I was reading the SDS EFI web site and notice they don't offer rotary
  ignition support.

  This is just an idea at this stage.

  A simple ignition system using RX8 coils with a 2.5 ms
  dwell time has a problem.

     7000 RPM is   116.7 rev per second or 42,000 degrees per
      second  or one e-shaft degree in .02 ms.

  1 ms is 1/1000 of a second.

  So the ignition will be retarded 42,000 / 2.500 or
  16.8 degrees. What is needed is advance at high RPM.

  In the old days that was done by a distributor with mechanical and
  vac advance.

  That is for a real simple system that fires when the
  CAS sends a trigger to the coil. A computer can fix this
  but there may be a simpler way.


  Hall Effect sensors are cheap and several can be used.
  Lets say we have 4. The first one is used for 0 to 2000 RPM.
  A small magnet would be mounted on the e-shaft pulley.

  #1 0 to 2000 RPM 0 advance for good starting.
  #2 2000 to 4000  14 degrees
  #3 4000 to 6000  22 degrees
  #4 6000 to 8000. 33 degrees

  There is a device called called a data selector.
  It is just a black box that can select one of these
  HE sensors depending on RPM. Or the pilot can select one.

  The black box can be controlled by a computer or an
  analog to digital converter chip.

  These charts are for cars but we have used a fixed advance
  22 degrees BTC with good results.
  If you set it at a greater number to compensate for the
  coil 2.5 ms dwell that means you would have 16.8 +_22 which
  might cause starting problems.

  Just thinking out loud here.

  Paul Lamar

 Paul,  This  would be a backup for a Hall effect sensor failure where the
 pilot could select one of the other timing points. Might need a toggle
 switch to bypass the variable timing system and read only one at 22
 degrees.
                            george grimes

 Yes built in back up.

 Paul Lamar

Paul,
I have mentioned before that Kawasaki used a hall effect sensor to advance
the timing on their 2 cycles by running a permanent magnet stator with a
projection and gapping the hall effect sensor as wide as you could get it
to trigger. They got a thyristor that triggered at at about 50% of max
voltage and the increase in the sine wave amplitude with rpm would trigger
the ignition sooner. Very effective and no moving parts.
Bill Jepson


Yes I remember that. Only a few degrees.
We are talking 10 and 20 degree difference here.


Paul Lamar