Engine no. 17

Struck by the low output of the steam engines that he saw at Conservatoire des Arts et Métiers, Rudolf Diesel devised an engine with a cycle similar to that proposed by Carnot, by injecting the fuel directly into the highly compressed hot air in the chamber. The surplus heat is converted into external working during combustion and the subsequent rapid expansion of the gases. After four years of tests, in 1897 he perfected the engine. Instead of pulverised coal, Diesel used heating oil injected by compressed air. His engine had an output unequalled by any other machine. Unlike petrol engines, the combustion process is controlled by an injector that regulates the amount of fuel entering the cylinder, which spontaneously ignites in contact with the hot air. The only drawback of the high pressures this creates is that the engine’s components are correspondingly oversized. Today, with electronic direct injection systems, the Diesel engine has achieved a level of reliability and performance that has enabled it to win the Le Mans 24 Hours race.