X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 21 Mar 2006 21:45:35 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m16.mx.aol.com ([64.12.138.206] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 1041813 for lml@lancaironline.net; Tue, 21 Mar 2006 18:55:20 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.138.206; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m16.mx.aol.com (mail_out_v38_r7.3.) id 7.313.b7f8fc (58677); Tue, 21 Mar 2006 18:54:31 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <313.b7f8fc.3151ec37@aol.com> X-Original-Date: Tue, 21 Mar 2006 18:54:31 EST Subject: Re: AW: high CHT X-Original-To: jschredl@web.de, lml@lancaironline.net X-Original-CC: n320g@hotmail.com MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1142985271" X-Mailer: 9.0 Security Edition for Windows sub 5300 X-Spam-Flag: NO -------------------------------1142985271 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable In a message dated 3/21/2006 1:23:05 P.M. Central Standard Time, =20 jschredl@web.de writes: Are you using bayonet type probes? Spark Plug Washer type CHT sensors can=20 yield a reading 50F higher than actual.=20 =20 Johannes: The probes I use came with the Vision Micro EPI800 system and are= =20 screwed into the cylinder. =20 OK, probe style has been eliminated. Scott, when looking to your values I noticed an error in my values while =20 converting fuel consumption (used Imperial Galons ;-(( my right fuel=20 consumption is: 8,7 US-gal/h Ahh, that helps. I wish I carried 43 Imperial Gallons instead of 43 US=20 Gallons. I suppose you are using metric measurements except for Knots. I also see your EGT is much lower than mine: my EGT peak at 4500ft is about= =20 1510=B0F! I lean always to the rich side at least -100=B0F as reccomended i= n the=20 lycoming manual. Is this correct? My probes are all 3" down from the tube=20= =20 flange: Interesting, my probes are 4" down and I am sure some of our difference is =20 because of that. Electronic Ignitions also reduce EGTs somewhat. a. Do you really mean 185 MPH or 185 Knots? The difference would be=20 significant in gph and cooling differential pressures. Johannes:I mean 18= 5 MPH =3D =20 161 knots (IAS) and 8,7 gal/h =20 Ah, now the numbers make sense. b. Is your oil cooler a Stewart-Warner (other brands are less efficient)? =20 How many vanes? Johannes: Stewart-Warner 6 vanes OK, then the high oil temperatures are probably not due to poor cooling =20 because of the cooler brand. =20 c. Is your Vernatherm correctly set to send all the oil to the cooler when=20 the temp exceeds 180F? Oil accounts for at least 1/3rd of the engine coolin= g. =20 The vernatherm can be tested in hot water to see if it fully shrinks (opens= )=20 at 180F. Johannes: I=B4m not shure. But on a hot summer day cruising at 7= 5%=20 oil temp does not exceed 205=B0F. I think is o.k. Is it?=20 I think this is not OK. Even on a hot day I see 180F at cruise speeds=20 although I have a separate NACA inlet for oil cooler air. There are severa= l=20 possibilities: 1. The cooler passages are clogged and the cooler should be flushed. 2. There is not enough air going thru the cooler vanes. Maybe you could=20 measure the upper and lower cooler air pressure? 3. The Vernatherm is faulty and should be replaced. Test in hot water =20 first. (I did have one fail on my engine) =20 e. Are you running at peak or lean of peak EGT? (I tend to see lower EGTs =20 because of the electronic ignition, but not that much lower.) Johannes: ri= ch =20 side -100=B0F=20 OK, then the CHTs are too high. I thought the "air speed" gives me an idea about the pressure situation... Airspeed is not comparable, pressure is. =20 In Knots, 135=3D11.9" H2O, 65=3D2.8", difference =3D 9.1" H2O certainly enou= gh for=20 cooling. =20 Johannes: The unit indicated in the graph is Knots (IAS) OK, it is better when we are talking about the same thing. While I think=20 the calculation above is correct, it would be best to actually measure airs= peed=20 with the pitot in the upper cowl and the static port in the lower. Remembe= r=20 to use something like a picolo tube at the open ends to eliminate false=20 pressures and eliminate the readings jumping up and down. Try to find a qu= iet=20 place for the pickups. =20 I found it interesting that your very nice cowling nose gear door made no=20 difference as I was just considering one to improve cooling efficiency and=20 thus reduce cooling drag. =20 Johannes: To be honest: I did only a short flight under "bad weather=20 conditions" and did not notice a huge drop of EGT (as expected ;-). As soon= I=B4ve=20 time I will repeat this tests using a static port and get more precisely d= ata! It would be more interesting to see pressure changes (and CHT changes) with=20= =20 and without the door. The short and sharp ending of the Lancair cooling air inlets tend to have a= =20 turbulence which makes the opening appear smaller to the air flow than it =20 actually is.=20 Johannes: I totally agree with you! But until now I refused to touch this=20 cowling part because of paint design...;-) Ahhh.... well, each lower expanding diffuser inlet is held on by 2 flat hea= d=20 machine screws into nutplates on the collar. the upper one could be=20 fastened the same way. Thus there would only be countersunk screw heads sh= owing. It=B4s time to start flying season! Great. =20 Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1142985271 Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable
In a message dated 3/21/2006 1:23:05 P.M. Central Standard Time,=20 jschredl@web.de writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Are you using bayonet type probes?  Spark Plug Washer type = CHT=20 sensors can yield a reading 50F higher than actual. 
 
Johannes: The=20= probes I=20 use came with the Vision Micro EPI800 system and are screwed into the=20 cylinder.
 
OK, probe style has been eliminated.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Scott, when lo= oking=20 to your values I noticed an error in my values while=20 converting fuel consumption (used Imperial Galons ;-((  my right= =20 fuel consumption is:  8,7 US-gal/h
Ahh, that helps.  I wish I carried 43 Imperial Gallons instead of=20= 43=20 US Gallons.  I suppose you are using metric measurements except for=20 Knots.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
I also see you= r EGT is=20 much lower than mine: my EGT peak at 4500ft is about 1510=B0F! I lean alwa= ys to=20 the rich side at least -100=B0F as reccomended in the lycoming manual. Is=20= this=20 correct? My probes are all  3" down from the tube=20 flange:
Interesting, my probes are 4" down and I am sure some of our difference= is=20 because of that.  Electronic Ignitions also reduce EGTs=20 somewhat.
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
a. Do you really mean 185 MPH or 185 Knots?  The=20 difference would be significant in gph and cooling differential=20 pressures.  Jo= hannes:I=20 mean 185 MPH =3D  161 knots (IAS) and 8,7=20 gal/h
 
Ah, now the numbers make sense.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
b. Is your oil cooler a Stewart-Warner (other brands are less efficie= nt)?=20 How many vanes? Johannes: Stewart-Warner 6 vanes
OK, then the high oil temperatures are probably not due to poor cooling= =20 because of the cooler brand.
 
c. Is your Vernatherm correctly set to send all the oil to the cool= er=20 when the temp exceeds 180F? Oil accounts for at least 1/3rd of the engi= ne=20 cooling.  The vernatherm can be tested in hot water to see if it f= ully=20 shrinks (opens) at 180F.   <= FONT=20 color=3D#0000ff>Johannes: I=B4m not shure. But on a hot summer day crui= sing at=20 75% oil temp does not exceed  205=B0F. I think is o.k. Is=20 it?
 
I think this is not OK.  Even on a hot day I see 180F at cruis= e=20 speeds although I have a separate NACA inlet for oil cooler air.  There= are=20 several possibilities:
1. The cooler passages are clogged and the cooler should be flushed.
2. There is not enough air going thru the cooler vanes.  Maybe you= =20 could measure the upper and lower cooler air pressure?
3. The Vernatherm is faulty and should be replaced.  Test in hot w= ater=20 first. (I did have one fail on my engine)
 
e. Are you running at peak or lean of peak EGT? (I tend to see lower=20= EGTs=20 because of the electronic ignition, but not that much lower.)   Johannes:&nb= sp;rich=20 side -100=B0F 
OK, then the CHTs are too high.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
I thought = ;the=20 "air speed" gives me an idea about the pressure=20 situation...
Airspeed is not comparable, pressure is.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
 
In Knots, 135=3D11.9" H2O, 65=3D2.8", difference =3D 9.1" H2O certain= ly enough=20 for cooling.  
Johannes: The=20= unit=20 indicated in the graph is Knots (IAS)
OK, it is better when we are talking about the same thing.  While=20= I=20 think the calculation above is correct, it would be best to actually measure= =20 airspeed with the pitot in the upper cowl and the static port in the=20 lower.  Remember to use something like a picolo tube  at the open=20= ends=20 to eliminate false pressures and eliminate the readings jumping up and=20 down.  Try to find a quiet place for the pickups.  
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
 I found it interesting that your very nice cowling nose gear do= or=20 made no difference as I was just considering one to improve cooling effici= ency=20 and thus reduce cooling drag.  
Johannes: To b= e=20 honest: I did only a short flight under "bad weather conditions" and did n= ot=20 notice a huge drop of EGT (as expected ;-). As soon I=B4ve time I will rep= eat=20 this tests using a static port and get more precisely=20 data!
It would be more interesting to see pressure changes (and CHT changes)=20= with=20 and without the door.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
The short and sharp ending of the Lancair cooling air inlets tend to=20= have=20 a turbulence which makes the opening appear smaller to the air flow than i= t=20 actually is. 
Johannes: I to= tally=20 agree with you! But until now I refused to touch this cowling part=20 because of paint design...;-)
Ahhh.... well, each lower expanding diffuser inlet is held on by=20 2 flat head machine screws into nutplates on the collar.  the uppe= r=20 one could be fastened the same way.  Thus there would only be countersu= nk=20 screw heads showing.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>  It=B4s time to st= art flying=20 season!
Great.
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)
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