Story by Tim Suddard and Scott R. Lear
The purpose-built Porsche 917 was an amazing race car and a smashing success at tracks around the world. For the small Porsche factory, the 917 was also about as complex and financially draining as a lunar landing program.
A dramatic change was needed, one that would bring down costs while keeping the Porsche brand on the top of the podium; there was no confusion at Porsche about the fact that racing success was 24 karat marketing gold. Transforming a road car into a racer was the most logical step. It was decided that the Porsche 911 would be prepared for racing and homologated for FIA Group 4 Special Grand Touring competition.
In early 1972, having recently taken charge of Porsche, Ernst Fuhrmann pushed hard to get the racing 911 program underway. Development for the new project began in earnest just a few months later, in May of 1972. Several of the go-faster ideas that had been applied to the Porsche 911R prototypes back in 1967 gave the team a good starting point.
Many of the engineers’ ideas got the trial by fire on June 25, 1972. Swedish pro driver Björn Waldegård and Porsche experimental engineer and club racer Günter Steckkönig entered a Porsche 911 into the Österreichring 1000 kilometer race. Because it featured a host of modifications that were being considered for the new Porsche 911 race car, the car they drove had to be classed in the Group 5 prototype category.
Armed with wide wheels, a Teldix anti-lock braking system, a 2.7-liter engine and some trick aerodynamic modifications, the prototype finished 10th overall, second only to open-cockpit race cars. With real-world data from the race, Norbert Singer, the lead engineer for the project, had to decide which modifications would be enough to make the car competitive and, of those, which would have to be included on the production run of 500 street cars for legal Group 4 homologation.
Choice Cuts
As impressive as the list of modifications was, more shocking was the roster of items that were deleted from the car in the interests of keeping homologation mass at a minimum. When Porsche was done, weight was cut down to 1985 pounds, about 210 less than the next-lightest Porsche 911.
To achieve this, the body was constructed of 0.07mm sheet metal instead of the usual 1.00 or 1.25mm stock. Belgian-made Glaverbel laminated safety glass shaved pounds up high. Lightweight fiberglass was used for the rear deck, rear aprons and even the rear bumper uprights on the non-street cars. Simple rubber mats replaced the carpeting and sound deadening material, and there was no undercoating.
The rear seats were nixed, and the fronts were special thinly padded units. The clock and sun visors also got the ax. The inner door panels were bare as could be, sporting only a cord to release the latch and a plastic handle to pull the door closed. The glove box had no lid. The door sills had no trim. There was not even a hook on which to hang your coat.
To this stripped-out shell, Porsche added only speed. Bilstein dampers saved 7.7 pounds compared to the usual 911 pieces and provided more aggressive handling characteristics. An 18mm anti-roll bar replaced the normal 15mm front unit, and a 19mm bar was used in the rear.
An “Enten-Bürzel” (or, loosely translated, “duck tail”) spoiler had a dramatic effect on aerodynamic lift. Without the tail, a Porsche 911 generated 320 pounds of lift at 152 mph. The duck tail reduced lift to just 93 pounds, and it also reduced drag from a coefficient of .41 to .40. As an added bonus, the tail created a high-pressure zone over the rear intake grille, diverting more cooling air to the engine.
The front wheel width was kept at six inches, but the rears were widened to seven inches in order to increase stability and help put the power down. The fenders were bulged out to accommodate the new wider track, and Pirelli CN36 radials—185/70R15 fronts and 215/60R15 rears—gave the newest 911 a measured lateral g rating of .912, the highest of any production Porsche.
At the heart of it all—well, maybe the butt of it all, considering the layout—was the new Type 911/83 flat-six engine. Porsche had bored out the standard lump from 84mm to 90mm, bumping displacement up to 2687cc. The engine was cutting edge, featuring a Bosch mechanical injection system and Mahle’s Nikasil finishing process, which helped protect the bores of the aluminum cylinders.
Street Carreras received an 8.5:1 compression ratio, which allowed the use of regular fuel. Still, they produced an impressive 200 SAE net horsepower at 6300 rpm, 20 more than the Porsche 911S.
To indicate the pure breeding of this new car, Porsche gave it the Carrera moniker, which had most recently been used in 1966 on the stunning Type 906 Carrera 6. Street cars would be called the Carrera RS (RennSport), while pure track examples would go by Carrera RSR.
On Display
The Porsche 911 Carrera RS was set to debut at the Oct. 5 Paris Auto Salon, and Porsche executives crossed their fingers and desperately hoped they could sell the necessary 500 cars. The cost was kept to a reasonable $10,300, about $500 more than a Porsche 911S.
Because several of the company’s bean counters feared people would shy away from the Spartan nature of the car, Porsche made sure a buyer could specify an option package that included complete upholstery and interior trim, as well as functional steel rear bumpers and guards. Porsche also made sure that this package was dealer-installed, so as not to risk diluting their production numbers for homologation purposes. A car so equipped was called a Carrera RS Touring.
Porsche salesmen pushed hard to get commitments from their distributors prior to the Paris debut, and every Porsche executive who qualified for a company car was signed up for a Carrera RS whether they wanted it or not. Existing 911S owners were encouraged to upgrade to the new model.
The No. 59 Brumos Carrera RSR took an amazing overall win at Daytona in 1973. The street version came with a lightweight, bare-bones interior plus a highly tuned, 2.7-liter flat-six.
Porsche had already sold 51 cars when the Carrera hit the Auto Salon floor in France. To say it was a success is a laughable understatement—a week after the show’s end, the entire initial run of 500 Carreras had been snapped up. By April 9, 1973, a second run had successfully sold out, bringing the tally to 1000 cars. This allowed homologation into Group 3 Production Grand Touring, which the FIA granted to the car that July.
A third production run was given the go ahead, and by July a total of 1580 original Carrera RS and RSR Porsches had been built. The Carrera enjoyed lots of ink as a media darling and was a hit with racers and Porschephiles on both continents. Many cars found their way to race tracks, where they more often than not showed their odd duck tails to the competition.
Porsche went a bit further in 1974, with the Porsche Carrera RS 3.0. It cost twice what the 2.7-liter Carrera RS had, but it included Porsche 917 brakes, a revised rear spoiler and a 230 horsepower three-liter engine. Production of the RS 3.0 was capped at 109 units.
The 911 RS Today
When you first sit in a Porsche RS today, it quickly becomes apparent that this machine is all business. From the grippy bucket seats to the sideways tachometer, this car is here to do a job.
Will Sanchez brought a beautiful, original example to the test day we had arranged at California’s Streets of Willow track. The instant we turned the dash-mounted key in it, the noise was unmistakable. There is no other engine that sounds like a Porsche 911 flat six.
The 915 gearbox moved easily into first gear. The clutch take-up was sharp and we were off for a few laps around this moderate-speed track located in Southern California’s Antelope Valley, not too far from Edwards Air Force Base.
By Turn 2, a slow, sharp right-hander, we quickly began to understand why this car is so loved. Given the 911’s reputation for oversteer and the current market value and rarity of a genuine 1973 RS, we added power gently and were greeted with no drama, just smooth, knife-edge precision and efficiency.
The next turn is a sharp, downhill, off-camber left-hander that needs to be taken in second gear. We had already received the message: There was no further reason to be gentle, as this amazing 2000-pound weapon could and would handle everything we could dish out—and then some.
Like any early 911, the RS will remind you of where the engine is located, but this car was designed for the track—it belongs on the track—and it’s one hell of a lot of fun when in its element. The brakes inspire confidence, and the whole package just works. Even when facing a blind rise in fourth gear, the confidence is there.
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Comments
In the Army in Germany in the late '70s I was friends with a law student who owned a Viper Green RS. His enthusiasm for it resulted in my getting #0058, an M471 Lightweight in early '79, in addition to my first Porsche, a '71 T Targa (I was single at the time). Over the next 8 years I put 50K miles on it as it was my only car for a while. Many wonderful experiences.
A person from Maryland had one that he autocrossed....73 or 74...Didn't they also have plexiglass door windows that were held in the closed position with a strap??
drjoe356 said:
In the Army in Germany in the late '70s I was friends with a law student who owned a Viper Green RS. His enthusiasm for it resulted in my getting #0058, an M471 Lightweight in early '79, in addition to my first Porsche, a '71 T Targa (I was single at the time). Over the next 8 years I put 50K miles on it as it was my only car for a while. Many wonderful experiences.
Wow, very cool story–thanks for sharing. Any pics? :)
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