The total length of the engine is basically determined by the bore, the bore pitch, and the cam gear train layout.
Gear train of the V6TDI engine
Comparison of gear train layout in V12TDI and V10TDI engines
Arrangement of the gear drive
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.