These superchargers are in fact derivatives of General Motors scavenging-air blowers for their two-stroke diesel engines, which were adapted for automotive use in the early days of the sport. The model name of these superchargers delineates their size – the once commonly used 6-71 and 4-71 blowers were designed for General Motors diesels having six cylinders of each, and four cylinders of each, respectively. Thus, the currently used 14-71 design can be seen to be a huge increase in power delivery over the early designs, purpose-built for the GM Detroit Diesel truck powerplants.