downfall to constantly run dual pumps?
with stock regulator huge psi at low demand. for an aftermarket regulator it really depends how much it can flow. i dont know how much heat would be a problem.a walbro draws right around 8 amps at 45 psi 10 amps at 60psi so your talking ~120 watts per pump which means 240 watts of heat dissipated into the gas. its not like the tank is insulated or anything and has airflow going over the bottom so how much heat can you actually build up? dont know. hot gas is a really big problem for mechanical pumps that draw gas from the tank (negative pressure in line) because any vapor in the line makes it very hard to work with suction... electric pumps though suck from the tank submerged and pressurize the lines which actually raises the boiling point of the gas making it much less likely to vapor lock.
one example of why i dont think heat is a problem though is this. the denso 290 fuel pump in the supra at 45 psi pulls 14.7 amps, and to compare to a single walbro at 45 psi pulls 8 amps. 2 walbros running constanly are pulling effectively the same amps. the supras dont have problems with "hot" fuel that i know of.
i believe one of the reasons gm went to the returnless style fuel system is to keep from adding extra heat to the fuel (hot engine compartment with fuel being returned through it) but i suspect that is more on the emissions side of things, not vapor lock.
so downfalls are potential high pressure at low demand, adding heat which may or may not cause problems and pulling an extra ~10 amps at all times unnecessarily. id just run a pressure switch
one example of why i dont think heat is a problem though is this. the denso 290 fuel pump in the supra at 45 psi pulls 14.7 amps, and to compare to a single walbro at 45 psi pulls 8 amps. 2 walbros running constanly are pulling effectively the same amps. the supras dont have problems with "hot" fuel that i know of.
i believe one of the reasons gm went to the returnless style fuel system is to keep from adding extra heat to the fuel (hot engine compartment with fuel being returned through it) but i suspect that is more on the emissions side of things, not vapor lock.
so downfalls are potential high pressure at low demand, adding heat which may or may not cause problems and pulling an extra ~10 amps at all times unnecessarily. id just run a pressure switch
Last edited by got-a-ls1; Jan 24, 2012 at 01:02 AM.
