Porsche is mixing things up in its 911 engine range. In 201, so far all but two 911s, the Turbo and Turbo S, are powered by naturally aspirated units.According to the automaker, this will change in the future. Porsche will introduce new turbocharged engines for all but two variants – the GT3 and GTS. IMAGE GALLERY: 2014 911 GTS CabrioSpy photographers captured images of the new 911 GTS Cabrio undergoing testing in Germany.The GTS will receive a detuned version of the GT3’s future 3.8-litre and will slot between the, then turbocharged, 911 Carrera S and the more potent 911 Turbo.The radical change in Porsche’s engine line-up will be as much a revolution as was the shift from air- to water-cooled engines over twenty years ago. The reasons, however, are the same - reducing fuel consumption.