 This engine started as a straight-five-cylinder Audi diesel in 1989 (itself derived from the EA827 series), but got reduced to an inline-four-cylinder for Volkswagens use.It is related (through several evolutions of engine families) to the EA827 series, indirect-injection diesels, 16 valves, and five-cylinder gasoline engines.Naturally aspirated direct-injection variants are known as Suction Diesel Injection, abbreviated to SDI.