ULPower 350is Fuel Flow

[pacecapt]

I have a Dynon HDX system (without the Red Cubes). My setup shows a K factor for both fuel flow to and return input setting in order to determine the Fuel Flow for the display. I know that the engine fuel flow formula is:
1. 48 l/h = 12.68 gallons / hr
2. 170 pulses / sec = 612,000 pulses / hr
3. 612,000 / 12.68 = 48,265 pulses / gal
4. Calculated K factor is 48,265. (This number is input into the fuel flow "To")

Here is my question: What K factor # do I input into the "return line"?

 

[Dynon]

Not quite following. The sensors (at least the red cubes and similar floscan products) are rated in pulses per gallon. There might slight variation over flow rates, but nothing appreciable. So generally you have two of those sensors, and you use their default K-factors for both (or the labeled ones if it has, in the case of some floscans). It is admittedly harder to figure out which one to adjust up or down if you're not close.

 

[pacecapt]

I have read on several postings that if you are using the "Red Cubes" which I understand are not required with the HDX, then the K factor for both to and return is 68000. If you don't use the cubes then for the UL Power which has a documented fuel flow of 48 liters per hour (12.68 gal/hr) the K factor on the "to" line should be set to 48265 which is achieved be doing the conversion calculation. What I don't know is if the "return" line K factor should be the same or something less? I currently have them both set at 48265 but my fuel flows are much higher than I actually am using which makes me think the return line needs to be another K factor value...

 

[sunfish]

I know it’s stupid, but just check you haven’t got a bleed orifice line ”short circuiting“ the fuel lines. The cubes need to “see” all the fuel going in and out. After that, check the EMS diagnostic page to ensure both cubes are indicating something. After that, try offsetting the K values between in and out by a thousand pulses or more. That should produce a reading. say, 68000 in and 65000 out.

 

[brianreid]

What fuel flow sensors are you using?

 

[pacecapt]

What fuel flow sensors are you using?

None, the Dynon HDX will calculate once you get the K factor number correct.

 

[ned]

I have a 260is. You do not use return fuel for calculation. The fuel usage is calculation is based on litres/hr actual usage. I think mine is 63000. The calculation does not care what return flow is.
A higher K factor is less usage. You will have to fine tune your k factor by verified consumption of metered fuel when filling tank. Works best on longer trips at cruise rpm.

 

[brianreid]

None, the Dynon HDX will calculate once you get the K factor number correct.

As I understand it, the K factor allows the computer to adjust pulses per second to gallons (or liters.) If you really have no sensors in either fuel line then there is nothing for the K factor to adjust and the HDX will just produce gibberish. There must be some kind of sensor (transducer) in the fuel line that will put out pulses per second. You are right that that sensor(s) does not have to be the Red Cube brand of sensor but there must be something.

 

[airguy]

Your "pulses" are either generated by a fuel flow sensor, or by an engine computer telling the injectors to fire. Which one do you have?

 

[terrybrd]

I have the UL Power engine using the Skyview classic. When I heard that the updated computer for the engine gives you the info that you need and don't need any cubes I contacted them to find out how to wire it. If I remember right there are 2 wires from the injector module and you use one of them to hook the dynon too. The input pulses are read by the dynon. It doesn't care how much fuel is going back to the tank-- just the amount that is getting burned. Contact UL Power and they should be able to help. Then you adjust your K factor to tweek it in to get an accurate reading on the Dynon