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Bobnotch
Samba Member
Joined: July 06, 2003
Posts: 22425
Location: Kimball, Mi
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 Posted: Tue Aug 28, 2012 8:33 pm Post subject: |
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| JSMskater wrote: |
| You don't need the special FI hose. Our cars see a max of 30 Psi, and they have a burst rate around 120. This has been answered over the years numerous times, and not a single reported failure or leak. |
Actually Russ did some testing on fuel hoses used on our cars. He found that the German hose (woven braided stuff), would burst at 60PSI (he dead headed a type 3 fuel pump, and the hose blew apart). The standard non-fi fuel hose (what carb cars would normally use, and what we've been talking about), is rated to 120 psi, and it actually bursts at 250 psi (he did this at work under controlled circumstances). That's more than enough for D-jet. And he also tested the expensive FI rated hose (lists a 250 burst pressure) and found it was good to 600 psi. This means that most of the American (SAE) hose is actually under rated to the actuall burst pressures. 
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http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
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| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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vlad01
Samba Member
Joined: October 27, 2010
Posts: 3069
Location: Australia
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| Posted: Tue Aug 28, 2012 9:36 pm Post subject: |
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And that why I use ONLY! use EFI hose on EFI systems. Coz over kill is the only way to unsure reliability and peace of mind. The thing is that as rubber hoes age the max pressure they can take falls considerably, so the higher the rating the more head room once the hoses deteriorate and less chance of premature failure (burn you vw to the ground  )
EFI hose is also specially designed to take more punishment and last longer due to the rubber compound and construction of the hose. general hose is for carbs and should stay on carbs, efi hoses for efi. simple.
its like stuffing around with lesser quality brake parts coz is cheaper and you think it more than good enough. Wrong logic!
for the sake of a couple of bucks just use the proper rated hose and be done with peoples. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sun Sep 02, 2012 7:22 am Post subject: |
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| vlad01 wrote: |
| JSMskater wrote: |
You don't need the special FI hose. Our cars see a max of 30 Psi, and they have a burst rate around 120. This has been answered over the years numerous times, and not a single reported failure or leak. Vlad is probably used to modern systems which run CONSIDERABLY higher pressures.
As far as length goes, I usually buy 14 feet -- and that does EVERYTHING with enough left over to use a bit as vacuum hose where it'll fit. 20-25 feet is overkill IMO. |
yes 43 psi, not much higher, but still a general fuel hose on efi regardless of efi specs is big no no! |
Yes.... a general fuel hose is a no-no on EFI....I dont care how much its been discussed over the years. There is a very good reason why every pressure range of hose has about a 5X overkill pressure margin.
The burst pressure is only good when there are no outside variables that lower its resistance. Every large variable thrown at the fuel hose drops its pressure rating by about 1X or more of the total 5X amount.
For example.... One very large variable is heat. When you add heat to any rubber product...synthetic or natural...it begins to flow and durometer, tensile strength and burst strength drop by a large factor. Add to this issue...the fact that the multiple plies and layers are made of different materials...and expand at different rates....this aids in long term delamination...which is one of the primary weakeners and failure factors.
Another variable is external oils and solvents (not to mention ozone). It weakens the outer sheath in multilayer hose (which you better be using)....allowing the inner sections to bulge outward furthering long term delamination.
Another variable is vibration. This causes inner layers to squirm just like the plies in a tire. This will...over time....always cause delamination of inner layers...always. Couple vibration with heat and pressure and hose begins a long slow degradation from the day it starts getting used.
Another huge variable is cold. Cycles of heat and cold cause raising and lowering of the durometer of the rubber layers. As mentioned they all epand and contract at differnt rates. It causes delamination and eventual failure.
This is not even mentioning age and fuel chemistry factors.
Based on these variable...the piddly 120 psi burst point of non-EFI rated hose...taken down by a real world factor of about 4X (heat/cold, vibration, fuel chemistry, pressure).....is good under working conditiosn to a real world 40 psi. The first high pressure spike from anything could break this hose.
These same types of considerations are taken into the mix with hydraulic unions and lines, brake pipes and air line systems. Any pressurized system.
The statement that we have used this line for years and discussed it at length...with no reported failures...is a bit extreme wouldn't you think?
As if all VW owners in the universe are:
(a) here on the Samba
(b) regularly report in on their fuel line status
(c) would even know what to look for (based on the mentality of the vast majority of bus owners...I think this is reaching a bit  ) ....considering the regular litany of charred vehicles that happens on the bus forums.
(d) and this is not to mention the input of an even vastly higher number of low pressure injection vehicle owners in the millions world wide.....who probably have not been part of this conversation on the Samba over the years.
Wouldn't you think that the low # of sampled owners here who "get away" with non rated line.....creates a bit of a stretch to say that non rated has definitively been found to be just fine? just sayin....not beating on anyone.....just use the best EFI rated hose you can get.
The difference between 30 psi and 52 psi (about 4 bars which is the most common EFI pressure range of most Euro vehicles now).....is not enough to say we can use 120 psi versus 255 psi with no issues ever. the engineers are not stupid. There are reasons why they want such a high margin.
Ray |
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HairyYeti
Samba Member
Joined: October 15, 2005
Posts: 35
Location: U.K.
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HairyYeti
Samba Member
Joined: October 15, 2005
Posts: 35
Location: U.K.
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| Posted: Mon Apr 21, 2014 9:50 am Post subject: |
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R6/7 is rated to 50psi so may be no good for EFI
R9 is good for 100psi so should be OK.
R12 is rated 145psi so is designed for it. |
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Typ3nut
Samba Member
Joined: October 08, 2002
Posts: 1192
Location: MI, MotorCity ManCave
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| Posted: Mon Apr 21, 2014 11:34 am Post subject: |
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I'm using this hose and it's been great without fail.
Parker : 5155-5 W.P. 2.1 MPa (300psi) SAE 30R3 8mm (5/16").
This hose has a smaller OD and will slip inside the rubber grommets that the FI hose must pass thru in three places. The pressure rating is more than enough for our cars and the smaller OD allows for a smaller bend radius than most 5/16 " hose.
It's a little pricey but well worth the extra cost.
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ataraxia
Samba Member
Joined: March 19, 2010
Posts: 4504
Location: Illinois
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| Posted: Mon Apr 21, 2014 11:43 am Post subject: |
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| Typ3nut wrote: |
I'm using this hose and it's been great without fail.
Parker : 5155-5 W.P. 2.1 MPa (300psi) SAE 30R3 8mm (5/16").
This hose has a smaller OD and will slip inside the rubber grommets that the FI hose must pass thru in three places. The pressure rating is more than enough for our cars and the smaller OD allows for a smaller bend radius than most 5/16 " hose.
It's a little pricey but well worth the extra cost.
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Where did you get it? Link? |
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vwsplitvan
Samba Member
Joined: April 11, 2008
Posts: 479
Location: UK
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| Posted: Wed Aug 20, 2014 3:23 pm Post subject: |
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There is the fuel line that runs across the top of the engine thru a heat proof tube.
What have others done here as the 5/16 fuel hose will not fit thru this.
I gather the tube is required to protect the fuel line from damage and heat?
I bought another length of fuel line a touch smaller in OD but am struggling to get it thru the tube.
cheers
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KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 34012
Location: Conejo Valley, CA
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| Posted: Wed Aug 20, 2014 9:42 pm Post subject: |
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| I think the tube was just a length of wiring sheathing. Some run it bare. I used the corrugated, split wiring wrap to give some airspace between the rubber hose and the hot metal. |
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KTPhil
Samba Member
Joined: April 06, 2006
Posts: 34012
Location: Conejo Valley, CA
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| Posted: Tue Aug 13, 2019 8:40 am Post subject: Re: rubber fuel hose specs |
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Found a link to this on the Bus forum... looks much like the original sheathing:
http://www.busdepot.com/n0180154 |
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