How important is fuel pump at 7-8psi?
05-19-2002, 07:29 PM
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How important is fuel pump at 7-8psi?
Boosting at 7-8psi on a B18B motor, is an upgraded fuel pump necessary at this point? I have everything I need already for my fuel system, except for the fuel pump.
05-19-2002, 07:32 PM
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Re: How important is fuel pump at 7-8psi? (E Swift)
depends on fuel management. are you using a rising rate fmu? if you are, then you need a pump. if not (add'l injectors or large injectors + standalone or vafc hack), then no.
05-19-2002, 09:00 PM
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Re: How important is fuel pump at 7-8psi? (E Swift)
It wouldn't hurt to get a inline or intank 255lph pump. You invested so much money into your car already, why cheap out now? The stock fuel pump has its' limitations and your pushing it. Get one to be on the safe side and get it re-tunned also, you might get more power out of it with the extra fuel pressure.
05-19-2002, 09:08 PM
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Re: How important is fuel pump at 7-8psi? (E Swift)
You can get a walbro intank for around $110.
I think that is what mine cost. I would say it is worth the piece of mind.
I think that is what mine cost. I would say it is worth the piece of mind.
05-20-2002, 01:13 PM
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Re: How important is fuel pump at 7-8psi? (HXMan)
how much are you planning on boosting hx man..??
i wanna boost 7psi...but i dont know if my fuel pressure will be too high
12:1 fmu
fpr
walbro 255lph
vafc
tahts my fuel setup...so i hope i can run that anyone running the same setup...sohcvtec btw
i wanna boost 7psi...but i dont know if my fuel pressure will be too high
12:1 fmu
fpr
walbro 255lph
vafc
tahts my fuel setup...so i hope i can run that anyone running the same setup...sohcvtec btw
05-20-2002, 06:41 PM
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Re: How important is fuel pump at 7-8psi? (FBP Ex-T)
Say a base fuel pressure of 50 psi. Now, for every 1 psi of boost, fuel pressure goes up 12. So its 50+(Boost psi*12)=max fuel pressure
Assume 7psi boost.
50+(7*12)=134psi!!!
I hope you got the high pressure walbro pump. 134psi is alot of pressure.
Now you see why you don't want to go much higher then that on stock injectors.
I am planning on 7-10 psi, but that is with 450cc injectors and hondata.
Assume 7psi boost.
50+(7*12)=134psi!!!
I hope you got the high pressure walbro pump. 134psi is alot of pressure.
Now you see why you don't want to go much higher then that on stock injectors.
I am planning on 7-10 psi, but that is with 450cc injectors and hondata.
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05-20-2002, 07:42 PM
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Re: How important is fuel pump at 7-8psi? (HXMan)
not even the walbro 342 will do that. i know this from experience. 
Say a base fuel pressure of 50 psi. Now, for every 1 psi of boost, fuel pressure goes up 12. So its 50+(Boost psi*12)=max fuel pressure
Assume 7psi boost.
50+(7*12)=134psi!!!
I hope you got the high pressure walbro pump. 134psi is alot of pressure.
Now you see why you don't want to go much higher then that on stock injectors.
I am planning on 7-10 psi, but that is with 450cc injectors and hondata.
Assume 7psi boost.
50+(7*12)=134psi!!!
I hope you got the high pressure walbro pump. 134psi is alot of pressure.
Now you see why you don't want to go much higher then that on stock injectors.
I am planning on 7-10 psi, but that is with 450cc injectors and hondata.
05-20-2002, 08:03 PM
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Re: How important is fuel pump at 7-8psi? (schwett)
ask any racer any real racer, it doesnt matter if you have a bosch high pressure intank pump or a walbro 342, intank is intank! errr, what i mean to say is you NEED AN INLINE FUEL PUMP if you are running 12:1 a fmu. it is not safe to run an intank with that much fuel pressure.
05-20-2002, 08:33 PM
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Re: How important is fuel pump at 7-8psi? (sushibug)
ask any racer any real racer, it doesnt matter if you have a bosch high pressure intank pump or a walbro 342, intank is intank! errr, what i mean to say is you NEED AN INLINE FUEL PUMP if you are running 12:1 a fmu. it is not safe to run an intank with that much fuel pressure.
05-21-2002, 07:51 AM
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Re: How important is fuel pump at 7-8psi? (E Swift)
you will need a fuel and injector with Hondata 2b.. it's a requirement mentioned on their web site
but I suppoes if you are only running 7psi, you dont even need a Hondata. of coz' it's better to have.. but you will live without it...
someone correct me if I am wrong.. I am learning about this stuff too, as I am customizing a turbo kit on my own
but I suppoes if you are only running 7psi, you dont even need a Hondata. of coz' it's better to have.. but you will live without it...
someone correct me if I am wrong.. I am learning about this stuff too, as I am customizing a turbo kit on my own
05-21-2002, 08:37 AM
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Re: How important is fuel pump at 7-8psi? (chusai)
if you need an intake i have a walbro or a gsr for sale
walbro used for 5-6 months
not in the car now...still have the box and everything
walbro used for 5-6 months
not in the car now...still have the box and everything
05-21-2002, 06:57 PM
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Re: How important is fuel pump at 7-8psi? (HXMan)
ok...wat if i use the walbro intank...BUT i run an 8:1 disk...
lets say 50 agian...and 7psi.times 8 is 48..
98psi of fuel pressure on the pump...that seems fine to me..but will it matter if i run an 8:1 or a 12:1??? im gonna lean it out w/my vafc so whats the bigge???
lets say 50 agian...and 7psi.times 8 is 48..
98psi of fuel pressure on the pump...that seems fine to me..but will it matter if i run an 8:1 or a 12:1??? im gonna lean it out w/my vafc so whats the bigge???
05-21-2002, 07:22 PM
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Re: How important is fuel pump at 7-8psi? (chusai)
but I suppoes if you are only running 7psi, you dont even need a Hondata.
You're probably OK for 7psi with the stock pump, but a walbro gss342 is cheap insurance from http://www.autoperformanceengineering.com
05-22-2002, 07:17 PM
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Re: How important is fuel pump at 7-8psi? (FBP Ex-T)
so isnt it possible to lean out the fuel pressure w/my vafc??
05-27-2002, 08:45 PM
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Re: How important is fuel pump at 7-8psi? (FBP Ex-T)
My whole setup right now is RC Engineering 450cc injectors, hondata stage 2b w/boost, fuel regulator, and a fuel rail. I was thinking about getting a Holley fuel pump, but, want to find out what's best for my setup???
05-28-2002, 11:10 PM
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Re: How important is fuel pump at 7-8psi? (FBP Ex-T)
what would 310's do to my pressure????
with FMU ? run a higher duty cycle about 85% and get an 10:1 or 8:1 FMU disk
you'll lower your fuel pressure by a siginificant amount
05-29-2002, 06:07 AM
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Re: How important is fuel pump at 7-8psi? (Flamenco-t)
So the consensus here is to run an inline fuel pump to safely run higher fuel pressure. Can you run a stock fuel pump + inline and FMU at the boost pressure posed here ? (7-8 psi) Or would you NEED both inline and intank pumps ? $bling$ Does sound like overkill at that level tho....
05-29-2002, 08:44 AM
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Re: How important is fuel pump at 7-8psi? (X2BOARD)
OK, enough already. Let's clear up some of this BS.
1. You cannot do the 50psi plus 12:1 makes 135psi bull. It is not reality so get with the real world. No FMU/pump will do that, not inline not intank, not in your dreams. The FMU's raise fuel pressure as best they can and it isn't a nice ratio like 12:1 or 8:1. its more like, raise as much as it can. You use the stock pump and the best fuel pressure you will see is 65psi. You get a well installed inline or intank and the best pressure it can hold is 110 psi. If you need more pressure than that, you are SOL.
2. The pump will determine the pressure, all the FMU can do is stop the flow and hope the pump raises the pressure. The pump will pump its guts out and basically be unstable trying to hold high pressures. See 1.
3. There is no difference between the inline pumps and the intank pumps. That's right you heard me! The reason why SOME people say intank pumps can't handle the pressure is because they are lazy and don't upgrade the WIRING to the pump so it gets the proper power to operate. Inline pumps are usually really close to the battery and require special wiring anyway, so people run nice big 10Ga wires to them with 30A relays, while the intank ones get stuck running off of 20ga wire and low cost relays that drops the available power for the pump substantially and the output of the pump suffers. So if you get a higher flow pump be aware that it needs a substantially bigger conductor to operate properly or you are wasting your money. I have installed intanks correctly and they perform EXACTLY as the comparable inline.
4. You will reach the marginal limits of the system at 7psi. The injectors will begin leaking after a few months of running the high rail pressures required for 7psi and stock injectors. If you want some reliability, don't run past 5.5psi with a FMU system unless you go with bigger injectors and a lower base fuel pressure.
5. Tuning is god, but a FMU system is almost untunable, so your turbo system will not run at peak performance, ever. If someone here can actually tell me how they "tune" their FMU system for peak power at all rpms, I will happily laugh at them.
6. I love you guys.
Randy
1. You cannot do the 50psi plus 12:1 makes 135psi bull. It is not reality so get with the real world. No FMU/pump will do that, not inline not intank, not in your dreams. The FMU's raise fuel pressure as best they can and it isn't a nice ratio like 12:1 or 8:1. its more like, raise as much as it can. You use the stock pump and the best fuel pressure you will see is 65psi. You get a well installed inline or intank and the best pressure it can hold is 110 psi. If you need more pressure than that, you are SOL.
2. The pump will determine the pressure, all the FMU can do is stop the flow and hope the pump raises the pressure. The pump will pump its guts out and basically be unstable trying to hold high pressures. See 1.
3. There is no difference between the inline pumps and the intank pumps. That's right you heard me! The reason why SOME people say intank pumps can't handle the pressure is because they are lazy and don't upgrade the WIRING to the pump so it gets the proper power to operate. Inline pumps are usually really close to the battery and require special wiring anyway, so people run nice big 10Ga wires to them with 30A relays, while the intank ones get stuck running off of 20ga wire and low cost relays that drops the available power for the pump substantially and the output of the pump suffers. So if you get a higher flow pump be aware that it needs a substantially bigger conductor to operate properly or you are wasting your money. I have installed intanks correctly and they perform EXACTLY as the comparable inline.
4. You will reach the marginal limits of the system at 7psi. The injectors will begin leaking after a few months of running the high rail pressures required for 7psi and stock injectors. If you want some reliability, don't run past 5.5psi with a FMU system unless you go with bigger injectors and a lower base fuel pressure.
5. Tuning is god, but a FMU system is almost untunable, so your turbo system will not run at peak performance, ever. If someone here can actually tell me how they "tune" their FMU system for peak power at all rpms, I will happily laugh at them.
6. I love you guys.
Randy
05-29-2002, 11:16 AM
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Re: How important is fuel pump at 7-8psi? (RGAZ)
Randy -
The reason in-line pumps perform better with FMUs is that two pumps operating in series can "add" their max pressure capacities. IE if your stock intank pump is pushing 50 PSI at a given flow and your bosch inline is pushing 100 PSI at that same flow, you CAN have 150 PSI rail pressure. If you put that same bosch pump in your tank all by itself, you can only attain 100 psi rail pressure.
2 identical pumps in series = twice the head at same flow
2 identical pumps in parallel = twice the flow at same head
I'm an engineer too but I only dance for a 10-spot or more.
The reason in-line pumps perform better with FMUs is that two pumps operating in series can "add" their max pressure capacities. IE if your stock intank pump is pushing 50 PSI at a given flow and your bosch inline is pushing 100 PSI at that same flow, you CAN have 150 PSI rail pressure. If you put that same bosch pump in your tank all by itself, you can only attain 100 psi rail pressure.
2 identical pumps in series = twice the head at same flow
2 identical pumps in parallel = twice the flow at same head
I'm an engineer too but I only dance for a 10-spot or more.