APR High Pressure Fuel Pump - Audi RS4 4.2FSI
A dual-lobe cam located on each intake camshaft drive the 4.2L FSI V8's Hitachi high pressure fuel pumps. As engine speed increases, so does each pump's ability to displace a greater volume of fuel per minute. The maximum volume each pump can deliver per revolution on the dual-lobe cam is dictated by the stroke length from each cam lobe's lift and bore diameter of each pump's internal pressurizing cylinder. It's important to understand, despite the name, APR's High Pressure Fuel Pump upgrades are not necessarily designed to increase the engine's fuel rail pressure. The primary goal is to increase the volume of available fuel.
The engine's fueling system is very capable without modification, even at high power levels generated using APR's previously available Stage III TVS1320 Supercharger System. However, APR's Stage III+ TVS1740 Supercharger System System is capable of generating significantly more power and requires modification to high pressure fuel pumps to keep up with fueling demands.