Should the return line be bigger or smaller than the feed line?

Ive heard both ways, first thinking being that the bigger should be feed, and smaller return.

On the other hand the feed is going to be high pressure, the return wont have as much pressure so you need a bigger line (and more volume) to get the fuel back to the tank)

 

depends on application and horsepower really....

from what i understand you want a big enough fuel return line so that it doesn't become a restriction when your regulator is bypassing what isn't being used

for example.....

Run dual in tank pumps with stock feed and return ALL the time. It wont work, you're fuel pressure will be high and you wont be able to get the pressure down enough because the return line cant handle so much fuel being returned so the pressure rises. INTM8 proved this the first time he put in his duals. I remember the post, i dont think he could get the fuel pressure down from like 54psi if i remember correctly

Kinda get the idea now?