Porsche website clears it up:
http://www.porsche.com/usa/models/911/

 

only since you missed it the first time posted it. also from wikipedia lol

930 Turbo 3.3-litre (1978–1989)[edit]

Main article: Porsche 930

https://en.wikipedia.org/wiki/Porsch...1_nomenclature

For the 1978 model year, Porsche revised the 930 with a larger 3.3-litre turbocharged engine with intercooler that produced 300 PS (220 kW; 300 hp). To fit the intercooler a newly designed "tea-tray" tail replaced the earlier whale tail. Porsche dropped the "Carrera" nomenclature for the North American markets and simply call it the Porsche Turbo worldwide. The larger engine helped reduce some of the turbo lag inherent in the earlier version.