X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 13 Nov 2005 23:16:29 -0500 Message-ID: X-Original-Return-Path: Received: from imo-d21.mx.aol.com ([205.188.144.207] verified) by logan.com (CommuniGate Pro SMTP 5.0.1) with ESMTP id 829421 for lml@lancaironline.net; Sun, 13 Nov 2005 13:43:06 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.144.207; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-d21.mx.aol.com (mail_out_v38_r6.3.) id q.1c1.35907ac5 (17377) for ; Sun, 13 Nov 2005 13:42:17 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <1c1.35907ac5.30a8e308@aol.com> X-Original-Date: Sun, 13 Nov 2005 13:42:16 EST Subject: Re: [LML] What Should My CHTs and Oil Temps Be? X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1131907336" X-Mailer: 9.0 Security Edition for Windows sub 5300 X-Spam-Flag: NO -------------------------------1131907336 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 11/13/2005 12:07:57 P.M. Central Standard Time, MikeEasley@aol.com writes: I am trying to determine whether I have an air flow problem or not. I'm getting CHTs in the 365 to 385 range in cruise, oil temps around 205 in my normally aspirated ES. 11,500 feet 2,450 RPM 25-50 deg ROP mixture +/- +6F OAT Do those temperatures match? What I mean is that about what you would expect for oil temp at that cylinder temp? It seems to me that at those CHTs I should be down around 185 on the oil temp. What is the "ideal" CHT temp in cruise? Do I need CHTs in the 350 range, oil in the 180 range in the winter to have a good summer airplane? I have to think my oil cooler is "cooling" because a 10 knot decrease in airspeed gives me a 10 degree increase in oil temp, so air and oil are flowing through the cooler. So what I'm getting at is do I need more air for both the cylinders and cooler? Or is the air flow fine and the cooler isn't working correctly? I think my baffling is pretty good, no leaks, and with only a 20 degree difference in CHTs between cylinders, I seem to be pretty well setup on the baffling. Before I start cutting into my cowl, I thought I'd do some more homework and make sure I need to. I'm going to download my JPI data today and take a closer look. Mike, MAP would provide more power info. Was the MAP about 19.5"? Also, maybe 80F to 120F ROP would be a mixture setting that would be less stress on the engine (as might be 40F-50F LOP). You asked: What is the "ideal" CHT temp in cruise? That is like a religious question......... But it depends on a lot of things. Otherwise, to me, your CHTs are OK. Some engines make more use of oil in the cooling scheme, such as spraying the bottom of the pistons. Thus it is more important to ensure oil cooler efficiency. New engines run hotter. How many hours on the engine? Oil coolers are different. Is yours a Stewart-Warner? They have been shown to be around 30% more efficient than less expensive competitors. Then there is the question of how well the air is being used in the area of the cooler. I am surprised that 10 KIAS slower results in a 10F rise in oil temp. I know mine rises 20F in the pattern, but that is because of the poorly placed NACA used for oil cooler air. BTW, I have to partially shut off the air to the cooler when cruising (always at high power) in an OAT of 0C or less. Lycoming (I assume you have a Continental) publishes the minimum oil temperatures that the engine would like to see in the winter - perhaps Continental does the same. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1131907336 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 11/13/2005 12:07:57 P.M. Central Standard Time,=20 MikeEasley@aol.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I am trying to determine whether I h= ave an air=20 flow problem or not.  I'm getting CHTs in the 365 to 385 range in cru= ise,=20 oil temps around 205 in my normally aspirated ES. =20
 
11,500 feet
2,450 RPM
25-50 deg ROP mixture +/-
+6F OAT
 
Do those temperatures match?  What I mean is that about what you= =20 would expect for oil temp at that cylinder temp?  It seems to me= =20 that at those CHTs I should be down around 185 on the oil temp.
 
What is the "ideal" CHT temp in cruise?
 
Do I need CHTs in the 350 range, oil in the 180 range in the winter t= o=20 have a good summer airplane?
 
I have to think my oil cooler is "cooling" because a 10 knot decrease= in=20 airspeed gives me a 10 degree increase in oil temp, so air and oil are flo= wing=20 through the cooler.
 
So what I'm getting at is do I need more air for both the cylinders a= nd=20 cooler?  Or is the air flow fine and the cooler isn't working=20 correctly?
 
I think my baffling is pretty good, no leaks, and with only a 20 degr= ee=20 difference in CHTs between cylinders, I seem to be pretty well setup on th= e=20 baffling.  Before I start cutting into my cowl, I thought I'd do some= =20 more homework and make sure I need to.
 
I'm going to download my JPI data today and take a closer=20 look.
Mike,
 
MAP would provide more power info.  Was the MAP about 19.5"? = =20 Also, maybe 80F to 120F ROP would be a mixture setting that would be less st= ress=20 on the engine (as might be 40F-50F LOP).
 
You asked:=20
What is the "ideal" CHT temp in cruise?
 
That is like a religious question......... But it depends on a lot of=20 things.  Otherwise, to me, your CHTs are OK.
 
Some engines make more use of oil in the cooling scheme, such as sprayi= ng=20 the bottom of the pistons.  Thus it is more important to ensure oil coo= ler=20 efficiency.
 
New engines run hotter.  How many hours on the engine?
 
Oil coolers are different.  Is yours a Stewart-Warner?  They=20= have=20 been shown to be around 30% more efficient than less expensive=20 competitors.
 
Then there is the question of how well the air is being used in the are= a of=20 the cooler.  I am surprised that 10 KIAS slower results in a 10F rise i= n=20 oil temp.  I know mine rises 20F in the pattern, but that is because of= the=20 poorly placed NACA used for oil cooler air.  BTW, I have to partially s= hut=20 off the air to the cooler when cruising (always at high power) in an OA= T of=20 0C or less.
 
Lycoming (I assume you have a Continental) publishes the mini= mum=20 oil temperatures that the engine would like to see in the winter - perhaps=20 Continental does the same.
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)



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