[crabandy]

I'm debating between mounting the red cube for my G3X (RV7 O-360) on a firewall angle like some have done, this would require 2 new fuel hoses and kinda PIA mounting and routing.
I'm wondering about pros/cons of mounting on the floor between the fuel selector and Facet electric pump. As I understand it It will give a slightly higher than normal fuel flow than actual only when the boost pump is on.
Thoughts/ideas?
Thanks,
Andy

 

[Bill.Peyton]

My 2 cents.... I would not mount it in the tunnel between the pumps. One reason is the addition of connections inside the aircraft, simply more opportunity to develop a leak. The other is the accuracy issue. I have tried both places (not RV ) and I can tell you that it does not like to be on the suction side of the pump. One day you will leave the electric pump on an never be sure of your true fuel remaing. I ended up doing an installation on a piper archer on the firewall. It did require a slightly longer hose, but performed flawlessly for years. On the the RV 10 I installed the red cube between the servo and the flow divider. If it were a carbureted engine, I would install it at the output of the mechanical pump.

 

[CharlieWaffles]

+1 for what Bill says plus I did it as future maintenance of the cube that far forward in the tunnel was going to be a pain. Besides the manufacturer of the cube itself says its best to mount between the servo and spider or mechanical pump and the servo, so its in better compliance with it's design and is way easier to maintain.

 

[GLPalinkas]

-7

I think Andy is asking about an RV-7. From what I know ( which may not be much) quite a few -6 & -7 owners installed the red cube between the fuel selector and the elec. fuel pump. Aft of the firewall prevents some heat related problems but may not be the most accurate sensing location.

I know Mel has had his there for maaany years.

 

[crabandy]

Thanks for the replies, still leaning towards the cabin mounting RV7 O-360. Maybe just the fresh memories of drilling and deburring stainless, working around the mount behind the engine through the hoses and lines mounting all the firewall goodies.

I have not mounted the Facet pump or made the line, and It should be realatively easy (in theory) to mount the red cube there.

If I mount on the firewall I would need at a minimum 1 more hose, more likely 3 more hoses $$$. I would have to drill/deburr stainless around the mount behind the engine...

One could argue fuel squirting FWF has a much better chance of actually igniting. FWF small fuel leaks could hide under the cowling than inside the cabin (smell/moisture).

Higher fuel flow because the boost pump was left on, no problem land early refuel and reset as full.

Red Cube not working properly in the cabin location much bigger issue.

Thanks for the replies and keep them coming.

 

[Bavafa]

. One reason is the addition of connections inside the aircraft, simply more opportunity to develop a leak.

Fuel leak is never good but I rather for it to be in the cabin where I can detected far faster than in the engine compartment where by the time I learn about it, it may very well be too late.

My 2 cents and experience with it....
I have my Red cube in the tunnel between the electric fuel pump and the mechanical fuel pump. I check and compare my fuel burn (from GRT) to the amount I fill up and it is always within 0.01% to a maximum of 0.02% accuracy. If I add 30 G of fuel it is within 0.2 or 0.3 g of difference from what GRT tells me that I have burnt.

 

[jetdriven]

Do you mean 1 or 2% accuracy? Thats all our FF meter is good for.

 

[Bavafa]

Do you mean 1 or 2% accuracy? Thats all our FF meter is good for.

You are correct (my bad writing) 1 to 2% accuracy.

 

[Wayne Gillispie]

Primer? Quadrant or vernier? Leather or cloth?

I think it works good in either place. Mine is in the tunnel and within .3-.5 gal on every fill-up. Short or long flights. My boost pump only runs 2 minutes per flight max. When I turn BP on, FP increases approx 5 psi and FF slowly increases 3-4 GPH for 5 sec then drops back to normal FF. When BP is turned off, FF decreases in the same manner.

 

[crabandy]

Any Pics on mounting on the floor?
Thanks,
Andy

 

[ron sterba]

For what it is worth, My friend on his 9 puts a paper towel under the fuel line connections in the tunnel. I asked why. He said the 100LL will stain blue if there is ever a DROP of fuel on the paper. My two cents. Keep the ideas coming because I just received my RED cube in the mail.
Ron in Oregon

 

[WingsOnWheels]

Here is how I installed mine just recently on my O-360 RV-6A. This location only required one new hose to go from the engine pump to the cube. I was able to use reuse the pump-to-carb hose. I put a 90* on the carb and a straight fitting on the Cube. The hose is just the right length. I swapped the outlet fitting on the pump from 90* to straight (at $3.90 part from ACS) and put a 45* on the inlet to the cube.

 

[ron sterba]

Colin , You did a nice job of running the lines straight in and out of the cube as it says on my info sheet. I think I'll go that route. Good install! Thanks Buddy.

Ron in Oregon

 

[crabandy]

Nice Install!

Colin that install looks great!

 

[BruceP]

How much of a problem...

do you think I will have with my installation? I was aware of the directions to have straight fittings but I ended up with a 90 in and 45 out. Rather than spend more money on new hoses and turn the cube around as shown in the previous post (nicely done!), I thought I would give it a go and see how the accuracy is before I changed it.

 

[Wayne Gillispie]

What is the white ? on your mech fuel pump outlet fitting?

 

[WingsOnWheels]

From what I have seen around the forum, the straight in/out requirement is not critical on the red cube. You will probably be just fine.

The main reason I ran my lines the opposite direction was to give better clearance to the vetterman mufflers. If I use the 45* fitting off the carb it puts the fuel hose very close to the muffler (almost touching). By running the hose up the middle I don't have to deal with that problem anymore, and my cube got installed at the same time.

 

[BruceP]

Thanks Colin. Wayne, strangely, the white is a camera flash artifact, there is nothing white in or around that area.

 

[crabandy]

Colin,
Where did you tap into for fuel pressure?

 

[WingsOnWheels]

Colin,
Where did you tap into for fuel pressure?

It's not in that picture (since I didn't have the parts yet), but the fitting that connects the outlet of the cube to the hose is a gauge adapter with a 1/8" NPT fitting on the side and 1/4 NPT and -6AN on the run. I used the Vans 45* restrictor fitting. The 45* is a little odd in that location, but I couldn't find a premade straight restrictor.

 

[crabandy]

Colin, do you have a part # and where did you buy the fitting? I really like your solution in moving the fuel hose away from the exhaust.
Thanks,
Andy

 

[Clouddancer]

I plan to use a similar approach as Colin for the plumbing of the fuel pressure line. The fuel flow sensor is mounted on the firewall after the engine driven fuel pump. Fuel pressure will be taken after the fuel flow sender (red-cube) on a T-fitting (AN 826-6). The restrictor fitting is of an own design, based on a steel -6 to -4 reduction. I tapped a thread in the -4 side of the reduction to insert a screw that I previously drilled with a small hole (1mm).

 

[crabandy]

My red cube instructions Rev C: 3/31/10 stating it must be downstream of the last fuel pump, wires installed up, and the outlet port not to drop down after exiting transducer. Nothing about 90 or 45 elbows.
I used the vans KB-090-T fuel pump fitting, vans VA-138 to a 822-6 inlet to transducer facing the cowl of airplane. Transducer outlet is 823-6 and another VA-138 with to an 822-6 on the carb. This clears the exhaust nicely and Three fuel hoses are all the same length. The Aluminum fittings are mockup only, steel are in the mail.

 

[rvsxer]

This revision of the EI Manual http://www.fdatasystems.com/Manuals/FT_60.pdf does indeed call for the transducer to be mounted after the last pump and why. This came after I put mine between the electric and engine-driven pumps on my carb-equipped -6. My accuracy has been the same as the earlier poster's so I'm gonna leave it for now.

 

[Brantel]

Here is something that I try to post each time a new thread shows up on these Red Cubes.

Matt works for the people that make the thing:

As far as I know Dynon distributes both the FloScan 201B as well as EI's FT-60.

The FloScan unit is much more sensitive to the angles/fittings entering and exiting the unit. EI's unit does not care. You can run 90 degree fittings in and out of ours without problems.

JPI does not sell EI's FT-60

Maybe you can get Dynon to trade you for a FT-60?

Good luck!

Matt

You do NOT want to rigid mount the transducer to the motor (any part) using just a fitting. It is a huge safety issue. The fitting could theoretically fatigue and break. You absolutely need to have flexible line on both sides of the Floscan 201B or the EI FT-60 (that Dynon now utilizes).

After manufacturing/supporting flow instruments for a good number of years we have seen that flow transducers accuracy is typically better when mounted after both fuel pumps. They simply seem to prefer to have fuel pushed through them, not pulled through. The truth of it though is that many installation drawings still read as though we were still using the older Floscan 201 transducers. I have seen installs that mount the transducer between the pumps with claimed success. The Floscan units were much more sensitive in regards to mounting location, angles of fittings in and out, and attitude. Our new design will tolerate a lot more. Frankly we don't care if the thing flows straight up, or if you put 90-degree fittings in and out (FT-60 only) of the transducer. Just don't mount it upside down or flowing sharply downhill.



Hope this helps,

Matt Sharp

Hello All!

Your friendly neighborhood EI Tech support rep here!

There are really two issues in regards to EI?s specifications on flow transducer placement.

1. Accuracy of the output of the flow transducer.
2. Safety.

Issue one is pretty basic. After manufacturing flow instruments for a good number of years we have seen that flow transducers accuracy is typically better when mounted after the mechanical fuel pumps. They simply seem to prefer to have fuel pushed through them, not pulled through. The truth of it though is that many installation drawings still read as though we were still using the older Floscan 201 and 231 transducers. I have seen installs that mount the transducer between the pumps with claimed success. The Floscan units were much more sensitive in regards to mounting location, angles of fittings in and out, and attitude. Our new design will tolerate a lot more.

The other more serious issue is in regards to safety. We want to make absolutely sure that the fittings on the transducers never are subjected to conflicting vibration planes. The engine will flex in the motor mounts creating conflicting vibration planes between the engine and the airframe. This is why the ?flexible line in? and ?flexible line out? is called out so often. This is also why we don?t want the transducer rigid mounted, via a fitting, to a carburetor or fuel pump. A contradicting vibration plane will focus the energy directly to the fitting. It is our sincere concern that with the two conflicting vibration planes here could cause the fitting to fatigue and crack. This would be bad?and we have seen it happen?.

On the bright side, we don?t care if the thing flows straight up, or if you put 90-degree fittings in and out of the transducer. Just don?t mount it upside down, flowing sharply downhill, or before the pumps.

Please let me know if you have any questions or if we may be of any assistance.

Matt Sharp

 

[crabandy]

Cool, thanks!

 

[BSwayze]

Here is something that I try to post each time a new thread shows up on these Red Cubes.

Matt works for the people that make the thing:

Brian, thanks so much for posting this! I've been trying to read up on this subject, and this is valuable information. I just received my red cube and I'm in the midst of trying to figure out where and how to mount it. Do you happen to have a picture of how you did yours?

Thanks!

 

[rzbill]

Here's mine

My red cube mounting is similar to what has already been posted but it is different enought to share. 100hrs with no probs.

The bracket is lighter weight fabrication and my fuel pressure connection is simpler.

Bracket Fabrication

Attachment to firewall

The following is the only shot I have of the hosing. It is during construction so not finished but the differences I wanted to show are there.

Inlet hose and fuel pressure

 

[crabandy]

Bruce,
On my install I was able to use the gascolator to fuel pump hose (I forget the part # but its the shortest one) for mocking up my fuel flow location.
I ended up with 3 hoses all the same length, 1 gascolator to fuel pump-1fuel pump to red cube-1red cube to carb. I used vans 90 fuel pump fitting with the port for fuel pressure, a 90 elbow on the inlet to the red cube and a 45 exiting the red cube and a 90 on the carb.

To find the best location for the cube I made my red cube bracket and inserted the fittings and hooked up the hose from the fuel pump to the red cube and vans stock fuel pump to carb line and moved the cube around the firewall until I found the best clearances for both fuel lines. You can get the approximate position reference the rivets for the firewall stiffener/brake lines.

I had TS Flightlines make my additional hose as well as shorten one of the stock vans hose.

Good Luck!

 

[Wayne Gillispie]

Same as Mike's on my -10.

Looking inside it at the small hole diameter(guessing 3/16"), it is a fuel vaporization/pressure drop issue more than accuracy. I have taken off solo once without boost pump on in hot wx flowing 25.5 gph with no problem, but would not make it a habit. The only rough running I have ever had was after a hot fuel stop while taxiing, and BP solved it.

 

[alcladrv]

My 2 cents.... If it were a carbureted engine, I would install it at the output of the mechanical pump.

I'm mounting one for use on a carbureted O-360.

Do you mean that you would install the red cube directly on the outlet of the mechanical fuel pump, perhaps with a close nipple, and then from there directly to the carb?

This could mean one less hose and maybe use the same hose already in use from the fuel pump to the carb.

Thoughts? Good? Bad?

Thanks, Mike

 

[Bill.Peyton]

I would NOT mount it directly to th fuel pump with steel fittings. Use an appropriate hose on each side. Fabricate an angle and mount it on the firewall