On September 25, 1997, about 1915 eastern daylight time, a Cessna 172N, N738SZ, collided the nose gear with the runway and nosed over at Greenville Downtown Airport in Greenville, South Carolina. The personal flight operated under the provisions of Title 14 CFR Part 91 and visual flight rules. No flight plan was filed for the touch and go practice flight. Visual meteorological conditions prevailed. The private pilot was not injured, and the airplane was substantially damaged. The flight originated from Greenville, South Carolina, at 1914. The pilot stated that, the initial takeoff started from the end of the runway and he had applied full power. At the mid field point of runway 36, the airplane lifted off. However, the pilot did not feel that the airplane had sufficient power to takeoff, so he aborted the takeoff. The pilot said he pulled the power all the way back and the airplane descended nose first on the runway. The nose gear collapsed, and the airplane nosed over. An eyewitness stated that during the takeoff roll, the airplane began to porpoise before the nose gear collided with the runway. An examination of the airplane failed to disclose a mechanical problem, and the pilot did not report experiencing a mechanical problem with the airplane during the attempted takeoff. The pilot's operation handbook states that the normal takeoff ground run is 478 feet. Runway 36 is 5393 feet long.