Sealing Inter-Cylinder Bafflles

I’m sealing up all the air leaks on the underside of my 540 and have a question about airflow past the inter-cylinder baffles.
See the attached photos.
Should I seal the areas circled in read?
Or do they need to flow air in order to pass heat removed from the adjacent fin?
I want as little leakage as possible but obviously don’t want to create unwanted hotspots.
Thanks, Sages!

In a word - yes.
Just a suggestion - use a torch in a close to dark hangar & shine it upwards at the bottom of cylinders/ baffles, especially at the aft end of the engine where the baffles meet the engine case & all the other baffles - you’ll surprised at the number of gaps you may find

Thanks, I’m using that method and I’ve got her sealed up quite well.
I’ve read through as many posts on the subject as I can find but I wasn’t sure if air needs to escape at these specific spots in order to remove heat from the surface of the fins they are next to.

In my engine the gap line of the center baffle against the case was the worst. Here are the completed gaps with goop. The flash light method will see all the gaps.

The two gaps in the first photo may have some merit in terms of heat transfer.

Is it really necessary to seal all gaps in the baffles? The factory installation of my 89’ M20J has only the baffle sheets with no additional sealing. Even longer climbs with closed cowl flaps never brought the temperatures at or above the upper edges of the green arc. The cowling is very tight and the speed range is comparable.

jakej said:

In a word - yes.
Just a suggestion - use a torch in a close to dark hangar & shine it upwards at the bottom of cylinders/ baffles, especially at the aft end of the engine where the baffles meet the engine case & all the other baffles - you’ll surprised at the number of gaps you may find

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Need to be a bit cautious here. In the US, a handheld light device is a flashlight. For us, a torch is a gas device that shoots flames in order to produce intense heating. Hoping nobody thought of using a propane torch to find leak areas

lr172 said:

Need to be a bit cautious here. In the US, a handheld light device is a flashlight. For us, a torch is a gas device that shoots flames in order to produce intense heating. Hoping nobody thought of using a propane torch to find leak areas

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Agreed, but it will quickly find fuel leaks....

Gap Width

DanH said:

The two gaps in the first photo may have some merit in terms of heat transfer.

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The width of the gaps is about the same as the space between the fins. That’s what made me wonder if it would be less of a “leak” and more of a heat escape path.

andoman said:

The width of the gaps is about the same as the space between the fins. That’s what made me wonder if it would be less of a “leak” and more of a heat escape path.

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The idea is to cause turbulent flow in close contact with a hot surface. If velocity is high and the space between parallel hot parts is narrow, flow should meet the criteria. Obviously here we're talking about flow between fins.

The little slots in the first photo squeeze the air through a small space for only a short distance. My guess is heat transfer from fin to air is likely good in the slots, but drops off significantly with increasing distance from the slot.

Want to get really exotic? Add a flat plate parallel to the surface of the outside fin, so flow remains trapped along more of the fin surface. Yes, diminishing returns, and no, I don't expect anyone to do it, but it illustrates the point.