With three new variants of its 911 due to be on sale by the end of next year, Porsche is looking for a big year from its flagship sports car.

For the current-generation 911, 2018 could be the biggest sales year in the U.S., even though it will be the last full year before a redesigned car is introduced, said Klaus Zellmer, CEO of Porsche Cars North America.

"911 is going to be very strong because we have the GT models that we're not delivering this year but next year," Zellmer told Automotive News. "The pent-up demand is enormous there — GT3, GT2 RS. We're going to see huge numbers next year."

Porsche announced the 500-hp GT3 in April, and deliveries started late this year. Deliveries of the GT3 Touring and the 700-hp GT2 RS begin in early 2018.

Another entry for next year is the 2018 911 Carrera T unveiled last month at the Los Angeles Auto Show. Orders are strong for the T (for Touring) variant, said Zellmer, who describes the entry as more of a purist's car.

Lighter in weight than other Carrera models, the T is powered by a twin-turbo, 3.0-liter flat-six engine producing 370 hp. It is expected to reach U.S. dealerships in March.

U.S. sales of the 911 in 2017 are tracking toward 9,000 deliveries — Porsche sold 8,197 through November, up 0.1 percent.

The biggest U.S. sales year for the current generation of the 911 was near the beginning of its life cycle, in 2013, when Porsche sold 10,442.

A redesign with a move to a new platform is in the works for the 911, with U.S. sales of the next generation expected to begin in the second half of 2019.