On March 7, 2006, at 2130 central standard time, an Ercoupe E, N94840, registered to and operated by a private owner as a 14 CFR Part 91 personal flight, made a forced landing in a field following loss of engine power near Wetumpka, Alabama. Visual meteorological conditions prevailed and no flight plan was filed. The commercial-rated pilot and passenger reported no injuries, and the airplane received substantial damage. The flight originated from Alexander City, Alabama, on March 7, 2006, at 2100. The pilot stated, that while enroute to the Wetumpka Airport at 2,500 feet, the engine began to vibrate and stopped. He contacted air traffic control personnel and declared an emergency. The pilot stated he made an emergency landing in an open field, where the airplane collided with a ditch on landing rollout, and nosed over inverted. Examination of the engine by an FAA inspector revealed that when the No. 2 upper spark plug was removed, it had foreign object damage. A compression check was performed and the No. 2 cylinder had no compression. The crankshaft was rotated and gear and valve train continuity was established. The No. 2 cylinder was removed from the engine case and examination of the cylinder assembly revealed that the exhaust and intake valves were broken. A review of the engine logbook revealed that the new Superior cylinders were installed on December 12, 2000, and had a total operation time of 272 hours since installation. The No. 2 cylinder, exhaust, intake valves, and piston were sent to the National Transportation Safety Board Material Laboratory for further examination. The valves from the No. 2 cylinder were disassembled and visually inspected. The exhaust fracture faces were so heavily damaged by post separation impacts that no original fracture features could be found. The fractures on the intake valve head were only slightly damaged with features consistent with overstress fracturing consistent with low temperature impact loading, secondary to the fracture of the exhaust valve.