Exploded view of MK1 alpha prototype of simple manifold.
External dimensions and ports labels.
It is 2 x 1.5 x 2 inches. About the size of a child's fist, or roughly half the height but thicker than a pack of cigarettes. It is made from machined billet aluminum. 2 allen head stainless steel bolts turns it into a single assembly. The check valves are sandwiched between the upper and lower plates. IP overflow enters from the top right and preferentially feeds into whichever fuel is currently being drawn by the pump through the two lower right fittings. Deliberately imbalanced check valves allows for intrinsic loop and purge. The single lower left fitting feeds into an FPHE. It is just as easy to make this into two independent d2/vo outputs for connecting to two heat exchangers for faster purge. The two upper left fittings connect to the pump's bidirectional in/out ports.
This MK1 simple manifold is an alpha prototype for testing the proof-of-concept only.
If successful, the MK2 beta prototype will become a direct replacement for the backplate of a small gear-pump's housing, leaving only 4 ports: vo and d2 inlet, fuel outlet to FPHE and IP overflow inlet. This will obviate the need for pump fittings and hoses, and the manifold will become integral to the pump head.
The MK3 gamma prototype will directly integrate the temperature and pressure sensors, and pump motor controller for automated switch and purge and possibly pressure modulated timing advance in vo mode. This will remove the need for additional sensor fittings and most external wiring. It would also be possible to integrate the automatic air bleed valve at this point and allow for automatic priming.
With space being a premium, I figure a small tightly integrated system with minimum plumbing and minimum active components would be useful for quick and easy conversions.
If it pans out, I may even integrate the FPHE and coolant heated fuel filter as a single unit sharing a unified cascaded low restriction coolant flow, with the manifold and pump assembly comprising the filter base. Perhaps a 4 x 6 x 10 package. This will get rid of a bunch more hoses and fittings.
Additional notes:
The prototype manifold could have been reduced to 1 inch in height, but would not leave enough space to attach fittings.
The check valves could have been tappets, but hardened alloy steel balls seal better, wear longer, and are cheap and easy for anybody to replace.
Hardened steel washers are used as valve seats instead of relying on the softer aluminum, and also makes it repair-friendly.
I wanted snap action check valves, and it occurred to me that there was a way to get this without resorting to piston/plunger style checks: Magnetize the valve seat washers, or have them backed by NIB ring magnets and kept in place with a circlip or retaining ring in a groove. This will allow snap action and fast reaction positive seating with a simple ball check.
Aluminum was chosen as I have a large pile of scrap aluminum available.
For proof-of-concept testing I'll just use the 12v HF vane pump.
If successful, then the next step is to find a suitable small and CHEAP miniature gear pump.
As always, comments and criticism gladly welcomed.