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jgh2(at)charter.net
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 Posted: Fri Sep 16, 2011 4:38 am Post subject: High CHTs |
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My 6A with 54 hours on a new O-320 still produces CHTs exceeding 400 degrees on all four cylinders when climbing to pattern altitude in 80 degree ambient conditions. They run around 380 degrees at cruise power leaned but the EGTs are about 1430 degrees (the probes are about 2.5 inches from the exhaust flange). The oil temperature never exceeds 200 degrees, the flexible baffles seal tightly to the upper cowling, the upper cowl "eyebrow" ends are sealed, the ignition timing is correct and the carb jet ID has been increased by .003".
I suspect the lower cowling air outlet area (obstructed by the nose gear strut, exhaust pipes, etc.) restricts the air flow needed to achieve Lycoming's recommended pressure differential between the top and bottom of the engine compartment. The ratio of the cooling air inlet-to-outlet areas appears to be around 1.05 on the stock cowling. Adding two purchased metal louvers would increase it to around 1.24. Measuring the pressure differential is certainly doable but I'm hoping other 6A or 7A owners will share advice based on adding louvers or otherwise improving the air flow through the lower cowling.
Thanks.
Jack H.
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mrobert569(at)hotmail.com
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| Posted: Fri Sep 16, 2011 5:52 am Post subject: High CHTs |
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Based on what you state adding the louvers, or increasing the opening of the cowl outlet area, will definately lower oil and cylinder temps.
Mike Robertson
> From: jgh2(at)charter.net
| Quote: | Subject: High CHTs
Date: Fri, 16 Sep 2011 08:35:05 -0400
To: rv-list(at)matronics.com
--> RV-List message posted by: Jack Haviland <jgh2(at)charter.net>
My 6A with 54 hours on a new O-320 still produces CHTs exceeding 400 degrees on all four cylinders when climbing to pattern altitude in 80 degree ambient conditions. They run around 380 degrees at cruise power leaned but the EGTs are about 1430 degrees (the probes are about 2.5 inches from the exhaust flange). The oil temperature never exceeds 200 degrees, the flexible baffles seal tightly to the upper cowling, the upper cowl "eyebrow" ends are sealed, the ignition timing is correct and the carb jet ID has been increased by .003".
I suspect the lower cowling air outlet area (obstructed by the nose gear strut, exhaust pipes, etc.) restricts the air flow needed to achieve Lycoming's recommended pressure differential between the top and bottom of the engine compartment. The ratio of the cooling air inlet-to-outlet areas appears to be around 1.05 on the stock cowling. Adding two purchased metal louvers would increase it to around 1.24. Measuring the pressure differential is certainly doable but I'm hoping other 6A or 7A owners will share advice based on adding louvers or otherwise improving the air flow through the lower cowling.
Thanks.
>======================
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[quote][b]
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robin(at)PaintTheWeb.com
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| Posted: Fri Sep 16, 2011 6:16 am Post subject: High CHTs |
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Jack, are your wheel pants and gear leg fairings in place?
Robin
Sent from my iPad2.
On Sep 16, 2011, at 9:00 AM, Mike Robertson <mrobert569(at)hotmail.com (mrobert569(at)hotmail.com)> wrote:
[quote] Based on what you state adding the louvers, or increasing the opening of the cowl outlet area, will definately lower oil and cylinder temps.
Mike Robertson
> From: [url=mailto:jgh2(at)charter.net]jgh2(at)charter.net (jgh2(at)charter.net)[/url]
| Quote: | Subject: High CHTs
Date: Fri, 16 Sep 2011 08:35:05 -0400
To: [url=mailto:rv-list(at)matronics.com]rv-list(at)matronics.com (rv-list(at)matronics.com)[/url]
>
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| Quote: | --> RV-List message posted by: Jack Haviland <jgh2(at)charter.net (jgh2(at)charter.net)>
My 6A with 54 hours on a new O-320 still produces CHTs exceeding 400 degrees on all four cylinders when climbing to pattern altitude in 80 degree ambient conditions. They run around 380 degrees at cruise power leaned but the EGTs are about 1430 degrees (the probes are about 2.5 inches from the exhaust flange). The oil temperature never exceeds 200 degrees, the flexible baffles seal tightly to the upper cowling, the upper cowl "eyebrow" ends are sealed, the ignition timing is correct and the carb jet ID has been increased by .003".
>
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| Quote: | I suspect the lower cowling air outlet area (obstructed by the nose gear strut, exhaust pipes, etc.) restricts the air flow needed to achieve Lycoming's recommended pressure differential between the top and bottom of the engine compartment. The ratio of the cooling air inlet-to-outlet areas appears to be around 1.05 on the stock cowling. Adding two purchased metal louvers would increase it to around 1.24. Measuring the pressure differential is certainly doable but I'm hoping other 6A or 7A owners will share advice based on adding louvers or otherwise improving the air flow through the lower cowling.
>
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| Quote: | Thanks.
======================
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ef="http://www.matronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-List
rums.matronics.com">http://forums.matronics.com
"http://www.matronics.com/contribution">http://www.matronics.com/contribution
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[b]
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dcw(at)mnwing.org
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| Posted: Sun Sep 18, 2011 3:04 pm Post subject: High CHTs |
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Jack:
Our local RV tech counselor Tom Berge has gone through all of the various solutions to high CHTs in his RV-7A and he thinks he has finally found the solution. Check out his article "Plan S" in our September newsletter. Here is the link:
http://www.mnwing.org/Sept2011.pdf
Doug Weiler
pres, Twin Cities RV Builder's Group
On 9/16/2011 9:14 AM, Robin Marks wrote: [quote] Jack, are your wheel pants and gear leg fairings in place?
Robin
Sent from my iPad2.
On Sep 16, 2011, at 9:00 AM, Mike Robertson <mrobert569(at)hotmail.com (mrobert569(at)hotmail.com)> wrote:
| Quote: | Based on what you state adding the louvers, or increasing the opening of the cowl outlet area, will definately lower oil and cylinder temps.
Mike Robertson
> From: jgh2(at)charter.net (jgh2(at)charter.net)
> Subject: High CHTs
> Date: Fri, 16 Sep 2011 08:35:05 -0400
> To: rv-list(at)matronics.com (rv-list(at)matronics.com)
>
> --> RV-List message posted by: Jack Haviland <jgh2(at)charter.net (jgh2(at)charter.net)>
>
> My 6A with 54 hours on a new O-320 still produces CHTs exceeding 400 degrees on all four cylinders when climbing to pattern altitude in 80 degree ambient conditions. They run around 380 degrees at cruise power leaned but the EGTs are about 1430 degrees (the probes are about 2.5 inches from the exhaust flange). The oil temperature never exceeds 200 degrees, the flexible baffles seal tightly to the upper cowling, the upper cowl "eyebrow" ends are sealed, the ignition timing is correct and the carb jet ID has been increased by .003".
>
> I suspect the lower cowling air outlet area (obstructed by the nose gear strut, exhaust pipes, etc.) restricts the air flow needed to achieve Lycoming's recommended pressure differential between the top and bottom of the engine compartment. The ratio of the cooling air inlet-to-outlet areas appears to be around 1.05 on the stock cowling. Adding two purchased metal louvers would increase it to around 1.24. Measuring the pressure differential is certainly doable but I'm hoping other 6A or 7A owners will share advice based on adding louvers or otherwise improving the air flow through the lower cowling.
>
> Thanks.
>
>======================
>===============
>
>
>
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[b]
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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jgh2(at)charter.net
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| Posted: Tue Sep 20, 2011 3:03 am Post subject: High CHTs |
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Doug,
Thanks for forwarding the link - very interesting reading. If you see Tom Berge please give him my contact information. I'd like to ask some detail questions about his experience if he is willing.
Jack H.
810.629.870
On Sep 18, 2011, at 6:58 PM, Doug Weiler wrote:
[quote] Jack:
Our local RV tech counselor Tom Berge has gone through all of the various solutions to high CHTs in his RV-7A and he thinks he has finally found the solution. Check out his article "Plan S" in our September newsletter. Here is the link:
http://www.mnwing.org/Sept2011.pdf
Doug Weiler
pres, Twin Cities RV Builder's Group
On 9/16/2011 9:14 AM, Robin Marks wrote: | Quote: | Jack, are your wheel pants and gear leg fairings in place?
Robin
Sent from my iPad2.
On Sep 16, 2011, at 9:00 AM, Mike Robertson <mrobert569(at)hotmail.com (mrobert569(at)hotmail.com)> wrote:
| Quote: | Based on what you state adding the louvers, or increasing the opening of the cowl outlet area, will definately lower oil and cylinder temps.
Mike Robertson
> From: jgh2(at)charter.net (jgh2(at)charter.net)
> Subject: High CHTs
> Date: Fri, 16 Sep 2011 08:35:05 -0400
> To: rv-list(at)matronics.com (rv-list(at)matronics.com)
>
> --> RV-List message posted by: Jack Haviland <jgh2(at)charter.net (jgh2(at)charter.net)>
>
> My 6A with 54 hours on a new O-320 still produces CHTs exceeding 400 degrees on all four cylinders when climbing to pattern altitude in 80 degree ambient conditions. They run around 380 degrees at cruise power leaned but the EGTs are about 1430 degrees (the probes are about 2.5 inches from the exhaust flange). The oil temperature never exceeds 200 degrees, the flexible baffles seal tightly to the upper cowling, the upper cowl "eyebrow" ends are sealed, the ignition timing is correct and the carb jet ID has been increased by .003".
>
> I suspect the lower cowling air outlet area (obstructed by the nose gear strut, exhaust pipes, etc.) restricts the air flow needed to achieve Lycoming's recommended pressure differential between the top and bottom of the engine compartment. The ratio of the cooling air inlet-to-outlet areas appears to be around 1.05 on the stock cowling. Adding two purchased metal louvers would increase it to around 1.24. Measuring the pressure differential is certainly doable but I'm hoping other 6A or 7A owners will share advice based on adding louvers or otherwise improving the air flow through the lower cowling.
>
> Thanks.
>
>======================
>===============
>
>
>
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[b]
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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