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FFR Master Builder
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why is it the we run a 5/16 fuel line to a stock fuel rail that is only 1/4, then a 1/4 return line to tank. running the 5/16 fuel shouldnt supply more fuel because it drops down to a 1/4 fuel rail.
 

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FFCobra Fanatic
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Originally posted by jammin1:
why is it the we run a 5/16 fuel line to a stock fuel rail that is only 1/4, then a 1/4 return line to tank. running the 5/16 fuel shouldnt supply more fuel because it drops down to a 1/4 fuel rail.
It won't supply more fuel, but theoretically it should create increased velocity and pressure.


See Ya

Jeff E.
 

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Charter Member
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theres just gotta be a fireman on this forum with some hydraulics background who can explain this to us... (Its not like firemen work everyday, 1 day on 3 days off, lucky bastards)
 

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To pump a fluid through a pipe requires a pressure differential; high on the inlet and lower on the outlet. If you have a given differential, a longer pipe will flow less than a shorter pipe, or a smaller pipe will flow less than a bigger pipe.
Every bend also adds restriction, as if the pipe was longer. More/sharper bends would require a larger pipe size to compensate.
The total restriction of the piping system as seen by the pump is the sum of the friction per foot, plus the friction of direction changes and size/shape changes, plus height changes, and determines the flow at a given pressure.
The supply pipe is larger than the return because there is less flow in the return line at load.
 

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Just Glad to be here - back to working on the car
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If you really want to know the flow restrictions download the trial version and see what you can find out.

Pipe flow software
 

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Cobra Colorist
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Stop! Stop! before Cory's head explodes and ruins a perfectly good helmet.
 

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I'm about half gooned out tonight, so what I post may not make a lot of sense. This is what I have found out about pipes, pressure,and other stuff.
Some years ago I decided to swap my oil fired heating system for a gas fired system. Since I had a gas line into the house it made perfect sense to me, and at that time gas was cheaper. My neighbor, an engineer who designed oil refineries for a living, told me, after being given the BTU's required to fire the furnance, the length of pipe run from the meter and the number of 90 degree bends, that I would need a feed line 4-5 inches in diameter. Being a little under-educated in these things, I believed him but thought that might be a little much. I went to an open house for a new development and checked the basements for the size of their gas supply lines. They were all 3/4" feed lines to the furnace regulators. That made me believe that the regulators had something to do with it.
Anyone see a similarity here? My furnace is keeping me toasty as I type this at 20 outside air temp. :D
Bill
 

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I'm about half gooned out tonight, so what I post may not make a lot of sense. This is what I have found out about pipes, pressure,and other stuff.
Some years ago I decided to swap my oil fired heating system for a gas fired system. Since I had a gas line into the house it made perfect sense to me, and at that time gas was cheaper. My neighbor, an engineer who designed oil refineries for a living, told me, after being given the BTU's required to fire the furnance, the length of pipe run from the meter and the number of 90 degree bends, that I would need a feed line 4-5 inches in diameter. Being a little under-educated in these things, I believed him but thought that might be a little much. I went to an open house for a new development and checked the basements for the size of their gas supply lines. They were all 3/4" feed lines to the furnace regulators. That made me believe that the regulators had something to do with it.
Anyone see a similarity here? My furnace is keeping me toasty as I type this at 20 outside air temp. :D
Bill
 

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Cobra Colorist
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Doug, that was a case of post mongering at it's finest. I remember when I had 300 posts and CC had 600, now I have 1500 and he has 3000. He actually keeps track of my posts, then doubles them...he needs help!
 

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Snake Charmer
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A post in which he didn't sday anything .... :D

Musta been to busy doing something on the
to think of some words to type.


Behaps he is wrestling with the fundamental question of this topic - why?
 

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Alright....OK....In the spirit of staying on topic I deleted my answer. Actually it was on topic just not about fuel rails....something Kathy said to me about size not being all that important...but you guys just wouldn't let it die would you....Nooooooo. You just had to get on my case. Had to get me going.....Geeesh! :rolleyes:

Well never mind that now. It was deleted.



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