According to the pilot, the airplane entered the downwind leg for runway 18, and he elected to use 20 degrees of flaps and a "slightly higher airspeed" due to wind gusts. While on final approach, he maintained an airspeed of 65 knots; however, the airplane floated, which prompted the pilot to perform a go-around maneuver beginning about halfway down the length of the runway. During the pilot's subsequent landing attempt, the airplane floated again; this time he lowered the nose. The airplane touched down on the main landing gear and subsequently bounced several times before coming to a stop. The pilot then taxied the airplane to the side of the runway and into the grass and secured the engine. One witness reported that the airplane, while on final approach, was "high and fast" with a nose-down attitude and landed flat. Another witness reported that the airplane landed in a nose-down attitude and bounced 4 or 5 times on the runway before coming to rest. All witnesses reported that the airplane "porpoised" after landing. Photographic evidence revealed substantial damage to the engine firewall. According to the pilot, there were no preimpact mechanical malfunctions or abnormalities that would have precluded normal operation.