New HPFP Upgrade - SpoolPerformance Helix


Apr 4, 2018
The piston just expands the bellows. Compared to a piston pump like on an F series or the majority of other DI cars where an actual piston compresses fuel directly.
There is a physical piston moving up and down compressing a hydraulic fluid. This pressure expands the bellows forcing them to expand to displace the fuel. Because it's coupled hydraulically, it needs a spring to assist in returning it back down. It is physically the same as a wobble plate hydraulic pump. The bellow just separates the two fluids because gasoline is not a good enough lubricant to lubricate this style pump. A true bellow pump would have the plunger mechanically coupled to the top plate of the bellow and would not be able to deal with the pressure needed for direct injection. Almost all true bellow pumps are low pressure. The lobe driven pumps you are referring to have very little thrust load on the cylinder wall and do not require that much lubrication. This is why they can get away with directly pumping the fuel.


Oct 18, 2016
Completely off-topic but I'd like to add that I know Chris's day job and it is a very well known company that everyone in this thread has heard of. So lets spare each other from the chest thumping about where we work, how big our house is or any of that. Being able to prove points in a polite manner indicates intelligence. Resorting to meaningless insults usually means you ran out of ammunition.

There is a very high probability that many or all of you have very specialized talent or skills that others here don't have. For example, I am not a Tuner. Nor a Tuna. I can't tune. Does this mean I'm incapable? Unintelligent? No, it just means I haven't invested the effort, energy and allocated the time and motivation toward that skill.

We should keep this thread on track or I'll have to start splitting it up. Lets debate, not get irate!