At the heart of the Porsche 911 Turbo was the three litre engine from the Carrera 3.0. It was an engine that in truth had reached the limits of its development. But it was given plenty more room to manoeuvre when Porsche fitted a turbocharger to it.

Porsche also had to make changes to the transmission, bodywork and suspension if the newfound unbridled power was to be tamed. At the front, the suspension received an anti-dive system, and at the rear, the linkage arms were reinforced with components from the Carrera RSR, a competition thoroughbred. To cope with the new tyre dimensions, the 911 Turbo received stiffer shock absorbers and a reinforced torsion bar at the rear.

Keeping the same external dimensions as the Type 915 gearbox, the 911 Turbo’s Type 930 transmission had only four ratios, but with hardened gears so that they would stay intact when transmitting power to the rear wheels. Interestingly, the gearbox in the 911 Turbo was Christened with the same designation as Porsche’s first turbocharged road car, the 930.

The mechanical tuning done on the Porsche allowed it to reach the dizzying top speed of 250 km/h. More astonishing was the fact that it took just 20 seconds for the 911 Turbo to reach 200 km/h. It was a performance that in 1974, crowned the car as the world’s fastest production road car.

By 1976, the first changes to the model were made by Porsche engineers. It included a new zinc-plating manufacturing process for the body, which extended the anti-corrosion warranty to six years. A year later, the fastest model in the Porsche catalog again underwent modifications, this time in much deeper detail than the 1976 facelift.

Aesthetically, the paint options increased, the wheels were redesigned and the interior trim level was also updated. New ventilation and anti-theft systems were now fitted as standard, and the vent control dials were illuminated to emphasize a redesigned centre console.

Mechanically, the 911 Turbo benefited from the addition of revised fuel pumps, an electric turbo pressure sensor and a safety switch. Pivotal to the car’s behaviour, the Type 930 gearbox was given new synchronisers, while on the front suspension, a 20 mm thick stabiliser bar replaced the previous three-piece unit. The brake system now also included a Type T52 vacuum servo as standard, and the clutch was equipped with an auxiliary spring to make its operation easier.

1977 would be the last year of service for the three liter engine, because, in 1978, Porsche introduced a 3.3 litre version of their boxer engine. This, equipped with a turbo-compressor had its compression ratio increased to 7: 1, and an intercooler was fitted to improve the charge density. The result of this engine upgrade was immediately obvious. Power had gone from 260hp to a whopping 300hp, and the 911 Turbo’s top speed crept up to an eye-watering 257 km/h.