The bottom line is that a filter must flow what the pump is capable of flowing, essentially acting as if it's invisible to the pump. Accomplishing this requires optimizing porosity-or micron rating-and the filtering medium's surface area. Extensive testing has proven that any fuel filter with a micron rating less than 100 is too restrictive for the suction side of a fuel pump. On the flip side, fuel pumps are not nearly as sensitive on the pressure side. Consequently, micron ratings of 10 to 40 will suffice on the pump's outlet side.
Another key factor is the surface area of the filtration media. You'll notice that we offer several different filters, including several recommended for the suction side of our fuel pump. If you have ever spent any time on our site or with our catalog, you may have seen our Power Planner diagram, which is a systems-based recommendation of properly matched fuel system components for many different applications. In each systems, we have very specific filters that we match to different fuel pumps. Some of our larger fuel pumps require a larger filter than others. We know this because we have spent an enormous amount of time testing our fuel pumps. By making very specific parts-matching recommendations, we can ensure that our fuel pumps will operate in their ideal scenarios, increasing their durability and performance.
Furthermore, maintaining filters is critical to the life of your fuel system. After installing a new system, the elements should be cleaned or replaced after the first 5-10 run hours. The dirtiest a system will ever be is before it's installed. It's also important to note that paper elements must be replaced, but the stainless steel elements can be reused after cleaning. We recommend servicing your filters at least once a year after the initial service.-Brett Clow
The ideal location for a fuel pump is right inside the fuel tank, which is why the OEs have been doing this for quite some time. Mounting a big, electric external fuel pump inside a tank is extremely difficult, but the people at Rick's Hot Rod Shop have been doing it for several years now. "With their help, we developed a baffling system that surrounds the fuel pump inside the tank and maintains fuel at the point of pickup at all times. The baffling also controls fuel slosh as the fuel level decreases in the tank. In an ideal world, all pumps would be submersed in every application, so we set out to develop a way that will allow everyone to do so with our Stealth system," says Powell. The heart of the setup is a sump box that can be welded onto almost any fuel tank and that features an Aeromotive A1000 or Eliminator fuel pump and prefilter built right into the assembly. "When you weld this sump box onto the bottom of your fuel tank, you now have an in-tank fuel system that is properly sumped, baffled, and capable of supporting in excess of 1,000 hp. In addition to simplicity, ease of installation, and a streamlined appearance, the Stealth setup runs cooler and provides insulation from operating noise. It also features a return port that returns the fuel right back into the sump and offers easily accessible internals for maintenance."
An external fuel pump, either electric or mechanical, should ideally be placed low and close to the tank. "Even if the pump is an Aeromotive A1000, which can pull like a freight train, you want to minimize the vacuum the pump has to create in order to draw fuel from the tank," Powell explains. "This avoids premature fuel vaporization and extends the fuel pump's duty cycle and ability to supply liquid fuel as fuel temperature elevates on hot days. This is very important because a liquid's boiling point drops as vacuum is applied on it. Airflow over the pump is not a bad thing, but will rarely solve other inherent design problems."
Aeromotive fuel pumps are extremely efficient by design, allowing them to create high pressure on the outlet and high vacuum on the inlet side. Cavitation to a pump is like detonation is to an engine and occurs when the liquid being pulled into the pump reaches a temperature where it boils and becomes vapor. A highly efficient pump matched with restrictive filters and feed lines can drop inlet pressure so low that fuel will vaporize unnecessarily at normal operating temperatures.
Fortunately, eliminating vaporlock is as easy as eliminating the causes. Proper line size is critical, especially on the suction side of the fuel pump, and filters must be up to the task as well. We recommend that 100-micron stainless steel filter elements be used on the suction side of the fuel pump. Many filters on the market today may say "100 micron" like we recommend, but what isn't mentioned is the filtration area. Our smaller filters have over 63 square inches of filtration media, ensuring there is ample room for flow, which eliminates the chance of pressure drop. We've seen numerous fuel pumps ruined by vaporlock because fuel filters with inadequate filtration surface area restricted fuel flow. Always look at the micron rating and the filtration area, as both are equally important to the life of your fuel pump.-Brett Clow