a wankel engine is neither a "turbine" nor "piston" engine. What kind of performance limits apply to wankels?
The Wankel is considerably less efficient, fuel wise, than a piston 4 stroke engine, but can weigh much less.
There are some smaller two stroke diesels (jet A) engines on the market that are extremely fuel efficient. I have no idea what that might weigh in the 1500-2000hp category, but certainly much more than a turbine or a wankel.