RedactedNarrative: Operator had fueled V1 prior to operating. He advised he activated the blowers for approx. 5 min prior to starting. He traveled approx. 50 to 60 feet when the engine compartment exploded and erupted in flames. Passenger 4 threw the children overboard as the fire was burning the floor area. The operator used a fire extinguisher to put out the fire after everyone abandoned V1. Upon inspection the throttle control was in the 1/4 forward position and the distributor cap was obviously incorrect as the engine was a 4 cylinder and the cap was for an 8 cylinder engine. There was also a strong odor of fresh fuel in the engine compartment and a leak of fuel at the area on top of the inboard fuel cell around the fuel line outlet to the engine. There were four lugs on the distributor cap that were uncovered leading to the potential spark hazard.