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· PTE 71mm dbb
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Discussion Starter · #1 ·
I have 1000cc injectors with a fuelrail with 2 -6an fittings. aeromotive btr and two walbros.

I only have one feed line right now -6an from the tank. and thinking of using of the stock return line.

But I have read around a bit now, and I think this is not enough.
So should I go for a -6an return line, and use the stock feed line as a second feeding line to the fuel rail?
Or is one -6an feeding line enough to support the enginge with fuel?
 

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Its hard to say, Ive seen a single -6 support some serious power but could have been from a BAP.
Why not use your stock return as the return, your -6 and the stock feed as the feed lines? Your post is confusing? Or are you saying your stock feed line was removed? If so, just run a cheap return line to the tank(its not presurised like the feed is) if money is your concern and use the stock feed and 6an as the feed. Im even more confused now, was your stock return line removed?
 

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That might be one of the worst setups I've seen lately...

1000cc for 750rwhp is too big
1x 6an is too small
and two walbros are just a really bad idea ... read about reliability with walbro ... also they won't hold pressure when output is required.

for 750rwhp you want:

750/780/800cc injectors
1x 8an feed from the tank (2x 6an for the rail is fine)
stock feed as return (6an from FPR to stock line is good)
2x denso oem-pumps or 2x bosch 044

:)
 

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That might be one of the worst setups I've seen lately...

1000cc for 750rwhp is too big
1x 6an is too small
and two walbros are just a really bad idea ... read about reliability with walbro ... also they won't hold pressure when output is required.

for 750rwhp you want:

750/780/800cc injectors
1x 8an feed from the tank (2x 6an for the rail is fine)
stock feed as return (6an from FPR to stock line is good)
2x denso oem-pumps or 2x bosch 044

:)
Safety rule: Always do 200cc above your goal on injectors. Better safe than sorry.

Agreed on the 1 -6= Not such a good idea. X2 -6

Walbros, youll be gambling. It will do fine, but i keep hearing bad shit about walbros going out. Last story i heard, one walbro went out, blew his motor, and now, its a bare shell. Not such a good idea, invest another 100$ and get 2 densos.
 

· PTE 71mm dbb
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286 Posts
Discussion Starter · #6 ·
Its hard to say, Ive seen a single -6 support some serious power but could have been from a BAP.
Why not use your stock return as the return, your -6 and the stock feed as the feed lines? Your post is confusing? Or are you saying your stock feed line was removed? If so, just run a cheap return line to the tank(its not presurised like the feed is) if money is your concern and use the stock feed and 6an as the feed. Im even more confused now, was your stock return line removed?
My english is maybe not the best, thats maybe why you got confused.
Everything stock is still there.

I only have a fuel rail with two fittings so I can only feed it with one -6 line. (didnt think about this when I first posted)
What is BAP? :)

Many people over here in Sweden are running 1000cc injectors when driving with a 71-72mm dbb turbo. Better to be safe.
But is the stock return line enough? Beacuse some dude said that when he was just driving around, the car was running a little bit to much fuel beacfuse of the return was to small?! Is this just bullshit or shall I just go for my stock return line?

Im doing my last order from summit in this weekend, so I want to have everything on the list so I dont need to order again.

Thanks everybody for helping me! :)
 

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Safety rule: Always do 200cc above your goal on injectors. Better safe than sorry.

Agreed on the 1 -6= Not such a good idea. X2 -6

Walbros, youll be gambling. It will do fine, but i keep hearing bad shit about walbros going out. Last story i heard, one walbro went out, blew his motor, and now, its a bare shell. Not such a good idea, invest another 100$ and get 2 densos.
You're forgetting about the effect of fuel-pressure on injector output!

A 750cc injector (usually rated at 43PSI) with a 1:1 FuelPressureRegulator will output 880cc at 90% duty-cycle!
 

· EchoDeDupra
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Right now, i'm running 880cc's with twin -6 feeds, dual walbros, and the stock return.

I'm really looking hard into upgrading to 1200cc's. Am I fine as far as my fuel lines and fuel pumps go?
 

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You're forgetting about the effect of fuel-pressure on injector output!

A 750cc injector (usually rated at 43PSI) with a 1:1 FuelPressureRegulator will output 880cc at 90% duty-cycle!
What? The 1:1 regulator just keeps the pressure differential across the injector constant as boost rises. You don't get more flow unless you bump the base pressure.
 

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What? The 1:1 regulator just keeps the pressure differential across the injector constant as boost rises. You don't get more flow unless you bump the base pressure.
wrong.
 

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LOL, sure thing man. Pressure differential moves a fluid, not absolute pressure. If you've got a base pressure of 43 psi and your running 30 psi of boost with a 1:1 regulator, you've got 73 psi of fuel pressure....BUT, you're now injecting into a region that is at 30psi, thus your net pressure differential across the injector is still 43 psi. Hence, no extra flow and you're 750cc injector is still a 750cc injector.

Careful giving fuel system advice.
 

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LOL, sure thing man. Pressure differential moves a fluid, not absolute pressure. If you've got a base pressure of 43 psi and your running 30 psi of boost with a 1:1 regulator, you've got 73 psi of fuel pressure....BUT, you're now injecting into a region that is at 30psi, thus your net pressure differential across the injector is still 43 psi. Hence, no extra flow and you're 750cc injector is still a 750cc injector.

Careful giving fuel system advice.
still wrong. Nice theory though ;)
 

· Wheel Fitment Guru
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You're forgetting about the effect of fuel-pressure on injector output!

A 750cc injector (usually rated at 43PSI) with a 1:1 FuelPressureRegulator will output 880cc at 90% duty-cycle!
WTF just happend here?

LOL, sure thing man. Pressure differential moves a fluid, not absolute pressure. If you've got a base pressure of 43 psi and your running 30 psi of boost with a 1:1 regulator, you've got 73 psi of fuel pressure....BUT, you're now injecting into a region that is at 30psi, thus your net pressure differential across the injector is still 43 psi. Hence, no extra flow and you're 750cc injector is still a 750cc injector.

Careful giving fuel system advice.
Exactly.

why is he wrong? Please explain.
I definitely want to here this explaination. Why upgrade your injectors at all:nervous: .

R.K.
 

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So what is your theory then....
I'm dying to hear it at well. What I explained is the whole point OEMs put 1:1 regulators on most forced induction cars -so fuel flow doesn't taper as boost pressure opposes the fuel rail pressure. Now some aftermarket companies sell 1.5:1, 2:1, etc regulators. In that case you actually DO get more injector flow as boost rises (assuming you've got a fuel pump that can keep up with the massive pressure jump).

To the original poster, the 1000ccs are fine (assuming you can tune the idle to your satisfaction) but I would do a single -8 feed or 2x -6s.
 

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I'm dying to hear it at well. What I explained is the whole point OEMs put 1:1 regulators on most forced induction cars -so fuel flow doesn't taper as boost pressure opposes the fuel rail pressure. Now some aftermarket companies sell 1.5:1, 2:1, etc regulators. In that case you actually DO get more injector flow as boost rises (assuming you've got a fuel pump that can keep up with the massive pressure jump).

To the original poster, the 1000ccs are fine (assuming you can tune the idle to your satisfaction) but I would do a single -8 feed or 2x -6s.
+1^ unless you are running oxygenated fuel 1000cc injectors are fine
 

· PTE 71mm dbb
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Discussion Starter · #19 ·

· EchoDeDupra
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7,159 Posts
^ Yup... the wiring is the same for the stock fuel pumps and the walbros. Just use two relays and wire it like above. It's also a good idea, if you have the extra wire, to wire in an LED warning light to the main power line to each fuel pump. Wire it in series, and mount the LEDs somewhere you can see that way you will always know when your pumps are on.

There are other variations of this, such as warning buzzers, etc., but it really comes to how technical you want to be. I kind of like the peace of mind of looking down before a WOT pull and knowing both pumps are running.
 
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