Gday guys, Just a thought.
Has anyone ever thought of increasing the size of the standard fuel tank breather on a LC/LJ???
I am going to be making a custom tank up at some stage and just looking at teh size of the puny little 3/16" line i thought that perhaps this may cause starvation at high revs/high fuel demand.
Seeing though I wont be thrashing the car except for on the quarter mile it probably wont be a drama, but i thought that perhaps a 5/16" line bent into a similar shape to the standard one would be better???
I dont want to vent into the boot area.
I wont be using the standard fuel tank pickup anymore, that will simply be in there for a fuel sender, so i was thinking that perhaps i might be able to cut the pipe off just as it goes into the tank (leaving one side of it to hold the sender if you follow me) and run 5/16" bundy up the back of the rear firewall as per factory.....
Just ideas.
Any thoughts? Has anyone ever had any dramas with this before?
Cheers.
Fuel tank breather
Started by
_Bomber Watson_
, Jan 04 2009 12:08 PM
27 replies to this topic
#2
_scottya!_
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Posted 04 January 2009 - 01:04 PM
Hello Bomberwatson, just my thought only. The amount of air being sucked into thr fuel tank should be equal too or greater than the amount of fuel
being sucked out to avoid any vacumm in the tank. cheers scott.
being sucked out to avoid any vacumm in the tank. cheers scott.
#3
_Bomber Watson_
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Posted 04 January 2009 - 02:38 PM
Exactly my thought.
Now fair enough the motor probably wont be drawing as much as the fuel lines heading to it can deliver, and with a standard motor the standard sized breather would be perfectly ample, but in a high performance application i think that a larger one could be beneficial.
Thats why i started this thread to discuss this..
Cheers for your input.
Now fair enough the motor probably wont be drawing as much as the fuel lines heading to it can deliver, and with a standard motor the standard sized breather would be perfectly ample, but in a high performance application i think that a larger one could be beneficial.
Thats why i started this thread to discuss this..
Cheers for your input.
#4
rodomo
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Posted 04 January 2009 - 02:40 PM
Just leave the cap off.
#5
_Drag lc_
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Posted 04 January 2009 - 03:23 PM
we have std breather pipe and suction on ours but it would be a good idea i think our fuel cap has a vent init
judging buy the amount of fuel that used to piss out of it.
Thanks hayden
judging buy the amount of fuel that used to piss out of it.
Thanks hayden
#6
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Posted 04 January 2009 - 03:48 PM
there is no way in hell an engine could use that amount of fuel to create problems with this... even on metho running half inch ruel lines from the tank/holley blue/uni filter still have never seen any probs but, if i was making a custom tank i would use 5/16 or 3/8 just because its easier to get one way valves etc for breathers which is what ascf rules used to specify for speedway use but most people simply use a fuel filter which is pretty scarey when you think about it... my lj used to use just under a litre a lap of methanol and never had a lean out problem admittedly with a fuel cell but had the same engine in my street car with standard tank as well but then again i used to get pinned at willowbank regularly for fuel coming out from around the cap when it launches as most lc/lj's dont seal properley...
cheers
micko
cheers
micko
#7
_Bomber Watson_
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Posted 04 January 2009 - 06:44 PM
Yes im thinking about going to a motorbike type fuel filler to stop the leaking.
So basically not really needed but i can do it if it makes me feel spethial (said with lots of spit). Also i never thought of a one way valve, i like that idea and will incorporate one.
Cheers.
So basically not really needed but i can do it if it makes me feel spethial (said with lots of spit). Also i never thought of a one way valve, i like that idea and will incorporate one.
Cheers.
#8
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Posted 04 January 2009 - 09:08 PM
what toranas and the like hq-hz fuel filler design really suffer badly from is when you launch they all pour fuel out onto the ground... i remember even when i had my hk's - hg's in the old days you could look in the side mirror when going around a left corner and watch the fuel cleaning the road... same with hq - z wagons they need something like a late model fuel filler neck with the unleaded style flap to alleviate these problems... on mine all i did was put half a roll of insulation tape around the end of the neck at willowbank one night and no more fuel leaks... i did not have any problems when i had the xu1 cap but ever since i was relieved of it i just have the standard torry one with the holden emblem in it...
micko
micko
#9
_sshatch355_
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Posted 04 January 2009 - 10:39 PM
a few years ago when we actualy had a drag strip that was open (yes im bitter n hate bob jane) there was i think it was a camaro with a full house pat mussi bbc that wasnt running the numbers it should of and after a lot of hair pulling it was found the fix was as simple as removing the petrol cap as the breather was not big enough to cope with the amount of fuel being used. as soon as it was removed the numbers dropped...
his engine was making huge power so not sure how relavent it would be but guess every lil bit helps
his engine was making huge power so not sure how relavent it would be but guess every lil bit helps
#10
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Posted 05 January 2009 - 12:23 AM
a few years ago when we actualy had a drag strip that was open (yes im bitter n hate bob jane) there was i think it was a camaro with a full house pat mussi bbc that wasnt running the numbers it should of and after a lot of hair pulling it was found the fix was as simple as removing the petrol cap as the breather was not big enough to cope with the amount of fuel being used. as soon as it was removed the numbers dropped...
his engine was making huge power so not sure how relavent it would be but guess every lil bit helps
mate do you realise how much volume even a 5/16 hose can move?? i mean look at it like this, you are talking about an engine if it has 1 carby say a 1050 dominator/bg demon/whatever for arguements sake and it runs 9.50's over the quarter... how much can it use during this time... lets say 1 litre which is way over the top... now get the same 5/16 hose and siphon some fuel for 10 seconds and see how much you get... i mean in theory if you hav a 5/16 breather you would need to have a larger than 5/16 size hose amount of fuel going into the engine for the effect to be reversed... its just physics... and common sense...
and did they seriously let this dude race without a petrol cap?? if so no wonder the place got shut down... or did someone get killed??
micko
#11
_sshatch355_
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Posted 05 January 2009 - 02:00 AM
mate its what the owner of the car said so weather or not he was just talkn shit i honestly wouldnt know but you try n draining a 44 gallon drum through a tap and see what happens if you dont crack the lid on the top????
it made sence to me at the time and i hadnt ever thought about it till i saw the post...
cheers pete
it made sence to me at the time and i hadnt ever thought about it till i saw the post...
cheers pete
#12
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Posted 06 January 2009 - 05:50 PM
my point exactly... this is what you are trying to say... and in theory couldnt possibly happen unless the outlet (in this case the jets/venturies)is bigger than the inlet(in this case the breather ie:5/16 hose)
micko
micko
#13
_Bomber Watson_
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Posted 06 January 2009 - 06:01 PM
The standard breather is 3/16" as i say in my first post mate.
I was thinking about changing it to 5/16".
I was thinking about changing it to 5/16".
#14
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Posted 06 January 2009 - 06:06 PM
yeah on an lj it is... correct... but sshatch was talking about a camaro if i am not mistaken??
cheers
micko
cheers
micko
#15
_Bomber Watson_
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Posted 06 January 2009 - 07:33 PM
True true.
But we are talking about Toranas here not Camaro's, it gets confusing once we start mixing these things up.
Where can i get one of those one way valves from?
Cheers.
But we are talking about Toranas here not Camaro's, it gets confusing once we start mixing these things up.
Where can i get one of those one way valves from?
Cheers.
#16
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Posted 06 January 2009 - 07:48 PM
yes correct... all of us were, except sshatch
i hear ya loud and clear bomber lol
micko
i hear ya loud and clear bomber lol
micko
#17
_scottya!_
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Posted 06 January 2009 - 08:39 PM
Hi bomber watson, speed flow do inline check valves, not sure what size they start at. Maybe -6 might be the smallest. Anyhow, go with your first thought and all should be fine. cheers !
#18
_lx-304_
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Posted 06 January 2009 - 08:48 PM
any hydraulic place will sell them as well
#19
_sshatch355_
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Posted 06 January 2009 - 09:08 PM
yes correct... all of us were, except sshatch
i hear ya loud and clear bomber lol
micko
was just relating a something i thought may be relevent to the issue
guess ill go back under my rock 
#20
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Posted 06 January 2009 - 09:24 PM
sorry mate i didnt read your post psoperley, yeah most places do them but you are paying for a name usually... i just get mine from lewis hoses and seals down here as the dont need to look pretty and brass does fine in the race cars... if you have dramas getting one let me know and i can call in and grab you one and post it up?? or maybe check out ebay also??
cheers
micko
cheers
micko
#21
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Posted 06 January 2009 - 09:25 PM
lol sshatch, its all good i was just trying to get you to understand the physics of your statement... after all this is a forum...
micko
micko
#22
_sshatch355_
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Posted 06 January 2009 - 09:40 PM
^^^^^^^^^physics never was my strong point but when it comes to drinkn then that i know 
ive got no problem being corrected when wrong, its one of the best ways to learn.....
ive got no problem being corrected when wrong, its one of the best ways to learn.....
#23
_Bomber Watson_
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Posted 06 January 2009 - 10:10 PM
Basically though the statement would work and its a valid one.
At the end of the day if X amount leaves the tank in Y time then X amount must get back into the tank in Y time.
Now dont try to tell me no motor would drain more than a 3/16" line can provide back, even if air is more viscous than fuel.
Cheers.
At the end of the day if X amount leaves the tank in Y time then X amount must get back into the tank in Y time.
Now dont try to tell me no motor would drain more than a 3/16" line can provide back, even if air is more viscous than fuel.
Cheers.
Edited by Bomber Watson, 06 January 2009 - 10:11 PM.
#24
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Posted 06 January 2009 - 10:29 PM
something else that should also be pointed out guys... what happens when you get a sealed drum of fuel and slosh it around??
micko
micko
#25
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Posted 06 January 2009 - 11:22 PM
Depends on what you are using for fuel?
Slosh some E85 and marvel at the lack of aeration.....
Bomber for reference. I have one x -6 vent in my system which is a replica of the system that is used in 90% of the current supercars. No problems at all either on track or dyno 496@the wheels.
Cheers Greg...
Slosh some E85 and marvel at the lack of aeration.....
Bomber for reference. I have one x -6 vent in my system which is a replica of the system that is used in 90% of the current supercars. No problems at all either on track or dyno 496@the wheels.
Cheers Greg...
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