That works fine for the font in the cells but the numbers on the
chart
are still small.

Here is the csv raw file. Give it a try.

Paul Lamar



Edit/Formet/Cells/Font worked fine for me.  I first saved the file in
MSExcel2009's *.doc format, so maybe that has an effect

Robin Bergland.

Did you chart the data? Send a screen shot of the chart.
It is the numbers on the  chart I am concerned with.
Not with the numbers in the cells.

Paul Lamar


Paul,

To answer Matt's question, no, I didn't make the hoses exactly the same
length.  That may account for some of the mismatch.  Looks like I need
to install the new vacuum ports and collect more data.

One other thing that we should mention is that the voltage goes up as
MAP goes up, and down when the MAP goes down.  So, the harder it sucks,
the lower the volts.  The sensors read approx. 1.7v at atmospheric pressure.

Mark

The pressure pulses travel down the hose at the speed of sound so that
should not significantly change the pressure with a longer or shorter hose.

When you get the CAS in there things will become clearer.

With the apex seal oil hole taps the amplitude of the wave will be reduced due to the small orifice  and the voltage will reflect the average of the air getting in to each rotor.

It is absolute pressure so as the voltage goes up the quantity of air getting in the engine is higher. Best not to think in vacuum or suck terms. Too confusing:) Best to think in number of air molecules getting in :)

What surprises me is the amount of air it takes to idle the engine.
If you have a MPX4250 sensor 1.7 volts is near atmospheric pressure.
Of course it is oscillating.

If you have a MPX4100 sensor it is half that. 1.7 volts is 7.25 PSI or
7.46 inches of Hg.

That would make more sense at idle.

Tracy uses the MPX4250 because it works for normally aspirated as well as turbo so he need stock only one part number I think.

Here is picture of my new stand alone high buck ($200)  Hytek with a USB chip. No computer in the aircraft needed.
I have not been able to get it to work yet. Something to do with the reading software I think. It uses a different package for the pressure sensor.

Paul Lamar