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Discussion Starter #1
Lift Pump info has been confusing to me.


At what horsepower point is (if) it necessary to add a Lift Pump.


I am planning to stack Quad 215 with Hot Juice.



Any Pros and Cons ?


Edited by: gmccall
 

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Full coverage insurance is always nice. If in doubt ...... Super Diesel


Edited by: Super Diesel
 

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I won't say it is a bad thing, in fact it is definitely a good idea. I wouldn't hold out for any major peak HP gains IMHO.
 

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Has anyone gotten better 1/4 mile times since adding a lift pump with the same mods before and after? I can see it helping at the track more than on the dyno since the injection pump doesn't have to overcome acceleration G-forces sucking the fuel from the tank. However, I'm not convinced I need one. I have one with all the plumbing, pressure switch, ect ready to go, but my truck seems to run just fine without it. I do change filters often, especially during racing season which probably doesn't hurt.
 

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Michael


Why don't you put that pump into play? You could give us a good heads up on how much it did ir did not help.


mike
 

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The issue that gets my attention is as follows.


GM designed the factory fuel system to bypass 30-40 % fuel for cooling/lubrication. At what HP level does the factory system struggle to provide adequate fuel to the injector oulet and also adequate injector/pump bypass flow?
 

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BassinRVer said:
JK, do you have a lift pump setup yet?




Not yet. Bear in mind that my lift pump project is NOT a high performance unit, just a "grade" unit to keep the system under pressure 90% or better of the time...





I may have a HP unit(s) available in the future, but nothing for now...
 

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So it would appear that for those that may even have 475 + - horsepower (rear wheel), should not have problems with Fuel starvation, providing they have fresh fuel filters and properly working fuel system. It appears that those with a whole lot more Hp than myself don't advertise to have them.





Thanks for the info
 

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I have heard from another member that he did gain hp on the dyno when the lift pump was on, compared to being bypassed, minimal, but a gain is a gain. Maybe he will chime in. I have heard others say it is dependent on the truck, It seemed to make a pretty good difference on mine, I cant prove it, but I think it made a difference.
 

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Ok , i'll chime in. I ran on the dyno the first of this week with and without my lift pump. I had a 11hp gain with the lift pump. Now the only variable is, my bypass has a couple of 90's in it which could restrict flow a little, which would put my non pump run a little low. Wether it would be that drastic i won't know, but i have a feeling it wouldn't be 11hp. Not to say 11hp is huge but any gain i/we can get is worth it in my book, and let those high horsepower tunes work like they are suppose too.
 

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Just curious, did you do a 3 run average for bothe setups?


I'll admit that I've not done this for lift vs. non, but I did not see any gains. After seeing dynojet runs, it appears that there is a lot of variance if the runs are not performed exactly the same.





Personally, I try to use a common setpoint to begin my tests. They all use the same mph, and I try to use the same EGT at my trigger point. This can make for some evry consistent runs, as 100° of EGT can make quite a difference in the upswing of the power curve.








Suffice to say, if you can consistently move power curve up or down by altering supply psi, it makes a difference, and should be pretty easily repeatable.Edited by: Kennedy
 

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I would think that those who are running 2 or more filters might see more of a gain from a lift pump, than those just using the OEM. And of course some of the additional filters will flow better than others, so that will also have an impact. So we are comparing apples to apples, those who have dynoed with and without the lift pump, should post what filters they are running, and how many miles were on those filters.
 

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I have run all the testing on both DynoJet and Mustang dyno's with the same results each time. Running High Hp requires a lift pump. What we have found is that all trucks are not the same and with age the lift pump helps more. So in the case of the three trucks we tested each truck preformed better and had a broader torque curve with a lift pump. The amount of gain varied between all three trucks from 9 RwHp to 37 RwHp. What we also found was that if your running 120 Hp or less it didn't make any difference. We ran 5 psi for a test pressure and didn't try any other settings. What we wanted was steady pressure 5 psi at idle and 5 psi at WOT. What we used for a pump was not something that could be used in a daily driven application but we just want things to stay the same for testing. None of the test trucks had any additional filters added. We also installed new fuel filters prior to starting the testing on each truck. Each and every truck was tested the same with the same starting EGT, ECT, TPS and RPM. The Fan was remove from the engine and forced cooling from external fans were used.
 

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Diesel Tech weren't you testing the injector driver(can't remember the name) to see if it would leak under pressure? How is that testing going?
 

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The EDU unit ran for 30 days at 5 psi 24 hours a day, no leaks! Will change to 10 psi next week and start test over again. Everyone need's to remember this is running on the bench and not on an engine. We are just testing to see if it leaks, on a running engine the results maybe different but you've got to start somewhere.
 

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Just an educated guess from a newbie to diesels...


If you are cutting a good 60' time, a lift pump will probably show on your ET. With a diesel, fuel = HP, which is not true in the gas world.


At a 1.91 60' you are pulling 1 g average. That means you are sucking fuel up hill at a 45 deg angle a long distance. I guess that you will lose some fuel pressure on launch. On a gas motor it shows up as lean on launch, which isn't always bad. But on a diesel, it would reduce power.


Just a thought.


PS - It would show up on the 330' split. After that, the g's aren't as much.
 
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