Introduced by Daimler, the supercharger made its first appearance in automobiles in April 1922, 100 years ago. Less widespread than the turbocharger, this type of supercharging is still offered, in different forms, by several manufacturers.
Today, turbocharging often rhymes with turbocharging. Introduced in the automobile in the 1960s, the latter acquired its letters of nobility during the following decade in competition with manufacturers such as Renault and Porsche before finding itself under the hood of sports cars then gradually becoming more democratic until to equip, “downsizing” obliges, almost all of the current heat engines. But in the shadow of the turbo, the supercharger enjoys an equally rich history, and at least as long since it has now been fitted to cars for 100 years.
The beginnings of supercharging in the automobile
While the turbocharger returns turbine-accelerated exhaust gases to the engine, the supercharger is powered by the crankshaft via a chain, belt or shaft. Compression can take place there according to different operating principles (via gears or screws in particular). The purpose of both systems is the same: force the combustion chambers to be filled with air in order to burn more fuel with each movement and thus increase the power. In either case, the patents for these devices applied to motors were filed between the end of the 19th century and the beginning of the 20th century. As for the turbo, Louis Renault was one of the pioneers in terms of compressor. But its use by the French, dating back to 1908, was then confined to aeronautics. The lobe compressor invented in 1860 by Françis Marion Roots, on the other hand, was adapted to the automobile by Daimler from 1921 on the Mercedes 28/95 PS.
Same displacement, double power
On April 2, 1922, the German manufacturer demonstrated the benefits with a victory in the category of production cars with a displacement greater than 4.5 L at the Targa Florio with the 28/95 PS supercharged Mercedes of driver Max Sailer. In the category of cars with a displacement of less than 1.5 L, Paul Scheef’s supercharged 6/40/65 PS Mercedes came third. Compared to naturally aspirated versions of these cars, the compressor almost doubled their power.
During the interwar period, major manufacturers followed in Daimler’s footsteps and produced racing or sports cars with supercharged engines. The Fiat 804-405, the Alfa Romeo P2 and the legendary Bugatti Type 35 distinguished themselves in particular with supercharged engines. Mercedes marked the end of this period as the beginning, with its SSK equipped with a screw compressor then the 500K and 540K which were derived from it.
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Turbo and compressor, pros and cons
As it is driven by the crankshaft, the supercharger uses some of the engine’s power. It is therefore best suited to large displacements. The oil crisis of 1973 contributed to the rise of the turbocharger, which allowed small displacements to gain significantly in power and torque without being too greedy as long as one does not have too heavy a foot. In recent years, the tightening of regulations on CO2 gave new impetus to the turbo. But the positioning of the turbine at the engine outlet induces a latency in its response, the latter being dependent on the load, the speed and the gas circulation time. Once activated, it suddenly sends its airflow with this famous “kick in the buttocks” effect, but its performance is limited by its diameter and its speed of rotation. The volumetric compressor, for its part, offers a behavior much more progressive and close to that of an atmospheric mechanism, increasing torque and power over the entire range of use of the engine.
The compressor at 21th century
In the 1970s, while the turbo developed in Europe, the supercharger retained a certain attraction in the United States, particularly under the hood of certain “muscle cars” which survived the oil crisis. But changing environmental standards, including in North America, have made it increasingly low-key over the decades. However, even today, some manufacturers are faithful to it. One of the most notable examples comes from this side of the Atlantic. Jaguar Land Rover’s supercharged 5L V8, which is living its last years, is equipped with an Eaton compressor (derived from the Roots system). Also in the United Kingdom, Lotus has renewed on the Emira the compressed version of a 3.5 L V6 of Toyota origin which already animated certain Exige and Evora. And Toyota, precisely, had made the unexpected choice to equip the Yaris GRMN with a compressor rather than a turbo like the other small contemporary GTIs.
After a few experiments in the 1980s, including the Lancia Delta S4 of Group B, certain manufacturers such as Volvo or the Volkswagen group have recently offered engines combining a volumetric compressor dedicated to low engine speeds and a turbocharger taking over beyond. This makes it possible to have a “full” engine at all speeds. At Audi, some current V6 TDI models use this system, except that the compressor is electrically driven. In the next all-electric era, will Mercedes dare to perpetuate the “Kompressor” badge in the name of the symbol? After all, Porsche does have its Taycan Turbo.
