I just built a prototype of my own design. Unlike most, I am not doing it closed loop....
I made my entire confirmed working system for about $35.00 ! Below are all the parts and where to buy them. I also bought a dehumidifier for inside of the cabin for another $25 so for a grand total of $60 and I have dry air running through my entire plane & engine :
Thanks to John here and his emails I used his idea and changed it up slightly then to make sure it's working I added a twist. You can see how the blue beads are turning pink as they absorb the humidity out of the air so I know the engine is getting dry air right?
Well actually the only way would be to monitor where the air is coming out of the engine so I took some pink beads (saturated beads that used to be blue) and put them in another short tube and inserted that into the breather tube. Now you can see how those pink beads are turning blue as the dry air blowing out of the engine goes through them.
Ok so now some things I have learned with this experiment and I hope it'll save you some time if you decide to try it out. I'm not a mechanic so if you decide to do this it's because you believe it'll help your engine, not because I'm doing it to mine :
1- I started with a low volume pump and I thought the engine wasn't getting enough air because I couldn't feel it coming out of the tube. I thought I might as well buy a bigger pump and test it. You DON'T have to buy an expensive pump, I bought this $13 pump at Walmart that has 2 air supplies. I had the aquarium tubing but if you don't then pick some up at Walmart too, it's the cheapest place to buy it anyway.
https://www.walmart.com/ip/Aqua-Culture-20-60-Gallon-Double-Outlet-Aquarium-Air-Pump/10532634
Boy what a difference when I used a T connector and was blowing both of the pump exits into my silica bead tube, but I also found out that I was blowing so much air that the beads were turning pink in 2 days (running continuously) ! So I now use only one output and that gives me more time between drying the beads. I run it continuously because apparently East Texas is more humid than I thought. You might want to try running it less often if you want. I live with my plane so removing and replacing the beads after microwaving them dry once a week (more on that below) is not a problem for me.
2- To connect the 1/2" hose to the aquarium hose just take the one way check valves that come with the pump and cut them in half, remove what's inside, and stick them into the hose. They fit perfectly !! See the picture above.
3- Regarding the top oil filler tube where I blow in the dry air, I just went and bought a $1.40 rubber plug at Lowe's and drilled a hole in it until I could fit the aquarium hose through it.
https://www.lowes.com/pd/Hillman-0-5625-in-Black-Neoprene-Hole-Plug/3013259
4- I also bought the 1/2" hose for $5.18 at Lowe's:
https://www.lowes.com/pd/EASTMAN-1-2-in-x-10-ft-PVC-Clear-Vinyl-Tubing/1000364771
5- I bought a quart of the blue silica beads on eBay for $13 (the price goes up and down weekly so just search for the best price. You can actually get it half that price if you want to wait a couple of weeks until it gets here from China. BTW a quart is an overkill because I can fill three 10' hoses with it but I just mention it so if you have a bigger tube or want to use a bottle you get an idea of how much to buy. You might be able to buy it locally too :
https://www.ebay.com/itm/1-Quart-Pr...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
6- For a filter I cut the hose and used a little Tupperware container I had in the kitchen with a spin off top. I hot glued the 2 pieces of hose to the 2 holes I cut in the sides. I then rolled up a cotton sock around some paper towels and inserted that into the container. This will stop any silica dust from getting to your engine.
7- When it comes time to dry the pink beads I could spend a couple of hours letting them dry in the oven but I researched and have confirmed that I can get them just as dry and blue (and it's just as safe to do it) by placing them in a shallow dish in the microwave for 6 minutes, and it's a lot cheaper due to less electricity to dry them in 6 minutes versus 2 or 3 hours. I recommend doing it in 2 minute phases so after the first 2 minutes you can move them around in the plate with a fork or spoon then nuke them again 2 minutes and move them around again then 2 more microwave minutes and you're done. *** Make sure you use a microwave safe plate. I used a plate that even though it didn't say it was microwave safe I always used in the microwave to heat up my food for 30 seconds with no issues, but when I heated it for 6 minutes, plus the heat off the beads, it cracked.
8- So I just came out of a condition inspection so I had my cowlings off. once they're back on I'll just plug in the oil filler part (oil filler is plastic and cools down in a few minutes after I shut down) so it starts blowing dry air immediately into the engine. Later when it cools down enough for me to touch the exhausts then I'll plug in the bottom part. After I play around with it like this for a while I might convert it to a closed system, but for now it works great and it was very cheap to build.
9- Not part of this system but 100% related, I also bought a small dehumidifier I leave running inside of my RV-8 and I can get at least 1/2 a cup of water out of it every few days !! When I bought it I only paid $25 so search for a lower price, at least you know what model actually works. You can also adjust it so it removes moisture up to a certain percentage and shuts down. I like it because I can also run it on 12 volts DC so I removed the transformer and now I'm running it off of my solar system:
https://www.ebay.com/itm/174036923824
... If I missed anything feel free to ask.