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From: Walter Atkinson <walter@advancedpilot.com>
Subject: Re: [LML] Re: Plugs and Mags for IVP
X-Original-Date: Tue, 25 Jan 2005 07:31:50 -0600
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Doug:

**Of interest, within the limits of my setup (VM1000, all altitude and 
engine parameters the same with the exception of a 15degF cooler OAT) I 
did notice a 20-30degF cooler CHT with the new Iridium plugs over a 
broad range of fuel flows, and a 2-3 knot improved speed at 
lean-of-peak operations (no change at ROP operations).**


I know of no scientific reason that the type of plug making the spark 
could make such differences.  It's more likely the OAT.  More O2 
molecules for combustion and better air cooling.  The improved LOP 
speed is O2 increases in the cooler air.  It allows for more FF at a 
given LOP setting.  If you were to set the same FF, the HP output and 
TAS would be the same.  We must be careful to assign the correct cause 
for an observed change.

Walter
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Doug:


**<fontfamily><param>Arial</param><x-tad-bigger>Of interest, within
the limits of my setup (VM1000, all altitude and engine parameters the
same with the exception of a 15degF cooler OAT) I did notice a
20-30degF cooler CHT with the new Iridium plugs over a broad range of
fuel flows, and a 2-3 knot improved speed at lean-of-peak operations
(no change at ROP operations).</x-tad-bigger><x-tad-bigger>**



I know of no scientific reason that the type of plug making the spark
could make such differences.  It's more likely the OAT.  More O2
molecules for combustion and better air cooling.  The improved LOP
speed is O2 increases in the cooler air.  It allows for more FF at a
given LOP setting.  If you were to set the same FF, the HP output and
TAS would be the same.  We must be careful to assign the correct cause
for an observed change.


Walter</x-tad-bigger></fontfamily>
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