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Discussion Starter · #1 ·
How come it's necessary to run 3/8" or 1/2" lines when the outlet of the fuel pump and the fuel filter are both 1/4"? I understand that the fuel pump is pushing the fuel under pressure, but isn't the smallest diameter in the fuel circuit the real determinent? :confused:

Michael~
 

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I'm not a fluid dynamics engineer, so don't ask me for the scientific formulas to explain all this. But you're partly right, maybe even mostly right. Single point restrictions - like the pump and filter - will have a detrimental effect on fluid flow. But long distance restrictions also have a significant effect. Your system will flow much better with with 3/8" lines, even though you have those single point restrictions. Just use 1/4" lines and see what I mean.

Optimally, you want wide open space throughout the entire fuel tract. That's why I eliminated all the stock components and used AN lines and fittings everywhere.
 

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Short version - friction between the sidewall of a pipe and the fluid within increases over distance. Therefore, pipe size has to get larger to lessen friction (volume cubes when area squares).

Same stuff happens when you're designing a water system in the streets, just on a larger scale.

All the best,
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