Red cube mounting for G3X (RV-7 O-360)?

[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]

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]

Originally Posted by Bill.Peyton

. 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]

Originally Posted by jetdriven

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]

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