Stupid Fuel Line question

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NitroWannabe

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I see guys with I swear 2 feet of fuel line between pipe & tank and between tank & carb. Is there a point to this or do some people just think it looks cool?
 

nitro dave

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I think some guys do it to help the engine stay running when it ends up on its lid, I could be wrong, but I think that is the reason.
 

WoodiE

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The purpose of having the extra lenght of fuel line between the engine and the tank is so in case the car/truck flips over the extra fuel in the longer lenght of the line will keep the car running until you or a turn marshall can flip you back over.


-WoodiE
 

NCNitro

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That can actually hurt performance, your fuel lines should be no more than 8-9 inches, a little longer fuel line will allow your truck to run a little longer while on its roof but there is no performance gain. I have tried it myself and went back to shorter lines, 8-9 inches.
 

x_789

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Like they said the line to carb is incase you flip it to give it a bit more run time to get her back on her wheels. The extra line on pressure side si to keep fuel from getting sucked into the exhaust pipe.
Almost forgot some guys will wind fuel line around all over and add TWO I said TWO Fuel filters so their fuel capcity is larger. This is to get that extra lap befroe needing to refuel. You think it sounds nuts but in a Hour long race this is valuable laps to these guys. X
 
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SkyMaxx

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The fuel line lengths pipe-to-tank and tank-to-carb should be about the same length. The optimal length is somewhere between 8-10 inches long.

If you make the tank-to-carb line longer, you will gain a couple of seconds more of run time should you end up on your lid...but there are some performance factors that need to be addressed concerning fuel line length. Hunter, this may answer your question.

The line from pipe-to-tank is basically acting as your fuel pump. This back pressure line can be shortened or lengthened. If you go shorter, the back pressure provided will increase causing the engine to be force fed fuel at a slightly increased rate. This will in turn cause a rich running condition. Lengthening the line has the exact opposite affect. If you go too far, one extreme or the other, you can impact the running condition beyond your ability to tune the engine.

The line from tank-to-carb can be lengthened or shortened, also. Its length can impact the running of the engine in a similar fashion as the back pressure line. The fuel delivery system is a self leaning system. This means that as the tank gets closer to empty, the engine will start to run leaner. If you shorten the line from tank-to-carb, you can counter this tendancy a little. The shorter line will move fuel to the carb more easily and at higher "flow rate". This increased volume of fuel delivered will cause the engine to want to run rich. By lengthening this line you create the exact opposite affect, and the engine will tend to run lean. As with the back pressure line, working with extremes of length or shortness can impact the performance beyond your ability to tune the engine.

Bottom line, if you know what the affects of changing the length of the respective fuel lines will be on the engine's running characteristics, you should be able to tune accordingly. Just don't go nuts...there is a point where no amount of tuning will counter what you do when you change the length of the lines.

Hunter, I think that is what NCNitro may have been hinting at. It doesn't hurt the performance persay, but it can impact your needle settings and in some instances too much of one can negate your ability to correct with the other.
 
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NCNitro

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Hunter I will try to find the article I read about fuel line lengths and post a link for it. If I remember correctly, if the pressure line is too long it can cause problems in pressurizing the tank properly. But let me see if I can find the article. Like I said I tried both ways and found no benefit to longer lines other than a little more run time on the roof, but if the pickup is out of the fuel you wind up with several inches of air in the line anyway. When it is turned back over in many cases it will only run until the air gets to the carb and die anyway.
 

SkyMaxx

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NCNitro, read my post...that about covers it.
 

NCNitro

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Thank you SkyMaxx, looks like we were posting at the same time. If I remember where I saw the article I will still post the link for you Hunter.
 

El Pirata

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Originally posted by WoodiE
The purpose of having the extra lenght of fuel line between the engine and the tank is so in case the car/truck flips over the extra fuel in the longer lenght of the line will keep the car running until you or a turn marshall can flip you back over.


-WoodiE
Only oval types use turn mashalls. I read some article on the length of fuel lines and exhaust return lines and it stated that they should only be 7 - 9" each. I cut my lines shorter and it has been working well.
 

Hunter

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NCNITRO if you find the article I would like to read it.

SkyMaxx I do understand the principle behind what your saying. I've used hydraulic and neumatic lines for along time and know the longer the line the less pressure you get at the end of the line. I also know we are using a neumatic hydraulic system in our rc's. Neumatic pressure is used to make hydraulic pressure, it takes more air pressure to move the fuel through the fuel line then it would take to move air through the same line. Here is a small tip double tap an old pipe ( run two lines from pipe to fuel tank ) and you wont have the pressure drop in your fuel tank you have now below the half tank mark.
 

SkyMaxx

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Hunter, thanks for the tip. I'm happy with the self leaning nature of the system. It actually increases the performance of my T towards the end of the tank. I tend to run a little on the rich side to begin with. My Fantom is geared toward the low end, so the extra performance running lean would gain me in the high range is not needed.

Amplifying question...do you run the second fuel line into a y fitting and have one feed into the tank or do you add another pressure line tap to the tank? Either way, cutting the length of the single back pressure line should accomplish the same as having two equal length back pressure lines. I'd have to do some math to figure the exact ratio, but it should be one 1/4A length line will result in the same pressure as two 1A length lines (or there abouts).
 
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Hunter

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I double tapped the tank. You can do the Y fitting but you would loose the pressur gain in doing so.
 

SkyMaxx

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Gotcha...may have to experiment with that some time, but as I said...still happy with what I've got.

What I want to see is an offroad tank that has the same kind of set up as aircraft have with the "bell ringer" fitting inside the tank to keep the feed line in the fuel no matter the orientation of the tank.
 

NCNitro

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Sky, I think they are used in RC planes, if I am not mistaken they are called clunkers. I have been thinking about trying to do something like that in my tank.
 

SkyMaxx

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Originally posted by NCNitro
Sky, I think they are used in RC planes, if I am not mistaken they are called clunkers. I have been thinking about trying to do something like that in my tank.

They have various names. Clunkers, Bell Ringers, etc...it all depends on whom you ask. Yes, they are used in RC planes. I think you need to read my posts a little more closely...I mentioned the fact that they use them in aircraft (meant to be read as RC aircraft as real ones use a pressure fed or gravity fed fuel system that is driven by a series of pumps and check-valves).

Anyway, I'd be interested to hear how your experiment works out. I may try one of my own, but at the moment don't have much in the way of free time.
 

ozz_man89

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ther is no performance gain it is if you flip but i have read that the should be less that 9 "
 

NCNitro

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Originally posted by SkyMaxx

I think you need to read my posts a little more closely...

Watch it Sky, I fight back, ;) You never said RC planes. And since I don't know anything about real planes, I have no idea how they are fed fuel in an upside down situation. We are not all in the military, or involved in aviation. :\ So instead of telling me to read your post more closely, maybe you should post more clearly.

BTW I see you have your thin skin on again, lol.
 

SkyMaxx

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No, problem...NCNitro, you are absolutely correct. I didn't say RC Planes. I made an assumption that this being an RC site, most would have read it as RC. Next time, I will make the distinction and post a more correct reply.

As for skin thickness, same as it ever was...just lost interest in beating on the moron. If someone piques my interest, I may come back into the fray, but so far no one has.
 
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