Electronic Ignition

Hi All!
My Sonerai is currently equiped with dual ignition. I've got a slick
magneto running off the flywheel end as well as a normal stock
distributor (that has been shortened somewhat and fixed timing) in
the normal distributor location.
The thing I don't like is the magneto hanging halfway through my
firewall as the Sonerai has the 1835cc VW motor mounted almost right
up against the firewall.

I want to make a new firewall, but I dont like the hole in the
firewall for the magneto.

Given that I hand prop the motor to start, I'm wondering about the
viability of maybe replacing the magneto with an electronic ignition
setup.
Question...?
What electronic ignition options are available that could run from
any location OTHER than the normal distributor location?
Would I save significant weight on going from magneto to electronic
ignition?
How do I get the ignition to fire on TDC for starting and then
advance to whereever once the engine's running?
Is this whole train of thought worth considering to start with or am
I just being stupid now and should live with the hole in my firewall?
Any thoughts welcome?
Regards
Andre
Posted to AirVW as well.

Andre,

I have put together three "scratch built from available and custom
component" systems. Two for VWs and one for a Subaru EA-81. The biggest
challenge was obtaining the "machine intellegence" needed in the systems to
optimise the timing. But, if you don't have access to expertise in this
area, I would suggest one of the "package" units.

There are a bunch of automotive companies, and a few aircraft ignition
companies, that sell good quality electonic ignition systems that can be
excited by other than a traditional engine driven distributor arrangement.
However, most require the use of the magnito or distributor "hole", or a
special plate on the crankshaft (trigger wheel), or drilling an aluminum
flywheel to carry the sensor magnents.

Since you don't want to use a actual distributor ignition wire head, you
need a system that, at least, has a different method of "distributing" the
spark. If you have a clever associate who knows ignition systems and
another who is a good machinist you can use half of the distributor base,
shaft, and gear to fabricate a low-profile dual exciter (optical or
magnetic) and then use off-the-shelf electronic ignition components from
there. This can reduce the "height" of the existing distributor assembly by
at least the dimension of the original cap and a portion of the original
distributor body. Some of the commercial "DIS" units save only the portion
of the height of the distributor cap represented by the "dome" and wire
attachments because the sensor assembly and cap replaces only the rotor,
condenser, and distributor cap. However, the "Slick" does extend quite a
ways from the VW case and you might find that you have "just enough" room
for one of these units. The abreviation for a fully distributorless igntion
system is "DIS".

There are "black boxes" available to drive the series of plug coils that can
be programmed for the correct timing from start" to high rpm. The best have
sensor inputs that can also be used to monitor head temps, vac, etc. to
optimise the timing. If you run auto-gas, some of the units can accept the
input from a air/fuel mixture sensor.

If you have the dual plug heads on your VW - all the better - this permits
you to run a full "secondary" system from a stand-by battery system
independent of the aircraft DC buss. If you don't have the dual plug heads,
you should still have a means of transferring ignition input power from the
aircraft system to an independant battery back-up. I used a "Recreational
Vehicle" battery isolator/float charge unit and a small motorcycle battery.
I have talked to a lot of guys who have done automotive engine conversions
and some of them chuckle over my concern for an independent back-up systems,
"When is the last time you had a car die because of an ignition system
component?" Okay, but I still like to have to second source of 12 VDC for
the ignition. I HAVE had altenators and batteries go into "sudden death".

You will probably get more specific responses from the VW users group, but
you can do web searches with "LeBurg", "Light Speed Engineering",
"Electromotive Engine Controls", "MSD", "Compu-Fire".

In my experience, the best system provided good starting (hot and cold), a
better power curve, and much better fuel economy than a magnito or even the
"stock" electro-mechanical system.

J

"Andre" wrote in message
...
Hi All!
My Sonerai is currently equiped with dual ignition. I've got a slick
magneto running off the flywheel end as well as a normal stock
distributor (that has been shortened somewhat and fixed timing) in
the normal distributor location.
The thing I don't like is the magneto hanging halfway through my
firewall as the Sonerai has the 1835cc VW motor mounted almost right
up against the firewall.

I want to make a new firewall, but I dont like the hole in the
firewall for the magneto.

Given that I hand prop the motor to start, I'm wondering about the
viability of maybe replacing the magneto with an electronic ignition
setup.
Question...?
What electronic ignition options are available that could run from
any location OTHER than the normal distributor location?
Would I save significant weight on going from magneto to electronic
ignition?
How do I get the ignition to fire on TDC for starting and then
advance to whereever once the engine's running?
Is this whole train of thought worth considering to start with or am
I just being stupid now and should live with the hole in my firewall?
Any thoughts welcome?
Regards
Andre
Posted to AirVW as well.