Scale Porsche

Porsche designed the GTS variant first to compete in the FIA-GT class at various international racing events. The the street-legal version debuted in 1964 in order to comply with GT-class homologation regulations requiring that a certain number of road-going variants be sold by the factory. Both versions featured a fibreglass body which was bonded to its steel chassis for extra rigidity. The 904's mid-engine layout was inherited from the Porsche 718, also known as the RSK, which was the factory's leading race car (the RS referring tro the German term for racing, Rennsport).

1964 models, of which one-hundred were built, featured an aggressively tuned 180hp version of the four-cam, flat four-cylinder "Fuhrmann" engine originally designed for race use in the 550 Spyder, and later featured in the 356 Carrera with 130hp. To satisfy demand, twenty 1965 models were produced, some featuring a variant of the 911's flat six-cylinder engine. Very few cars that were raced by the factory featured a flat eight-cylinder power plant derived from the 1962 F1 car Porsche 804. The six-cylinder and eight-cylinder units were varyingly identified as either 904/6 or 904/8