Fuel pump choices?
I have to agree. I've worked on Ford medium trucks with the famed 534 Super Duty gas engine. Small, mechanical fuel pump with 5/16 lines and a Ford style Holley 600 type carburetor.....probably in the 500 range, because those engines didn't spin a lot of RPM. It's how hard an engine works that dictates how much fuel it will eat. Right?
Right. And they generally have a very low volumetric efficiency. So they don’t use a bunch of fuel for the power they produce. And of course, rpm IS a factor.
If someone would think it through, the more firing cycles you have in any given minute, the more fuel you will burn even at the same BSFC and VE.
To claim that displacement and VE is how you pick a fuel pump is simple minded at best. You still have to figure in G forces, the length of fuel line (all fuel pumps are measured at free flow rates) as the longer the line the greater the pressure drop. That means you have to up the pressure for the longer line just to maintain whatever pressure you have established you need.
When that happens, the GPH the pump is rated at goes down significantly. In much greater proportion than the graphs show. The longer the carb feed hose, the greater the flow loss.
Same with fittings. The more fittings you have, especially 90’s and tighter reduce flow and increase the load on the pump.
If you don’t consider all those things then you can’t make an informed decision on what size pump you need.
Buy too big a pump and no one knows. Buy too small a pump and everyone knows. And as a rule, never dead head an electric pump.