Now that I am done traveling for awhile I am going to get serious
about measuring the p-port intake manifold pressure wave at different
RPMs.

I will order this low cost data acq system and hook it up
to the kind of pressure sensors Tracy is using.
That way we don't need to open Tracy's computer.
Also we will learn a lot about tuned p-port intake systems on the
rotary. Right now we have only a snippet amount of data from
Mazda.

I'll also trigger it off the ignition pick up so the data
can be correlated with the ignition pulse angle.
http://www.labjack.com/labjack_u3.php?prodId=52


I don't need this info for the 555 system or the Holley carb but
there are a lot of people out there with Tracy's system that need help.
The 555 uses the mass airflow sensor that works far better than just
sampling the intake manifold pressure once per rev.


----------------------------------------------------

I found one I like better. It is about the size of a credit
card. It has a stand alone mode that saves data to a
USB stick. USB sticks are up to 32 gig
and that is weeks of data even at 32,000 samples per second.
It also has drivers for Linux if you want it to work with
an EeePC. Â It has eight 12 bit(resolution is one part in 4000),
zero to 5 volts analog inputs if you want to use it as a engine
monitoring data aq system. One of the many digital
inputs (on off) could be used for the ignition trigger to
correlate the data to the e-shaft position.

The price is lower and most of the software is free.

http://www.hytekautomation.com/Products/IUSBDAQ.html


---------------------------------------------------

I just ordered some Free Scale 2.2 to 36.5 psi pressure sensors from
Digikey and the price dropped to $10 bucks each. I suggest if you
are having trouble tuning Tracy's EFI you might want to see what is
going
on with the manifold pressure.


Paul Lamar


FYI Tracy Cook has modified my ec2 to mitigate the low rpm tuning
problems.
The mixture correction table now uses rpm only from 0-2500 rpm and below
13"
hg. MAP.. Above these values manifold press determines map table
address.
John Prendergast


Sounds like a step in the right direction as anything below 13" of Hg
manifold
pressure is not relevant to an aircraft engine. The engine idles at 2000
RPM.

Paul Lamar

Seems like 13" is idle..At least I think when my 182 is running
properly that's about what I see.

Matt-

It is kind of curios that Tracy was staging the injectors at 15" :)
That caused a lot of confusion :)

Paul Lamar

Paul,
Did you see this one?

http://www.dataq.com/gl/?source=googleda&gclid=CIqS9uy_lJoCFQZeswodJjIDNg

Joe

Yes I saw it. The low end is only 240 samples per second. Not fast enough
for the intake wave sensor which is about 1000 samples per second. It requires
a RS232 to USB adapter hiking the cost. Those don't always work depending
on the brand. It is also is 10 bits rez which is one part in one thousand which
is probably good enough for most things. 12 bits is one part in 4000 for
just a bit more money in other brands. They probably make higher cost versions
that work better.

Paul Lamar