Complex sentence: The first Allard mounted a Ford flathead V8 in a body mostly sourced from a Bugatti racing car, and used the American engine's high torque to great effect in this slow-speed competition.
Split into simpler sentences: The first Allard was powered by a Ford flathead V8 in a body that was mostly sourced from a Bugatti racing car. It used the American engine's high torque to great effect in this slow-speed competition.