Mailing List lml@lancaironline.net Message #12156
From: George Braly <gwbraly@gami.com>
Subject: RE: Electronic ignition
Date: Sat, 2 Feb 2002 17:29:33 -0600
To: 'lancair.list@olsusa.com' <lancair.list@olsusa.com>
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Since I plan an all electric airplane (no vacuum system), a dual
buss/alternator/battery will be my redundancy.  I am interested in the Prism
Electronic Ignition, maybe George Braly will give us some details.  Is the
advance curve tailored to the leaning procedure for GAMI injectors?

Steve Colwell   Legacy 2K  Placerville,CA   (530) 621-3408 <<

Steve, One of the interesting features of the PRISM system is that it really does
not have anything that is comparable to the traditional automotive world's
"advance curve".

If will advance or retard the timing as required in order to directly
optimize the magnitude and interval (after TDC) of the combustion pressure
event in order to obtain maximum torque.

And for a given  MP, RPM, and F/A ratio,  the  optimization continues to
take place and change the spark advance, as a function of the type of fuel
coming from the tanks.

The really remarkable thing about all of this is that it can be done with a
single sensor. We do this demonstration rather routinely.  Set up an engine at cruise
power, and then switch the fuel from 100LL, to unleaded AVGAS, to 87octane
MOgas, and back again, without making any changes in MP or RPM or Mixture
control.  It is rather startling to see the changes that take place in the
spark timing as the fuels change over and "clean up" in the fuel line from
the external fuel valve servo box to the engine. Regards,  George

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