Make Your Own
The Tempest device appears to be open loop; that is, it draws in atmosphere, drys it and pumps it through the engine crankcase and out the vent. It is continuosly drying air, and uses up the desicant. I built my own system using a one gallon plastic jug that can be sealed, an aquarium pump, desicant beads from Harbor Freight Aviation Division (very cheap), a few fittings and plastic tubing. I added a rubber plug that pushes into the crankcase vent hose accessible through the lower cowl exit and ran a tube back to the air stone in the desicant jar. This is a closed system that recirculates the same dry air through the system, and makes the dessicant last for months. Total cost maybe $40.00.
My airplane is hangered, so 120VAC power is not a problem. If I kept my airplane outside, I would buy a cheapo HF power inverter and connect it through a countdown timer switch to run for an hour or two off the airplane battery (very low draw) to dry out the crankcase and then shut off after each flight. Maybe use an external battery that would recharge from the car while flying!
