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Old 04-13-2004, 04:50 PM   #1
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Default Extended Return Pressure Tubing

What advantages does this have.

I see soem cars have then long and cable tied up, and others just keep them short.

Thanks
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Old 04-13-2004, 05:51 PM   #2
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One thing I noticed with a long pressure line was that it made my engine idle better.
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Old 04-13-2004, 07:28 PM   #3
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Manticore show'd his car with his extended return pressure tubing...

take a look
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Old 04-13-2004, 07:52 PM   #4
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I did the same thing with mine too
but i did it on the fuel line
I was having trouble with a 5 port making time (5minute qualifyers) but now she runs 30 minute mains with only 1 pit stop!
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Old 04-13-2004, 08:17 PM   #5
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The theory with long pressure line is that it will soften the pressure wave from each combustion cycle (since the tube will flex (expand) more if it is longer, thus not foaming the fuel and evening the pressure waves out a little. In reality, it probably adds more weight than anything. I usually just use a line that is about 12 cm long or so. Just enough to where you can connect it without any sharp bends. This works just fine and is how most factory guys run. Longer fuel line will give you the advantage that you will run a little longer, and if your car goes belly up your engine will run longer before stalling, but it typically also puts you above the 75 cc limit in sanctioned racing, and it adds resistance to the fuel supply. (try sucking on a straw that is 5 feet long rather than one that is 7-8 inches and you know what I mean).
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Old 04-13-2004, 09:11 PM   #6
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Quote:
Originally posted by fmolzer
Longer fuel line will give you the advantage that you will run a little longer, and if your car goes belly up your engine will run longer before stalling, but it typically also puts you above the 75 cc limit in sanctioned racing, and it adds resistance to the fuel supply. (try sucking on a straw that is 5 feet long rather than one that is 7-8 inches and you know what I mean).
So true.
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Old 04-14-2004, 02:03 AM   #7
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Quote:
Originally posted by fmolzer
The theory with long pressure line is that it will soften the pressure wave from each combustion cycle (since the tube will flex (expand) more if it is longer, thus not foaming the fuel and evening the pressure waves out a little. In reality, it probably adds more weight than anything. I usually just use a line that is about 12 cm long or so. Just enough to where you can connect it without any sharp bends. This works just fine and is how most factory guys run. Longer fuel line will give you the advantage that you will run a little longer, and if your car goes belly up your engine will run longer before stalling, but it typically also puts you above the 75 cc limit in sanctioned racing, and it adds resistance to the fuel supply. (try sucking on a straw that is 5 feet long rather than one that is 7-8 inches and you know what I mean).

Ahh the pressure line, from exhaust to tank can be any length last time i checked...

A long pressure line is good for high speed, fast tracks, where you want the amount of fuel supply to be basically kept constant...

Whereas, a short line is for shorter twistier tracks, so the amount of pressure fluctuates quicker...
A long fuel line on a short twisty track will really starve the engine... running from a slow corner onto a high speed straight
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Old 04-14-2004, 03:47 AM   #8
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Thanks for the help everyone.

I'll have a go at longer and compre with shorter lines.
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Old 04-15-2004, 04:21 PM   #9
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I've noticed that running a long fuel line (about 8") really causes the motor to be really hard to tune and the performance goes way down. As soon as I made it as short as possible, the motor ran like a dream.
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Old 04-15-2004, 05:20 PM   #10
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Were all those cars you saw the long pressure line on NTC3's? They run them to keep the tank from foaming so much when the fuel level gets low, so the engine doesn't get lean.

ROAR has a limit on the length of fuel line going to the carb...You can get longer run times, and spoil the 75cc fuel tank rule. If your running a 5 port in a MTX3, I imagine that your running outlaw. Or someone may protest your entry, out of a Main.
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