Baffle Sealing

Time: 4 Hours

One last step that I needed to do on the baffles is to seal up any gaps in the baffles where they meet to engine. The idea is you need to imagine a molecule of air and you want the molecule to cool the engine. That molecule needs to travel past the cooling fins of the cylinders to me the most efficient. If there are other spaces that the molecule can go then that reduces the effectiveness of the cooling properties. So to force as many of those molecules around the fins you need to close any other escape paths for them. One area that had a very large gap was on the right side of the forward baffle. I think it would have been tough to fill it with just RTV so I made a filler strip out of .025″ sheet. Once I had it to the shape I needed I drilled, deburred, primed and painted it to match. Most of the areas that need seal are pretty obvious to see for the not-so-obvious areas I used a light shining up from the underside of the engine to identify them. I used a grey colored RTV sealant, think caulking for environments that get hot and have contact with oils/fuels. It seals well and creates a good bond however can be removed when needed. It’s messy and hard to get it to look good but it is needed to properly cool the engine. I bought a couple large tubes that fit in a caulking gun to make it easier to apply. A couple areas that were too hard to access with the nozzle on the tube so I used a piece of 1/4″ plastic hose that was extra brake line stock attached to the nozzle to help get to those. I was able to use a wet finger to smooth some of the areas but others it was just too tight to get a finger on the seal. They aren’t beautiful but the will accomplish the task. I’m glad I was able to find a color that didn’t stick out like the red RTV that most planes use and would really be an eyesore.

I have a few areas that I want to clean up a little once they cure all the way. In the mean time I went ahead and cleaned all the baffle seals for the top of the baffles and installed them.

Overall I’m happy with how the baffles turned out. I think they will provide good cooling but will have to wait until I’m flying to confirm that.

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