APR High Pressure Fuel Pump - Audi TTRS 2.5T FSI
A three-lobe cam located on the exhaust camshaft drives the 2.5 TFSI's Hitachi Generation III high pressure fuel pump. As engine speed increases, so does the pump's ability to displace a greater volume of fuel per minute. The maximum volume the pump can deliver per revolution on the three-lobe cam is dictated by the stroke length from the cam lobe's lift and bore diameter of the pump's internal pressurizing cylinder. It's important to understand, despite the name, APR's High Pressure Fuel Pump upgrade is 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 Stage II+ ECU Upgrade and exhaust. However, APR's Stage III Turbocharger System is capable of generating significantly more power and requires modification to high pressure fuel pump to keep up with fueling demands.