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Date: Thu, 22 Dec 2005 15:36:53 -0500
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From: N301ES <lancair@ustek.com>
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Subject: Where has all the power gone?
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Oh boy I sure love getting opinions that diverge from the same starting 
point and go 180 degrees!  Perhaps they who are knowledgeable with no 
axes to grind would fill me in with details.  The situation involves 
comparing/contrasting a TSIO550 with dual mags vs dual electronic 
ignition.  The route that I chose was dual LSE, hoping that the variable 
advance would give me higher power at cruise and better fuel efficiency, 
and would eliminate mag failure with age or high altitude. 


Today I spoke with an engine rebuilder who stated in his dyno testing 
that an IO540 (factory rated at 315 hp and rebuilt for 340 hp) yielded 
only 280 hp when run at 2700 rpm WOT.  They attributed that power loss 
to the spark advance profile built into the LSE and so always recommend 
dual Bendix mags to their customers.  I would assume that their test 
numbers are valid for the specific engine tested that day, but in 
general should users of dual LSE ignition expect to sacrifice such 
power?  Have any builders swapped out and tested both configurations?  
Theoretical or theological arguments accepted. 


Robert M. Simon,  ES-P N301ES