It's been decades since Porsche built a four-cylinder engine, with the 968 the last model to feature its straight-four unit. But if rumors emanating from flat6news are to be believed, a new turbocharged flat-four engine could make its debut at September's Frankfurt Motor Show. The all-aluminum engine will serve as the marque's entry-level sports car powerplant. Based on the current 3.8-liter flat-six that powers the Carrera S, the new 2.5-liter four-pot unit will feature two less cylinders, direct fuel injection, VarioCamPlus and a single turbo.

It will likely develop around 350 horsepower and 360 pound-feet of torque, while redlining at 7,500 rpm and mated to Porsche's seven-speed PDK transmission. The Boxster/Cayman's naturally-aspirated 2.7-liter mid-mounted flat-six will make way for the new 2.5-liter turbo-four and may even finds a home in the "S" models, whose 325-hp 3.4-liter flat-six it also outperforms. Of course, with no official details this all remains speculation for now.