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Red Cube Placement Opinions

mulde35d

Well Known Member
Friend
I am installing a fairly traditional fuel system in the RV-10 and need to emplace my Red Cube FT-60. Of course the manual shows it after the electric boost pump and before the engine driven boost pump in the center console. The Red Cube manuals states it must be installed after all boost pumps to prevent vapor lock.

Installing in the center console per the Van's manual is of course the easiest and probably best for the red cube as it doesn't expose the transducer to the heat and vibration of the engine compartment.

Installing after both fuel pumps abides by the manuals, but finding a good location away from heat, vibration, and chemicals is difficult as they tend to fail faster when exposed to those conditions. The firewall would be the best location to mount it in the engine compartment, but that requires some interesting hose routing. Mounting to an engine mount tube is likely best to reduce vibration, but difficult to find a secure mount type (zip ties are not what I would consider secure). The RV-14 solution shown below may be possible, but exposes the FT-60 to exhaust heat and engine vibration.

Which one did you do? Pictures are appreciated if you ended up putting it in the engine compartment.
 

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Mine is suspended by the fuel line in between the mechanical fuel pump and the fuel servo and covered by a length of firesleeve that Aircraft Spruce sells for this purpose. IOW it’s not rigidly mounted to anything.
 
Considering the multiple trips around the tree to resolve a fuel flow error on an RV-14, I recommend not mounting it like the RV-14 plans say to do.
Side note - it seems we were not the only ones with this problem - it was a combination of location, vibration and hose lengths. We solved the problem by moving the sender to a new location.

On my first RV-10 build I mounted the sender per plans. If the boost pump was off it gave an accurate reading. Turing the boost pump on the reading jumped up. I also note that on rare occasion during a hard climb fuel pressure would drop below normal (boost pump off). I attribute this to the cube location.

The attached photo shows how I mounted it on the RV-8 project. It meets all the fuel sender install instruction requirements and I can report it is rock solid in use. I will do something similar on the new RV-10 project. I know the steel fittings should be aluminum but this is the only photo I have.

Carl
832-C4473-A655-4-EDC-A92-A-B0-CD7-C3732-DB.jpg
 
Considering the multiple trips around the tree to resolve a fuel flow error on an RV-14, I recommend not mounting it like the RV-14 plans say to do.
Side note - it seems we were not the only ones with this problem - it was a combination of location, vibration and hose lengths. We solved the problem by moving the sender to a new location.

On my first RV-10 build I mounted the sender per plans. If the boost pump was off it gave an accurate reading. Turing the boost pump on the reading jumped up. I also note that on rare occasion during a hard climb fuel pressure would drop below normal (boost pump off). I attribute this to the cube location.

The attached photo shows how I mounted it on the RV-8 project. It meets all the fuel sender install instruction requirements and I can report it is rock solid in use. I will do something similar on the new RV-10 project. I know the steel fittings should be aluminum but this is the only photo I have.

Carl
832-C4473-A655-4-EDC-A92-A-B0-CD7-C3732-DB.jpg

I like the idea of mounting to the engine mount with two adel clamps. Would just need to determine the exact location and hose lengths for that install.
 
While there are many RV10s flying just fine with the transducer in the tunnel, alot of you requested that we come up with a FWF location. WE settled on this location, mainly due to the offset rotation of the flow divider, and the ease of install.
Pictured below is the protoytpe location as tested by our beta testers. Yes, we changed the fittings to steel, and the supply hose was shortened to eliminate contact with the firewall. Current version ships in our FWF RV10 hose package with the integral firesleeved hoses.
WE have done some with the transducer mounted above the servo near the sump parting line. Still takes 2 hoses to do the install.
Most of the divider mounts we've seen put the divider at the top of the case on the centerline. That eliminates the use of our 4 Cylinder version bracket with our alot of changes. So we chose the aft engine location. Maybe not the best for all parties, but it is universal, and it works well.

Tom
 

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Installation instructions

Pressure drop is stated as 0.5PSI @ 28 Gal/Hr.
This means that with a fuel flow of 14 Gal/ hr you will have pressure drop of
0,125 psi, almost nothing. My own RED CUBE is installed after the electric
puel pump aft of the fire wall. 180 hp engine.
The best installation situation is with electric wires pointing UP.
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.

https://iflyei.com/wp-content/uploads/FT-60-Info-Rev-F.pdf

Good luck
 
While there are many RV10s flying just fine with the transducer in the tunnel, alot of you requested that we come up with a FWF location. WE settled on this location, mainly due to the offset rotation of the flow divider, and the ease of install.
Pictured below is the protoytpe location as tested by our beta testers. Yes, we changed the fittings to steel, and the supply hose was shortened to eliminate contact with the firewall. Current version ships in our FWF RV10 hose package with the integral firesleeved hoses.
WE have done some with the transducer mounted above the servo near the sump parting line. Still takes 2 hoses to do the install.
Most of the divider mounts we've seen put the divider at the top of the case on the centerline. That eliminates the use of our 4 Cylinder version bracket with our alot of changes. So we chose the aft engine location. Maybe not the best for all parties, but it is universal, and it works well.

Tom

It doesn’t appear that the red cube is supported in any way besides the fuel hose. Wouldn’t that result in increased vibration on the transducer? I would think it would have a longer life if it were secured to the mount. Any feedback on longevity from the field without it being supported?
 
It doesn’t appear that the red cube is supported in any way besides the fuel hose. Wouldn’t that result in increased vibration on the transducer? I would think it would have a longer life if it were secured to the mount. Any feedback on longevity from the field without it being supported?

8 years and still ticking. If you read EI’s install instructions, they talk about this very type of installation.
 
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Gustav---with your installation with the wires up, everything reads fine. If you fly inverted, the wires are down, does the reading get crazy? The answer is no, from many thousands of flight hours over 11 years of installs. Same for the wires pointing to the sides, like our 4 cylinder Lycoming bracket kit. If there is an anomaly, its not the location of the transducer, or its attitude.

Tom
 
Gustav---with your installation with the wires up, everything reads fine. If you fly inverted, the wires are down, does the reading get crazy? The answer is no, from many thousands of flight hours over 11 years of installs. Same for the wires pointing to the sides, like our 4 cylinder Lycoming bracket kit. If there is an anomaly, its not the location of the transducer, or its attitude.

Tom

Hi Tom.
Do you have any pics or placement recommendations for a carbed 0320. I have had a hose replacement quote from you sitting on my desk but have just procrastinated ordering because I’d like to move my fuel flow to between the mechanical fuel pump and the carburetor. Just haven’t figured exactly where and how. Any suggestions appreciated!
 
possible -9 fuel cube location

Hi Tom.
Do you have any pics or placement recommendations for a carbed O320.

Hi Steve,

I have some photos of a JPI fuel flow transducer (similar size to the EI, different exterior shape) in a carbed O-360 in -6A. Should be similar to your O-320/-9 setup. I spent a bunch of time trying to figure out how to mount it as specified...between the engine driven pump and the carb. It has worked pretty well since installation (1100 hours). I think it is similar to your setup. PM me if you'd like me to send the photos.
 
It seems like theres a million ways to mount these things and the only thing they have in common is that sometimes they work and sometimes they don't.

I'm stuffing an IO390 in my RV7 and it just made sense to me to follow factory guidance for the IO390 from the RV14 instructions that you pictured above.

It may be a horrible idea, but I'd hope that Vans wouldn't lead me astray.

I'll be sure to report back if it doesn't work, but given how many RV14s are out there now with this exact setup, I feel like we would have seen lots of problems by now if they were pervasive.
 
Considering the multiple trips around the tree to resolve a fuel flow error on an RV-14, I recommend not mounting it like the RV-14 plans say to do.
Side note - it seems we were not the only ones with this problem - it was a combination of location, vibration and hose lengths. We solved the problem by moving the sender to a new location.

On my first RV-10 build I mounted the sender per plans. If the boost pump was off it gave an accurate reading. Turing the boost pump on the reading jumped up. I also note that on rare occasion during a hard climb fuel pressure would drop below normal (boost pump off). I attribute this to the cube location.

The attached photo shows how I mounted it on the RV-8 project. It meets all the fuel sender install instruction requirements and I can report it is rock solid in use. I will do something similar on the new RV-10 project. I know the steel fittings should be aluminum but this is the only photo I have.

Carl
832-C4473-A655-4-EDC-A92-A-B0-CD7-C3732-DB.jpg



Carl,
Re. the comment that the fittings should be aluminum and not steel, why is this? I was under the impression that steel fittings are less likely to gall. The FT-60 data sheet does not specify what material type fittings should be used.
 
Careful with 90 fitting

Careful with a 90 degree pipe fitting between a moving and non moving item. I tend to worry that the movement will work the pipe fitting lose. I added a brace on my red cube that picks up one of the mounting bolts to support the hose near the 90 fitting.
 

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This is where mine is and has been for 1460+ hours. This is and old pic from my construction album with the test fit bolts, so don’t flame me for not having threads showing😱
View attachment 39868
 

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Another option that works well.
 

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Which one did you do? Pictures are appreciated if you ended up putting it in the engine compartment.

I started with my red cube in the tunnel per the RV-10 plans. In that location, operating the boost pump caused erratic and erroneously high fuel flow indications. I moved my cube to a location suspended in the fuel line between the fuel servo and spider, not attached to any structure, covered by firesleeve. It's been about 1000 hours since I moved it. I like the new location. Solid fuel flow indications.

Reference: page 26 of 32 from the FP-5 installation instructions, https://iflyei.com/wp-content/uploads/FP-5L-II.pdf
 
Two points not mentioned here yet

My IO 0360 RV 4 made it difficult to install the red cube AFTER the mechanical pump without hoses I considered undesirable (excessive). I mounted it with adels on the mount behind #3 with a short hose to the spider on top of the case parting line. This encountered two issues you may find useful.
1- to secure the cube and hoses with minimum motion, vibration , i used a small piece of rubber baffle sheet between the adels and the red cube. Very secure with no shaking hoses and good vibration isolation.
2- the cube needed to be mounted vertical for ideal hose length, no 90* elbows and bubbles into the bottom and out the top. The wire needed to exit horizontal, not vertical. RED CUBE advised no problem with performance. There might be a slight variance in bearing life on the impellar.
 
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Steve, and others----here are a few pics of carbureted installs. 2 schools of thought here. 1- Fuel is pushed through the transducer and if any bubbles were in the fuel they would end up in the upper carb bowl, and not in the cube. 2) In Glen's install, its more like the STC mandated install. Fuel is pushed up and then to the carb. I guess supposedly to move the bubble to where it either breaks up or is pushed to the carb.

NOT TESTED--but i think that once the boost pump pulls the fuel from the tanks, then pushes it forward, any large bubbles (hopefully none at all with a tight system) would be pushed into the carb, and they would dissipate.

HUM-----I wonder----well if someone wanted to donate an engine with a carb, not for running purposes but for test bed testing, we could make a mockup fuel system and really see what happening. Oh gee----need the 2 tanks, valve, boost pump, etc----need more space. Could use clear hose since its for VISUAL purposes only, not for flight. This way we could see if bubbles actually move, breakup, or arent existent.

Tom
 

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Tunnel

Mine is in the tunnel, about 6" downstream of the electric Andair boost pump/filter. It has worked flawlessly for 1700 hours and reads very close to actual gallons used. You don't have to install it downstream of the mechanical fuel pump. I worry about high temps below the engine forward of the firewall.
 
Mine is mounted between fuel servo and flow divider, suspended in the fuel line and not secured to structure. I have it heat shielded. Flying for 6 yr and no problems.
 
Mine is in the tunnel, about 6" downstream of the electric Andair boost pump/filter. It has worked flawlessly for 1700 hours and reads very close to actual gallons used. You don't have to install it downstream of the mechanical fuel pump. I worry about high temps below the engine forward of the firewall.

Like Tim, I've run a cube both before and after the engine-driven pump. When between pumps, the fuel used indication was accurate in cruise with the aux pump OFF. However, it read high with the aux pump ON, and the GPH indication (on a GRT EIS) was never really stable, pump on or off. Relocating to a position after the fuel servo settled all issues.

Any restriction contributes to vapor formation when lowering pressure on the downstream side with a pump. Placing the cube after all pumps makes the restricted flow area irrelevant.

Placement above the servo or up near the divider significantly reduces radiated energy from the exhaust tubes.

Any reduction in hose length reduces fuel heating. Keep 'em short. 45 degree fittings don't seem to bother the cube at all.
.
 

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I started with my red cube in the tunnel per the RV-10 plans. In that location, operating the boost pump caused erratic and erroneously high fuel flow indications. I moved my cube to a location suspended in the fuel line between the fuel servo and spider, not attached to any structure, covered by firesleeve. It's been about 1000 hours since I moved it. I like the new location. Solid fuel flow indications.

Reference: page 26 of 32 from the FP-5 installation instructions, https://iflyei.com/wp-content/uploads/FP-5L-II.pdf

Photo attached
 

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