A

ao.frog

Well Known Member
Is the hole in this connector on the "Red Cube" too small for adequate fuelflow?

It has been rather difficult to find someone in Norway who can work on teflon fuel-lines. (I need to install the Red Cube FF-sensor on the fuel-line on my Lyc IO-360)

To make an attempt, I had a company do the best they could.
They had to make up a connector, but the hole in the connector they used is so small?

On the pic below, the orginal blue connector has a hole with ID just shy of 5/16 inch, so the hole in the connector the company made up (the black one) is much smaller.

My gut tells me that this hole is too small to give enough FF. What do you engine guru's out there think?






 
The inlet at the engine flow divider is a -4 fitting and it will easily pass adequate fuel to the engine.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
Its a common misconception that if you have say a 1/2" pipe carrying water that you need a 1/2" valve on the end or it will cut back the flow.

In reality one time restrictions add a miniscule pressure loss..This why in high purity (expensive) systems you will see smaller valves than the pipe they are connected to.

Also this is the same reason, if you measure the pressure loss across a valve there is no measurable pressure loss until the valve is almost closed.

This is a long way of saying.."What Mahlon said"..:)
 
Looks like to me that the Brown one is AN816-4-4D and the blue one is a AN816-6D. Pictures can be deceiving.
Teflon help is available in the states, US Priority mail is cheaper than Fed EX. Ask me how I know--
 
Car racing

If you still want the exact fitting did you try performance car / racing equipment suppliers. I have found they also use and thus supply the AN fittings.

Cheers

Jim
 
It is easy to test the flow, just remove the line at the fuel injection servo, or carb whichever you have, and run it into a bucket.

Hit the boost pump for 15 seconds, and see what kind of fuel flow you get.

Now insert the red cube with the small fitting into the setup, and repeat the flow test.
 
Alf Olav,

Send Tom at TS Flightlines an email - he can ship Teflon fuel pipes to Europe at a reasonable price.

Regards, Peter
 
frankh said:
Its a common misconception that if you have say a 1/2" pipe carrying water that you need a 1/2" valve on the end or it will cut back the flow.
Click to expand...
I agree that in a *static* system, that a 1/16" hole is no different than a 1" hole... In time the pressure on each side of the restriction will stabilize. But in a flowing system, there will be a flow loss. The important thing is whether it will be enough of a flow loss to cause a problem with your fuel flow.
 
Yes but a momentary restriction has to be very small to make a worthy pressure loss..A short restriction is not the same as a long small bore pipe.

Lots of folks think you have to make sure the same hole size is there the entire length of the system in order to maintain flow whereas that rarely proves to be the case.

Like I said, thats why you often find smaller valves in line with larger pipe.
 
I test flowed 42 gph

through the red cube in the tunnel with flex line taken loose at fuel servo "in" connection, and 15' ft of 3/8" id rubber hose attached going into container. The red cube has approx 3/16" hole inside. That hole is smaller than a -4 fitting. I was initially worried, but not after getting the minimum 125% of takeoff fuel flow(25.5 gph). No problems so far. I have -6 fittings on both sides of red cube.
 
I bet I'm not the only guy having fluid dynamics lecture flashbacks while reading this! Every 10 years or so, that engineering degree really comes in handy! ;)
 
Hah..Just be thankful you don't have to dig it up every day...:)

Going to get my PE license (including the FE/EIT exam) after 25 years out of school was not fun....Oh and coming from Europe I had to learn the "English" system of units...:)

Frank
 
You must log in or register to reply here.