X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 10 Mar 2009 22:37:05 -0400 Message-ID: X-Original-Return-Path: Received: from blu0-omc3-s31.blu0.hotmail.com ([65.55.116.106] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3541814 for lml@lancaironline.net; Tue, 10 Mar 2009 07:56:01 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.55.116.106; envelope-from=gary21sn@hotmail.com Received: from BLU130-DS3 ([65.55.116.73]) by blu0-omc3-s31.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Tue, 10 Mar 2009 04:55:24 -0700 X-Originating-IP: [68.186.114.52] X-Originating-Email: [gary21sn@hotmail.com] X-Original-Message-ID: X-Original-Return-Path: gary21sn@hotmail.com From: "Gary Edwards" X-Original-To: "Lancair Mailing List" References: Subject: Re: oil cooling/ head temps X-Original-Date: Tue, 10 Mar 2009 04:55:24 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="----=_NextPart_000_074A_01C9A13C.6C5D18C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.60.0053.2200 Seal-Send-Time: Tue, 10 Mar 2009 04:55:24 -0700 X-OriginalArrivalTime: 10 Mar 2009 11:55:24.0921 (UTC) FILETIME=[18FD6690:01C9A177] This is a multi-part message in MIME format. ------=_NextPart_000_074A_01C9A13C.6C5D18C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Good information Randy. =20 On this bird, the cylinder with the highest CHT (#3) has the least = amount of exhaust piping in its vicinity. As you know the exhaust pipes = are routed around the left side. Those side cylinders (#2, #4) have = CHT's lower than #3. Also, the headers are heat coated on the inside. = The engine has been sealed up with RTV at every opening. That was the = first thing I did 10 years ago. The bottom wrap-under baffling on #3 = was opened up then also. I have modified the rear baffling on #3 head = so as to create an air space where there was none before (the rear of #3 = has no cooling fins so the baffling is typically tight against the = head). Removing the 4" exit scat tubing from the oil coolers did = nothing to lower the CHT's or RAISE the oil temps. Bottom cowl rear = exit area (sq. in.) was calculated and is equal to or more than standard = 320 and RV cowls. =20 How do you do visual condition inspections on the headers with the pipe = wrap on them? Of all the repairs I have had to do in the engine = compartment, the most have been to the headers. Multiple cracks to weld = - stainless headers. Gary =20 ----- Original Message -----=20 From: randy snarr=20 To: lml@lancaironline.net=20 Sent: Monday, March 09, 2009 10:41 AM Subject: [LML] Re: oil cooling/ head temps Gary, One side note on the head temps. I made my plennum similar = to yours. My head temps run within 6 deg of each other usually 310-360 F = depending on power and temps. One thing that I did was to shine a light up through the bottom = of engine with the hangar lights out and found and sealed EVERY gap in = the baffeling except where cooling air needs to go with high temp RTV. I also opened up the gap on the bottom of each cyl to 2.6" times = the dept of the cooling fins as I read somewhere NASA had done some = testing and determined that was the optimum opening. I also radiused the = baffeling exits inder the cylingers rather than 90 deg bends on the = exits. I understand that helps flow as well. I have also come to the conclusion that there is airflow coming = into the cowl through the nose gear slot and bottom exit cowl area. I = see this when I get an oil leak. the oil runs down and then blows = forward. Weird. Ayway, you may need a small 45 deg lip on the bottom of = your cowl exit like I probably do. One last thing of note, in my pictures you will see the exhaust = wrap, that did make a difference on head temps and it also evened them = up. My exhaust wraps around the engine like yours does and runs close = under the cyinders. I wrapped those areas with 4 layers of exhaust wrap = and 2 or 3 layres everywhere else and have had good results lowering = engine compartment temps-unmeasured but it appears to be so. I tested = the heat wrap on my heat gun. With 4 loose layres I could hold my hand = on a heat gun nozzle on the high heat setting. That sold me on that = stuff. FWIW... Randy Snarr N694RS --- On Sat, 3/7/09, Gary Edwards wrote: From: Gary Edwards Subject: [LML] Re: oil cooling To: lml@lancaironline.net Date: Saturday, March 7, 2009, 6:33 PM It seems that most temp issues are with oil. Mine are not = with oil, but with CHT's. As you know (you have seen pictures), I have 2 smaller (6" = round) oil coolers, one on each side (mounted to the engine mount) with = naca ducts and short 4" to 6" long straight 2" inch scat duct to them. = The scat duct is connected via glass enlargers. On the outlet side, = there are glass reducers down to 4" scat duct, with the duct routed down = to near the nose gear front cover on the firewall. It as close to the = lower cowl outlet area that I could get. The oil temps. are too low, especially in winter. It is = difficult to get the temp to 180. In summer, the oil temp is about 190 = to 200 climb and cruise. I tried (for winter) closing off one cooler = with duct tape over the cowl inlet to raise the temp and it didn't make = any difference. Tried it on both sides. I also removed the 4" outlet = duct (reducers left on), to let the outlet flow directly into the rear = cowl area, with no change noticed. In only one case, have I had a high = oil temp; in Bend, Or., giving a friend a ride after a previous flight. = Outside temp in the '70's. Never has happened again. Now, if I could just get my CHT's down. I have to step climb = with that issue when at gross weight. Gary Edwards LNC2 235/320=20 ------=_NextPart_000_074A_01C9A13C.6C5D18C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Good information Randy.  
 
On this bird, the cylinder with the highest CHT (#3) has the = least=20 amount of exhaust piping in its vicinity.  As you know the exhaust = pipes=20 are routed around the left side.  Those side cylinders (#2, #4) = have CHT's=20 lower than #3.   Also, the headers are heat coated on=20 the inside.  The engine has been sealed up with RTV at = every=20 opening.  That was the first thing I did 10 years ago.  The = bottom=20 wrap-under baffling on #3 was opened up then also.  I have = modified=20 the rear baffling on #3 head so as to create an air space where there = was none=20 before (the rear of #3 has no cooling fins so the baffling is typically = tight=20 against the head).  Removing the 4" exit scat tubing from the = oil=20 coolers did nothing to lower the CHT's or RAISE the oil temps.  = Bottom cowl=20 rear exit area (sq. in.) was calculated and is equal to or more than = standard=20 320 and RV cowls.  
 
How do you do visual condition inspections on the headers with the = pipe=20 wrap on them?  Of all the repairs I have had to do in the = engine=20 compartment, the most have been to the headers.  Multiple = cracks to=20 weld - stainless headers.
 
Gary     
----- Original Message -----
From: randy=20 snarr
Sent: Monday, March 09, 2009 = 10:41=20 AM
Subject: [LML] Re: oil cooling/ = head=20 temps

Gary, One side note on the head temps. I made my = plennum=20 similar to yours.
My head temps run within 6 deg of each = other=20 usually 310-360 F depending on power and temps.

One thing = that I=20 did was to shine a light up through the bottom of engine with = the hangar=20 lights out and found and sealed EVERY gap in the baffeling = except where=20 cooling air needs to go with high temp RTV.
I also opened up = the gap=20 on the bottom of each cyl to 2.6" times the dept of the cooling = fins as=20 I read somewhere NASA had done some testing and determined that = was the=20 optimum opening. I also radiused the baffeling exits inder the = cylingers=20 rather than 90 deg bends on the exits. I understand that helps = flow as=20 well.

I have also come to the conclusion that there is = airflow=20 coming into the cowl through the nose gear slot and bottom exit = cowl=20 area. I see this when I get an oil leak. the oil runs down and = then=20 blows forward. Weird. Ayway, you may need a small 45 deg lip on = the=20 bottom of your cowl exit like I probably do.

One last = thing of=20 note, in my pictures you will see the exhaust wrap, that did = make a=20 difference on head temps and it also evened them up. My exhaust = wraps=20 around the engine like yours does and runs close under the = cyinders. I=20 wrapped those areas with 4 layers of exhaust wrap and 2 or 3 = layres=20 everywhere else and have had good results lowering engine = compartment=20 temps-unmeasured but it appears to be so. I tested the heat wrap = on my=20 heat gun. With 4 loose layres I could hold my hand on a heat gun = nozzle=20 on the high heat setting. That sold me on that=20 stuff.

FWIW...
Randy Snarr
N694RS

--- On = Sat,=20 3/7/09, Gary Edwards <gary21sn@hotmail.com> = wrote:

From:=20 Gary Edwards <gary21sn@hotmail.com>
Subject: [LML] = Re: oil=20 cooling
To: lml@lancaironline.net
Date: Saturday, March = 7, 2009,=20 6:33 PM

It seems that most temp issues are with oil.  Mine = are not=20 with oil, but with CHT's.
 
As you know (you have seen pictures), I have 2 smaller = (6" round)=20 oil coolers, one on each side (mounted to the engine mount) = with naca=20 ducts and short 4" to 6" long straight 2" inch scat duct to=20 them.  The scat duct is connected via glass = enlargers. =20 On the outlet side, there are glass reducers down to 4" scat = duct,=20 with the duct routed down to near the nose gear front cover on = the=20 firewall.  It as close to the lower cowl outlet area = that I=20 could get.
 
The oil temps. are too low, especially in winter.  = It is=20 difficult to get the temp to 180.  In summer, the oil = temp is=20 about 190 to 200 climb and cruise.  I tried (for winter) = closing=20 off one cooler with duct tape over the cowl inlet to raise the = temp=20 and it didn't make any difference.  Tried it on both = sides. =20 I also removed the 4" outlet duct (reducers left on), to let = the=20 outlet flow directly into the rear cowl area, with no change=20 noticed.  In only one case, have I had a high oil temp; = in Bend,=20 Or., giving a friend a ride after a previous = flight. =20 Outside temp in the '70's.  Never has happened = again.
 
Now, if I could just get my CHT's down.  I have to = step=20 climb with that issue when at gross weight.
 
Gary Edwards
LNC2=20 235/320

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