Return-Path: Sender: (Marvin Kaye) To: lml Date: Sun, 14 Jul 2002 20:29:38 -0400 Message-ID: X-Original-Return-Path: Received: from [65.66.11.38] (HELO qbert.gami.com) by logan.com (CommuniGate Pro SMTP 4.0b4) with ESMTP id 1628176 for lml@lancaironline.net; Sun, 14 Jul 2002 20:04:19 -0400 Received: by QBERT with Internet Mail Service (5.5.2650.21) id <3HF344HB>; Sun, 14 Jul 2002 19:05:17 -0500 X-Original-Message-ID: <52548863F8A5D411B530005004759A931C2A90@QBERT> From: George Braly X-Original-To: "'lml@lancaironline.net'" Subject: RE: [LML] Lean of peak X-Original-Date: Sun, 14 Jul 2002 19:05:17 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C22B93.4D3067C0" This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------_=_NextPart_001_01C22B93.4D3067C0 Content-Type: text/plain; charset="iso-8859-1" "... my guess is that we are about 60F ROP ..." Phil, That is probably one of the least desirable places you can pick to set the mixture. Why? Because that is a mixture setting that will guarantee that the engine operates with the absolute highest peak cylinder pressures that it is possible to generate for any MP and RPM you select. We get phone calls every day by somebody asking "Where should I set the mixture." That takes a book to answer. But if you change the question - - just a little bit, to the following: "Where should I *NOT* set the mixture then the answer gets very much easier. The answer to this second question is much easier: ********************** A) At very high cruise power settings, set the mixture anywhere OUTSIDE of the range from about 10-15F LOP out to 125 to 150F ROP. B) At low power settings, set the mixture anywhere you want. You will not cause some major problem, other than if you run the engine too rich, you will, over time cause increased deposits and higher spark plug cleaning costs and you may, eventually cause enough deposits to result in premature maintenance. ********************** That only now leaves the question as to what is HIGH and what is LOW power settings. For your engine, anything over about 200 Hp probably falls into the "high" power setting range. There is nothing magic about 1600F on your EGTs. 1600 is just fine. There are some normally aspirated engines that will show 1600F EGTs during cruise. The *absolute* value of EGT readings on these engines is nearly immaterial - - when looked at in isolation (in the context of other things, high EGT values can be significant... but not necessarily harmful). For example, in cruise, if you turn off one mag, the EGTs will SOAR to very high levels. Doesn't hurt anything, because the reason the EGTs go up is that the single mag operation effectively retards the timing and that causes the EGTs to rise - - but it also causes the peak cylinder pressures to drop rapidly - - along with the CHTS. The lower CHTs keep the exhaust valve cool, inspire of the higher observed EGT values. Regards, George -----Original Message----- From: Phil S [mailto:phil@giant-steps.com.au] Sent: Sunday, July 14, 2002 9:06 AM To: lml@lancaironline.net Subject: [LML] Lean of peak Wondering if anyone would care to share their experiences with operation of their TSIO550E in a IVP. We normally operate around 18 to 20,000ft at 28inches and 2500RPM. Running ROP we are usually set up around 1600 TIT, max EGT is around 1550 to 1560 and fuel flow is around 21.5GPH (CHT's are around 360). We use a Vision Microsystems engine monitoring system. Usually, indicated airspeed is around 210 and TAS around 250. My guess is that we are around 60 ROP on the first to peak cylinder. When we go to LOP it is fairly straight forward to get the TIT back to 1600 but the range of EGT's is worrying...from as low as 1430 to as high as 1570...if we lean further to try and get the highest EGT back to around 1550 we start to run rough, so abandon and go back to ROP. Is this a job for balanced injectors or is there something we are missing? Phil Sexton VH LLW Melbourne Australia ------_=_NextPart_001_01C22B93.4D3067C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lean of peak
 
 
"...=20 my guess is that we are about 60F  ROP ..."
 
Phil,  That is probably one of the least desirable places = you can=20 pick to set the mixture.
 
Why?  Because that is a mixture setting that will = guarantee that the=20 engine operates with the absolute highest peak cylinder pressures that = it is=20 possible to generate for any MP and RPM you select.
 
 
We get=20 phone calls every day by somebody asking "Where should I set the=20 mixture."    That takes a book to = answer.
 
But if=20 you change the question - - just a little bit, to the=20 following:    "Where should I  *NOT* set the = mixture then=20 the answer gets very much easier.
 
The=20 answer to this second question is much easier:
 
          &nb= sp;           &nb= sp;           &nb= sp;           &nb= sp;    =20 **********************
 
A)  At very high cruise power settings,  set the = mixture=20 anywhere OUTSIDE of  the range from about 10-15F LOP out to 125 to = 150F=20 ROP.
 
B) At=20 low power settings,  set the mixture anywhere you want.  You = will not=20 cause some major problem, other than if you run the engine too rich, = you will,=20 over time cause increased deposits and higher spark plug cleaning costs = and you=20 may, eventually cause enough deposits to result in premature=20 maintenance.
 
       &nb= sp;           &nb= sp;           &nb= sp;           &nb= sp;       =20 **********************
 
That=20 only now leaves the question as to what is HIGH and what is LOW power=20 settings.
 
For=20 your engine,  anything over about  200 Hp probably falls into = the=20 "high" power setting range.
 
There=20 is nothing magic about 1600F on your EGTs.  1600 is just = fine.  There=20 are some normally aspirated engines that will show 1600F EGTs during = cruise.=20
 
The=20 *absolute* value of EGT readings on these engines is nearly immaterial = - - when=20 looked at in isolation  (in the context of other things,  = high EGT=20 values can be significant... but not necessarily = harmful).
 
For=20 example, in cruise, if you turn off one mag,  the EGTs will SOAR = to very=20 high levels.  Doesn't hurt anything, because the reason  the = EGTs go=20 up  is that the single mag  operation  effectively = retards=20 the timing and that causes the EGTs to rise - - but it also causes the = peak=20 cylinder pressures to drop rapidly - - along with the  = CHTS.  =20 The lower CHTs keep the exhaust valve cool, inspire of the higher = observed EGT=20 values.
 
Regards,  George
 
-----Original Message-----
From: Phil S=20 [mailto:phil@giant-steps.com.au]
Sent: Sunday, July 14, = 2002 9:06=20 AM
To: lml@lancaironline.net
Subject: [LML] Lean = of=20 peak

     Wondering if anyone = would care=20 to share their experiences with operation of their TSIO550E in a = IVP.
We=20 normally operate around 18 to 20,000ft at 28inches and 2500RPM. = Running ROP we=20 are usually set up around 1600 TIT, max EGT  is around 1550 to = 1560 and=20 fuel flow is around 21.5GPH (CHT's are around 360). We use a Vision=20 Microsystems engine monitoring system. Usually, indicated airspeed is = around=20 210 and TAS around 250. My guess is that we are around 60 ROP on the = first to=20 peak cylinder.
When we go to LOP it is fairly straight forward to = get the=20 TIT back to 1600 but the range of EGT's is worrying...from as low as = 1430 to=20 as high as 1570...if we lean further to try and get the highest EGT = back to=20 around 1550 we start to run rough, so abandon and go back to = ROP.
Is this a=20 job for balanced injectors or is there something we are missing? =
Phil=20 Sexton
VH LLW
Melbourne Australia =
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