Paul:
As a side-project for my HomeBrewedGlassPanel project, I am researching
and soon will be acquiring sensors to feed analog data to my DLP-IO20
data acquisition board.

I believe that the automotive sensors that I have experience with in the
past are all variable resistive devices of some sort. The internal
bellows-construction of most old pressure-sensors is obvious. And I
always had the impression that there was a little plunger on the end of
of some pressure sensors. I also suspect that temperature sensors were
nothing more than thermistors. These resistance-based sensors would all
be relatively high-current devices... something I would like to stay
away from.

I once did an engine-swap on a Ford and managed to get my wires crossed,
couldn't figure out at first why it took so long to get decent
oil-pressure, and why the engine temperature was normal immediately
after startup. :)

So I am breaking ground here in the digital world. I would like some
advice from the RotaryEngine bunch. Let's break down my search for
sensors into catagories ...

TEMPERATURE
There is no problem finding low-current analog temperature sensors for
use in the -50F to 250F temperature range, there are hundreds/thousands
of them available. The only problem I will have is finding one/some
inexpensive enough for my R&D budget that are bullet-proof enough for
the FWF environment of an aircraft.  I might land up boring a hole in a
bolt or brazing a plug into a pipe-fitting to make a socket that will
accept a cheapy sensor, then epoxy the device into the socket, leaving
some teflon-insulated leads exposed to the outside world.

I know these cheap sensors should work for water temperature and OAT,
but what about oil-temp, CHT, and perhaps even exhaust temp?  Platinum
thermocouples are a bit out of range of my R&D budget, I think.
I don't know how sensitive the A/D input is on the IO20 board, but I
suspect that thermocouple-based temperature sensors would require a
transistor or op-amp to give a usable signal. ???  Any suggestions.

PRESSURE
There are also quite a variety of pressure sensors available: classified
as gauge-pressure, absolute-pressure, and pressure differential.
It is interesting that some very inexpensive pressure differential
sensors are available, they are used as water-level sensors on
automatic-washers.  I should be able to find some of these and create my
own test version of air-speed and vsi indicators.  Somewhere in the last
month or two I saw a graph of pitot-tube air pressue (in H20") vs
airspeed... I've got to track that down again.  I'll probably have to
stick a pitot tube through the sun-roof of my wife's Subaru and go out
and break a few speed limits to test it.
Higher pressure/gauge-pressure sensors are more expensive, and perhaps
picking up the voltage-drop across a resistor in an high-current legacy
automotive oil-pressure sensor would be OK too.  Anyone know what latest
cars use for oil-pressure sensing?

ATTTITUDE
As you've discussed, there are solid-state gyroscopes, and solid-state
magnetic compasses available, and there are many solidstate sensors out
there that are used in these products.  However, most of these require
digital I/O, I believe.  And interfacing my GlassPanelDislay with
several digital signals will require more ports than are supplied on the
DLP-IO20 data acquisition-board. I will need to do more studying on
these issues.

So ... if anyone has any advice or experience with sensors, I am
listening.

R Berglund