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Old 12-04-2012, 08:14 AM
CHEROKEE66 CHEROKEE66 is offline
Join Date: Mar 2005
Posts: 22
Question Dynon Fuel flow

Question, building an RV-8 and the dynon fuel flow sensor instructions say you need 6 inches of straight line before and after for accuracy. I have the Airflow Performance fuel injection and the only place I have that legnth is from the mechanical pump to the airflow unit below the cylinders and above the exhaust, not what I would consider ideal. How critical is this?
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Old 12-04-2012, 11:59 AM
gear1 gear1 is offline
Join Date: Sep 2008
Location: Pagosa Springs CO
Posts: 266
Default Fuel flow sensor location

My Flowscan sensor was originally mounted downstream from the mechanical pump, adjacent to the #4 exhaust. This bothered me as it seemed to be a fire hazard. Additionally the engine ran roughly for several minutes after a hot start. Therefore I moved the sensor to the aft baffle bulkhead inside the plenum above cylinder#3. The fuel from the fuel injection servo going to the distribution spider passes through the sensor. The sensor is wrapped in firesleeve insulation material. It was necessary to use 90 degree fitting at both the inlet and the outlet. However, I have found the accuracy to be excellent: typically .2 gallons error in a 30 gallon flight, or 0.67% error. The error is the same as it was in the original location. The post-hot start roughness still exists, but it now clears within thirty seconds. The Flowscan unit seems unaffected by the 90degree fitting.
Craig Taylor
RV8 flying
2022 VAF dues paid with thanks
Navy A7E Vietnam era
Ret. Corporate Pilot: Gulfstream, IA Jet, Jetstar, Falcon 10, 20, 50, HS125
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Old 12-04-2012, 12:24 PM
RVG8tor's Avatar
RVG8tor RVG8tor is offline
Join Date: Mar 2007
Location: McKinney, TX
Posts: 1,267
Default Metered line

I ran my install with Don at AFB, the fuel line that runs from the fuel control to the purger valve then the spider runs up between the 1 and 3 cylinders. I had to get a new hose but the flow now goes from the fuel control to the flow meter which is suspended with cushion clamps on my engine mount tubes (RV-8A so there a lot of them. Then this connects to the line to the spider. Don really likes the flow meter to be in this line, not before the engine pump or fuel control but many have installed the flow meter on the firewall and other such places. This is what I did.

I passed the AW the other day and hope to fly when the weather gets better maybe next week.

This will be wrapped in fire sleeve as well.

Mike "Nemo" Elliott
RV-8A (First Flight 12-12-12!)

Dues Paid 2021
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Old 12-04-2012, 01:24 PM
Join Date: May 2007
Location: Quincy, Florida
Posts: 680
Default sensor

Mine is mounted on the firewall and has a 45 degree nipple in either end. The accuracy of the flow sensor can be adjusted with a Dynon unit by changing the K factor in the setup mode. It took me about four tries to get it right, but with the 45 degree inlet/outlet nipples, I'm spot on now. My Dynon is a D180. Yours may not be adjustable. Good luck.
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Old 12-06-2012, 06:33 AM
Skysailor Skysailor is offline
Join Date: May 2011
Location: Atlanta, GA
Posts: 308
Default Skyview K factor

The K factor for the fuel flow sensor is adjustable in the Skyview.
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Old 12-06-2012, 09:39 AM
CHEROKEE66 CHEROKEE66 is offline
Join Date: Mar 2005
Posts: 22
Default DYNON Fuel flow answers.

Thanks for the suggetions, it was a big help.
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Old 12-06-2012, 10:48 AM
Rupester Rupester is offline
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,195
Default FWIW ...

My Red Cube is located exactly where RVG8tor's (Nemo) floscan is shown in the pic. Works great and is VERY accurate. (Once I got rid of the first red cube with the leaking defective threads!) I was thankful it was in such an accessible location, given the many futile hours I spent removing and resealing inlet and outlet fittings.
Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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Old 12-07-2012, 04:55 PM
drakerv drakerv is offline
Join Date: Feb 2006
Location: Redmond Wash
Posts: 96
Default Flowscan

Remember that the flowscan transducers are supposed to be mounted horizontally to have long life.The impeller in the 201 pivots on a small jewel and if not mounted horizontally can fail prematurely. marc
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