how neccesary is a return line for a electric fuel pump?
I say "with today's fuel" ANY carbureted engine can benefit with a vapor return system, even and especially mechanical pumps. First one of those I ever saw was on my old 70 RR sixpack car, AND IT WORKED.
Wix and other filter manufacturers make this easy to implement, they make a couple of sizes of throwaway filters with a built in vapor return port
Wix no. 33040/ 33041 are 5/16/ 3/8 fuel line with a built in 1/4" return port
You mount them either vertically as shown below, or horizontally, as long as the 1/4 port is UP
The other argument FOR a return on ANY motor drive pump is that the pump impeller sits back there on a "non return" system, and when the needles are closed, the impeller churns and generates foam and heat.
The higher volume and pressure your pump is rated for, the more you need a return.
Having said that, the Holley Red pumps don't need a regulator nor a return line. I just think they are beneficial
Bear in mind that the following destructions cover more than just the red pump:
http://www.holley.com/data/Products/Technical/199R7914-3rev3.pdf
http://www.holley.com/data/Products/Technical/Fuel Pump Tech Info.pdf
I say "with today's fuel" ANY carbureted engine can benefit with a vapor return system, even and especially mechanical pumps. First one of those I ever saw was on my old 70 RR sixpack car, AND IT WORKED.
Wix and other filter manufacturers make this easy to implement, they make a couple of sizes of throwaway filters with a built in vapor return port
Wix no. 33040/ 33041 are 5/16/ 3/8 fuel line with a built in 1/4" return port
You mount them either vertically as shown below, or horizontally, as long as the 1/4 port is UP
The other argument FOR a return on ANY motor drive pump is that the pump impeller sits back there on a "non return" system, and when the needles are closed, the impeller churns and generates foam and heat.
The higher volume and pressure your pump is rated for, the more you need a return.
Having said that, the Holley Red pumps don't need a regulator nor a return line. I just think they are beneficial
Bear in mind that the following destructions cover more than just the red pump:
http://www.holley.com/data/Products/Technical/199R7914-3rev3.pdf
http://www.holley.com/data/Products/Technical/Fuel Pump Tech Info.pdf