Milo dropped off a complete running RX8 engine
   mounted on trailer with Tracy's EFI. It is on loan for two years.
   First thing we will do is reverse engineer Tracy's
   EFI system by measuring WHEN the fuel is injected relative
   to the e-shaft angle.

   Paul Lamar

 Is that a dual prop system?
 Norm

 One Ivo 3 or six blades but I have other props I can try.

 Paul Lamar


Paul,

Do you plan on testing the ignition system that you designed as well as the
555 EFI?  Any time frame?

Joe Berki
Limo EZ

Yes. I have everything I need to test that. I am not sure when I'll
get to it. Here is the idea for the new guys.

These are inductive coils and they normally require a computer.
Inductive coils are turned on for a period of time and then
they fire when the current is suddenly turned off. This off time
is called dwell. If the dwell is too long the coils over heat.
If too short you don't get full spark energy.

The breakthrough on how to make this stand alone and work without
a computer just occurred to me. The trick is to slot the trigger
wheel and use a  IR photo transistor, an IR emitter LED and FET switch
instead of a magnetic pickup or Hall Effect sensor. These devices
put out a single narrow pulse. Not what we need.

When the IR photo transistor sees the infra red emissions from the
IR LED it turns the coil current on using an high voltage FET solid
state switch. I used something like this for years on my computerized
road test equipment and it is very reliable and durable.

It will work with just about any stock inductive plug on coil system
including the Corvette GM coils. The length of the slot controls the
dwell time. The end of the slot controls when the coil fires.

I have been thinking about this problem ever since the stand alone
coil on plug systems first appeared. How do we get rid of
the computer?

If you want to fire the leading and trailing plugs at different
times you can use four slots with four photo TX's and four
LED's other wise each photo TX fires both leading and trailing
plug coils at the same time.

Now some of you electronic types might say "why not just
use a 555 one shot with a fixed pulse width to turn on
the current in the coil for a fixed period of time triggered
by a magnetic sensor or Hall Effect "?

The problem with that is the spark timing will vary with RPM.
You want the plugs to fire at 22 degrees TDC over a wide range of
RPM's so that approach will not work.

Basically this thing works like distributer points.

Paul Lamar