DTSFab.com (Desert, Trail and Sand)

Automotive Powered Off Road (AKA: Buggys, Jeeps, Trucks, Etc,Etc. ) => "AP" General Discusion => Topic started by: BrianN on January 30, 2021, 11:55:01 AM

Title: Fuel tank vent
Post by: BrianN on January 30, 2021, 11:55:01 AM
I have built a larger fuel tank. What size of vent fitting do ya'll recommend? -6, -8, -10? I may have to build a bigger motor, this thing(full) is freakin heavy!
(https://i.postimg.cc/Lg1dxFXL/20210130-124646.jpg) (https://postimg.cc/Lg1dxFXL)
Title: Re: Fuel tank vent
Post by: DeepBusch69 on January 30, 2021, 04:03:53 PM
How many gallons do you estimate you have now?  I used 3/8" line just because I had some.  5/16" would work I bet.  I did change the vent line routing, it used to leak with a full tank parked on hill.  I ran it up around the roll bar then back down along the bottom and back up to about where it starts.  I didn't really want to test it, but first trip, yea I rolled it.   LMAO   5:   :m  It did work great though, not a single drop leaked!
Title: Re: Fuel tank vent
Post by: BrianN on January 30, 2021, 05:10:15 PM
I am guessing close to 9-10. I have been researching vent lines, and what the desert racers do. The subject gets very involved,  concerning safety. It sounds like yours could create a air lock if fuel got into the line while driving.  Am I reading that correctly? I  do read that it should go to the top of the cage, across to one side, then back down to bottom of the frame. Do you have a filter on the end? I know the roll-over valves are definitely something that different people/teams have different opinions on. DSRACE and I have discussed this,  also. I am now spraying my tank with what is supposed to help keep heat out of the tank.
Title: Re: Fuel tank vent
Post by: DeepBusch69 on January 30, 2021, 05:15:41 PM
I have the roll over valve at the tank.  The line then routes just like you described, I did add a filter.  Like you said, it's the way desert racers do it
Title: Re: Fuel tank vent
Post by: BrianN on January 30, 2021, 05:44:10 PM
I need to add that I am not doubting your method, just want to learn the reasoning and proven methods.
Title: Re: Fuel tank vent
Post by: dsrace on January 31, 2021, 06:57:05 AM
this is important and mine had a roll over valve but it didn't vent well. i think the fuel got to it and have been looking into a diff idea. on the last trip when i parked on a slant with a full tank, it ran out my vent.  i do think up the cage and over then back down it a good idea but always open to other ideas!
Title: Re: Fuel tank vent
Post by: dsrace on January 31, 2021, 07:02:03 AM
one issue on mine is the line isn't large enough. i am running 3/8" and it goes to the top of my radiator. that is 2' above the filler neck but while running parked on decent slant it pushed it's way out that pod filter and ran down the tail pipe. luckily it's double wrapped but that could've been very bad! i will be addressing that before the next trip.

https://www.tanksinc.com/index.cfm/page/ptype=results/category_id=160/mode=cat/cat160.htm

i am not sold on the tip over valves as i run e85.
Title: Re: Fuel tank vent
Post by: dsrace on January 31, 2021, 07:07:35 AM
something like this maybe



(https://i.postimg.cc/SnfhSXzb/fats1.jpg) (https://postimg.cc/SnfhSXzb)
Title: Re: Fuel tank vent
Post by: dsrace on January 31, 2021, 07:14:40 AM
brian you should post up some pics of what you've been up to...... you know in between the T.H.A meetings  rofl rofl turbo holics anonymous  LMAO i skipped the last meeting  :m :m




 :nw ;D ;D 
https://i.imgur.com/SFKKdgS.gifv
Title: Re: Fuel tank vent
Post by: BrianN on January 31, 2021, 08:08:10 AM
Yes,  we missed you last week. Nobody knew how to start the meeting without their leader! But I might say, I am starting to think that THA is having a  reverse affect on me. I am simply learning new tricks and meeting new holics. So, boys and girls, if you are trying to kick the boost habit, DON'T call dsrace!

I will share some pics later, when I get organized better.

I went with -8 on my vent. I am considering going straight up to the top of my cage, then a "T", going with larger hose to each side, then down to bottom rails. Criticizing welcome here, because I may be missing something.
Title: Re: Fuel tank vent
Post by: dsrace on January 31, 2021, 09:34:48 AM
last meeting was just new member introductions. i was front row :m :m

https://youtu.be/t8fSwzRzKGg
Title: Re: Fuel tank vent
Post by: fabr on January 31, 2021, 08:40:54 PM
something like this maybe



(https://i.postimg.cc/SnfhSXzb/fats1.jpg) (https://postimg.cc/SnfhSXzb)
That is the only proper way and a vent line doesn't need to be any larger than even an 1/8" *(ya,I used 5/16)unless you are using a dump can to fill the tank like racers do.  Then like 1" or more!
Title: Re: Fuel tank vent
Post by: dsrace on February 01, 2021, 10:14:46 AM
i run 3/8" now and have considered 1/2". i'll give .25" a try when i adapt that diagram.
Title: Re: Fuel tank vent
Post by: dsrace on February 01, 2021, 10:15:18 AM
i do need to figure out a larger tanks before the next st a trip.
Title: Re: Fuel tank vent
Post by: fabr on February 02, 2021, 07:24:01 AM
No need at all for a large vent line. Truth be told ANY size vent will allow plenty of air into the tank to avoid any chance of vacumn. Hell ,  .005" would do!  . ;)  Now,if we were using dry break dump cans to fill our tanks , a very large vent line is required.
Title: Re: Fuel tank vent
Post by: fabr on February 02, 2021, 07:36:17 AM
BTW,a roll over valve is pretty much useless.Almost no sanctioning bodies will accept them.
Title: Re: Fuel tank vent
Post by: dsrace on February 04, 2021, 12:47:22 PM
the brass looking tip over vent i bought from speed is/was useless. the e85 locked it open or corroded. yes brass doesnt do that and the outside is brass. i have no idea what the core is made of, all i know is the check ball quit rolling and fuel kept rolling  :D
Title: Re: Fuel tank vent
Post by: fabr on February 04, 2021, 08:18:02 PM
Route the vent line as far left as possible then as high as possible then continue routing as far as possible following that diagram and you will never have fuel come from it in a rollover no matter how you end up.
Title: Re: Fuel tank vent
Post by: BrianN on February 05, 2021, 09:11:04 AM
Thanks to everyone for ideas. I will go this route. I always consider passenger safety first, so my previous vent ended at drivers side, but we can never predict what the situation will really be. If I burn, that's just the way it goes, but a passenger is a whole different story.
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