Fueling & Injection - Inline and intank fuel pump discussion

I am having a debate on the installation of an inline pump after the intank to boost/help with pressure & flow.

Here is the debate:
If you take Pump A(intank) rated at 255lph @60psi and Pump B(inline) rated at 190lph @ 60psi, would you, under ideal conditions, actually have ~445lph @60psi, or would Pump B cut your flow back down to 190lph @60psi due to the fact that it is only rated to flow at that?

Tim

You will not get any more flow it will help keep the pressure up but you are not going to pull any extra through the intank pump.

Nate

thats like taking 1 step forward w/ the intank, and 2 back by adding that inline. now, if you were to add two inline 255LPH inline pumps side by side, into a single line, then you could effectively double your flow, but even then any inline is only s good as the amount of fuel you put to it. i'd stick w/ the intank or, if you needed more, go to a sumped setup w/ a big inline.

Thanks for the replies guys.
Anyone else have any opinions and/or facts to back their statement?

treat it just like batteries in a flashlight

if you put two in series (head to tail) it will be twice as bright, but last only as long as one batterly.. if you put them in parallel (side by side) it will only be as bright as one, but last twice as long

for you the brighness is pressure and the lasting time is flow.. we have a regulator which holds pressure constant, so flow is what you want to increase.

maybe that helped?

I understand the concept of the parralel/series thing.
I'm trying to figure out who's right and who's wrong in my debate with someone about putting 2 pumps together and what the outcome is.

you most likely get the full flow of the inline pump. a pumps volume is inversly proportional to the presure you ask it to push.

look at the chart below, i dont know what the stock pump is but lets just say it is similar to the307 like the chart or at least will have similar charistics but at lower numbers. at 60psi it will flow about 50gallons per hour, that is the presure if it has to feed the injecotrs. if you lower that to 5 psi(the presure that would be needed to just pump gas to the inline) the volume goes up to about 73 gallons per hour. the numbers are not exactly right but you get the idea, i would be money that a stock intake pump at 5psi can flow the same volume as a gss340m at 60psi.

http://www.gnttype.org/techarea/fuelsystem/pumpflows/gss307340.gif

one more thing, here is a killer site on fuel systems, there are good articles on fuel pumps, injectors, fuel line and return line sizing. all sorts of good stuff.

http://www.gnttype.org/techarea/fuelsystem/fuelpage.html

hmm, sorry, just reread your post. i thought you were wondering about the benifits of an inline with a stock intake but you allready have a larger intake pump.

the only way that smaller 190 pump would help is if you ran it parallel some how, inline i think it would be a restriction

This is a good topic, I have the racetronix plug and play fuel pump in the car(GSS340 255lph) and a inline 200lph fuel pump from a old s/c set up that I left in the line thinking it would be a good thing. So I am actually hurting the flow of the GSS340 with the inline? Would I be better off removing it or upgrading the inline to a larger unit? The inline turns on at 3psi(hobbs switch) Any help would be great. I need to get a FP guage on this car too:eek2:
Again good topic,
J:D

that one gss340 is good to around 600rwhp, i would think that inline would hurt you more than help.

if you need more than that i am not sure what the best route would be.

Thanks buddy, I am going to pull the fuse on the inline tomorrow to see if that takes away the stumble I have when coming into 5psi(2700rpm to 3900) I think that the intank is fighting the inline and causing a slight fuel lean out until the inline is able to "catch up" with the intank.
I left the inline in because I thought it would be a good thing to do. Guess not? Yeah if I needed more I would go with the dual intank racetronix set up like my bro has in his 95 formula. I also need to get rid of my FMU but that is another topic that I will start when I get pics of how its set up.
J:D:cheers:

just being inline probably causes a restriction. i would take it out completely.

yes do not just pull the fuse.. you'll get even worse pressure drop dragging the fuel through the idle pump.

If you have the 255lph pump IN-LINE and the 190lph IN-TANK , then the 255lph will help the 190lph , but you will decrease the life of the 255lph pump because it will have the drag on it from the 190lph .
Adding the 255lph IN-LINE pump will allow your fuel system to pump more fuel though so it would be beneficial .
However , if you had the higher flowing pump in the tank and the 190 in-line , then you would be hurting your fuel system . Make sense ?
One more thing , if the 255lph pump you are talking about is efficient to 60psi , then you are talking about the GSS307 , which is good to 550 horsepower .