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Old 12-24-2002, 11:30 PM   #1
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Default Pressure Line....

Is a longer pressure line better? im a n00bie still and wondering what it does, plz help.
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Old 12-25-2002, 09:42 AM   #2
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i've wondered the same. i noticed in pics that a lot of people have a few coils there. does that help build up a stronger pulse?
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Old 12-25-2002, 10:52 AM   #3
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NOOBS;

a longer line, WEAKER pulses. One coil 6-8" in total length is normal for most 1/10 On-Road Car pressure lines. I like to keep my Fuel lines, short as reasonably possible. Your engines will have much better response this way and it is very noticable when racing.

Last edited by popsracer; 12-26-2002 at 10:47 AM.
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Old 12-25-2002, 10:53 AM   #4
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Sometimes when you have car or buggy that has a .21 engine you may have to try different lengths of pressure line tubing to insure proper engine response.

Somtimes with 1/8 onroad after going down the long straightaways, whe you let off they'res a syphoning effect that tries to suck the fuel out of the tank by the pressure line for a brief second.

By trying longer or shorter pieces of fuel line you can eliminate this problem.

If you have to long of a pressure line the pressure want be enough to sustain the engine with fuel causing a possible lean motor.

with .12 motors this problem hardly exist ecept for the associated Nitro-tc-3 due to its poor tank desisn. It works good for off road not for onroad
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Old 12-25-2002, 01:49 PM   #5
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if we dont need it for .12 engines, then why do i always see longer lines on these cars? are they just trying to look like they know something special? or have i just been seeing tc-3s with this?
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Old 12-25-2002, 03:16 PM   #6
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.12 engines benefit from it as well. Typically .12 engines use 6-10" and .21 engines use 10-14". As already mentioned, you may have to do a little experimenting to find the proper length for your engine/car combo.
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Old 12-26-2002, 02:16 AM   #7
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basically, a longer line SMOOTHS out the pulses. . .

when your motor goes through each cycle, it gives a pulse of exhaust - part of this travels through the pressure line to the gas tank. The smoother the pressure from the pipe to the tank, the steadier the fuel pressure will be.

If you have a larger volume of air (longer tube) you will get smoother pulses because the larger volume of air tends to moderate everything.


There is another reason - if you have several coils of tube and you end up on your lid (which I absolutely NEVER do. . . ) less fuel will run out your pipe. . .
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Old 12-26-2002, 02:33 AM   #8
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The other advantage that I have found running a longer pressure line, that is not often discussed, is that it helps to stop the fuel mixture changing throughout your run. By that I mean it lessens the amount of oil getting back in your tank. Using a fuel filter on the pressure line also helps this.
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Old 12-26-2002, 10:52 AM   #9
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sparksy;

I doubt very much that a fuel filter on the pressure line will stop the oil from getting back to the tank. If you are concerned then just use fresh fuel for every run. All the filter is doing is adding volume to the pressure line, same as running a long line. I've seen people do it at the track, but they usually have removed it by the next weekends race.
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Old 12-26-2002, 04:40 PM   #10
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Quote:
Originally posted by tekrsq
.12 engines benefit from it as well. Typically .12 engines use 6-10" and .21 engines use 10-14". As already mentioned, you may have to do a little experimenting to find the proper length for your engine/car combo.
So if 6-10 inches are useful for the pressure line, how much should i use for the fuel line, i have recently purchased a used MTX2 and it has very short fuel and pressure lines. And i have noticed fuel in the pressure line.
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Old 12-26-2002, 06:07 PM   #11
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My MTX-2 has a 5 1/2" fuel line & 10" pressure line, my MTX-3 has a 6" fuel line & 9" pressure line. No real math to it. I cut/position my fuel line the best route possible, then start with a 10" pressure line. Cut the pressure line if you want to experiment, remember where you had the best performance, and cut a new piece.
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Old 12-26-2002, 06:30 PM   #12
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First of all, any newbie should pay attention and try to search for what he/she wants in the Forum prior to post any new thread. What's the use of "Search" if he/she never does so, but just keep posting new thread. I remembered we have been through this weeks ago.

Anyway, keep it at 8" is what seems to be best according to all the advice we've got.

Sorry for being grumpy my wife's just said no to 950!
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Old 12-26-2002, 07:09 PM   #13
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Quote:
Originally posted by eddiethefish
Sorry for being grumpy my wife's just said no to 950!
You should not go back to Thailand !
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Old 12-26-2002, 08:33 PM   #14
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tekrsq;

Well said.

Quote:
Typically .12 engines use 6-10" and .21 engines use 10-14". As already mentioned, you may have to do a little experimenting to find the proper length for your engine/car combo.
eddiethefish;

The PROBLEM with doing a search is that you always pull up pages and pages of useless information that seemingly takes hours just to find that little bit of info you were looking for.

EVERYBODY;

I get the impression many times that the only answer some will accept is a EXACT answer. (IE: 8" pressure line verses 6"-10" pressure line. What's the best? this or that.). However, most of the questions asked in these forums do not have an EXACT answer.

No two Persons are alike, just as no two Machines (our cars) are alike. Most of the time there are too many variables in this hobby for there to be an EXACT answer to a question.
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Old 12-26-2002, 10:27 PM   #15
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thanks to all who replied, now i know more. i am going to try an 8 inch pressure line instead of the direct, no slack 4" line stupid hpi has on it. i bought fuel line today along with my tranny!! fun fun.
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