Toyota Racing Development
The 503E was used to power a number of Toyota Sports cars, including the Toyota 88C Group C entry and the All American Racers-built Eagle HF89/HF90 and Eagle MkIII IMSA Grand Touring Prototypes. - It was hand-built by Toyota Racing Development in Torrance, California and produced up to 800 horsepower. The 3SGTE was later based on its design. They are similar engines, though not identical.