High pressure for the charge air.

More engine output at the touch of a button? It’s very simple: just press the pedal beyond the full throttle position and the assembly will supply 60 percent more “horsepower” than in normal mode. This is made possible by the Roots compressor as a mechanical charge air compressor. This occurrence is accompanied by a distinctive operating noise, which is music to some people’s ears.

The Daimler-Motoren-Gesellschaft (DMG) inspired the experts and the public with this innovative technology 100 years ago. The first two compressor vehicles of the brand from Stuttgart premiered at the 1921 German Motor Show in Berlin – the Mercedes 6/25 PS and the Mercedes 10/40 PS. They marked the beginning of a great success story.

Sensation: The Mercedes 6/25 PS (right) and the Mercedes 10/40 PS premiered at the 1921 German Motor Show in Berlin (the exhibition poster on the left).

Paul Daimler, head of DMG vehicle development from 1907 to 1922, and the Mercedes 10/40 PS as a sports two-seater.

High-tech from aircraft construction.

The new models were developed under the direction of Paul Daimler, the eldest son of automotive pioneer Gottlieb Daimler. The engineer headed the vehicle development of DMG. He knew the principle of the Roots compressor from aviation engine development during the First World War. Now he was relying on the concept of the belt-driven supercharger and wanted to use it in a car.

A first attempt with the sleeve valve engine of a Mercedes-Knight 10/40 PS was not successful. That is why two new valve-controlled engines were developed at Daimler: both were inline four-cylinder engines with overhead camshafts, V-shaped valves and centrally embedded spark plugs. An upright shaft on the end of the engine powered the camshaft and water pump. The Roots compressor was fitted to the front of the engine and powered by the crankshaft.

Powerful sportiness.

Due to the difficult economic conditions, the two new models were not launched on the market until 1923. But it was worth the wait for the customers as the calculation of the constructors around Paul Daimler, including Albert Heeß and Otto Schilling, paid off: the effect of the compressor was huge; the turbocharger got around 60 percent more performance out of the engine.

In the Mercedes 6/25 PS with 1,568 cubic centimetres displacement, when switching on the rotor supercharger, output increased from 15 to 18 kW (20 to 25 PS) to 28 to 29 kW (38 to 40 PS). In the 10/40 PS model with 2,614 cubic centimetres displacement without the compressor 26 to 29 kW (35 to 40 PS) were available and with the belt-driven supercharger it was 48 kW (65 PS).

Chassis of the Mercedes 10/40 PS with 2.0 litre compressor engine. From 1924, the model was called Mercedes 10/40/65 PS.

Compressor performance in the model designation.

In order to make clear the potential as soon as you saw the name of the model, the two vehicles received further model designations in 1924: from then on, they would be known as the Mercedes 6/25/38 PS and Mercedes 10/40/65 PS. The last number stood for the output in PS with the compressor switched on.

Successful in racing.

The powerful compressor engines were also ideally suited to racing. The 1.6 litre engine of the Mercedes 10/40 PS was transformed into various racing engines with 1,500 and 1,986 cubic centimetres displacement in the 1920s. This includes the Mercedes 2-litre Targa Florio racing car of 1924, which was powered by one of these engines. The legendary red racing car can be experienced in the Mercedes-Benz Museum in the Legend 7 room: Silver Arrows – Races and Records.

Compressor winner: With the red Mercedes 2-litre Targa Florio racing car, Christian Werner won the famous Targa Florio road race in Sicily in 1924. 

Compressor victory in the one-thousand-mile race: 90 years ago, Rudolf Caracciola and Wilhelm Sebastian won the Italian “Mille Miglia” road race in the Mercedes-Benz SSKL (W 06 RS) compressor touring car on 12 and 13 April 1931.

Legendary compressor touring cars.

The great potential of the compressor technology made the cars of the brand with the star equipped with these engines famous. The compressor sports cars of the K, S, SS, SSK and SSKL model series, in particular, became legendary from 1924. They inspired both as super sports cars of their time for ambitious private drivers and as successful racing vehicles.

Renaissance in the 1990s.

From 1995, compressor technology celebrated a comeback in passenger cars by Mercedes-Benz. First, the 2.3-litre four-cylinder engines in the C-Class, SLK and CLK had the belt-driven supercharger. The C 230 KOMPRESSOR premiered at the IAA in 1995.

Performance and efficiency: Mercedes-Benz C 230 KOMPRESSOR Estate of the 202 model series (production period 1997 to 2000) with corresponding lettering on the tailgate.