Sorry to ask such a basic question, but does anyone know the thread
 dimensions for the plugs that Mazda uses in the 13b, I'm looking to make
 an
 adapter for a Fluke PV350 pressure transducer for a compression tester.
 Combined with a peak hold meter it would make a great tool for the shop.
 Thanks,
 C. Smith

Larry sent Craig a modified spark plug that will do the job.

This little $50 CPU board I am getting from FreeScale would make a good
compression tester. It talks to a PC through a USB cable and it has
a bunch of analog to digital converters on it. All you need is a
pressure sensor and a bit of simple asm software to read it
and send the compression data to the PC over and over again. One
can get a sample every millisecond while the engine is turning over
with the starter. (.001 second) I'll know more in a couple
of days as I will have one up and running.

It can also study the tuned intake manifold in real time as Matt
suggested by putting in a couple of tiny pito tubes and pressure
sensors on either end of the intake runner. Sort of like
a $10,000 storage oscilloscope only better. Fascinating stuff.

I am going to get it working on my Linux EeePC 1000 solid state drive
for a portable data acq system that will work in airplanes. There
are all sorts of things that can be done with that including cooling
system pressure measurements. Of course a whole raft of engine parameters
can also be measured and recorded.

If you want to do an EFI system with one of these boards I recommend
the $75 one with a lot of I/O. Use two and a relay for redundancy
like Tracy does.

A few years or months ago we were thinking of doing the same thing
with a PicAxe but PicAxe did not quite have their act together.
FreeScale (Motorola) has spent an order of magnitude more money on the
software for this board so I expect it will work much better.
It will be a lot faster. PickAxe was programed in BASIC which is
very very easy to learn but I already know 68xx asm language :)

Paul Lamar



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