bhp in qualifying trim and a ‘safe’ 445bhp in race tune, allowing factory drivers Herbert Müller and Gijs van Lennep to clinch a phenomenal second overall at the 1974 Le Mans 24 Hours – not bad for the first-ever turbocharged car to compete at the French epic.

Its sister car, the one we’re driving today, clinched a podium at the Spa 1000km but had a less successful Le Mans campaign courtesy of a broken conrod – an experience we’re keen to avoid replicating.

This bewinged Porsche 911 racer showed the turbo’s potential

Sliding behind the steering wheel does little to quell the nerves.

Look to your right and, instead of a passenger seat, you’re met with the sight of the endurance-spec 120-litre fuel tank, while the aluminium rollcage is wrapped with braided hoses that lead to the boost gauges.

It’s an intimidating environment, but one that will feel oddly familiar to those who have driven a roadgoing G-series 911.

It even starts with a key – no buttons, no histrionics – and features a surprisingly light clutch and a pleasingly accurate five-speed gearbox.

The Porsche 911 Carrera RSR 2.1 turbo’s cabin is closely related to the road car

It all feels remarkably civilised until you attempt to accelerate out of the pits, at which point the 2.1-litre motor suffers a series of splutters and coughs before it roars into life past 4000rpm.

The Porsche mechanics warned that the engine has tremendous turbo lag, but this is on another level, with the only way to quell the ‘burr-sing-burr-sing’ soundtrack being a wide-open throttle and plenty of revs.

Getting a decent exit from Goodwood’s medium-speed Lavant corner demands some deft left-foot braking on entry.

This, in turn, enables you to get on the power much earlier than you would in a quick-witted non-turbo car.

‘The 2.1-litre motor suffers a series of splutters and coughs before it roars into life past 4000rpm’

And while the traction provided by the 17in-wide rear tyres is immense, the car doesn’t exactly feel stable, with the front end going light when the engine comes on song.

This sense of instability remains when you transition from the throttle to the brakes.

Porsche might have replaced older RSRs’ front torsion-bar system with MacPherson struts, titanium coil springs and Bilstein dampers, but the nose-dive remains quite severe and the long travel of the brake pedal makes it difficult to gauge exactly how much grip you have to play with.

The Porsche 911 Carrera RSR 2.1 turbo’s huge wing was painted black in an attempt to make it less pronounced

The only really confidence-inspiring part of the package is the wonderfully weighted steering, alive with information, which allows you to manage the car’s inherent understeer through the fast sweepers.

It’s hard to imagine having to wrestle this unproven package around some of the world’s most dangerous circuits, but that’s exactly what the likes of Helmuth Koinigg, Müller and van Lennep did, earning the 2.1 turbo third overall in the 1974 World Sportscar Championship, three points ahead of Alfa Romeo’s full-fat Tipo 33 prototype.

While the RSR turbo project was subsequently put on ice at the end of the 1974 season, Porsche implemented many of the lessons learnt with the 2.1 turbo in its forthcoming 935 silhouette racer.

The Porsche 911 935/78 started off with a low wing (above), but it was raised by Norbert Singer following testing in the Volkswagen wind tunnel

And it’s the ultimate iteration of that car which is the next monster on our hit list: the 1978 935/78.

Walking around this spectacular machine, it is hard to believe that just four years stand between it and the RSR.

Because while there are some similarities, such as the wide arches, the sloping lines of the front splitter and the extended wing supports, the 935/78 exudes the aura of a purpose-built prototype rather than a production-based racer.

And that’s because, in essence, that’s exactly what it was.

‘Unlike in the RSR, there is no sense of being strapped to a runaway train: the Porsche 911 935/78 feels more communicative the faster you go’

After two years of supplying customer teams with the dominant 935/76 and 935/77, for 1978 Porsche decided it would leave all national racing championships to the privateers and instead focus on international events with a car that took full advantage of a loophole in the recently re-drafted silhouette rulebook.

Specifically, a clause that defined production ‘body structure’ as the section between the front and rear bulkheads.

This allowed chief engineer Norbert Singer to use only the central structure from the 930 shell as a base for the new racer, with the front and rear sections made out of lightweight aluminium tubes.

When they were bolted (not welded – that would be illegal) to an aluminium rollcage, what you had was a complete spaceframe chassis.

The Porsche 911 935/78 is a silhouette racer

That construction was then hidden beneath a flowing expanse of white glassfibre bodywork that earned it the nickname ‘Moby Dick’ among the mechanics.

Perhaps the most significant change from the ‘regular’ 935 was in the tail.

Porsche’s engine maestro, Hans Mezger, enlarged the factory 935/77’s flat-six (by then featuring twin turbochargers) from 3 to 3.2 litres and introduced a water-cooled, twin-camshaft, four-valve cylinder head.

‘The expansive, Martini-liveried bodywork somehow manages to make “Moby Dick” look even more intimidating’

With a peak power output of nearly 850bhp in qualifying trim and a little over 750bhp in race tune, Moby Dick remains the most powerful 911 ever produced.

Is it any wonder that Porsche adopted the basic engine design for the 956?

As suggested by its slippery, streamlined bodywork, the car was primarily designed for the lengthy straights of Le Mans, but to get the 935/78 dialled in ahead of the iconic 24-hour event, the team entered the Silverstone Six Hours.

With Jacky Ickx and Jochen Mass at the helm, the car not only secured pole, fastest lap and overall victory, but also finished a scarcely believable seven laps ahead of the second-placed 935/77A at the flag.

The 230mph Porsche 911 935/78 feels surprisingly tractable

This momentum was then carried on to Le Mans, where in practice Moby Dick managed to outpace both the Renault-Alpine A442B prototype that ultimately won the race, and the two Porsche 936 prototypes that secured second and third places.

It was an achievement that would ultimately be the car’s highlight of the event, however, with massive fuel consumption and mechanical gremlins contributing to an eighth-place finish.

Yet on the Mulsanne it was timed at 227.5mph – 13mph quicker than the 936 prototype.

In person, the expansive, Martini-liveried bodywork somehow manages to make Moby Dick look even more intimidating than those mighty numbers suggest.

The Porsche 911 935/78’s stripped-out cockpit still has plenty in common with a G-series road car

Mercifully, once you’ve opened the correct door (unlike the RSR 2.1 turbo, it has its steering wheel on the right, placing the driver nearer the apex of the corners on most of Europe’s clockwise-running circuits), slid down into the felt-covered bucket seat and avoided putting your foot through the raised glassfibre floorpan (another of Singer’s innovations), the interior feels familiar.

Similar to the RSR turbo, the glasshouse is instantly recognisable; you grip a gorgeous, thin-rimmed wheel and there are five analogue dials in front of you, marked with old-school Dymo labels.

It’s only when you look left at the central boost knob, exposed gear linkage and floor-mounted anti-roll-bar adjuster that you remember you’re in something serious.

The Porsche 911 935/78’s innovative, rule-dodging tubular spaceframe wraps around its ridiculously potent flat-six engine

With only four gears and a top speed of nearly 230mph, the ratios are immensely tall.

Despite that, the 3.2-litre engine feels much more tractable than the 2.1-litre unit in the RSR.

Push the long-travel throttle to the floor and, once the boost gets on top of the ratio, a catapult-like thrust shoves you down the track and into the next braking zone.

Unlike in the RSR, however, there is no sense of being strapped to a runaway train, with the 935 feeling stable on the way into, through and out of high-speed corners.

Porsche mechanics gave the 935 its nickname, Moby Dick

This is a racer that feels better and more communicative the faster you go, with a chassis balance that is more reminiscent of a modern-day Radical than a 911-based production car.

It’s a completely transparent driving device, a machine that was more than 20 secs quicker around the Circuit de la Sarthe than the 2.1 – and one that encourages you to brake later and pick up the throttle earlier.

Without realising it, you’re soon trying to piece together a half-decent lap in a one-of-one museum piece, letting the car move around underneath you on the exit of Madgwick as you take full advantage of the 700bhp-plus pulsating through the rear axle.

It must have felt sensational at Le Mans.

Three Porsche 911 turbo racers on an empty Goodwood circuit

The 935/78’s otherworldly pace led customer teams to petition Porsche to retire the car at the end of the season, a request it duly respected.

But it makes you wonder. When the engineers pushed Moby Dick into storage, did they pause to contemplate where the development of the turbocharged 911 racer would end up?

Just four years had separated the RSR turbo and 935/78. What could the same team achieve in 20 years?

Fortunately for us, we don’t have to speculate because at the other end of the paddock awaits the ultimate iteration, the 1998 911 GT1.

Stéphane Ortelli powers the winning Porsche 911 GT1 through Virage Ford at Le Mans in 1998

Its existence came about through the revival of international sports-car racing in the mid-1990s via the BPR Global GT Series, which later morphed into the FIA GT Championship.

Having not secured a win in the top category since 1994 with the Dauer 962, team boss Herbert Ampferer recognised that Porsche needed to develop a radical GT1 competitor if it was to compete with the might of the Toyota and Mercedes-Benz factory teams.

After draft designs initiated in 1995 and subsequent early incarnations over the next couple of years, the 1998 911 GT1 adopted an entirely new strategy.

Not much of the Porsche 911 remains bar the name in the outrageous GT1

Employing a clean-sheet design, Porsche adeptly exploited the rulebook once again, engaging in an effective reverse-engineering process to homologate a road car derived from its racer, with only one unit required.

This innovative approach empowered the engineering team to pioneer Porsche’s inaugural carbonfibre monocoque chassis, introduce carbon-ceramic brake discs, and craft an aerodynamic carbonfibre body using computer-aided design.

At its centre sat a fully water-cooled (for the first time on a 911), 3.2-litre twin-turbocharged motor, based on the engine first seen in the 962.

Despite the enormous engineering effort put into the GT1, it was not the fastest car on the Le Mans grid in 1998.

‘Despite being 200bhp down on Moby Dick, the Porsche 911 GT1 feels even more animalistic as its wheels scrabble for traction’

Mercedes-Benz secured first and third positions in qualifying, with its CLK-LMs split by a Toyota GT-One.

Porsche, meanwhile, had to settle for fourth and fifth, with its GT1s almost three seconds off the fastest lap of the polesitting Benz.

To finish first, however, first you must finish, and over the course of the following 24 hours both CLK-LMs retired with water-pump failure and the GT-One with a broken gearbox.

This turn of events paved the way for the two Porsche entries to cross the finish line in graceful formation, securing a celebrated 1-2, a triumph that marked both Stuttgart’s 16th Le Mans victory and the GT1’s swansong.

The Porsche 911 GT1 has a fully water-cooled flat-six that foretold the forthcoming 996-generation road car

It never returned to compete at Le Mans after the discontinuation of the GT1 class.

Nevertheless, it had fulfilled its purpose, landing an outright win for a ‘production’ car in the same year customers were taking delivery of the first fully water-cooled roadgoing 911 model, the 996.

Not that the two cars shared a whole lot in common, mind.

When climbing into the GT1, you might just notice that it features 996 doorhandles, but as the panel swings up and forward to reveal the all-carbonfibre chassis, any notion that this is a road car immediately dissipates.

The Porsche 911 GT1’s snug, complex driver’s compartment feels a world away from the bare-bones 935

This is a full-on prototype racer with a cramped cockpit, poor vision and a sequential gearbox on the right that, when combined with the impossibly low roof, must have made quick pitstops for the three drivers a real challenge.

The cockpit is a curious mix of old and new, with the bare Momo steering wheel at odds with the thoroughly modern carbonfibre sill.

During the belting-in process, this unusual juxtaposition serves as a handy reminder that this is not a modern Le Mans Hypercar (LMH) because, despite its futuristic exterior aesthetic, once you’re on the move there is no getting around the fact that this is an analogue racing machine that deserves your respect.

Despite being more than 200bhp down on Moby Dick, the GT1 somehow feels even more animalistic, its rear tyres scrabbling for traction with every flex of your right foot.

The Porsche 911 GT1 was a clean-sheet design from Stuttgart

And, while there’s a sequential transmission to help keep the peaky engine on the boil, it’s nothing like a modern ’box, requiring the use of the clutch on up and downshifts.

This is not a problem in theory, but the grabby brakes make it tricky to heel-and-toe; the sense of satisfaction when left foot and right hand successfully match revs to wheel speed is wonderful, but get it wrong and it locks the rear wheels faster than you can say achtung!

The rest of the package, though, is nothing short of astonishing.

The nose responds to the smallest steering input, you can feel real downforce being produced by the wings and underbody (the mid-engined layout allowed for a huge rear diffuser), and the punch in the kidneys from 4-6500rpm is utterly addictive.

Porsche’s wind-tunnel models show the evolution of the shape, from bewinged 911 to slippery prototype

It eggs you into taking advantage of its colossal limits, even if you know in your heart you’ll never reach them.

Across 50 years, the drivers and engineers at Porsche have developed some of the most thrilling, advanced turbocharged racers ever to grace the track, putting their reputations – and, in the case of the drivers, their lives – on the line in the name of creating faster, more accessible and more exciting road cars.

Today, with even the base 992 Carrera incorporating forced induction, it’s clear that the lessons learned in motorsport have profoundly and permanently reshaped the trajectory of the roadgoing 911.

Images: Mark Riccioni/Porsche

Thanks to: Jens Torner in the Porsche Museum Archives

Factfiles

1974 Porsche 911 Carrera RSR 2.1 turbo

Construction steel monocoque with glassfibre panels
Engine magnesium-crankcase, alloy-head, sohc-per-bank, air-cooled 2142cc flat-six, Kühnle, Kopp and Kausch turbocharger, Bosch mechanical fuel injection
Max power 493bhp @ 7600rpm
Max torque 413lb ft @ 5400rpm
Transmission five-speed manual, RWD
Suspension independent, at front by MacPherson struts rear semi-trailing arms, coil springs, telescopic dampers; anti-roll bar f/r
Steering rack and pinion
Brakes 11¾in (300mm) drilled and vented discs; finned calipers
Length 13ft 10¾in (4235mm)
Width 6ft 6¾in (2000mm)
Height 4ft 4in (1320mm)
Wheelbase 7ft 5½in (2271mm)
Weight 1825lb (828kg)
0-60mph 3.2 secs
Top speed 189mph

1978 Porsche 911 935/78

Construction steel monocoque with aluminium subframes, glassfibre floorpan and bodywork
Engine all-alloy, dohc-per bank, air-and-water-cooled 3211cc flat-six, twin Kühnle, Kopp and Kausch turbochargers, Bosch mechanical fuel injection
Max power 845bhp @ 8200rpm
Max torque 578lb ft @ 6600rpm
Transmission four-speed manual, RWD
Suspension independent, at front by MacPherson struts rear semi-trailing arms, coil springs, telescopic dampers; anti-roll bar f/r
Steering rack and pinion
Brakes 13in (330mm) drilled and vented discs, floating aluminium calipers
Length 16ft ½in (4890mm)
Width 6ft 6⅓in (1990mm)
Height 3ft 11¼in (1200mm)
Wheelbase 7ft 5¾in (2279mm)
Weight 2260lb (1025kg)
0-60mph 2.6 secs
Top speed 227.5mph

1998 Porsche 911 GT1

Construction carbonfibre composite monocoque tub, carbonfibre panels
Engine all-alloy, dohc-per-bank, water-cooled 3164cc flat-six, twin K27.2 Kühnle, Kopp and Kausch turbochargers, multi-point sequential fuel injection
Max power 542bhp @ 7200rpm
Max torque 465lb ft @ 5000rpm
Transmission six-speed sequential manual, RWD
Suspension independent, by double wishbones, pushrod-actuated transverse coil springs and Bilstein telescopic dampers, anti-roll bar f/r
Steering rack and pinion
Brakes 15in (380mm) carbon-ceramic discs, AP Racing monobloc calipers
Length 16ft 2in (4925mm)
Width 6ft 6⅓in (1990mm)
Height 3ft 8in (1140mm)
Wheelbase 8ft 8⅓in (2650mm)
Weight 2094lb (950kg)
0-60mph 2.6 secs
Top speed 193mph