Ran the engine on the test bed to check the inputs.

The scope can store the data as a csv file which can be imported into a spreadsheet and plotted.  Here is the pressure within the cylinder:

Looks about right for a gas engine running at no load.  Here is the raw signal from the variable reluctance sensor used to track crank angle:

On the shaft is a trigger disk with 60 tooth positions, but 2 teeth are missing to provide a gap used for reference.  So there are 58 cycles of the signal between the two gaps. The two plots are on different time scales. The top plot represents 10 rotations and the bottom plot represents about 1.5 rotations of the engine.

One use for this program is doing good quality evaluations of HHO injection. By running the engine at a controlled speed and load, measurement of fuel consumption under highly controlled conditions may be possible. Hopefully, the measurement will be maybe 99% as good as what could be done in an engine lab, yet, as you can see, it is a rather simple inexpensive setup. The most expensive part was the fiber-optic sensor which cost about $1,100. Still, that is a lot cheaper than an eddy current load absorber and associated equipment.

Takes a long time to put everything together, so the progress is very slow.

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Comment by charles ware on March 14, 2016 at 8:43pm

Hi Peter,The sensor does not have anything like a digital interface which would be nice.  It is just a voltage analog output.  The scale factor is 2.69 mV per psi. Recommended power is 12 volts DC. That little circuit board in the video is just a piece of perf board with a home-made power supply on it: 120 VAC to 18 VAC transformer, diodes, a few capacitors and an LM7812.  Probably will be adding a 7805 to power the VRS on the crank,  

Eventually, I will make module from a PIC18F46K22 demo board.   I have a little Pickit 3 programmer, MPLab X development environment and the C8X compiler. Writing C code is one thing I've done a lot. For now,  I will use a step motor actuator to operate the  carburetor throttle. Then the module can regulate speed and load on the engine. It will have a USB/serial interface so test and control function would go through Minicom on a laptop.

Comment by Peter Kiproff on March 14, 2016 at 10:59am

Hi Charles

Excellent scope shots, can you tell us more about the pressure sensor " link "



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