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Fuel Line Question

Fuel Line Question

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Old 09-29-2009, 06:44 AM
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Default Fuel Line Question

Does anyone know the approximate CC one foot of fuel line will hold?
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Old 09-29-2009, 06:55 AM
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It can't be much. I use the most direct route. Too much fuel line can decrease the fuel pressue to te engine.
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Old 09-29-2009, 07:44 AM
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I dont believe liquid lose pressure over distance. Think about a garden hose you connect a few together and you still have the same pressure. Yes it takes longer to get there at first, but the pressure is the same... Or am I way off on my thinking???
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Old 09-29-2009, 07:54 AM
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Originally Posted by datracing View Post
I dont believe liquid lose pressure over distance. Think about a garden hose you connect a few together and you still have the same pressure. Yes it takes longer to get there at first, but the pressure is the same... Or am I way off on my thinking???
The longer the line the lower the pressure. Sometimes you wont notice the pressure drop. But like if you are in the shower and someone flushes the pisser you fell the pressure drop. You have to look at how much pressue is pushing the fuel through.

First of all Y do you need so much fuel line. When you go to a big race they will tech you and most likely tell you to get rid of the line.......
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Old 09-29-2009, 08:25 AM
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The fuel line question was to figure out the total CC for my system to meet the ROAR rules...

The reason I asked about the pressure drop, is I am not sure if it is true. Just like you stated if you take a shower and flush a toilet. That is another source taking the water causing the water pressure to drop.. You can not compare the two.

So I just wanted to know if someone really know the answer to the question. I not taking a guess like I am on the garden hose... I am not trying to be a jackass about it just wanting to find the real answer.
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Old 09-29-2009, 08:26 AM
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as long as tank+line < 125cc you're ok.

yes you're losing a bit of pressure with the longer line - then again the pressure is almost nothing at the beginning... the pressure line is more of an equalization one.

R. Savoya (euro champ 08 and 09 and 3rd at the worlds in 08) runs crazy-long fuel lines... and so do I (). Helps you when you're upside down as it then takes longer before dying of fuel starvation (doesn't apply to the great losi take if I understood properly).

Size matters - longer is better

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Old 09-29-2009, 08:27 AM
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Originally Posted by datracing View Post
Th

The reason I asked about the pressure drop, is I am not sure if it is true. Just like you stated if you take a shower and flush a toilet. That is another source taking the water causing the water pressure to drop.. You can not compare the two.
you aren't a jackass - this was a poorly chosen example.

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Old 09-29-2009, 08:41 AM
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Originally Posted by Lonestar View Post
as long as tank+line < 125cc you're ok.
I understood that. So that why I want to know how much 1' of fuel holds. I guess I am headed down to buy a syringe.
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Old 09-29-2009, 09:22 AM
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Originally Posted by Lonestar View Post
as long as tank+line < 125cc you're ok.

yes you're losing a bit of pressure with the longer line - then again the pressure is almost nothing at the beginning... the pressure line is more of an equalization one.

R. Savoya (euro champ 08 and 09 and 3rd at the worlds in 08) runs crazy-long fuel lines... and so do I (). Helps you when you're upside down as it then takes longer before dying of fuel starvation (doesn't apply to the great losi take if I understood properly).

Size matters - longer is better
+1 ... were not talking 100 feet of fuel going through...in general theory you will loose pressure if a hose is ridiculous in length simply because there is more weight to push down the line but a matter of a few inches shouldnt make a HUGE difference.
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Old 09-29-2009, 09:43 AM
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Fuel line length deos have an effect on fuel pressure. Or in our case it restricts the flow of fuel. (We don't really have any pressure)

A NG or LPG fuel line is a good example. If you have to run a long line to reach your furnace/stove/generator, you need a line with a larger diameter or use a higher pressure fuel source. Many co.s try to run long lines and can't figure out why one end of a pipe has good pressure but the other pipe has very little when ever a fuel demand increases.

Also the lower the pressure the more sensitive it is to the length and size of the pipe. So you run 2 pounds of pressure to as close as you can get to your furnace/stove/generator then step it down to 4 onces of pressure.

Because our pressure is near 0, line size and lenght can have a bad effect on fuel flow. You may need to retune for line length changes.




Even worse is that haveing a long fuel line puts it in places where it can get knicked by the brack linkage, header spring, gears etc. I keep my lines reasonably short. My car can run upside down at least 20 seconds.

I run mine just like in the Xray 808 manual except they lay the line over top of the brake linkage and under the air filter. I leave mine loose over the air filter there. That way it deosn't rub the moving brake link and the body holds it down.

I try to stay around 8-10 inches on both lines. The fuel line can be a little longer. I go around the front of my tank once and to the carb.
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Old 09-29-2009, 08:10 PM
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Kyosho (the good large ID blue type) fuel line is .9CC per foot.

(Thats the only one I know...)
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Old 09-29-2009, 09:02 PM
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Originally Posted by datracing View Post
I understood that. So that why I want to know how much 1' of fuel holds. I guess I am headed down to buy a syringe.
The fule line that I have on my bench has about 0.090" i.d. pi/4*(0.090)^2 give the area, multiply by 12" gives a volume of 0.07634 cubic inches which is about 1.25cc/foot.
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