The turbocharger turns 100 years old this week

First 911 with Turbocharger Technology

Maximum output of 260 horsepower, top speed of 250 km/h (155 mph) plus, acceleration to 100 km/h in 5.5 seconds – boasting supreme performance figures of this calibre, the first Porsche 911 Turbo made a proud appearance at the Paris Motor Show in 1974. This supersports developed its peak output at a low 5500 rpm, with torque peaking at 343 Newton-metres or 253 lb-ft at 4000 rpm. Back then this kind of torque achieved by Porsche was absolutely unheard of in a turbocharged power unit. Porsche's engineers were able to give the engine this relatively harmonious flow of power through the skilful use of a bypass valve. And to reduce the "turbo gap", Porsche's development engineers used a small turbocharger responding at an early point in time and reducing the lack of torque accordingly.

Entering the market in 1977, the successor to the original Turbo developed an even more significant 300 horsepower from 3.3 litres. The increase in output was achieved at the time by a brand-new feature, an intercooler seen for the first time on a production car. Cooling the hot turbocharger air to less than 100°C, the intercooler was able to reduce turbocharger pressure without the engine losing any of its power.

The eighties saw the turbo-charged era of motor racing which culminated in the most comprehensive domination of a Formula 1 season by any car before or since – the McLaren Honda Formula One team won 15 of 16 races, lead 1003 of the 1031 laps in the season, take 15 of the 16 pole positions and see the two MP4/4s finish one-two ten times from 16 starts. The Honda-powered McLaren MP4/4 dominated the 1988 season partially due to the extraordinary quinella of drivers, (the late Ayrton Senna and Alain Prost) but mainly due to its 800 horsepower 1.5 litre turbocharged engine.

Turbocharging was banned in 1989 and where other manufacturers stopped development of turbo engines when the ban and 1988 fuel consumption penalities were announced, Honda developed a miserly horsepower machine which trounced the competitors. Indeed, had it not been for a remarkable incident where Ayrton Senna was comfortably leading the Italian Grand Prix at Monza and crashed into a driver he was lapping, the car would have won every race of the season.

A Clean Performer in Every Respect In 1990 Porsche enlarged the top segment through the introduction of a new 911 Turbo. An intercooler now 50 per cent larger, a turbocharger also increased in size, and pressure-controlled mapped ignition served to boost maximum output to 320 horsepower. And at the same time the new car was also a very clean performer, advanced exhaust gas management featuring a fully controlled three-way catalytic converter in metal substrate technology fulfilling the strictest US emission standards. Even the emissions coming out through the bypass valve were cleaned by means of a separate catalyst.

The fourth-generation 911 Turbo made its appearance in early 1995, based on the 3.6-litre power unit carried over from the 911 Carrera. The engine's performance figures, however, now entered a new dimension, with the new power unit featuring a twin turbocharger. So following the Porsche 959 technology spearhead boasting a second exhaust gas turbocharger for the first time in 1987, bi-turbocharger technology now made its way successfully into series production.

Maximum output of the new 911 Turbo was a shattering 408 bhp at 5750 rpm, with peak torque of 540 Newton-metres or 398 lb-ft at 4500 revs. Clearly, this ensured truly sensational performance, the Turbo accelerating to 100 km/h in 4.5 seconds and continuing on consistently all the way to a top speed of 290 km/h or 180 mph. Once again, the entire process of developing power was even more harmonious, the two smaller turbines responding even more quickly to the flow of exhaust gas.

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