Al Gietzen wrote:

Here are some interesting curves.
We can't move the spark plugs but they suggest that
there may be some better BSFC to be had if the trailing
plug was fired at some time other than the leading plug.
Perhaps Tracy could have two ignition modes. Both plugs
fire at the same time in case one system fails
and an economy mode with the trailing plug firing at
optimum BSFC. If the engine quits or starts running strange
switch over to both firing at the same time.

Paul;

These curves are for partial load performance.  My understanding was that
experience has shown that for the power levels and rpm we typically run at
in the air there is no noticeable difference for firing at the same time.

Al

Yes. Tracy cruises as low as 50% power at altitude. Maybe not in HP. Perhaps 
the BSFC could be improved. Would not hurt to try.

Paul Lamar
 
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