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algrajek

Well Known Member
I know this subject has been brought up before but... I know a lot of you with fuel injection are putting your EI Ft60(red cube) in line, between the Servo and the fuel divider, as was I, but aftyer talking with Pete at Precision Airmotive today, I am having second thoughts. He suggests mounting the sensor BEFORE the servo to get a better reading, and more importantly, he is not comfortable having ANYTHING between the servo and the fuel distributor. Now I dont know what to do.
Any thoughts??
Al
 
Could you please elaborate his concerns and how it equates to a better reading?

I don't see the discomfort with having it between the spider and servo. A blocking failure on these would seem to be highly unlikely and does it matter if the main fuel line is blocked before or after the servo as either way will kill the flow.
 
I'm guessing his objection to a location between servo and spider is structural. Very few builders are providing a solid bracket to mount the red cube, thus the mass of that aluminum block is left to flail about suspended in space only by the connecting fuel lines.

Is this a bad thing? Well, it certainly was when a builder tried to suspend it on a hard line. Plus the fittings are smaller on the servo outlet side, and nobody knows what the resonant frequency might be for the hanging assembly.

Precision has been sued a few times. Can't blame them for conservative recomendations.

BTW, mine is on the firewall.
 
Dan,

I see teaser pics of your project all the time on here....Is there somewhere I can go to see this project documented? Your work looks amazing! At least what I have seen of it does!
 
One of his concerns was any kind of disruption of the fuel going to the spider. He mentioned pulses etc. that may be induced by the sensor.
It seems like it may be easier, anyway to put the sensor between the engine driven pump and the servo inlet, by just cutting the supply hoses and inserting 2 fittings. Probably sounds easier than it is.
Al
 
Interesting,

DanH said:
I'm guessing his objection to a location between servo and spider is structural. Very few builders are providing a solid bracket to mount the red cube, thus the mass of that aluminum block is left to flail about suspended in space only by the connecting fuel lines.

Is this a bad thing? Well, it certainly was when a builder tried to suspend it on a hard line. Plus the fittings are smaller on the servo outlet side, and nobody knows what the resonant frequency might be for the hanging assembly.

Precision has been sued a few times. Can't blame them for conservative recomendations.

BTW, mine is on the firewall.
Click to expand...

I know he cruises the forum so maybe he can chime in as to why...
However, here is the link to the EI installation instructions. The interesting thing here is that is shows a Flow Scan in the RV7 example and the Red Cube in the 8 example. Additionally, unless hidden, it appears the Red Cube is mounted to hard tubing suspended in free air. Bad idea.
JPI's instructions for the flow scan are to mount it on flexible line, in free air. Mine is mounted on the top of the engine between the divider and the baffle unsupported on flexible fule line.
http://www.fdatasystems.com/Manuals/FT_60_install.pdf
 
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Installed in my 8

I highly regard the professionals at EI but I did not like their recomended spot for the red cube installation. (on the vertical line to the spider)
Mine has a constant flow return but only one flow transducer installed just before the fuel line enters the fuel servo. The return comes out of the engine driven fuel pump and does not affect fuel flow readings. Readings of pressure and flow are extremely accurate.

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JonJay said:
However, here is the link to the EI installation instructions. The interesting thing here is that is shows a Flow Scan in the RV7 example and the Red Cube in the 8 example. Additionally, unless hidden, it appears the Red Cube is mounted to hard tubing suspended in free air. Bad idea.
JPI's instructions for the flow scan are to mount it on flexible line, in free air. Mine is mounted on the top of the engine between the divider and the baffle unsupported on flexible fule line.
http://www.fdatasystems.com/Manuals/FT_60_install.pdf
Click to expand...

I spoke to him regarding the installation and this instruction and he clarified that those instruction is not from EI and it should not to be followed at all which I agree with him. Connecting the red cube on hard line without any support such as pictured here is very dangerous. Having said that, I have installed mine in the tunnel and it is physically supported/mounted to prevent any vibration. The reading has been amazingly accurate, well within 0.013 of a gallon accuracy which is pretty darn good for me, I have about 1/3 of gallon discrepancy for every 25 gallon of fuel.
The fuel flow reading has been very stable as well, it goes up momentarily when I turn my fuel pump on and after a couple of seconds or less it comes back to what it was reading before. I like it in the tunnel because it has made the installation safe for my standards.
Hope this helps.
 
Over the years I have mounted the fuel flow sensor in a lot of different locations. From my experience I would have to say that all locations work well as long as the unit is installed properly.
 
BTW, if you're going to mount your cube on unsupported sheet metal (like the firewall), best to use a double bracket arrangement. A single piece of angle used as a shelf doesn't really fixate the cube.....and it should be firmly fixed if connected to aluminum lines.

 
Good point

Bavafa said:
I spoke to him regarding the installation and this instruction and he clarified that those instruction is not from EI and it should not to be followed at all which I agree with him. Connecting the red cube on hard line without any support such as pictured here is very dangerous. Having said that, I have installed mine in the tunnel and it is physically supported/mounted to prevent any vibration. The reading has been amazingly accurate, well within 0.013 of a gallon accuracy which is pretty darn good for me, I have about 1/3 of gallon discrepancy for every 25 gallon of fuel.
The fuel flow reading has been very stable as well, it goes up momentarily when I turn my fuel pump on and after a couple of seconds or less it comes back to what it was reading before. I like it in the tunnel because it has made the installation safe for my standards.
Hope this helps.
Click to expand...

Now I dont know whether I should delete the link to remove any future confusion or to leave it to make the point. I will leave that to a moderator I guess. Sorry for any confusion.
 
Bavafa said:
I have installed mine in the tunnel and it is physically supported/mounted to prevent any vibration. The reading has been amazingly accurate, well within 0.013 of a gallon accuracy which is pretty darn good for me, I have about 1/3 of gallon discrepancy for every 25 gallon of fuel.
The fuel flow reading has been very stable as well, it goes up momentarily when I turn my fuel pump on and after a couple of seconds or less it comes back to what it was reading before. I like it in the tunnel because it has made the installation safe for my standards.
Hope this helps.
Click to expand...


I have mounted mine in the tunnel (under the selector valve). And solid mounted it to the floor. But since mounting it there I have concerns of vibration in the floor damaging the unit. When You say it is physically supported/mounted to prevent any vibration. Are you saying it is solid mounted so it doesn't vibrate around and cause fatigue to the tubing? (as it most likely would if it was swinging, supported only by the tubing). Or are you saying you have fixed mounted it on rubber mountings or similar?

Anybody can chime in here on their thoughts on my mounting ,if you would please.
 
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There is a straightforward alternative. A duplicate of the steel angle mount on Lycomings that holds the spider can be purchased (or made) and it fits on the threaded hole on other side of the top of the engine from the spider. It also has holes drilled so the bolt holes on the flow cube match directly with no change. It is a good example of plug and play with straight lines in and out.
Hose goes from the injector to the flow cube then toward the rear and around to the spider.
 
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