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Discussion Starter #1
I've been looking for some info on at what point is a Lift-Pump upgrade needed? And why is this....?2004 GMC c.c.s.b.4x4 lb7 Quad/215 /edge
 

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Typically a lift pump is needed for BIG single programs and/or big stacked programs. The lift pump is there to keep a constant pressure at the low pressure side of the injection pump, which in turn keeps the injector rails happily supplied with the desired amount of pressure. In a nut shell....:D
 

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General concensis around here is that lift pumps are never a bad idea, Bosch calls for them with the fuel system, but GM decided that they were not necisary. I would have to say that when you get above the +150 area that lift pumps should be the next upgrade that you make. There are several vendors on this site that have nice lift pump setups.
 

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From our testing lift pump assemble will start helping above 300 RwHp. Now do not think it is going to give you 20 extra Hp or anything like that. What is will do is keep the fuel system full of fuel how Bosch had the design to start with. The Big programs like our Xtreme will need these to run properly at full power. Without pumps and with a big program you can be down 20 - 25 Hp from where you could be. We have two different kits for the different power levels. Check out our web site and you can see them install. Our kit come complete with everything you need to install them..
 

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Discussion Starter #5
How about going w/ a single carter pump they make one that puts out 15 psi..w/ 3/8 fittings.I think that would work instead of a dual pump set up?????
 

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How about going w/ a single carter pump they make one that puts out 15 psi..w/ 3/8 fittings.I think that would work instead of a dual pump set up?????
The reason for the duals is not pressure but volume. You really don't need that much pressure as you are feeding a pumping system that is designed to pull fuel at vacuum, and being positive displacement - adding pressure at the inlet has no effect on the outlet. But adding big volume at low pressure will allow the system to perform without loss of intake volume and subsequent fuel rail pressure.
 

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Discussion Starter #7
That does make good sense!! thanks>> Is there any-one running single pump systems on big stacks, that is actually working for them????
 

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Yes, someone (I wont volunteer their name) is running a carter on one truck and an edelbrock pump on the other. Essentially the same pumps with different price tags. Both have performed well, very well Id say.
 

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Discussion Starter #9
See I new it can be done,Prob a pretty simple set up too...The set up super diesel came up with was a very simple local auto build..We run basically the same set up on our aircraft race motor when we throw the juice to it..
Did the set up your talkin about use the Carter 7 psi 100 gph pump or the 15 psi pump??
 

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Hmmmm, that gets me to thinkin' if a fuel accumulator is all that's really needed instead of dual pumps. If you have, for example, a one-quart "can" up near the injection pump that is pumped up to the output pressure of your single fuel pump, wouldn't it provide enough "surge volume" to keep the pump fed during 1/4 mile runs or sled pulls without having to plumb and wire in a second fuel pump?
 

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Discussion Starter #11
See now were gettin somewhere, I cant see the injector pump starvin with with say 10 to 15 psi feedin it.. I've got both the 7 and 15 psi pump. Need to try it, I'm just questioning the high pressure effect on it.If you don't run out of fuel in a high hp nitrous motor (gas motor) and it's also adding exta fuel when the bottles on I dont see a diesel doing it on a high stacked unit.. Just my opinion, I need to do some trial and error!
 

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Think volume lb7diesel. 8 feet of 3/8" tubing pumped up to 15 psi doesn't hold much more fuel than the same tubing pumped up to 7 psi (remember, fuel is not very compressible!) When the "big dawg" begins to eat, you better have some Kibbles in the bowl! I think a quart or so of pressurized fuel close to the pump (with a check valve just upstream, so it won't "backflow" into the fuel line in both directions when the pump starts to really suck on the fuel) would handle short term fuel demands.
 

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Discussion Starter #13
Kinda like a horse at a trauf (when she's thirty it there for her to drink!) I follow you. Bottom line you want something with more gallons per hour capability. Or a "canaster" so at any sudden moment she can drink>Really I was just wondering is if any-one was running a big stack on an lb7 , And has found a single pump system that has worked for them??
 

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Just remember what pressure is. It is the resistance to flow. So when that big program commands a lot of fuel with an accumulator you need to have enough stored to cover the surge and allow the fuel pump to recover before it becomes a problem.
 
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