Vierte

iTrader: (2)

Probably a dumb question, but can you run 2 fuel pumps in series? Im new to building fuel systems and Im looking to build a budget system that can support about 400 to 500 whp on E85. I currently have a s5 NA pump and also have access to a walbro 255 inline pump. Could I run these in series? Seems like the NA pump would choke the 255. What about in parallel? Seems like the pumps should be the same size to run in parallel.

Should I just man up and buy a second inline 255 and run them in parallel? Could I run 2 255s in series?

bumpstart

in series= same flow rate across the pumps but at double the head
ie minimum flow rate ( 2.25 lpm of stock NA pump ) at 80 psi

in parallel ( comparing 2 NA pumps )
NEARLY twice the flow at the same head
ie min 2.25 x 2 = 4.5 lpm at 40 psi

in your situ, 2.25 + 4.5 lpm ( 341 walbro ) = 6.75 LPM at 40 psi

or alternately two walbro GS342 teed at outlets and dropped into tank
( and wiring revision )
= 2 x 4.5 = 9 lpm at 40 psi


in theory that is--
what may fudge the pressure heads higher than anticipated is the walbro's gear design compared to roller cell bosch/ nippon

ie , its more a positive displacement pump, rather than non
and the other type roller cell could easily be considered much more centrifugal in nature

Vierte

iTrader: (2)

Ok, good info.

so theoretically if i were to run 1000cc/min primaries and 1600cc/min secondaries at 40psi, I would need at least 1Lpm x 2 + 1.6Lpm x 2 = 5.2 Lpm flow rate to the injectors.

So theoretically a NA pump in parallel with a 341 should flow enough at 40psi to properly feed 1000's and 1600's?

fd_neal

iTrader: (4)

Dont forget to add in boost pressure and line drop pressure and give the pump ~20% extra capacity to maintain the desired pressure. If you nover exceed 80% duty cycle with the injectors then youll want to make sure the pumps will flow 5.2L/m at ~65-70psi