Bend radius of integrally sleeved teflon hoses

Background: I would like to use integrally sleeved Teflon hosed FWF on our RV-4. Those are Aeroquip AE466-6, Stratoflex 124-6J or similar hose from Titeflex. All those hoses have a minimal bending radius of 4.0?. I have foreseen to place the fuel flow sender on the firewall between the engine driven fuel pump and the carburator, resp. throttle body injector. The available space FWF on the RV-4 is marginal, especially if I want to place the fuel lines as far away as possible from the exhaust stacks. I came up with solutions that would require a bend radius of 2.5?. I also tried around with different angled fittings. But I still require the 2.5? radius. A possibility is to use non Teflon hose for that part of the fuel line. Those have smaller minimum bend radii. But that?s not the preferred solution.

I have seen that the high pressure (rated 3000psi) variants of above hoses (Aeroquip AE446-6, Stratoflex 171-6J) have a minimum bend radius of 2.5?. Has someone used them FWF? Or perhaps someone has another idea how to solve my dilemma?

For the pressure side (after fuel pump), I believe you can use -4 hose. Bending radius 4" seems to be for -6, while -4 is half that, 2".

Not sure about carbs, mine is injected, and the hoses post engine pump are -4. What say others?

Andreas--
Have any pictures of your application? Several Rv4/Rv3 guys are using AE466 hose.
Tom

pics

Here are some pictures that I have at hand:


Those are cm not inches! The garden hose is a mock-up oil hose for the inverted oil system.


This is a version of mock-up line routing. Would need to assure that the line is not chaffing on the firewall. The current version is more direct. I will take a picture tomorrow. For information: The fuel pressure is taken on a T-fitting with a restriction after the red-cube.

Andreas--
Try mocking up a 90* hose end at the pump, and a straight at the transducer. Looking at the picture, it looks like you have room to have sufficient bend radius in the hose with out contacting anything.
Tom

different versions

Tom

Thanks, that's just what I did:



The doted line on the paper sheet is a 2.5" radius. So I would still need a hose that has a minimum bend radius of 2.5". For aviation Teflon hoses with integrally silicone sleeve these are Aeroquip AE446-6, Stratoflex 171-6J to my knowledge. Is this enough slack? And would this work with the rather stiff Teflon hose?

Vans calls out a -6 fuel hose for the carbed engine, even after the engine driven fuel pump.

Here's a pic of the mock-up line on other side (between red cube and the TBI). Not a problem here.

Andreas---
with a 90* hose end at the pump, it may allow the hose to turn more directly towards the transducer. Use it in conjunction with the 90* adapter you have in the pump. See how that works out.
Tom

Red cube

Aren't therre some spec's about a certain amount of straight line fittings before and after the red cube? Does the curve compromise the accuracy of the unit?

Jim Frisbie
RV-9A

Hi! My fuel pump output goes directly into the fuel pressure sender, thence to the carb. The flex line (303 equiv in stratoflex w/firesleeve) runs between the left gear socket and the mount struts. Really close fits....and been running that way for 1200 hours and two hose replacements (not abrasion, just old (I have an antique RV4)). No significant abrasion and well above the stacks. Looks if you have the pressure sender airframe mounted, so not sure this helps.

I have read lots of "don't mount senders on the engine because of vibration". Instead, "you must airframe mount the senders with many additional connections and hoses" (multiple additional failure modes, if you ask me) Well, my VWs and Porsches have had the Bosch (read Rochester) senders attached via tapered plumbing fittings on the engines that vibrate, lots. Oh, and Piper engine mounted the Rocherster senders on the Traumahawk....I have not had any "vibration" or other troubles with them on either the cars or my 86 RV4. maybe other types have troubles...just not my experience. My set up is oil pressure sender into right front galley and fuel sender at pump output....I have an antique, so my MP is a hose to gauge....MTCents, J

3rd try

Here is my third try with a 45? fitting on the fuel pump and then a 90? fitting on the flexible hose. This will give a nice radius. Not sure if there will be enough slack in this short line for engine mouvements?
Two 90? angles seeem not to work, as it will get me an offset which the short hose can probably not handle.


The cardboard thing should represent the 90? fitting on the hose mockup (at least it has the exact dimensions)

Waking up an older thread here, but since it's not real often that I have useful info to pass on....thought I should. I spoke to the red cube manufacturer yesterday about 90's and 45's in or out, mounting to the engine etc and he said the older units had issues that the new ones do not. Mount to the engine, no problem...vibration is irrelevant. 90's or 45's in or out, no problem the cube doesn't care. They prefer the out line to run uphill a bit to let any air bubbles out...so a 45 out running uphill is perfect.

His only caveat is it must be after both fuel pumps.