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RV-10 Fuel System Question

BlackhawkSP

Well Known Member
Hi Guys:

I'm at the point of starting my plumbing for the fuel system. What's the consensus for the placement of the fuel flow meter. The plans (Pg 37-2) shows the flow meter in the tunnel, but I've read in other threads that when the fuel pump is on, that it will read a higher flow rate than actual, and throw off the total gallons used calculation. Some have solved that problem by mounting the flow meter just upstream of the fuel spider on the engine. Which way is the best?
 
I've read in other threads that when the fuel pump is on, that it will read a higher flow rate than actual, and throw off the

Yep, mine has about a 2 GPH error with the boost pump on.

But, I only run the boost pump for rather short periods of time so the error ends up being pretty small in the large picture.

And, the error is actually in your favor, giving a bit of a cushion to your remaining reserve.

How is the project going by the way??

Photos??
 
I put the last one in the tunnel and had Mike's results exactly. The one I'm on now is a Floscan on the case line 3 inches in front of the manifold valve (spider). Easy hose route and a solid pipe between Floscan and manifold valve. Simple.
 
This is just an observation - - 10's have higher fuel flow, there are higher temps in the tunnel around the fuel lines. Some have needed blast tubes on the mechanical pump. The red cube is the same as the lower fuel flow applications on the 6,7,8,9. The manufacturer recommends placement after the mechanical engine pump.

All these things combined would lean towards the space between the pump and spider as the best location. Higher fuel flow is higher pressure drop across the cube.

Plans location may not cause a problem, but margins would be improved with the forward location. Other 10 drivers can say if they have had fuel heat issues.

Food for thought, facts and data from 10 flyers would help.
 
Agree with mike

I also have mine in the tunnel in the plans location. Show 2gph high with the fuel pump on. But overall incredibly accurate. Used 53 gal from Osh to Atlanta and then a local flight for 1 hr. Fuel totalizer was 53.3. Filled it with 53 gal.
 
Same here

Mine is stock, tunnel location. Reads a bit high with boost pump on. I've made heat-soaked takeoffs from 5000' and 100+ F, never a hint of vapor trouble even after the boost pump was turned off.

For me, the fewer hose connections in the engine compartment, the better.

BTW, previous poster mentioned using solid line instead of a hose. This needs careful engineering to avoid vibration fatigue, fracture failure.
 
Yep, mine has about a 2 GPH error with the boost pump on.

But, I only run the boost pump for rather short periods of time so the error ends up being pretty small in the large picture.

And, the error is actually in your favor, giving a bit of a cushion to your remaining reserve.

How is the project going by the way??

Photos??

Mike:

Thanks for asking. The project is going great. I got a good head start by purchasing an empennage kit that was almost completed by a great builder, John Ely. That save me tons of hours. I have the empennage joined to the fuselage. The wings are all done with conduits/tips, and wiring installed. I plan on going everything Garmin with G3X panels and an Aerosport panel. My engine is sitting in the hangar too waiting for me to get to that stage (soon I hope :)). Here are a few picts. I just finished all the interior panels and am working on the fuel plumbing (chapter 37 ish).

200qmnr.jpg


sbj41y.jpg


259ld8z.jpg


91ifxe.jpg
 
I placed mine between the fuel servo and the fuel spider per the manufacturer of the red cube itself. MUCH easier to maintain, per the manufacturer and more accurate - why not? Be sure to fire sleeve it per their recommendations too.

Last page of the manual has the install location and recommendations for placement (page 20).

http://buy-ei.com/wp-content/uploads/2013/06/II-FP-5.pdf
 
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Larry, looking great, much better than the last time I saw it;)

Will pass the photos on to John and Karen.
 
Red cube in the tunnel going on 3 yrs. Works fine and within 1/2 gallon at fill-ups. Getting to it is easy unless you put a lower console, arm rest, carpet, etc on top of the tunnel cover.

You will want a Matco parking brake valve where your brake lines terminate now.

Also, it is easier to install the oil cooler mount now.
 
I have a Flowscan in the stock location. It has the 1.5 to 2 GPM high reading with the fuel pump on. I put a LED right next to the switch to remind me to turn it off. I am also usually within .5 gallons on fullup.

That said, if I were to do it again, it would be a Red cube in the line to the spider. No issues with the fuel pump and accuracy and a major improvement in maintenance when the Flowscan goes belly up. From my experience they will.

(Is there a definite answer as to the cause of the inaccurate reading with the fuel pump on?)
 
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Best?

Best location will be in the mind of the beholder, I think.
Manufactures of the flow devices generally recommend upstream of the fuel spider.
This is probably the location for most precise fuel readings but requires 2 hoses with fittings for installation, no big deal I guess.

The tunnel is where the airframe manufacturer recommends it be placed.
Mine is there and for more than one reason.
Using mogas I wanted a fuel system installation with minimal exposure to heat
for any fuel system components.
It works very well for me without any issues. Service is not generally needed on the fuel flow sensor so access is not really an issue. Flow accuracy has no practical impact compared to the other location.

The choice is yours ;)
 
RV-10 Fuel Question

Thanks all for the great info, and the PDF file Mark. I'm ordering the red cube Monday and will go from there. I'm leaning towards mounting between the engine pump and the spider. Thanks again.
 
This may be a minor issue, but having the flow sensor in the stock location can serve as a reminder that your boost pump is on. It reads higher (~2gph) with the pump on, so if you are reading higher flows than normal, you probably have your boost pump on. It has worked this way for me on many occasions.
 
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