Begun as the Type 547, its development began in 1953, when the previous VW-based flat-four, used in the contemporary 356 and rated at , hit the limit of its potential. Porsche realized it needed something all-new. The brainchild of Ernst Fuhrmann, later technical director, it was hoped to achieve an "unheard of" per , relying on hemispherical combustion chambers and -throat 46IDA2 two-choke Weber carburetors to generate from the four-cam engine. The 1.5 liter weighed dry, eventually producing . A complex design that proved "very taxing" to build and assemble, but very durable, it was used in 34 different models, including 550 spyders, 356 Carreras, and F2/1s.