Another "Red Cube" Question

[Blizzard]

Earlier in my build I was just going step by step as per the plans. Put my red cube in the tunnel right where the plans say it goes. About to hang the engine and star the cowling. I have an IO-540 engine and I now realize that the tunnel may not be the ideal location. Has anyone used this location and how well does it work there? I have an extra red cube. If I decide to change it's location is there a problem with leaving the original one in the tunnel and mounting another one somewhere between the fuel pump and the the spider. Obviously I would disconnected the wiring from the one in the tunnel and rewire to the new one. I have the braided fuel lines from Flightlines and everything fits perfectly in the tunnel as is. Plumbing firewall forward would be so much easier than re-plumbing my tunnel. I have a couple of options.

1. Leave the original one in the tunnel and see how it works.

2. Leave the original one in the tunnel and add a second one firewall forward with the option to swap the wiring to see which one works better.

I feel like option 2 is a better choice as long as having an "inert" red cube in the tunnel is not going to cause some kind of flow problem.

Thoughts?
Thanks

 

[Bill.Peyton]

The most successful consensus is mounting it between the servo, and the fuel spider. This usually results in the most consistent readings. As expensive as these cubes are and as frequently as they fail, I would definitely remove the one you have in the tunnel, move it forward and keep the other one as a spare.

 

[TS Flightlines]

Earlier in my build I was just going step by step as per the plans. Put my red cube in the tunnel right where the plans say it goes. About to hang the engine and star the cowling. I have an IO-540 engine and I now realize that the tunnel may not be the ideal location. Has anyone used this location and how well does it work there? I have an extra red cube. If I decide to change it's location is there a problem with leaving the original one in the tunnel and mounting another one somewhere between the fuel pump and the the spider. Obviously I would disconnected the wiring from the one in the tunnel and rewire to the new one. I have the braided fuel lines from Flightlines and everything fits perfectly in the tunnel as is. Plumbing firewall forward would be so much easier than re-plumbing my tunnel. I have a couple of options.

1. Leave the original one in the tunnel and see how it works.

2. Leave the original one in the tunnel and add a second one firewall forward with the option to swap the wiring to see which one works better.

I feel like option 2 is a better choice as long as having an "inert" red cube in the tunnel is not going to cause some kind of flow problem.

Thoughts?
Thanks

Yes--later opinions do prefer (as we do) to move the transducer FWF, generally between the pump and the servo. HOWEVER---there are alot of 10s out there flying reliably with the transducer in the tunnel.

 

[Carl Froehlich]

The first RV-10 build I put the red cube in the tunnel following Van’s instructions. It worked, and was very accurate other than when the boost pump was on (indicated fuel flow would go up 1-2 gallons per hour). I also suspect that under normal cruise (boost pump off) this location was not the best for keeping the engine driven fuel pump happy (as in pump suction pressure) in all attitudes.

Builds after that mounted the red cube on the engine mount, fuel lines running from the engine driven pump to the fuel manager. This location meets all the red cube installation guidelines. This location has proven to work well.

Take the red cube out of the tunnel and mount it on the engine mount (using adel clamps) after the mechanical fuel pump. Run a 3/8” aluminum fuel line from the fuel selector to the firewall fitting in the tunnel and call it done.

Carl

 

[Walt]

The most successful consensus is mounting it between the servo, and the fuel spider. This usually results in the most consistent readings. As expensive as these cubes are and as frequently as they fail, I would definitely remove the one you have in the tunnel, move it forward and keep the other one as a spare.

Agree this is the preferred location. You really should not be pulling fuel thru the cube.

 

[Blizzard]

Survey says……Tom, I’ll be calling soon to order a new fuel line that goes directly from the boost pump to the firewall. I’m guessing you already know the exact length I will need. I’ll be removing the cube from the tunnel and relocating when I install the engine. Thanks.