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Question about fuel line and exhaust pressure line?

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Old 04-19-2003, 01:13 AM
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JCJR
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Default Question about fuel line and exhaust pressure line?

My question is....

Some racers loop their fuel line so if their car flips there will be more gas in their lines to prevent the engine from turning off and having to go back and bump start.

I've seen off-road trucks loop the pressure line? What's the reasoning?
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Old 04-19-2003, 03:26 AM
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Default Question about fuel line and exhaust pressure line?

Fuel lines usuall ysip fuel from the bottom of the tank.
When your airborne, your car isnt always vertical, and that means your fuel line isnt getting any fuel.

I guess because you have more fuel in your fuel line, the car will be running till you land.

But, if your upside down and your car doesnt get fuel, your car WILL SHUT DOWN eventually. Theres no escaping that!

MY guess is that if they have to run out of fuel this way, at least they will run out of fuel after they land and not while theyre mid air and trying to control the car.
Acceration pitches up the car and braking does the opposite. This will be very hard to achoice without fuel and might result in a crash.

Well thats my take, dont know how realistic it is!

ram
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Old 04-19-2003, 04:42 AM
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Default Question about fuel line and exhaust pressure line?

LOL the only way a car will loose fuel and die on a jump is if either A. the fuel line pops off. B. the fuel tank is dry. C. If the car is in the air for more then ten seconds or so upside down.

Now most do it for the simple fact ,the more fuel heading to the carb, the longer the car will run upside down after a flip, you know sometimes those fellas on the sidelines flipping all the cars, have a distance to run from one to the other. Also it proves to be a very good idea when your out bashing and say your truck flips about 2 hundred yards away from you, if you got alot of fuel line the truck will more than likely still be running when you get to it. But if you just use the minimum amount of line to reach the carb then you will probably have to prime it and restart it, that is if you didnt forget your starter or plug lighter. And I almost forgot a very good reason is because when the engine is getting a lean amount of fuel it will start to rap up rapidly, and with the wheels off the ground this is VERY BAD!! Get my point? Just remember the ole saying (more is better then not enough)
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Old 04-19-2003, 12:49 PM
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Default Question about fuel line and exhaust pressure line?

But why do some people double loop their exhaust pressure line?
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Old 04-19-2003, 01:25 PM
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Default Question about fuel line and exhaust pressure line?

My understanding of the looping of the exhaust pressure line is:

If you don't have a loop in this line and the truck flips over fuel can go into the exhaust line, especially when the tank is full. Looping prevents it from continuing to the exhaust and leaking fuel out the exhaust. If your truck is a long way away and this happens you can loose a large amount of fuel before you get there.

I've also heard that there may be something that helps with exhaust pressure as well, but that doesn't seem to make sense to me.

My .02 worth...
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Old 04-19-2003, 06:40 PM
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Default Question about fuel line and exhaust pressure line?

If the car or truck flips, the car shuts off cuz the tank is inverted and no fuel will get to the carb?

How would gas come back through the exhaust?

I've heard it creates back pressure But Why? Wouldn't a longer exhaust pressure line make it more difficult to get the tank pressurized?
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Old 04-22-2003, 01:31 PM
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Default Question about fuel line and exhaust pressure line?

My take:

Not sure for the reason of the loop, but by changing the lenght of your pressure line, you can actually help tune your engine.

Example, you add a little length to your line, you now help your engine run a little more lean from probably mid throttle on up.

Not sure this is the reason you see guys loop em, but probably why.
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Old 04-22-2003, 02:28 PM
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Default A little off subject, but:

Ive been checking other discussions on the pressure problems on the Savage. Seems there is a one way valve you can put in line to muffler for a more constant pressure thru the system...Anyone else trying this? Heres a link to the valve in use
http://www2.towerhobbies.com/cgi-bin...?&I=LXG850&P=7
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Old 04-22-2003, 02:37 PM
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Default Question about fuel line and exhaust pressure line?

I have a one-way on the pressure feed to my heli. I don't necessarily use it to help with pressure.

It basically just aids in keeping fuel out of exhaust during fuel up. Heli's fuel through electric fuel pump.

But to answer your problem, yes I use one on the heli w/o ny problems
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Old 04-22-2003, 04:08 PM
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Default Question about fuel line and exhaust pressure line?

Originally posted by JCJR
But why do some people double loop their exhaust pressure line?

I believe these guys hit it right on the nail. To keep fuel from going into the exhuast, and if im not mistaken it will cut down on the pressure in the tank. But as it is alot of folks use it that way, so whats it gonna hurt to give it a shot??
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Old 04-22-2003, 05:50 PM
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Default Question about fuel line and exhaust pressure line?

I have though about making a header tank for the savage.. sometimes when I am running low on fuel I can here the engine lean out on jumps and such.. a header tank should fix that.

should be too hard to pull off. filling it would be a bit difficult though...
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Old 04-22-2003, 05:55 PM
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Default Question about fuel line and exhaust pressure line?

I had one for a short while while running my 8 port on my Savage.

After filling the main tank, I just used air compressor to force air into exhaust which forced gas into the header tank, and into the carb.

Only problem, the header tank wouldn't stay full. Not enough back pressure from the 8 port or RB 086 or something.

I ended up taking it off.

Header tanks work great on Heli's, but I just couldn't get it to go right on the Savage. Although I ended up getting rid of the 8 port because of air leaks, so that may have been the reason the header wouldn't remain full.
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