Fuel line fittings
06-02-2010, 03:18 PM
#1
Burning Brakes
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Fuel line fittings
What size are the fuel line fittings on my '88 S4. I'm interested in doing custom lines, but I need to be able to connect to the supply and return lines, as well as all of the dampners and pressure regulator. TIA
06-02-2010, 05:39 PM
#2
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I don't know about the fuel lines of your S4 but the fuel lines of my '78 were NLA. I had them redone at Pirtek reusing the old fittings. High pressure reinforced hoses were fitted with the steel braiding. I can send you a picture if you like.
06-02-2010, 05:59 PM
#3
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All the fittings are reusable - replace with EFI hose - 5/16th ID.
Make sure you use SAE30R9 hose.
Fuel system is very low pressure in the later non CIS cars - only circa 55PSI.
Even in the CIS cars its only circa 80 PSI. No need for high pressure lines.
Make sure you use SAE30R9 hose.
Fuel system is very low pressure in the later non CIS cars - only circa 55PSI.
Even in the CIS cars its only circa 80 PSI. No need for high pressure lines.
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
06-03-2010, 04:25 PM
#4
Burning Brakes
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Roger, I am going to make high pressure teflon-lined braided stainless lines for the car. The lines are very high pressure-rated (up to 2000 psi, min burst pressure is 8000 psi). The only piece of the puzzle I am missing is the type of fitting needed to connect to the fuel system.
06-03-2010, 08:23 PM
#5
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Thomas-
The extreme-pressure stuff is overkill. Most teflon hoses have problems if they aren't used with just the right connections; they either crack or slide off, and don't take well to the clamps we use for "regular" hose connections. Be aware also that the minimum bend radius on TFE lines is a lot less forgiving than most common hoses. Visit your hose supplier with a couple of your fittings and get their blessing and advice before you dive in. The lining often fractures without any apparent damage to the outside. Braided stainless covers look cool but hide internal tube damage until you have a leak. Fuel leaks are almost always a problem, in my limited experience anyway.
The extreme-pressure stuff is overkill. Most teflon hoses have problems if they aren't used with just the right connections; they either crack or slide off, and don't take well to the clamps we use for "regular" hose connections. Be aware also that the minimum bend radius on TFE lines is a lot less forgiving than most common hoses. Visit your hose supplier with a couple of your fittings and get their blessing and advice before you dive in. The lining often fractures without any apparent damage to the outside. Braided stainless covers look cool but hide internal tube damage until you have a leak. Fuel leaks are almost always a problem, in my limited experience anyway.
06-03-2010, 11:33 PM
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Thomas,
The medium pressure PTFE lines you are going to use will not meet the tight bend rads required for the hoses unless you reroute them.
Roger
The medium pressure PTFE lines you are going to use will not meet the tight bend rads required for the hoses unless you reroute them.
Roger
06-04-2010, 12:47 AM
#7
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I do plan to rerout them and not use the barbed lines. The barbed fitting on the fuel supply line can be unscrewed. I want to simply screw the teflon line onto the hard line and connect the other end directly to the fuel pressure regulator (or maybe it's the dampner, I can't remember right now). I plan to also modify the rear section to delete the u-bend. When all is said and done, I will have only hard lines or teflon ones. The fittings will be permanently affixed and leak-tested. I am not worried about teflon lines ever leaking if they don't leak before they go on the car.
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06-04-2010, 02:06 AM
#8
Three Wheelin'
do some good research first
I looked into teflon too- in Aeroquip it's either their 666 or 2807 series.
they don't have a 5/16 so the closest they would have is a 3/8 (or dash 6)
Their bolt on ends are the "super gem" series and the flares don't match
our plumbing so you will need metric to "an" adapters. By the time you put
2 adapters on the back, the "u" shaped hose would be way under the minimum bend radius.
Important to think about- there has to be compliance in the hoses especially the hoses from the fuel cooler to engine & the hose on the pass side that goes to the hard line on the fender to allow for engine torque. Too stiff a
hose = stress transferred elsewhere where something may crack / break.
I really wanted to go with teflon stainless, but in the long run it seems more practical to go with new 5/16 fuel injection hose & clamps & just renew the hose every few years. I have done a lot of Aeroquip/ Earls plumbing in the past, but just couldn't find a clean way to do it that made sense.
If you can find the proper metric ends that will work with - 6 teflon & use no adapters then it might be worth following up on, but watch the bend radius.
they don't have a 5/16 so the closest they would have is a 3/8 (or dash 6)
Their bolt on ends are the "super gem" series and the flares don't match
our plumbing so you will need metric to "an" adapters. By the time you put
2 adapters on the back, the "u" shaped hose would be way under the minimum bend radius.
Important to think about- there has to be compliance in the hoses especially the hoses from the fuel cooler to engine & the hose on the pass side that goes to the hard line on the fender to allow for engine torque. Too stiff a
hose = stress transferred elsewhere where something may crack / break.
I really wanted to go with teflon stainless, but in the long run it seems more practical to go with new 5/16 fuel injection hose & clamps & just renew the hose every few years. I have done a lot of Aeroquip/ Earls plumbing in the past, but just couldn't find a clean way to do it that made sense.
If you can find the proper metric ends that will work with - 6 teflon & use no adapters then it might be worth following up on, but watch the bend radius.
06-04-2010, 02:49 AM
#9
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When I redid my fuel lines last year with the help of Jim Morton and Bill Ball, Tim Murphy had a lead
on AN to metric fittings, since he uses them in his supercharger kit. They are on page 87 of this
catalog:
http://www.kinsler.com/072707/Cat31_...LR_CanCopy.pdf
Jim also did some custom welding on the fuel rails and assorted fittings.
on AN to metric fittings, since he uses them in his supercharger kit. They are on page 87 of this
catalog:
http://www.kinsler.com/072707/Cat31_...LR_CanCopy.pdf
Jim also did some custom welding on the fuel rails and assorted fittings.
06-04-2010, 05:23 PM
#10
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On this page is a 'thread size chart' that will answer your questions. Once you know the sizes you can call this company (BAT inc) & they can provide you with all of the metric fittings & hose. Ask for Eric, he's very knowledgable & helpful.
See here, http://www.batinc.net/mocal.htm
Regards, Hammer
See here, http://www.batinc.net/mocal.htm
Regards, Hammer
