Replies to This Discussion

Permalink Reply by Clint L Gosch on July 25, 2020 at 10:03pm

Hi Douglas,  what's the ambient temperature, and how are your CHT's?  My oil gets up to about 210 on a 90 degree day.  Also, have you verified your oil temp sensor accuracy?  My MGL setup was 30F off before I calibrated it.

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Permalink Reply by Gary Welch on July 26, 2020 at 1:13am

The simplist and most obvious would be to check for baffle leaks or air bypassing cylinder fins.

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Permalink Reply by Jimmy Young on July 26, 2020 at 6:58am

 Mine ran 225-235 on my first flights, that was with a fresh overhauled Continental not broken in and I'd have to back off to keep temps from climbing. After a few tweaks on intake inlet size  and exit cowl size, adding a lip at the exit cowl, and completing the break in process, I've got mine stabilized in the 190-205 range on summer days here in Texas where you are. As Clint asked, what are your CHT's? Ultimately, that will be the key to dropping your oil temps.

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Permalink Reply by Jimmy Young on July 26, 2020 at 7:30am

Also forgot to ask, are you making your first flights with a fresh overhauled engine?

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Permalink Reply by Clint L Gosch on July 26, 2020 at 11:07am

Here is some additional info you might consider, by adding these under engine baffles and cutting some holes in my cowl I lowered my oil temp by 8-10F. This was after I spent some time getting my CHT's optimized.

Attachments:

• 20190602_114535.jpg, 2.6 MB
• 20200515_140108.jpg, 3.4 MB
• intercylinder_baffles_343.pdf, 188 KB

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Permalink Reply by Douglas Rosser on July 26, 2020 at 2:16pm

My o200 is mid time so no break in problems. I don’t have cht probes. All of the heat is staying on top of the engine. My exhaust runs out the bottom so there is not a very large exit area for the heat. I changed lip some with no change. Wondering if I should put more vents on cowling or change my exhaust location. Where is the best place for vents?

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Permalink Reply by Clint L Gosch on July 26, 2020 at 2:55pm

Hi Douglas,  Do you have any pictures of your cowl outlet?  I had to make a rather large change to get my CHT's down on warmer days, thankfully most of my test flight period was done during the colder months, so I had a good safety margin while figuring things out.  It seems most folks have found that the cowl outlet size and geometry is very important for allowing hot air to escape. But send some pictures of your inlet, outlet, and baffles if you can, it might help spur some other ideas.  My exhaust is quite different than the zenith setup, but the zenith setup has worked for others it will work for you too, might take some experimenting.

Attachments:

• 20190330_165349.jpg, 1.4 MB
• 20190330_165331.jpg, 2.2 MB

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Permalink Reply by Jimmy Young on July 27, 2020 at 2:51pm

Speaking of changes to the cowl outlet size, I am including a photo of how much I changed mine and how I added a lip to it. That change, along with increasing the cowl intake sizes by about 3/4” in height, helped to get my cht’s and oil temps down to good numbers even on hot summer days. The minimum ratio of inlet to outlet sq. inches is 1 to 1.5, and that is the minimum. The outlet can be larger and it only helps.

Cowl outlet mods

Intake mods

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Permalink Reply by Douglas Rosser on July 26, 2020 at 3:08pm

My exhaust is straight pipes exiting out the bottom. I’ll take some pictures. Thanks

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Permalink Reply by christopher fryatt on July 27, 2020 at 3:50pm

i'm running with an oil cooler, no problems with oil temps, only mod is a lip on the cowl outlet

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