Paul,

I made a major breakthrough today.  In preparation for hooking up the
Hytek data logger, I decided that it would be good to install check
valves on each vacuum line leading from each rotor housing.  (For
     those
who are unaware, I am running a peripheral port 3-rotor with a PL
     slide
throttle.)  My system measures MAP from the unused oil injection
ports in each rotor housing.)  Not sure what possessed me to do a
ground run right then, but I ran the engine right after installing
the check valves.  Now keep in mind that typical MAP readings at
idle up to this point was approx. 17" Hg.  Well, today MAP readings
were in the 14.4" -
15.0" Hg range.

Then it dawned on me that the way the vacuum lines were
plumbed the RWS EC-2 would see an average of all three rotors.
Since each rotor is 120* (crank degrees) apart in their 4-stroke
cycle, the MAP would be quite a bit different for each rotor.  By
installing check valves in the vacuum lines, I have isolated each
rotor from the other two and I am measuring the lowest vacuum.  Idle
is now down around 1500 rpm, but the mixture is way lean, so it
appears that a re-tune is in order.  I'll probably re-set the RWS EC-
2 to the factory defaults and start the process over from the very
     beginning.

We need to stress to anyone that is measuring MAP in the rotor
     housings to install check valves in each of the lines.

Mark

Good work Mark. Here is the latest voltage to pressure chart.

Paul Lamar

Mark,
     To me check valves tells me you allow "flow" one way and block the
     other. If
     that is the case you either inhibit sense or trap it. Also, is there
     a crack
     pressure for these check valves? Crack pressure is the pressure
to     get it to open.

     Dale Davies

Dale,
You have put your finger on the same issue that Tracy Crook pointed out.
   If there is no way for the MAP to rise, then the engine may have a
stumble when accelerating.  I did not experience that during my brief
ground run, but will be looking for that on the next run.  (It is
possible that the check valves I am using don't seal very well and
are allowing a controlled leak.)  I may have to re-think this, but
it sure opened my eyes to a problem I hadn't realized that existed until
yesterday.  I may have to try using only one rotor's vacuum for the
EC-2, and/or a small vacuum chamber.  I'm open for ideas here.

By the way, those little bolt-looking things that screw into the oil
injection ports are actually check valves.  Anyone know what they are
used for in street applications?

Mark S.

Those those little bolt-looking things are custom made for Mazda. I
would not use them for monitoring intake manifold pressure.

I have some  pressure taps for that purpose that are custom made by
NC lathe. $20 each free shipping in the US. They have a small hole
for damping purposes. I think you will need to T all of them
together as Tracy uses only one pressure sensor to set the mixture
for all rotors.

Here are some data on the old manifold pressure taps downstream from
the slide throttle and some data from the oil injection hole data.
The small hole in the NC made tap smooths the data greatly and
averages it as you can see.

In your case I would like to see the data from each rotor before it
went into a T directly from a pressure tap down stream from the
slide throttle but I don't think you have pressure taps installed
there right at the moment. See the pictures of Mark Suspinski's installation.

I would also like to see the data very close to the open part of the
slide during idle. That will take some tiny tubing welded into or JP
Weld bonded to the back slide cover near the opening just beyond the
Teflon.

Since the wave is very strong Tracy's reading voltage number is
going to depend on when he takes the sample relative to the e-shaft
position. So far we don't know that but it can be found out when you
connect the injector voltage and CAS to the HyTek with an opto
isolator. The computer only takes microseconds to completely read
the sensor sample.

The time of the peaks and valleys changes with RPM so the wave must
be damped out some how. The car racers use a large section of PVC
pipe for this purpose.

Paul Lamar



Inlet pressure should be virtually the same for all cylinders/rotors in a
running engine in good mechanical condition. Using only one to read the MAP
should work however it is better to average the readings. A thought on
restricters as per the Mega squirt manual, air bleeds or jets for carbs,
furnaces or catalytic heaters can be stuffed in a hose. In your instance one
per rotor. I like the fuel filter for a volume bottle also as it is easy to
install in a hose and are readily available, meaning inexpensive. Also fairly
light.

Dale Davies