The 14 CFR Part 91 instructor pilot was providing instruction while scouting an off-site landing area. He said during a low pass the airplane started to settle, and he applied power to climb, but the engine failed to respond. He said the airplane touched down, and during the landing roll the airplane nosed over. In his written statement to the NTSB, the pilot wrote that the throttle should have been applied more slowly for the go-around, and that there were no mechanical malfunctions or failures associated with the accident.