Hello Mr. Lamar,

I have been reading various articles on your website, rotaryeng.net, over
the last couple of months, and am pleased with all the information and
research you have provided.

I am just getting into rotary engines, over the last couple of months after
becoming very excited about the potential of the rotary in various
applications (through your site, and the availability of parts online) I
have gone from never having used or worked on a rotary, to now having 3
engine cores and a complete 13b N/A.

My first project with the rotary is to fit it into a small  boat hull, and
mate it to a water jet drive (equally suited to simple hp gains by spinning
faster).

Once I have completed this project, I would like to transition over to a
Wing In Ground Effect (WIG) vessel powered by the Rotary.

I am very interested in your simple 555 EFI circuit.  Would you be able to
tell me what the values for R1 and C1 are in the injector driver circuit?
Will this work equally well with the 1987 second gen fuel injector?  Also
will the rx7 stock airflow meter work?  Presumably the Crank angle position
sensor could be used as a trigger for the drivers?!

Thank you very much for your time and effort in responding to this email,
and for the information on your website.  I would be glad to receive your
newsletter.

Best Regards,

Tony Reynolds

We have not tested the pure 555 system yet and it is in the category of
highly experimental. I have not up dated the web site yet. Here is the
latest schematic.
I have decided to do away with the mass air flow sensor and use a pressure
sensor instead. The mass air flow sensor puts out a non linear signal and
this pure 555 system requires a linear signal hence the pressure sensor.

Development is now on the back burner as I have discovered a way of using a
cheap PC mother board as a EFI control computer. More about that as we go
along. I will control the 555 systems with an D to A out of a par. port on
the PC mother board. This will serve to test the 555 modules. Here too is a
schematic of that.


Our primary goal now is to get a system working on the dyno and the data
acquisition possibilities are enormous with the high speed DOS PC mother
board approach.

I will just  off load the time critical stuff to a bit of hard ware.
a simple resistor ladder configuration D to A can  output a zero to five
volt signal that will control the pulse width of four 555s driving the
injector transistors. This value can be stored in an array so non linear
sensors can be accommodated.

The RPM calculation is done with out any input from the computer. The
computer just reads it when it gets around to it. The RPM can be measured
with a preloaded down counter triggered by TDC on rotor one. Here is a
preliminary schematic.

This means the computer does not need to do anything at a precise time and
is allowed to do a lot of other stuff like save data on the hard disk and
display engine info on a screen.

I found the ideal low cost single chip A to D for the manifold pressure
sensor or a mass airflow sensor. Your choice. Same pc board module. Plugs
into one of the three parallel ports. Cost five bucks from DigiKey. Directly
compatible with the $10 pressure sensor that Tracy uses. The pc board can be
part of the connector and hold the pressure sensor as well as the A to D
chip. The only connection will be the hose to the manifold.

I intend to write the DOS software using Power Basic. Ten times faster to
write than C and ten times easier to learn for people.
DOS is way more real time than windows. DOS PB instructions execute in less
than a microsecond on a modern 6.5" by 6.5" VIA $90 PC mother board. High
precision floating point divide in less than 5 micro seconds.

Later on one can go back to the simple 555 system once we have the test data
needed.

Paul Lamar



Thanks Paul,

Look forward to reading about your progress.

Brgds,

Tony