SEA92FA147

During the take off ground run, witnesses reported that the eng sounded normal, however, the airplane remained on the rwy for an unusual length of time. When the airplane finally lifted off near the end of the rwy, the angle of attack increased above normal. The airplane continued to climb in this attitude, with the wings wagging up and down. The airplane attained an alt of approx 100 200 ft when the rt wing and nose dropped toward the ground. The airplane collided with the ground approx one half mile north of the arpt in a nose down, rt wing low attitude. A post crash fire ignited and consumed the airplane. During a post crash eng teardown, it was found that the number six cylinder could not hold compression. Further teardown revealed a section of the cylinder around the exhaust seal was missing. Metallurgical examination revealed that the damage most likely occurred as a result of extremely lean operations which lead to detonation. The plt had recently purchased the airplane, which was equipped with a turbo charger, and was taught to lean the mixture for take off. The operators manual states for take off to have the mixture full rich.