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Old 09-20-2007, 11:22 AM
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Too Much Fuel Line?

Is there a downfall (other than $$) to using to large a fuel line?

Im planning out a EFI fuel system and was going to run 1/2 hard line for pressure side and 3/8 hardlind for return, these line connected to fuel rails and pump/filer by -6AN (3/8) Braid.
The pump outlet is 1/4NPT and fuel rail inlet is 3/8NPT, The pump will flow about 50GPH at 45psi.

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Old 09-20-2007, 11:42 AM
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Fuel line

What would be the point other than looks? The 3/8 lines in the system will act as choke points negating any flow advantage of the larger line. To answer your question directly, I don't think they would hurt your system.
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Old 09-20-2007, 12:08 PM
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This was acctuly an old trick in nascar.

The teams would put a 1/2", 5/8", or 3/4" line in diffrent areas on the car so that they could squeese that much more fuel into the system and go that extra lap or two between fuelups.


no downfall that I can see in it, where are you planning on mounting the pump??

Electric pumps are made to push and not pull, so if your planning on mounting it in the engine compartment you may want to add another small/low psi pump at the tank to get the fuel to your injector pump.
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Old 09-20-2007, 03:19 PM
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Quote:
Originally Posted by crash70rs
Is there a downfall (other than $$) to using to large a fuel line?

Im planning out a EFI fuel system and was going to run 1/2 hard line for pressure side and 3/8 hardlind for return, these line connected to fuel rails and pump/filer by -6AN (3/8) Braid.
The pump outlet is 1/4NPT and fuel rail inlet is 3/8NPT, The pump will flow about 50GPH at 45psi.
My hero, Smokey Yunick used really big fuel lines, like 4 inch pipe to increase fuel capacity, worked just fine till NASCAR officials outlawed pipe for fuel lines.

In the real world within reasonable bounds the pump won't care.

Bogie
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Old 09-20-2007, 09:57 PM
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Barry Grant has fuel line diagrams for various systems that support different HP ranges, it is located on the back end of the catalog. Example: he suggest @ 400 HP.... tank to pump AN10 pump to press regulator AN8, to carb AN6 . EFI I think would be AN10 tank to pump and AN8 return, fuel rail AN6, fuel volume is what you are after, but to make sure you have the right answer get his catalog.
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Old 09-21-2007, 09:08 AM
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Thanks for the reply's

The pump is an in-tank set-up, so it'll be pushing the whole way. External pumps for a street car make me nervous..

-10AN for 400hp? thats seems to be really big fuel line, I'm really not flowing all that much. But thanks for the info. I'll check out the catalog and post what I come up with.
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Old 09-21-2007, 10:08 AM
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Quote:
Originally Posted by oldbogie
My hero, Smokey Yunick used really big fuel lines, like 4 inch pipe to increase fuel capacity,
Bogie
Smokey had a mind just a slight bubble off center!! My hero also
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Old 09-23-2007, 11:35 AM
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I have AN 10 from the tank to the pump then AN 8 forward to the motor and pressure regulator. Since I have as relativel cool motor I only use AN 6 to each float bowl. Later when the blower comes I have an AN 8 for a return and I can use up to an 10 for the rest of the system. It's a lot of work to plumb hard line.

Get at least 3 times as much tubing as you figure you need, get some 1/4 to make patterns, get the 37 deg flare tool, don't make the whole line in one piece. Make a practice bend first, make a practice flare. Don't make your first bend on the "good stuff". No matter how many times you cut it off it is still too short.

Be sure to put the nut and sleeve on before you flare the line. Don't ask how I know this. haha
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Old 09-23-2007, 06:00 PM
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Quote:
Originally Posted by bentwings

Be sure to put the nut and sleeve on before you flare the line. Don't ask how I know this. haha

Haha, Yea i've been there to. Russel has these compression type fitting fot hardline, Im gonna give those a go. I'll let everyone know how I make out.
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Old 02-14-2009, 04:13 PM
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fuel line

If you are using a stock oem pump and fuel rail one thing to watch out for is the pressure regulator the oem pump may not pump enough thru the bigger fuel line and could cause driveability issues.just something to keep in mind
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Old 02-16-2009, 03:48 PM
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Quote:
Originally Posted by pepi
Barry Grant has fuel line diagrams for various systems that support different HP ranges, it is located on the back end of the catalog. Example: he suggest @ 400 HP.... tank to pump AN10 pump to press regulator AN8, to carb AN6 . EFI I think would be AN10 tank to pump and AN8 return, fuel rail AN6, fuel volume is what you are after, but to make sure you have the right answer get his catalog.
Thanks for the mention. A lot of our fuel line size requirements relate back to the sizes of pumps that we manufacture as well.Witht he higher volume carbureted pumps they require 1 line size larger to feed them compared to what size line will be ran forward otherwise the pumps can cavitate. that being said would explain why we suggest using a -10 an line to feed a pump that will have -8an running to the regulator. Typically -8 an forward is good up to about 650hp carbureted.

Fuel lines for EFI will differ though because now you are looking for low volume/high pressure as opposed to the high volume/low pressure associated with a carbureted system.
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Old 02-16-2009, 03:49 PM
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Quote:
Originally Posted by johns496
If you are using a stock oem pump and fuel rail one thing to watch out for is the pressure regulator the oem pump may not pump enough thru the bigger fuel line and could cause driveability issues.just something to keep in mind
This would be correct in most cases.
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Old 02-27-2009, 11:42 AM
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Kinda late, but since this thread showed up again i may as well post.

I did set up the fuel system as I mentioned in the first post and it seems to be working good.

I tried keeping the braided sections as short as possible. Since I've heard/read of hydrocarbon seeping through the hose. Seemed kinda odd, but took it under consideration. I did notice some odor at first, but haven't since the cars been parked.

The compression fittings I mentioned work very well also. They were real easy to put on and haven't had leaking issue. You just need to make sure the have a few inches of straight, round tubing.
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