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  #1  
Old 07-04-2019, 09:23 AM
CJ in EP CJ in EP is offline
 
Join Date: Apr 2017
Location: Eden Prairie, MN
Posts: 52
Default Red Cube Install - A new look at an old challenge

There seems to be a lot of information on how to mount these, no two are alike, and each method is a unique combination of benefit vs. compromise. Here's my take.



It starts with a new bracket made from a 12" x 12" sheet of 4130 purchased from McMaster. A hacksaw, files, and the dirt-cheap break from Harbor Freight was all it took to make this. The tapered shape and bends were made to exactly match the existing Lycoming bracket which mounts the fuel divider, and the bracket uses the same 1/4-20 bolt as its primary point of attachment. Opposite this bolt there are two tabs which, with the use of Adel clamps, provide additional support to the bracket by attaching to the push rod tubes. This is admittedly the compromise in this design, but great pains (and three different attempts) were taken to build this so there isn’t any load in tension or compression on the tubes.



Two new fuel lines were necessary, made by the very capable hands of Tom Swearengen of TS Flightlines; one a stainless steel hard line running from a bulkhead fitting at the rear baffle to the transducer input, and one flexible/firesleeved line with 45° fittings running from the transducer output to the divider. On a side note, it’s been said many times and I’ll add to the chorus, Tom was a great guy to work with, his knowledge is unsurpassed, and he demonstrated a great amount of patience in dealing with a rooky like me.

The next two photos show the clearances of the new plumbing with the existing injector line plumbing. I’ll finish the install with an Adel clamp to secure the flex line to the divider bracket.




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  #2  
Old 07-04-2019, 09:30 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
Posts: 8,276
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Not what I would recommend. Adding a bunch of hose length above the engine will result in heating a bunch more fuel while parked. Engine starts after a quick turnaround could be more challenging.
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  #3  
Old 07-04-2019, 09:40 AM
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rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,306
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In addition to Scott's comment you now have a loop at the highest point for vapor to accumulate.

Not going to work well.

Old pic but this custom fitting is the best approach IMO.

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  #4  
Old 07-04-2019, 10:05 AM
RV Jerry RV Jerry is offline
 
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Location: Chino, CA
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Why is fuel inlet from rear of engine?, all the ones I’ve seen divider is clocked so inlet is in front which makes install easier with less plumbing
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  #5  
Old 07-04-2019, 10:42 AM
j-red j-red is offline
 
Join Date: Dec 2015
Location: Lewes, DE
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Compliments on nice workmanship.
Just wanted to pass on another concern about penetrating the baffle with a hard line at that location. Unless well braced, that spot can be the source of significant vibration, especially if an oil cooler is hanging off the baffles. Mine is rock solid now, but I learned the hard way after cracking the oil cooler flange on the onboard side.
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  #6  
Old 07-04-2019, 11:10 AM
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maniago maniago is offline
 
Join Date: Aug 2014
Location: Bowie MD
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Looks beautiful. But.....you know Red Cubes are notorious for being susceptible to vibration and heat......but it wont cause any fuel issues if it fails, so give it a try!

I'd also agree with the hesitation on a hard line thru the baffles however....
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  #7  
Old 07-04-2019, 11:19 AM
Pdtofly Pdtofly is offline
 
Join Date: Jan 2012
Location: Reno, NV
Posts: 256
Default Red Cube mounting

Where you did a nice job of mounting your cube, you have done a few things not recommended in your install.

General Placement Recommendations for Fuel Flow Transducer

1. Do not install the fuel flow transducer, hoses and fittings near exhaust system or turbocharger. Excessive heat can damage fuel system components.

2. Do not install 90 degree fittings (elbows) on the input or output of the fuel flow transducer. Doing so will cause turbulence in the fuel flow which causes inaccurate fuel flow data.

3. Install the fuel flow transducer with the three wires pointed UP.

4. Install a fuel filter UPSTREAM of the fuel flow transducer to screen out debris.

5. For best measuring performance, the fuel should travel uphill by one to two inches (25-50 mm) after leaving the fuel flow transducer.

6. Placement of the fuel flow transducer relative to other items in the fuel system like fuel pumps is left to the builder. It is common to place the sensor downstream of any auxiliary electric boost pumps but upstream of the engine driven fuel pump.

BIG NOTE: Due to vibration issues, never connect the fuel flow transducer directly to the engine.

ANOTHER BIG NOTE: When sealing the fittings on the fuel flow transducer, do not use Teflon tape! Instead, use a sealant such as “United EZ-Turn Fuel Resistant Lubricant” or “Permatex Thread Sealant”.

I would reconsider where you mounted your cube, unless you want it to fail prematurely.

Brian
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  #8  
Old 07-04-2019, 10:36 PM
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Z-EDD Z-EDD is offline
 
Join Date: Oct 2013
Location: Harare, Zimbabwe
Posts: 177
Default Moving goal posts

Quote:
Originally Posted by Pdtofly View Post
Where you did a nice job of mounting your cube, you have done a few things not recommended in your install.

General Placement Recommendations for Fuel Flow Transducer

1. Do not install the fuel flow transducer, hoses and fittings near exhaust system or turbocharger. Excessive heat can damage fuel system components.

2. Do not install 90 degree fittings (elbows) on the input or output of the fuel flow transducer. Doing so will cause turbulence in the fuel flow which causes inaccurate fuel flow data.

3. Install the fuel flow transducer with the three wires pointed UP.

4. Install a fuel filter UPSTREAM of the fuel flow transducer to screen out debris.

5. For best measuring performance, the fuel should travel uphill by one to two inches (25-50 mm) after leaving the fuel flow transducer.

6. Placement of the fuel flow transducer relative to other items in the fuel system like fuel pumps is left to the builder. It is common to place the sensor downstream of any auxiliary electric boost pumps but upstream of the engine driven fuel pump.

BIG NOTE: Due to vibration issues, never connect the fuel flow transducer directly to the engine.

ANOTHER BIG NOTE: When sealing the fittings on the fuel flow transducer, do not use Teflon tape! Instead, use a sealant such as “United EZ-Turn Fuel Resistant Lubricant” or “Permatex Thread Sealant”.

I would reconsider where you mounted your cube, unless you want it to fail prematurely.

Brian
Hey Brian

I believe EI have moved the goal posts on this one. Current guidance linked here
https://buy-ei.com/wp-content/upload...Info-Rev-F.pdf

If one reads all the guidance ever written on mounting this thing then the only place for it is in close formation with the aeroplane along with the antennae and magnetometer!

Note main differences from what you posted:

Removed advice not to mount near exhaust, heat source or directly to engine.

Removed advice to not use 90 degree fittings.

Added insistence that the unit MUST be downstream of the last fuel pump (their capitalization)

personally I am mounting mine like this:http://www.vansairforce.com/communit...d.php?t=134975

Just spent an hour mocking up and checking hose lengths and I believe it will work well.
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  #9  
Old 07-05-2019, 07:15 AM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
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In defense----Chris had the 'unusual' plumbing of routing the servo hose to the aft baffle. At the same time, with all the flame wars about where and how to mount it, not mount it, plumb it, etc he had the unusual install of the flow divider being installed with the inlet port facing AFT.

YES we discussed the possibility of heat related issues after shutdown, and he was going to test things, and change if necessary. As everyone on VAF and others have seen, there is NO one one to do this. Everyone has an opinion, and all are right, no one is wrong. We tried for 8 years to get EI to tell us HOW THEY wanted the transducers mounted ( so we could develop a kit for that install), but their answer has been, "Its experimental, the builder can do whatever they want."

Also in defense, we've plumbed alot of these transducers, in alot of different places for ALOT of you. Some similar, some different. Yep, for some individual reasons, some were changed around. The fact of the matter is there is no recommended install location or plumbing. The RV14 IO390 FWF package as designed by VANS, has it between the mechanical pump and the servo mounted with an adel clamp on the #4 intake tube. I know of several OE install on certified planes where its mounted on top of the engine, with 2 hoses, so if its good enough for a certifed install, why not an experimental?

Chris did his homework and alot of research, and in his case came up with a plan. Yes he will try this out, and has accepted the fact that he maybe changing it around, IF it doesnt perform as it needs to. As for the transducer, yes the wires are UP---until he flies inverted--significant straight in/out of the cube---kinda per EI's recommdation. NO this install isnt in the finished stages, but getting there.

Tom
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Tom Swearengen, TS Flightlines LLC, AS Flightlines
Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com, www.asflightlines.com
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  #10  
Old 07-05-2019, 07:49 AM
TS Flightlines TS Flightlines is offline
 
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Location: Ridgeland, SC
Posts: 2,323
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BTW---there seems to be some 'crossover' in the install instructions for the FT-60 and the FloScan. The Flo Scan was definitely susceptable to all the things that have been stated here---needing 2 inches of straight inlet/exit before an angled hose or rigid tube, definitely no hard mount and wires up up.

"The overall accuracy and linearity of the Red Cube FT-60 is superior to most other flow transducers. The Red Cube FT-60’s design vacates bubbles and is not nearly as susceptible to debris as other units on the market. " "The Red Cube FT-60 should NOT be installed with the wires pointing DOWN (the best situation is with wires pointing UP). Also, the fuel line on the outlet port should not drop down after exiting the transducer. Both of these configurations can trap bubbles in the transducer causing jumpy readings. The inlet port, outlet port and flow direction are marked on the top of the Red Cube FT-60." That is a quote from EIs install guide. Wires not DOWN, transducer exit not down. So in most of the installs, even those near the servo, the wires are either UP or on the side, NOT DOWN, and the exit is either horizontal or vertical, not DOWN. Even in our flow divider location, we adhere to those guidelines.
Dave Arata of Ei, back in 2016 stated this:
"The main reason to not mount the transducer between the boost pump and engine driven pump is the because the boost pump can create a hammering affect against the engine driven pump when turned on. This causes the impeller in the transducer to be pulsed forward and backward quickly which is counted by the instrument as increased fuel flow.
An additional concern, while we have never seen it, is the possibility of vapor lock. The transducer was not designed for fuel to be sucked through it. It was designed for fuel to be pushed through it.
It is best if installed with the wires pointing up, as that is where the transducers were tested. However, ease of installation should take precedence. Flexible like should ALWAYS be used to provide vibration protection and the output port should not be pointing down. Installing the transducer in such a way can trap air bubbles and cause erratically high fuel flow readings due to the optical sensor seeing refracted signals."

One other thing----The Flo Scan was a pretty weak thing---Yeah I broke one one time installing a AN nipple. The FT 60 is a much more robust unit. TO MY KNOWLEDGE, and please correct me if I'm wrong, I have NOT heard of a failure of a FT60 that the root cause was because it was hard mounted to a bracket. ANYWHERE.

Be advised---because we do ALOT of these installs, I will AGAIN be talking-or trying to talk --to EI at OSH and get them to give us a recommendation so we can develop an install package thats universal for most all of you guys. Yep---I'll report back after OSH.

Oh----if someone has a better idea, I'd love to hear it.

Tom
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Tom Swearengen, TS Flightlines LLC, AS Flightlines
Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7 Tail Kit Completed, Fuse started-Pay as I go Plan
Ridgeland, SC
www.tsflightlines.com, www.asflightlines.com
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