Turbo-diesel

The term turbo-diesel, also written as turbodiesel and turbo diesel, refers to any diesel engine equipped with a turbocharger. As with other engine types, turbocharging a diesel engine can significantly increase its efficiency and power output, especially when used in combination with an intercooler.

Turbocharging of diesel engines began in the 1920s with large marine and stationary engines. Trucks became available with turbo-diesel engines in the mid-1950s, followed by passenger cars in the late 1970s. Since the 1990s, the compression ratio of turbo-diesel engines has been dropping.

Diesel engines are typically well suited to turbocharging due to two factors:

As per turbocharged petrol engines, an intercooler can be used to cool the intake air and therefore increase its density.

The turbocharger was invented in the early 20th century by Alfred Büchi, a Swiss engineer and the head of diesel engine research at the Gebrüder Sulzer engine manufacturing company. The turbocharger was originally intended to be used on diesel engines, since Büchi's patent of 1905 noted the efficiency improvements that a turbocharger could bring to diesel engines. However, the first production turbocharged engines to be manufactured did not occur until 1925, 10-cylinder turbo-diesel marine engines used by the German passenger ships Preussen and Hansestadt Danzig. The turbocharger increased the power output from 1,750 PS (1,287 kW) to 2,500 PS (1,839 kW). In 1925, Büchi invented sequential turbocharging, which according to Helmut Pucher (2012) marks the beginning of modern turbocharging technology.

By the late 1920s, several manufacturers were producing large turbo-diesels for marine and stationary use, such as Sulzer Bros., MAN, Daimler-Benz, and Paxman. Subsequent improvements in technology made feasible the use of turbochargers on smaller engines that ran at higher engine speeds, so turbo-diesel locomotive engines began appearing in the late 1940s. In 1951, MAN built the K6V 30/45 m.H.A., 1 MW prototype engine, which had, for its time, an exceptionally low fuel consumption of just 135.8 g/PSh (184.6 g/kWh), equivalent to an efficiency of 45.7 per cent. This was possible because of the advanced turbocharger design, comprising a five-stage axial compressor combined with a nine-stage radial compressor and an intercooler.

Use of turbo-diesel engines in road-going vehicles began with trucks in the early 1950s. The prototype MAN MK26 truck was unveiled in 1951, followed by the production model MAN 750TL1 turbo-diesel in 1954. The Volvo Titan Turbo truck was also introduced in 1954. By the late 1960s, demand for increasingly powerful truck engines led to turbo-diesels being produced by Cummins, Detroit Diesel, Scania AB, and Caterpillar Inc.

In 1952, the Cummins Diesel Special became the first turbocharged car to compete at the Indianapolis 500 motor race and qualified on pole position. The car was powered by a 6.6 L (403 cu in) inline-six engine producing 283 kW (380 hp).