David Carter wrote:

Paul Yaw and Tracy Crook,

Good exchange of info and perspectives - as usual.

Looks like you are pretty much in agreement about what the two respective
items of equipment do, you both have hard data, but there has yet to be
direct dyno or "in-flight" comparison.

I normally print and file all this stuff and analyze it off -line but this
one is pretty important.  Based on what PY said about MSD, I pretty much
decided last week I wanted the improved fuel burning efficiency (lower BFSC)
and maybe a bit more power and was willing to pay the dollar and weight
penalty.  Was just going to "lurk" here a few more weeks then e-mail Tracy
and ask if his system could interface in any way with the MSD things, even
though I already have a feeling that they will not be compatible and that
I'd have to install the MSD system as one separate independent ignition
system and use Tracy's system as a separate system - which would then give a
a TRIPLE re?dundant ignition system.  Using two separate systems that both
fire all 4 plugs would require use of the MSD brand "Y"  or "T" connector on
top of each plug to allow each plug to be attached to both separate systems.
Tracy's system uses the stock Mazda trigger device.  Assume I'd have to
install a Hall effect device on flywheel to trigger the MSD system.

However, Tracy's response, and PY's response to Tracy's response, seems to
show that the Stock Mazda coils are about as good as you can expect and in
fact the MSD's might not provide that much improvement.

Here's my questions:  1) Does the MSD system provide longer spark duration
and better burn  than Tracy's system using the acknowledged efficient stock
Mazda coils?  2)  Could Tracy's system be modified to provide longer
duration sparks to emulate the MSD capability?

I am quite willing to incur the expense and wt penalty to install both the
MSD and Tracy's system and run one at a time for side-by-side comparison.
It will be a year before I am ready to install my 13B engine.  I'm just
starting to work on my RV-6 Quick Build kit.

Another question:  I couldn't tell which of you commented on the SDS
system - who was it and can you give us a brief evaluation of the system and
how it was used and on what engine?  If SDS is using crummy GM components,
have they been given feedback to suggest using different components to
improve performance?  I am interested because they seem to have a really
good system and it is used in racing, both 13B rotaries and piston engines.

David Carter

BTW it is fairly stright forward to convert Tracy's system to
a multiple spark capacitor discharge system if you so desire.
I will work on a skematic soon.

Paul Lamar
 
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