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Old 06-03-2020, 01:41 PM
raisbeck raisbeck is offline
Join Date: Mar 2013
Location: Laramie, WY
Posts: 29
Default Installing red cube on carburated engine

I've been following the various red cube threads for a couple weeks, but can't decide how/where to install my fuel flow sensor on a RV8 with a Lyclone engine.

Basically, it seems that these sensors are very susceptible to heat and vibration. In fact Vic Syracuse, in his most recent EAA webinar called out a couple of installations that had it mounted to the engine mount as a potential source of failure. So I'd planned to put it on the firewall with a heat shield between the gascolator and the engine driven fuel pump with a teflon/SS line from the cube to the engine pump, all uphill.

On the other hand, when I opened the package yesterday, the instructions from EI said that it HAS to go between the "last fuel pump" (i.e. the engine pump) and the carburator, otherwise it may lead to vapor lock and inaccurate readings.

I can live with iffy readings, but vapor lock got my attention.

How has everyone with a non-fuel injected set up done it, and how well did it work?
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Old 06-03-2020, 02:38 PM
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tkracmer tkracmer is offline
Join Date: Jun 2005
Location: Fort Myers, Florida
Posts: 20
Default Red Cube

I mounted mine on the engine mount with Adel clamps between engine driven fuel pump and carburetor. Works well.
Tom Kracmer
Fort Myers, Florida, KFMY
RV-7A Tip-up
2021 Donor
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Old 06-03-2020, 02:53 PM
pa38112 pa38112 is offline
Join Date: Mar 2008
Location: Clarksboro, NJ
Posts: 1,004

I have mine in the cockpit after the electric pump. It works OK, but the flow jumps around a bit. The totals are always very close. My son mounted his on the firewall and ran a hose from the fuel pump to the red cube and then from the red cube to the carburetor. His is more stable than mine.
2004 RV6A Flying
2002 RV6A Flying
1978 PA38-112
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Old 06-03-2020, 04:11 PM
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Rick_A Rick_A is offline
Join Date: Oct 2005
Location: Jacksonville, FL
Posts: 1,572

Before I switched to fuel injection, I had the Red Cube mounted on the cold side of the firewall just a few inches down stream of the Facet pump. It worked perfectly.

I made custom bracket that was riveted to the firewall. The bracket was angled so that the output was slightly higher than the input.

At some point along the way, I learned that it should have been mounted closer to the carb. However, since it worked fine, I did not move it.
Rick Aronow,
Flying 7A Slider;
Jacksonville, FL
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Old 06-03-2020, 07:03 PM
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OZCleco OZCleco is offline
Join Date: Dec 2018
Location: Maylands, Western Australia
Posts: 60

On taking ownership of our preloved RV9A I found the unit was flopping around between the gascolator and mech pump not mounted to anything particular, sitting vertically. FF indications were terrible, and every time I selected the aux pump on it would spike to a large number.

Following the instructions to the tee I attached it to the lower left engine mount (just prior to the carby and after the mech pump) on-top a rubber standoff.

Happens to sit just over the left cowl louvre which would no doubt provide additional cooling air to the conventional cowl.

Indications are now rock solid with no change to FF reading when the aux pump is selected on.
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Old 06-03-2020, 08:01 PM
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bhester bhester is offline
Join Date: Jan 2005
Location: Hopkinsville, KY
Posts: 1,037
Thumbs up Here is my Red Cube

The cube mounted between the fuel lines pretty much just sits there. The mounting plate just stabilizes it.
I was asked how long those fuel line are and it appears from my pictures that I took while installing them they are about (hose only without fittings) 7” long. I’d make one and then see if it fit both locations. One might be 6.5”

Bobby Hester - Builder/Pilot/A&P
Surfing the web from Hopkinsville, KY
N857BH RV7A XP-O360 - Garmin G3X ADS-B IN/OUT 2020 Compliant
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Dec. 2020 VAF donator - alot better than any magazine subscription

Last edited by bhester : 06-04-2020 at 09:23 PM. Reason: fixed pic links, added hose length
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Old 06-03-2020, 08:04 PM
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OZCleco OZCleco is offline
Join Date: Dec 2018
Location: Maylands, Western Australia
Posts: 60

That's gold. I may do this next annual.
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Old 06-03-2020, 08:43 PM
Larry DeCamp Larry DeCamp is offline
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 1,157
Default Instructions for install

I had recent conversation with The manufacturer regarding how important it is to have the wire lead vertical. Bottom line they said if the output is above the input and the wires are slightly up, there may be a slight degradation of accuracy and service life expectancy due the fact, apparently, the impeller bearings are optimized for vertical shaft orientation. That said, my -3 is perfectly oriented per instructions and performance is stabil at 220 hours. My -4 is a little wire out up, stay tuned for conclusions.
Larry DeCamp
RV-4 fastback in process w/ Superior roller 360/AFP/G3X/CPI/Catto3b
Clinton, IN
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Old 06-03-2020, 08:45 PM
Scott Hersha Scott Hersha is offline
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 2,028

I have the red cube mounted between the electric fuel pump and the engine driven fuel pump on my carbureted RV4, inside the cabin on the cold side of the firewall. I know this is not the geometry that is suggested by the manufacturer, but there is literally no room in my engine compartment between the engine pump and carburetor to install it. If my only choice was that, I wouldn?t be able to have a fuel flow indication. As it is, it works well where it is, and my fuel flow calculations in my EFIS are spot on, so my location works for me.
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
RV6/Used kit purchased 2021 building
Cincinnati, OH/KHAO
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Old 06-04-2020, 03:56 PM
TS Flightlines TS Flightlines is offline
Join Date: Apr 2010
Location: Ridgeland, SC
Posts: 2,935

Various places to locate the cube----under cylinder#4 and near the lower dynafocal cup usually works well.

Tom Swearengen, TS Flightlines LLC, AS Flightlines
Joint Venture with Aircraft Specialty
Teflon Hose Assemblies for Experimentals
Proud Vendor for RV1, Donator to VAF
RV7A Tail Kit Completed, Fuse started-Pay as I go Plan, on hold while we develop new products for RV builders
Ridgeland, SC,
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