Product Details
When we set out to find every fuel system restriction in the FSI platform, we left no stone unturned. After taking apart the HPFP we were shocked to find that the inlet measured out at less than 1.5mm! When compared with OEM HPFP inlets on the TSI platform as well as other VWAG platforms such as the Audi 3.0T, the difference was staggering. The FSI inlet is microscopic by comparison.
These suspicions were backed up by logs from 3 big turbo MK6Rs and a big turbo B7 A4 on our in-house Mustang dyno. At higher engine speeds the fuel flow into the pump can't keep up, causing low-pressure readings to drop sharply as pump demand increases. This issue is worked around by larger in-tank pumps or HPFP inserts, but even with APR HPFPs, Hellcat in-tank pumps and upgraded controllers, the same issue persisted. The LPFP pump simply cannot flow enough fuel into the HPFP to prevent the high-pressure pump from being drained faster than it can refill.
By replacing the inlet with our high-flow version we were able to see massive improvements in low-pressure readings at higher pump demands. Our pump fitting boasts an internal diameter of 5.5mm for an increase of 366% over the stock fitting! In our opinion, this is the most overlooked bottleneck in the FSI fuel system but the first one that should be replaced.
This fitting upgrade has been dyno-tested and proven to support a reliable 620bhp/500awhp with no auxiliary fueling (port fuel, WMI, etc) on the same vehicles that previously had shut-down issues due to fuel pressure dropping outside of specification. This is not a substitute for a proper MPI or high-flow WMI setup, but is an important upgrade for higher power Stage 2/Stage 2+/Mild Stage 3 setups that aren't quite ready for auxiliary fueling.
Torque Spec: 30nm
Note: We supply only brand-new Hitachi fittings, not a used part taken off of another pump! Make sure the original sealing washer remains inside the HPFP during replacement.
