Closer to the Goal

The recent effort has been directed towards getting the engine to run properly, with the RWS EC3 system. There are all sorts of variables to work through; new throttle body, injectors, homemade induction pipes, the list is long.

Right now, I'm working through getting the mixture and ignition timing properly adjusted. This is a pretty big deal and will take a while.

To complicate things, the readings from the mixture meter have been unreliable. Here is the one I'm using.

It turns out, I mounted the sensor too close to the end of the exhaust pipe. The O2 sensor is very sensitive and I guess that ambient air is getting sucked back into the exhaust pipe, between pulses, particularly at lower RPMs. This winds up showing the mixture to be too lean. As suggested, I clamped on a piece of pipe I had laying around and the mixture meter reading instantly got better.


Again, the use of this meter and sensor is only temporary, until I get everything calibrated.

Right now, I'm running the engine without the canopy installed, which is giving me a real wind-blown hairstyle. The best I have seen, at full throttle is about 2,200 RPM and 29" hg. I have old data that I had attained 2,340 RPM and 29", so I have little way to go.

I'm getting some of the wiring tidied up and pretty soon it will be time to, hook up the rudder cables, install the back-up battery and install the canopy.

On another successful note, my custom designed and built fuel flow circuit board works just great. The Dynon D180 allows you to connect a flow transducer. These transducers typically have a little fan in it, that rotates as fuel flows. A sensor picks up the pulse count and sends it to the D180 and indicates flow in gph. The problem with my system is that fuel passes through an open loop, starting at the header tank, running through pumps and filters, past the fuel injectors, and then back to the header tank. Because of this, any fuel flow transducer will sense ALL the fuel flowing and not just the fuel consumed.

Note: the flow out of the injectors is controlled by the duration of time that the injectors open. More fuel demand - the injector pulse width increases. Less demand - narrower pulse width. The number of pulses per engine revoultion is fixed.

Mike Dwyer to the rescue. Mike is a Dynon dealer and an electronics whiz. Mike designed a circuit that takes a signal from an injector. It converts an increase in pulse width to an increase in pulse frequency. It's all black magic, to me.
I got with Dennis Hannon, the avionics instructor at SIU, and an avionics student, and they fabricated and bench-tested the converter. I named the piece the Dwyer-Hannon Frequency Converter.
And what do you know? I works! Fantastic!


Mike designed in a calibration potentiometer, but the Dynon also has an adjustment multiplier. There is a little formula to dial in the calibration, so in a short while my fuel flow indicator will be correct.

Sweet!