From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] Re: FADEC Rough idle explanation
To: lml
Date: Sun, 27 Feb 2005 13:15:59 -0500
Message-ID: <web-761623@logan.com>
In-Reply-To: <4d2b872b63b0658acb57581c0e73227a@advancedpilot.com>
References: <list-760048@logan.com>
 <4d2b872b63b0658acb57581c0e73227a@advancedpilot.com>
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Posted for W Atkinson <Walter@advancedpilot.com>:

  Rob:
  
  **But if we have another computer to seek the perfect
  .072 Fuel/Air mixture, we can eliminate the inefficiencys
  of amount of fuel (mixture) toward our goal of best power.**
  
  That's two assumptions I do not share.  .72 is not the ideal mixture and 
best
power mixture is not the ideal goal in my book.
  
  **now are all the Aerosance sensors (MAP, temp, RPM, cross
  checked with EGT and CHT) more reliable than PRISM's ICP
  sensor cross checked with EGT and CHT?**
  
  I think direct measurement is a more accurate determiner of reality than
calculations.
  
  **is the inter cycle variability so great the problem
  can't be monitored this closely?**
  
  It is not a problem and a sample rate of 50,000 samples per second has been
determined to be quite adequate.
  
  **When would you not want to run at best power?
  ie: (neck out on a limb) my guess with no data to back
  it up is 240HP at best power will have a lower CHT
  (lower ICP) than 240HP lean of stociametric (with a higher
  MAP to make the same HP) if both use a perfect 16^o thetaPP.**
  
  It is a common misconception that MP has as much to do with ICP as mixture.
  
  The data shows clearly that 240 HP at best power, vs 240 HP at best economy
(with the higher MP) will result in CHTs about 30-35dF higher and
significantly higher ICPs at the best power mixture.  As a matter of fact, I
can run my IO-550 at lower CHTs and lower ICPs at much higher power settings
LOP than at Best Power ROP.  Personally, I'd rather produce 85% power (263hp)
with lower CHTs and lower ICPs and go faster than I can with higher CHTs and
higher ICPs at 75% power (225hp) while going slower.
  
  Why would anyone want to run at best power at 225hp when they can run at
263hp and place less stress on the engine while doing it?  I made a flight
from Baton Rouge to Atlanta yesterday at 90% power (270hp) with the hottest
CHT at 358dF.  My A36 Bonanza was going 211 ktas.  Why would I want to slow
down to 75% power and run the CHTs higher by doing it at Best Power (80dF
ROP)???
  
  The DATA is compelling.
  
  Walter
  
[ you are using fuel to change the burn rate as a poor man's
sparc advance. My theory is less peek ICP with the
same thetaPP. (requires PRISM or FADEC) -Rob ]