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Twin fuel pumps

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Old 09-18-02, 06:59 PM
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Shellhouse
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Question Twin fuel pumps

Anyone ever tried a twin setup using a TT pump and an NA pump?? Could there be any adverse effects to this setup?
Old 09-18-02, 08:13 PM
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Bean
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if they feed into the same line that gets sent to the fuel rail; then i don't see an issue...

but if they used the documented PHR setup where the two pumps 'T' into the fuel rail and exit out the middle; then that would pose a problem because one side of the rail would not be getting enough fuel...

other than that; i don't see why not; except for fitment issues; which shouldn't be an issue
Old 09-18-02, 08:36 PM
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If I go w/ a dual feed rail, I may just T into a single line and back into two by the rail.. Whaddayathink?
Old 09-18-02, 10:04 PM
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The only draw back to that may be that NA pumps are not normaly setup to flow at the higher PSI that you will need to overcome boost. So you might not get much GPM at the pressure you will want to run. Walbro makes intank pumps that will flow well at high PSI and only draw 11amps ea. they sell for $200 ea. and will support upto 1000hp in forced induction application.


good link on fuel pumps

Last edited by NONE; 09-18-02 at 10:10 PM.
Old 09-19-02, 09:43 PM
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Why do a dual feed rail? Using a HKS single rail and fitting some nice 720cc injectors would do just fine

And screw Walboro, get a Weldon race pump <-- a joke for anyone thats heard a Weldon pump before lol
Old 09-19-02, 11:38 PM
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sc300tt
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I have the HKS rail and I had it dual fed, but there are numerous ways it can be done, including single feeding. I would not run a TT pump with an N/A pump for the reason that "NONE" had stated.

I have a Weldon in my 97 and it's quieter than my previous dual Walbro setup due to the nice feature of the Weldon line which, when coupled with the dial-a-flow, the pump rate can be slowed to a crawl when idling and cruising making the pump inaudible. When more fuel is needed, the Weldon triggers into full flow, at which point the pump loudens, but this is usually at WOT so it is not really heard.

But the biggest reason I spent over $1000 on a pump setup was to reduce fuel circulation and the corresponding fuel overheating in a daily driven High HP vehicle. These big pump setups, like a dual walbro, are cooled by the fuel itself, and this fuel is just being circulated over and over and not being used, resulting in EXTREMELY high fuel temps, which can leading to pump failure and more importantly less dense fuel, ie, lean conditions. Cold fuel makes more horsepower and combusts more predictably.

I am advising fuel coolers to be used on all high hp setups, especially when they are daily driven.
Old 09-19-02, 11:47 PM
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Dohc3l
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I run dual walbro, into one line -8 fitting into a aeromotive fuel filter then run the lines up to the fuel rail. It's not that loud and noticable unless you sit in the back seat. Just crank up the music
Old 09-20-02, 12:08 AM
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NONE
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Originally posted by sc300tt
I have the HKS rail and I had it dual fed, but there are numerous ways it can be done, including single feeding. I would not run a TT pump with an N/A pump for the reason that "NONE" had stated.

I have a Weldon in my 97 and it's quieter than my previous dual Walbro setup due to the nice feature of the Weldon line which, when coupled with the dial-a-flow, the pump rate can be slowed to a crawl when idling and cruising making the pump inaudible. When more fuel is needed, the Weldon triggers into full flow, at which point the pump loudens, but this is usually at WOT so it is not really heard.

But the biggest reason I spent over $1000 on a pump setup was to reduce fuel circulation and the corresponding fuel overheating in a daily driven High HP vehicle. These big pump setups, like a dual walbro, are cooled by the fuel itself, and this fuel is just being circulated over and over and not being used, resulting in EXTREMELY high fuel temps, which can leading to pump failure and more importantly less dense fuel, ie, lean conditions. Cold fuel makes more horsepower and combusts more predictably.

I am advising fuel coolers to be used on all high hp setups, especially when they are daily driven.
This is a very good point heated fuel is a major concern. Clint the Weldon you are running is the Dial-a-flow a automatic feature or a manual kinda like the old kenny bell boost-a-pump reostats?
Old 09-20-02, 03:38 AM
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sc300tt
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NONE, the Dial-a-flow is a PWM, Pulse-Width-Modulator meaning that rather than reducing the voltage on the pump, it just sends out short pulses of 12V, which is easier on the electronics in the pump. It has a Rheostat that you can adjust from approximately 0-50% flow. It also has a switch that switches it to race mode of 100% flow. I have this hooked up to a window switch at 3500 rpm. I had also thought about using a Hobbs switch to activiate it once any positive boost was made.
Old 09-20-02, 09:50 AM
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Great info! Didn't consider that the stock pump would crap out at high fuel pressures. May just run dual TT pumps for now.. Good point about the fuel temp.
Old 09-20-02, 11:05 AM
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NONE
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Originally posted by sc300tt
NONE, the Dial-a-flow is a PWM, Pulse-Width-Modulator meaning that rather than reducing the voltage on the pump, it just sends out short pulses of 12V, which is easier on the electronics in the pump. It has a Rheostat that you can adjust from approximately 0-50% flow. It also has a switch that switches it to race mode of 100% flow. I have this hooked up to a window switch at 3500 rpm. I had also thought about using a Hobbs switch to activiate it once any positive boost was made.
Very nice, Sounds like what I am looking for in the 300zx and as luck would have it I havent installed the new pumps yet. Might use those in the SC since it will be a much smaller setup and try the Weldon to feed those 850cc inj in the Z, that would overcome the fuel heating problems we have been trying to avoid.
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