Winning foursomes: Four-cylinder engines from Mercedes-Benz

OFFICIAL PRESS RELEASE

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Innovations regularly experience market launch in four-cylinder passenger car engines
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Ground-breaking DIESOTTO drive in the Mercedes-Benz F 700 premiered as a four-cylinder engine

What do four-valve technology, supercharging, common rail technology and CGI direct gasoline injection have in common? Answer: They all celebrated their Mercedes-Benz premieres in four-cylinder engines. Throughout the history of the brand from Stuttgart, this seemingly unspectacular engine type has always been at the cutting edge of outstanding innovation. Even the DIESOTTO technology, which was premiered in the F 700 research car at the 2007 International Frankfurt Motor Show (IAA), was first introduced by Mercedes-Benz in a four-cylinder engine.
Along with many other factors, the number of cylinders an engine has is indicative both of driving culture and prestige. The greater the number of cylinders, the better the ride quality � it is a rule of thumb followed by almost all markets worldwide. Mercedes-Benz Cars enjoys a reputation for supplying passenger cars equipped with a diversified range of superb internal combustion engines. The smart has three cylinders, the S-Class twelve, and between the two extremes there exists an entire spectrum of other configurations. While the four-cylinder versions may seem rather unspectacular at first sight, these are the very engines to which great importance is attached time and again.

The earliest vehicles had engines with one or two cylinders but if the automobile was to prove successful it was essential to boost output by increasing the number of cylinders to four. The Phoenix car of 1898 was the first Daimler road vehicle to feature a four-cylinder engine based on the principle devised by Nikolaus Otto. It had an output of 17 kW (23 hp) � quite impressive for the day. And true to Gottlieb Daimler�s vision of mobilizing vehicles on the land, on the water and in the air, it was not long before four-cylinder engines were also being used in aviation.
Developments with Carl Benz followed a similar course. One of his major achievements, for example, was the so-called contra engine, which made its debut in 1899 as a two-cylinder unit, bringing the principle of the horizontally-opposed piston engine to production standard before it appeared with four cylinders in 1900. However, this engine was used exclusively in what was the most powerful Benz racing car at the time. That same year DMG built a four-cylinder unit for use in the first Mercedes. In many ways it was a pioneering development, featuring for example intake and exhaust valves controlled by two lateral camshafts.

Early innovations: Four-valve technology, superchargers and diesel engines

The designer engineers introduced various measures to significantly increase the output of vehicle engines, particularly in the first decade of the twentieth century. One glorious highlight was the 200 hp Benz record-breaking car � more familiarly known as the Lightning Benz � which, with its powerful 21.5-liter four-cylinder engine, became the first car to pass the magical 200 km/h barrier at Brooklands in 1909. At Benz & Cie. in 1910 four-valve technology celebrated its premiere in a four-cylinder engine. That same year DMG launched the Mercedes Knight, equipped with a four-cylinder unit that was considered both powerful and unusually quiet. 1921 saw the start of the supercharger era, when DMG introduced the world�s first production passenger car equipped with a supercharged engine � again a four-cylinder model. And in 1923 the automotive world was further enhanced by another new combustion principle, when Benz & Cie. unveiled the world�s first salable diesel truck � featuring a four-cylinder engine that attracted considerable interest as a result of its outstanding fuel economy.

When Daimler-Benz AG was established in 1926, the new company soon attached key importance to the four-cylinder engine. By this time the automobile was rapidly gaining popularity in all sectors of society; as a result the four-cylinder engine began to take on an increasingly important role. The turning point came with the Mercedes-Benz 130 (W 23), which appeared in 1934. Its relatively moderate success had less to do with its four-cylinder engine than with its unconventional design and the rear-mounted engine configuration which needed getting used to. It prepared the ground, for example, for the 170 V model (W 136) of 1936, which was built in large numbers throughout the 1930s and 1940s, and after the Second World War flourished again in modified form with such success that it played a significant part in financing the reconstruction of Daimler-Benz AG.

Four-cylinder innovations at Mercedes-Benz then alternated between diesel and gasoline engines with the advent in 1936 of the world�s first series-produced diesel passenger car, the Mercedes-Benz 260 D (W 138). A recurring leitmotif of the new engines was their increased output � although set against pure horsepower this usually went hand-in-hand with improved fuel economy. For the engineers were clear about one thing: Customers would only accept higher output if running costs remained proportionate. The 1960s saw a sharper focus on the topic of emissions, followed closely � particularly during the oil-price crises of the 1970s � by renewed calls for more fuel-efficient engines. Once again it was the various designs of four-cylinder engines that scored top marks.

Fuel-efficient and low-emission four-cylinder engines

At first sight it would seem engine development during this period followed the maxim �evolution not revolution� � and yet a second glance reveals one or two quite remarkable revolutions. Take, for example, the Mercedes-Benz 190 D, which appeared in 1983 with an encapsulated four-cylinder diesel engine to keep operating noise to a minimum � soon earning itself the sobriquet �whispering diesel�. That same year, four-valve technology also experienced a renaissance in the modern gasoline engine of the 190 model. A good ten years later another historic piece of technology was to become the focus of interest once again, when Mercedes-Benz revived the supercharger for use in its four-cylinder engines. As in the 1920s and 30s, it served to boost output � but on this occasion less with the aim of achieving top sports handling and performance than in lending the four-cylinder improved power yield and fuel efficiency. Many automotive journalists of the day lavished praise on the supercharged Mercedes-Benz four-cylinder engines which would later come close to the mark set by the brand�s six-cylinder units � praise which the designer engineers were only too pleased to hear. Because regardless of the number of cylinders, an engine in a vehicle bearing the three-pointed star should always fit the character of a Mercedes-Benz.

The four-cylinder engines then became an integral element of vehicle design in the A-Class (W 168) which made its debut in 1997. These are designed in such a way that in the event of a frontal impact they slide along the pedal floor beneath the passenger compartment. That same year, the diesel engine was hailed a hero of the revolution in engine design when Mercedes-Benz introduced CDI technology � once again in a four-cylinder unit. Then in 2002 came direct gasoline injection, first in the CLK 200 CGI (C 209) and shortly afterwards also in the C-Class. From 2005 onwards the low-emission diesel engine was given a new name � BLUETEC technology for passenger cars made its debut in a research vehicle, the Mercedes-Benz bionic car. The first production car with this technology was a six-cylinder model, the E 320 BLUETEC.
Finally, in 2007 the brand presented the F 700 research car at the International Frankfurt Motor Show (IAA), powered by the DIESOTTO engine. In this revolutionary engine the company�s researchers succeeded in combining for the first time the advantages of both gasoline and diesel principles. The vision, of which this engine is the tangible expression, extends far into the future of the internal combustion engine. And one thing is certain for the years ahead: Whether powered by four cylinders or some other cylinder configuration, the Stuttgart brand will continue to stand for economical and low-emission combustion engines as a source of power for outstanding motoring refinement.

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