Mailing List lml@lancaironline.net Message #23227
From: George Braly <gwbraly@gami.com>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: RE: [LML] Re: relative temps? A more technical exchange.
Date: Sun, 28 Mar 2004 21:51:47 -0500
To: <lml@lancaironline.net>
<<<<<<<At high power ... changing the spark timing over a  range of  plus/minus
3 or 4 degrees off of  Max Brake Torque (MBT) timing has remarkably
SMALL effects on Hp.  Almost unnoticeable to a pilot.
>>>>>>>>
 
 > I can buy that.  What about torque?   <
 
Same .   At constant RPM,  Hp is directly proportional to torque.    A 1% change in Hp = to a 1% change in torque - - at constant RPM - - as in 2700 for takeoff.
 
 
****************************
 
 
<<<<<What do your EGTs run at full power on take off ?   At what fuel flow?
>>>>>>
 
 > As I said in the post you are responding to, 1280-1290 and 15.4 gph.  Note that the fuel flow could be less than accurate.  After a long flight, the EPI totalizer will claim I used about 5% more fuel than that measured by those very accurate fill-up trucks (this includes same truck at the same airport on the same day).  Of course, that was not flown at WOT.  However, I will record more environmental data (Baro, Palt, OAT) when I collect this information next time, including WOT lo altitude runs with and w/o LASAR.
 
Thanks for keeping at this, <
 
is the 1280 EGT at takeoff on the LASAR or on the Magnetos ???
 
 
1280-1290 @ 15.4 gph or 90 pph or (assuming 160 Hp) at a BSFC of about 0.56  (90/160 = 0.56).        1280 sounds ** about ** right at full power for that BSFC at 25d timing, so maybe the sparks at full power and are not being advanced past 25d.   BTW... I much prefer about 0.6 BSFC on these engines for normally aspirated full power operation - - especially at 25d timing. 
 
The 9:1 pistons would cause the EGTs to be  a bit lower than stock engines.
 
Regards,  George
 

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