As Porsche was interested in winning Can-Am Championship, they needed more power to their cars. Always thinking big, Piëch started development of the 16-cylinder engine. The experimental turbocharged 12-cylinder was also created. When they understood that it was easier to get the power out from the turbocharged 12-cylinder than from the 16-cylinder, the 16-cylinder version of the 917PA Spyder remained a one-off prototype. The 917/10K Turbo became the first turbocharged Porsche.
With conventional wastegated turbochargers or fixed geometry turbochargers (FGT), a turbine flow area cannot be adjusted during operation.
Knocking is abnormal combustion in which the air-fuel mixture ignites prematurely due to exposure to high temperature and pressure, creating an unwanted high-frequency noise. When the compression ratio is increased, the temperature at compression top dead center (TDC) also rises, increasing the probability of knocking.