.15 size engines come in both standard and turbo versions. It is hard to say what this engine actually is. They could mean it is a .15 standard engine or by the letter T in its name they could be saying it is a .15 Turbo 7-port with a standard crankshaft.
Not sure as I haven't really looked much at the Sirio .15 engines. Maybe someone else has this engine and can bring more light on the subject.