Porsche 911 2.7

The 911 Carrera RS

In 1973 Porsche wanted to enter the GT competition. For that purpose the 911 Carrera RS was designed as a racing-car. To homologate the car for the Group 4 GT class Porsche planned to sell 500 because rules required a minimum 500 be built. The price wasn't set too high to ensure they were sold. 

They needn't have woried however: the RS was a big hit. In total 1636 were ultimately produced. With that the RS was reclassified as a Group 3 series-production GT, for which it was required that at least 1000 were built. 
As a homologation-special the RS was much lightened (thin-gauge body steel for instance) and weighed less than 1000 kg's, about 150 kg's lighter than a stock 'S'. The first cars all had these thinner steels bodies, but because Porsche never expected the car to sell in such large numbers the supply wasn't sufficient, so that the last 300 cars had to be built using the normal-weight body parts. 

Ducktail

The chassis was upgraded with gas-pressurized Bilstein shocks, super-stiff sway bars, and aluminium wheels measuring an inch wider at the rear than a roadgoing 'S'.
Outside, RS 2.7s were unmistakable. Most were finished in white, and Zuffenhausen designers played up the return of a production based Carrera by putting an outsize version of the traditional name script (in blue, red, black or green) above the rocker panels. Rear fenders were further flared to suit the wider wheels (with centers in the same color as the carrera-script). But the most prominent feature of the RS was a prominent rear spoiler molded into the engine cover.
Aptly nicknamed "ducktail", it kept the rear firmly planted at speed by reducing lift from 145 to just 42 kg's. It also improved airflow through the engine-cover grille and moved the effective center of pressure about six inches rearward as another aid to stability.

The 911 RSR 3.0

In 1974 an even wilder 911 was built: the carrera RSR 3.0. This car was built for homologation as a 2.7 'evolution'. Only 109 were produced. The RSR 3.0 had 20 bhp more power, but weighed 180 kg more than the 2.7 because the thin-gauge body steel of the first RS's had run out, so that normal steel had to be used. The heavier 'whale-tail', a bulkier front spoiler with large rectangular air intake, and even wider wheels than the 2.7 ( 9 inch rear, 8 inch front ) also added extra weight. This extra weigth explains why the RSR 3.0 wasn't much quicker then the RS 2.7, but because of the wider tires it did have better roadholding than the 2.7.

Of all 109 RSR 3.0's 60 were finished as roadgoing RS models.

Besides the RSR 3.0 some more civilized models were offered in 1974: the base 911, a 911 'S' and the 911 Carrera. With the new Carrera, the 'S' became the middle model and equivalent to the former 'E' in trim and performance. The Carrera had the new 'black-look' as standard: window frames, wipers, doorhandles and on the Targa the rollbar, were black and the rings around the headlights were painted in the color of the body. The 'chrome-look' was however still available as an option. In 1977 all Targa's got the black-look as standard, while previously only the Carrera Targa's had featured this 'black-look'. 

Accordian-pleat rubber boots neatly filled the gaps between body and bumpers, which were overlaid in color-keyed plastic with black rubber inserts. The new bumpers were placed higher on the car and therefore the side-indicators had to move from the fender to the bumper. American cars had two units placed next to eachother, while European cars had only one unit at each corner of the bumper.

In the same year (1974) the 911 featured new seats with integreted headrests, and a full-width taillight lens bearing the Porsche name. 
In 1975 the H-series Carrera gained a deeper front spoiler and a (optional) IROC-style rear spoiler. The 911 'S' was visually unchanged, but the base 911 disappeared. The same year a special limited-edition Silver Anniversary 'S' appeared. Each wore diamond-silver metallic paint, custom interior trim of woven silver-and-black tweed, and a numbered dash plague with Ferry Porsche's signature. Only 1500 were built. 
In 1976 ( I-series) another limited-edition 911, the 'Signatur 911 S' was sold with black and beige interior, the Carrera 3-spoke steering wheel, and platina metallic paint and wheels in the same color.

Carrera 3.0

The 911 Turbo introduced in 1975 featured a new 3.0 litre engine with a turbo-charger. A year later (1976) the Carrera 3.0 was equiped with the same engine, but without the turbo, still delivering 200 bhp. Besides the more powerful engine the Carrera 3.0 also had wider wheels arches. The 1977 J-series was the last model to use 2.7 engine.

Wheels

In 1974 the 911 was for some markets equiped with steel wheels, while for other markets the car wore the new ATS (cookie-cutter) wheels. The Carrera had black Fuchs wheels.