On August 20, 2017, about 2055 eastern daylight time, a Mooney M20C, N6833N, was substantially damaged during a forced landing following a total loss of engine power after takeoff from Flagler Executive Airport (FIN), Palm Coast, Florida. The commercial pilot and passenger were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the planned personal flight to Fort Lauderdale Executive Airport (FXE), Fort Lauderdale, Florida. The airplane was privately owned and operated under the provisions of 14 Code of Federal Regulations Part 91.According to the pilot, he and a passenger were flying back to FXE from a flight earlier in the day to St Marys Airport (4J6), St Marys, Georgia. They stopped at FIN for fuel. During the subsequent takeoff, the pilot noticed that the engine did not seem to be producing full power. During the initial climb, he felt the engine continue to lose power and about 400 ft above ground level, the engine lost total power. He told the local air traffic controller that the engine lost all power and he was going to land on a road. During touch-down, he noticed flames coming into the cockpit around the passenger's feet. He stopped the airplane and both occupants egressed as quickly as possible. The pilot further stated he did not turn off the master switch or boost pump, nor could he get back in the airplane to turn it off as the flames were too intense at that time. According to a witness, he was working in his hangar, approximately 75 yards away from the self-service fuel farm, when he heard an airplane start up. He stated the engine was running very rough and walked outside to see what the problems was. He saw the accident airplane sitting at the fuel farm and noticed the engine exhaust was "shaking." Then he stated the airplane taxied away towards the runway. After a few minutes, the airport authority came down and locked up the fuel farm and stated that the Mooney just crashed on a road. Examination of the of the airplane following the accident revealed that the cabin was consumed by fire. The engine compartment was black from soot, but intact. The wings, tail section, and landing gear were intact. Thumb compression was attained on all cylinders except the No. 4 cylinder. Borescope examination of the cylinder and revealed that the head was cracked from the exhaust valve to one of the spark plug holes. The fuel pressure gauge line was burnt approximately 3 inches from the carburetor. The bottom of the firewall, in front of the co-pilot's seat, and just below the rudder pedals, was burnt through and the metal was drooping from heat exposure. The four seat, low-wing airplane, was manufactured in 1968. It was powered by a Lycoming O-360 series, 180-horsepower engine, driving a Hartzell two-blade, constant-speed propeller. According to FAA and aircraft maintenance records, the airplane was originally issued an airworthiness certificate on May 30, 1968, and registered to the owner on November 15, 2012. According to maintenance records, the most recent annual inspection was conducted on November 1, 2016, with a recorded time in service of 7,644.5 hours. The engine was last overhauled on December 4, 2001 and had accumulated 680.4 hours of service at the time of inspection.