The pilot reported that he intended to land on an asphalt runway in night visual conditions. As the airplane approached the runway, he added engine power because the flight controls felt mushy. The airspeed was approximately 85 knots with full flaps and the airplane remained in ground effect longer than usual. When the airplane touched down, it bounced and the propeller struck the runway surface. The airplane porpoised, but eventually came to a stop. The airplane sustained substantial damage to the engine mount structure and support assembly. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operations.