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Help needed with Twin Gas lines

Tech Talk for Nissan owners.

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Help needed with Twin Gas lines

Post by showtime393 »

I've got 2x scuba tanks and a large tank at rear in my 88 GQ (2xB2 converters GT35/40).
Drove 3 hours to have my car dyno tuned and wind some boost in, after sorting out a couple of misfire problems (plug gaps),
first run up showed leaning off at 180rwkw. Cant get enough gas to the converters.
As it stands, it is all a mess under there as far as where gas lines run (thanks to an un-named gas installer.).
I have installed a tee in the single line as close to the tanks as i could. This is clearly not enough feed.

Now I'm in the process of running twin lines all the way but wanted to get some opinions and ideas on the best way to do this.
This is what I have in mind: Scuba tanks are linked together, I was thinking of having a single solinoid on each scuba tank and have them operated together, run one scuba tank to one converter and the other to the other converter. that seems reasonably strait forward.
the rear tank how ever, I'm told only has a single outlet.
Can you have a second outlet installed? I have been told you can remove your guage and run another line from here. Is this possible? and how will I know how much fuel I have?

Any advice much appreciated
Posts: 65
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Re: Help needed with Twin Gas lines

Post by showtime393 »

Come on guys where are you getting your twin lines from. Are you's just putting a tee right at the fitting on the gass tank????
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Re: Help needed with Twin Gas lines

Post by xygthoph351 »

Hi why do you need to run 2 lines ????? What size line do you have now .. Is it a copper line or is it an 8mm flex line ????
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Re: Help needed with Twin Gas lines

Post by cooki_monsta »

mate at that power id be running 10mm line up. Its massive and expensive!!
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Re: Help needed with Twin Gas lines

Post by BadMav »

I don't know gas systems well at all, but (with limited experience) I thought the solenoids at each end would be somewhat of a restriction long before the tubing. Maybe you can get higher flow units?
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Re: Help needed with Twin Gas lines

Post by Tuflux308 »

Hey, this is a very common thing mine was leaning out a 160rwkw and had to install twin lines and converters. The T peice needs to be wound into the tank, then one line comming out each way. Make sure you are using the big fittings which i cant remember the size but its the ones that need a 21mm spanner, Another thing you should do is remove the exess flow valve from your tank because with that power you car will use so much gas the valve will think that a line is cut and shut the gas off, this will instantly lean out the mixtures and could make your engine go bang,
gq wagon now a gq ute, straight gas tb42 with a thing on the side that makes it go fast
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Re: Help needed with Twin Gas lines

Post by stimpy »

how many k's to a tank of gas do you guys get with that set up
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Re: Help needed with Twin Gas lines

Post by Tuflux308 »

460 kms from 110 l tank down the freeway and 200 kms when my right foot gets really heavy. That with 35's, 6 inch lift and 230rwkw.... its not to bad i rekon
gq wagon now a gq ute, straight gas tb42 with a thing on the side that makes it go fast
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Re: Help needed with Twin Gas lines

Post by MyGQ »

thats good considering i did 450-500K's around town and 600+ on the freeway on 100L usable gas and a TB42S
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Re: Help needed with Twin Gas lines

Post by stimpy »

wow thats good i am only get 300 ks out of 90 useable liters
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Re: Help needed with Twin Gas lines

Post by toy77 »

Yeah i'm the same - 300 - 350 out of just under 90L. Mine is a stocker efi / gas tb42. Maybe a turbo soon - i would do it much sooner if i thought i would get an extra 150kms out of a tank!!!
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Re: Help needed with Twin Gas lines

Post by PGS 4WD »

I haven't read all responses so forgive me if I repeat.
You can run two lines two two converters, one from each tank, each tank requires a high flow one way valve (not the rubbish low flow hydrostatic "T" that gas fitters sell), and a hydrostatic valve. Each tank needs the one way valve on the inlet so they cannot back fill each other, which they will do as lockoffs only seal gas from coming out not in. The reason is so one tank cannot cause the other to overfill via the supply line. You can get duel outlet, it requires the removal of the gauge or APA was making a combined overpressure valve with another valve(can't remember which, fill, gauge or oulet). You wil need twin lines and twin converters once you get to about 160 rwkW depending on the dyno.
If you want to switch between tanks, you can't legaly operate off flow one tank due to the excess flow valve operation reducing flow on rapid acceleration.
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Re: Help needed with Twin Gas lines

Post by showtime393 »

Ok thanks guys for all your replies.
Gettin Lockers and lift fitted next week so Im not going to start pulling it apart until i get it back.
Ok If im hearing this correctly I cant legally have it set up to switch between tanks. I mean I dont mind either way. I f I have to set it up to draw out of all tanks at once it just means I wont have a reserve tank.
Where do you get these high flow one way valve from and also where do i get the double outlet guage/valve combo from.
I've looked at a couple of different set-ups now and I've seen the tee piece in the tank outlet. But JPC (who Dyno'd it) told me this will not flow enough as its still only the one small outlet in the tank which wont improve the flow in the lines.
(Oh and they are already the larger lines)
I already have all of the hydrostatic valves and things fitted to pevent overfilling.
Is there such thing as a high flow solinoid. If I could put a high flow solinoid and high flow one way valve on each tank, Surely this would be legal and also allow me to switch betwwen tanks. ( I also have 2 seperate fillers No1 for main tank at rear No2 for scuba tanks which have the hydrostatic valve.)
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Re: Help needed with Twin Gas lines

Post by showtime393 »

Come on guys need more info. Where to find more gas parts? All that sort of stuff.
Will be starting next week and would like to have as much info as possible.
I know there is heaps of guys out there that have similar set-ups. Please post your set-ups and do's and don'ts.
I would rather get it right. Most mod's I have done have generally lead me to a better way of doing it.
Don't wanna set it all up and then have to pull it all back out again to change it.
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