The APR High Pressure Fuel Pump (HPFP) increases maximum volume of fuel the HPFP can deliver by 37% over stock! In doing so, the direct injection fueling system is capable of satisfying fueling requirements set forth by high horsepower setups. This is accomplished by increasing the displacement of the pump using high quality components to exacting tolerances.How the direct injection system works:A low pressure fuel pump (LPFP) in the fuel tank delivers fuel to the high pressure fuel pump (HPFP) at roughly 4 to 6 bar. Fuel pressure is then bumped up to a maximum of 200 bar, depending on factory parts, with the HPFP. Finally, high pressure fuel is delivered to the injectors, which spray directly into the cylinders.The problem:The volume of fuel the HPFP pump can displace is directly tied to the displacement of the pump (Internal bore size, and camshaft dictated stroke), and engine speed. The pump is driven off of a lobe on the camshaft. Larger turbocharger systems, and ethanol usage are capable of taxing this system, especially in the mid to lower RPM range where fuel volume is lower.The APR solution:We dramatically increase the volume of fuel the HPFP can displace at every RPM by increasing the displacement of the HPFP. This is accomplished by increasing the bore diameter of the pump's internal pressurizing cylinder. It's important to understand, despite the name, a HPFP upgrade is not necessary designed to increase the engine's fuel rail pressure.
