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Date: Thu, 22 Dec 2005 22:59:18 -0500
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From: John Huft <aflyer@lazy8.net>
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Subject: Re: [LML] Where has all the power gone?
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N301ES wrote:
> 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
> Robert M. Simon,  ES-P N301ES
> 

I would ask Klaus if the timing map is different for turbos...yours is 
turbonormalized? Or, does it provide boost above atmospheric pressure?

On my normally aspirated engine, the LSE does not advance timing at all 
for the case of full power (i.e. 2700 rpm and > 26 in. Hg. manifold 
pressure). So, I would not think the advance curve comes into play in a 
full power run on the dyno. I doubt that the stronger spark causes a 
power loss. I wonder if there was something else wrong when the engine 
guy made his dyno run.

John