RS = rennsport

Here are 10 ways that Porsche’s race cars made road cars better

From the 550 Spyder to the Le Mans-winning 919 Hybrid and beyond.

Jonathan M. Gitlin – Oct 16, 2023 8:27 am | 43

The Porsche Museum brought plenty of its toys to Laguna Seca for Rennsport Reunion 7 in September 2023. Credit: Jonathan Gitlin

MONTEREY, Calif.—Few car brands have managed to stake out the kind of mindshare occupied by Porsche. Celebrating its 75th anniversary this year, the company just held its seventh Rennsport Reunion, a car show crossed with a race meet at the Laguna Seca racetrack in Northern California. It drew a crowd of more than 90,000 Porschephiles at the end of September.

From its start in the aftermath of World War II, Porsche has concentrated on using clever engineering to make cars for people who like to drive. Much of that clever engineering was first proven at the racetrack before making the jump to something a bit more road-legal. And almost all of it was on display at Rennsport Reunion, from early engines with twin spark plugs and early experiments with aerodynamics through turbocharging, hybrids, and now extremely high-performance EVs.

The early days

The first Porsche-designed racing cars predate the family firm and date back to 1934 and the fearsome Auto Union V16. But the first factory-built Porsche racing car took five years to follow the company’s first road car, which appeared in 1948. When Porsche started building 356s, customers started racing them in sprints, hill climbs, and long-distance races, complete with pleas to the factory to see if it couldn’t deliver a little more power, particularly from American owners.

Porsche-engined specials built by Walter Glöcker raced in Europe and the US in 1951 and 1952 with some success, but it wasn’t until 1953 that the first Porsche 550 took a race start, in this case at the Eifel Races at the Nürburgring that May. It won its first time out. A second car was ready for Le Mans that June—a coupe like the first—and the pair finished first and second in their class, for cars with engine capacities of 1.5 L or less.

A blue Porsche 550 Spyder — The Porsche 550 Spyder was the company’s first purpose-built race car. It’s best known for being the car that James Dean lost his life driving. Credit: Jonathan Gitlin

About that engine: It was located between the cockpit and the rear axle like that first 356 prototype, but unlike all the subsequent 356s—which were rear-, not mid-engined—this was preferable for weight distribution and handling.

The 356 used a modified Volkswagen air-cooled flat-four with pushrod valves, and these were also used in early 550s. But in 1953, Porsche commissioned a new engine for the 550, and designer Ernst Fuhrmann went a bit more radical. With a capacity almost exactly at 1.5 L (1.498 to be accurate), it had a larger bore and shorter stroke than the pushrod engine, or indeed most engines of the time. Ferrari also favored this oversquare approach, which took another 20 years or so to catch on with everyone else.

Instead of pushrod-operated valves, Fuhrmann opted for a complex arrangement of shaft-driven cams, two for each cylinder bank. And there were two spark plugs per cylinder, mounted in the sides of the combustion chamber rather than using a single one in the center. Aspects of this Type 547 engine would go on to inform future Porsche engines, although sometimes with some lag—Porsche didn’t introduce twin spark plugs in a road car engine until 1988.

The importance of aero

The racetrack was also a useful place to learn about aerodynamics. 1963’s Porsche 904 was the first to start applying those lessons. The car was designed to meet new 2.0 L sports car racing rules—it would be another few years before the company built race cars with engines large and powerful enough to go for overall wins at races like Le Mans.

Styled by “Butzi” Porsche, son of Ferry and grandson of Ferdinand, it needed to look good while slipping through the air—Porsche had to make 100 cars to homologate the design, although it ended up making 159 in total. Butzi kept the height of the car as low as possible to minimize its frontal area, and at first, the prototype’s front fenders were so tightly wrapped around the wheels that they weren’t able to turn enough. The focus was then on reducing drag, and the 904 had a drag coefficient of 0.33—not bad for a racing car, even for those of us now inured to EVs with Cds in the 0.2 range.

The 906 followed the 904, and one big change was the introduction of a 2.0 L six-cylinder engine. This car was even lower, at 38.6 inches (980 mm), and for its debut at the 1966 24 Hours of Le Mans, three of the four cars were fitted with long nose and tail extensions to make them more efficient through the air. The 906 longtail had a drag coefficient of 0.31 and could reach 174 mph (280 km/h) at Le Mans, but the faster it went, the more lift it generated—the very last thing you want in a race car.

That trait was amplified in the 917. It first raced in 1969, with decidedly evil handling and an early form of active aerodynamics—a flap above each rear wheel that would unload as the driver turned the wheel. The early 917 was a terrifying thing by all accounts, with at least one driver accidentally-on-purpose breaking the car early in the running in the name of self-preservation. But it was made famous by the Steve McQueen film Le Mans, which depicted (sort of) the 1970 running of the race.

For that year, the problem of lift generation at speed was mostly solved, thanks to some shadetree engineering by John Horsman, chief engineer of the Gulf Racing team. He noticed at a test that when the car returned to the pits, it was covered in dead gnats except for the rear deck of the car. Realizing that this indicated a problem with the airflow over the car, Horsman and a pair of mechanics used some sheet metal to create a new tail shape that generated downforce, pushing the rear wheels into the ground rather than lifting them off.

Porsche started paying more attention to the aerodynamics of its road cars around that time, too. In 1971, the company added a front spoiler to the 911 to try to prevent that car from generating lift at speed and followed it with the now-iconic Carrera RS 2.7, which featured an adorable ducktail at the rear. Then came whale tails and, by 1988, an active rear spoiler for the 911. Today, the 911 GT3 RS can generate 1,895 lbs (860 kg) of downforce at 285 km/h, with a low-downforce setting for lower speeds courtesy of active front and rear wing elements.

Forced induction

We’ll stick with the 917 for another big breakthrough. In addition to running at Le Mans and other races held to those rules, Porsche also wanted to build a car to compete in North America’s CanAm championship. The closest thing to a no-rules formula, CanAm was dominated by McLarens with increasingly enormous V8 engines capable of huge power outputs. Porsche built an open-top 917 to contest CanAm, but its naturally aspirated flat-12 was almost 200 hp (150 kW) down on the competition. Enter the turbocharged 917/10.

In fact, Porsche worked on two strategies, also creating a naturally aspirated, air-cooled flat-16 engine as well as a turbocharged flat-12. But the latter proved far less complicated and offered prodigious power levels. Although perhaps not especially reliable at first either, the 917/10 test car sometimes barely made it out of the pits before expiring.

The pair of turbochargers (one for each cylinder bank) didn’t make the car any easier to drive, either. A turbo works by using exhaust gas to spool up a turbine that forces more air into the cylinders, but it can’t do that until there’s sufficient exhaust gas pressure to make that happen—this is known as “turbo lag.” These days, it’s barely a problem, but for the 917/10, it meant planning ahead.

“The 917/10 was a brutal car because of its horsepower and braking capabilities, and it didn’t like high-speed corners. It was good on slow corners, but the fast ones—and Road Atlanta has some fast ones—it was like you had to walk it through the corner on a leash before you unloaded it. And you better be pointing it straight when you did,” said George Follmer, who won the 1972 CanAm championship with the 917/10.

“It wasn’t until the Mid-Ohio race where I really felt comfortable in the Porsche. Mid-Ohio was a difficult track to drive because of the turbo lag off slow corners. It took me a while to learn to tell myself it was OK to put the throttle down,” Follmer said. Controlling somewhere in the order of 900 hp (671 kW) with ’70s-era tires and safety can’t have been easy, but the following year, the 917/30 could generate 1,600 hp (1,193 kW) during qualifying, with the boost cranked up to 40 psi (2.76 bar).

The fuel crisis put an end to CanAm’s glory days at the end of the 1973 season, but in 1975, Mark Donohue set a new closed-course record of 221 mph at Talladega in Alabama. When Donohue came into the pits after his record laps, the back of the car was literally on fire.

Porsche’s first turbocharged road car went on sale in 1974, and today, almost every one of its internal combustion engine-powered cars features forced induction, with the exception of the 718 Cayman GT4 and 911 GT3 variants.

I’m sorry, I can’t pronounce that

I’m cheating slightly for this one because while there were quite a few Porsche 956s in attendance at Rennsport Reunion 7, technically, none of them were fitted with a Porsche Doppelkupplungsgetriebe, or Porsche double-clutch transmission. Now common across Porsche’s road car range—and used by many other automakers as well—this technology dates back to the 1960s, when it was brought to Porsche by a Hungarian engineer called Imre Szodfrit.

The name of the part gives the game away—the transmission features two clutches and two shafts, one with the even gears, the other with the odd gears. Only one clutch is engaged at a time, but a gear can be selected on the other shaft and rapidly engaged by closing one clutch and opening the other. PDK was originally envisioned as an automatic transmission for Porsche road cars, but nothing really happened with it until the early 1980s.

In 1983, Porsche started testing a PDK gearbox in one of its factory-run 956 race cars, racing it for the first time in 1984 in Imola, Italy. It was not an auspicious start; a clutch pack exploded on the car’s first practice lap, and over the race, the car managed to exceed that mileage and then expired on the second lap. PDK appeared on one 956 at some races in 1985, finishing fifth overall at Brands Hatch in the UK and leading a race in Malaysia before a half-shaft broke.

In 1986, the 956 was replaced by the 962, which, among other things, moved the driver’s feet back behind the front axle. The PDK box added an extra 88 lbs (40 kg) to the car’s weight, but the much faster speed of the gearshifts (compared to a human driver manually shifting) showed a speed advantage of up to 1.2 seconds a lap in testing at Paul Ricard in France. In April of that year, a PDK-equipped 962 won a race for the first time at Monza in Italy.

A Porsche 956 in Rothmans colors — Porsche’s 956 and then 962 dominated sportscar racing in the 1980s but also acted as a testbed for the company to try new technology. Credit: Jonathan Gitlin

Tellingly, Porsche never considered PDK mature enough to risk using it at Le Mans. And not all the drivers loved it. “At times during my time at Porsche, I’d get tweaked up about something, developing the PDK gearbox or ABS brakes,” Derek Bell told Motor Sport last year.

“I said I joined Porsche to be a racing driver, not a development driver,” he continued. “If you want me to develop something, I’ll spend six months at Paul Ricard, but I want to win the races. Professor [Helmuth] Bott never argued, and at least you knew you could say it to him. But his retort was always: “Herr Bell, we have to develop things because on a Monday morning after a race meeting, we have to tell the board what we have found. And every race has to be a development of something.” Every time I bitched and moaned, that’s what I got in my ear. And they were right; I respect that. Once you understand that, you can understand why Porsche went racing.”

It wasn’t until 2008 that Porsche felt PDK’s technology was mature enough to make the transition to the road, when it replaced the conventional torque converter “Tiptronic” transmissions that were the alternative to a manual gearbox in a 911. Now, roughly three-quarters of 718 and 911 buyers opt for PDK, although that drops to about half for more specialized models like the 718 GT4 and 911 GT3.

Porsche’s first supercar

The 1980s saw another superfast Porsche appear on the scene. The 956 and then 962 were designed to rules called Group C, which were for sports prototype race cars. Another set of regulations also published at the end of 1981 was called Group B. Instead of prototypes built in low volume, this category required a manufacturer to build 200 examples to qualify for entry into the World Rally Championship.

Group B gave rise to some odd-looking machinery, often with over-engined versions of more mundane models, like an MG Metro or Renault 5. Not Porsche, though; it wanted a supercar, with 400 hp (300 kW) for road cars and 450 hp (335 kW) for rally cars. PDK was ruled out for its then-state of complexity, and instead, the 959 would feature a six-speed manual transmission and four-wheel drive.

It took a little time to get the computer-controlled 4WD system working effectively. Rear-engined Porsches until then had gained a nasty reputation for oversteer thanks to all that mass behind the rear axle. But at first, the 4×4 drivetrain suffered from horrid understeer in tight corners. Wider front tires and a tweak to the front anti-roll bar dialed that out, and the result was much more stable handling than the rear-engined, rear-wheel drive 911.

While still being developed, the 4WD system was given an extreme test in 1984 when Porsche entered the Paris-Dakar rally with a 953—essentially a 911 with rally suspension and the 4WD drivetrain. It won easily.

Sadly for the 959, by the time it was ready for production in 1987, Group B was banned by the sport’s organizing body after the deaths of Henri Toivonen and his co-driver Sergio Cresto at a rally in Corsica. A version designed for the race track rather than rallying, called the 961, raced a few times in 1986 and 1987, finishing in seventh place at Le Mans in 1986.

Porsche built 282 examples of the 959, which suffered in its day from comparison with Ferrari’s F40. That car also featured exotic materials like kevlar composites and a very powerful turbocharged engine, but it didn’t bother with 4WD. And unlike the 959, it could actually break 200 mph (321 km/h); despite targeting the double-ton, the 959 could only reach 197 mph (317 km/h) in standard trim.

Porsche added 4WD as an option to the normal 911 in 1988 with the Carrera 4.

Water cools faster than air

A common characteristic shared by most of the Porsche engines mentioned above is the use of air cooling. But as rudimentary physics tells us, water is a much better conductor of heat than air, and water-cooled engines have been the norm for decades.

Porsche wasn’t allergic to water-cooling—the engines in the front-engined 924, 928, 944, and 968 all used water-cooling. But the venerable flat-six in the back of a 911 was resolutely air-cooled. Its first fully water-cooled flat-six engine showed up in 1986, mounted in the 962 race car, and the 959 featured water-cooled cylinder heads. Production 911s didn’t get radiators until the introduction of the 996-generation car in 1997.

But its engine took to the track a year earlier in the 911 GT1, a Le Mans racer built to new rules that were meant to encourage more production-based race cars. This featured the front half of a 993-generation 911, with a mid-mounted twin-turbo water-cooled flat-six. Porsche ran the GT1 for three seasons, introducing the 996’s styling on the 1997 car and then building an all-new car for 1998 that was essentially a prototype with styling cues from the 996. That car gave Porsche its 16th overall win at Le Mans.

21st-century vibes

There was no LMP2000 in attendance at Rennsport Reunion, and few even knew that car existed until relatively recently. It was designed for Le Mans with the expectation that it would race in 2000, and Porsche knew its flat-six engine was no longer suitable for the job. The factory decided on a 5.5 L naturally aspirated V10, having designed a 3.5 L V10 (that never raced) for Formula 1. But Porsche’s boss at the time was more concerned with keeping the lights on than going racing, and the LMP2000 was shelved in favor of developing the Cayenne SUV, which, as already mentioned, went on to save the company.

But the V10 didn’t die. Instead, it reappeared in the back of a stunning concept car at the 2000 Paris Motor Show called the Carrera GT. Four years later, Porsche’s second proper supercar (after the 959) went on sale, now with a 5.7 L version of the V10 engine. The car you see in these photos is not the production Carrera GT, although I did spot a couple in one of the parking lots. Nope, it’s the show car from Paris, fitted with the prototype 5.5L V10 and some marvelous details on the interior.

At the end of 2005, Porsche was ready to go prototype racing once more, and it built a new car called the RS Spyder to compete in the LMP2 class. The company chose IMSA’s American Le Mans Series to contest and contracted with Penske to run a pair of cars, renewing a relationship that brought so many victories in the CanAm years.

Under its bright yellow bodywork, the RS Spyder featured a 3.4 L natural aspirated, water-cooled 90° V8. Despite being an LMP2 car, the RS Spyder offered strong competition to Audi’s heavier, more powerful LMP1 cars. It won its class the first time out, and the following year, it dominated LMP2 and even took an overall win at Mid-Ohio that May. In 2007, the RS Spyder won eight times overall in the ALMS and took another three class victories. 2008 saw a revised V8 with direct injection, and, despite a weight increase, one of the cars won the grueling 12 hours of Sebring outright.

Add some electrons

The RS Spyder’s engine went on to another life. With the stroke increased to raise capacity from 3.4 L to 4.6 L, it was put to work in the 918 Spyder, which went on sale from 2013 to 2015. The 918 Spyder represented a new breed of performance car, evolving from the supercar to the hypercar. A hybrid system with a pair of electric motors driving the front wheels complemented the V8, which sent its power and torque to the rear via a seven-speed PDK transmission. (Another derivative of this V8, now fitted with twin turbochargers, returned to the racetrack this year in the Porsche 963.)

That hybrid system was also race-proven before it crossed over to the showroom. In 2010, Porsche unveiled what looked like a normal 911 GT3 R race car at the Geneva Motor Show. But the orange and white car wasn’t like any other 911 race car.

Open the passenger-side door of the 911 GT3 R Hybrid and you’ll notice a black carbon fiber box with some cables coming out of it. This is an electrical flywheel connected to a pair of 80 hp (60 kW) electric motors driving the front wheels. Under braking, the electric motors would harvest kinetic energy and store it in the flywheel, spinning at up to 40,000 rpm. When needed, the motors could draw power from the flywheel, deploying it in short bursts of up to 8 seconds. The superior efficiency of the hybrid system gave the car an advantage at the 2010 24 hours of Nürburgring, where it led for much of the race before breaking down with two hours left to run.

Flywheel hybrid systems haven’t really amounted to much; Audi adopted the tech and won Le Mans overall using it, but road car applications appear unlikely. But the front axle hybrid system in the 918 Spyder is a direct evolution of the GT3 R Hybrid.

The mighty 919 Hybrid showed up in 2014, a year after the 918 Spyder. It, too, was a hybrid, but it was a prototype race car powered by a turbocharged V4 engine and a hybrid system almost as complicated as the ones you’d find in an F1 car. Then again, the 919 program is believed to have cost Porsche an F1-level budget to design and campaign. But that investment returned results: Porsche won Le Mans with the 919 Hybrid three times in a row, from 2015 to 2017. Then it went on to break lap records with the 919 Evo.

Of most relevance to this article is the 919 Hybrid’s battery pack—it operated at 800 V, which taught Porsche lessons it went on to apply to its first battery-electric vehicle, the Taycan.

BEV race cars represent the next frontier for Porsche’s engineers. There aren’t really any suitable championships to enter yet, but the Mission R and 718 GT4 ePerformance are examples of how it’s exploring the concept, with a goal of developing an EV capable of racing for 30 minutes flat-out between charges. For these cars, Porsche has turned up the battery pack to 900 V, with a 603 hp (450 kW) race mode and a 1,088 hp (800 kW) qualifying mode.

The 718 GT4 ePerformance is in the midst of a development program as Porsche takes the car to different markets around the world to gather feedback. While that will be used to inform a customer racing EV, you can be sure anything Porsche learns there will probably appear on its road cars in time, too. And we’ve got a good idea of what one of those might look like—the 900 V powertrain also appeared in this year’s Mission X concept.

Listing image: Jonathan Gitlin

Jonathan M. Gitlin Automotive Editor

Jonathan is the Automotive Editor at Ars Technica. He has a BSc and PhD in Pharmacology. In 2014 he decided to indulge his lifelong passion for the car by leaving the National Human Genome Research Institute and launching Ars Technica's automotive coverage. He lives in Washington, DC.

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