Quote:
Originally Posted by alpinelakespilot2000
Can anyone point me to a simple, preferably quick, means to check the pressure differential between top and bottom?
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You want quick and dirty? Pick up two aquarium bubble rocks, about 20 feet of 1/8 vinyl tubing, and 4 feet of 1/4" vinyl tubing. Ziptie one rock (with connecting tubing) to the top center seam of the engine case. Ziptie the other rock to the engine mount somewhere behind the engine. Neither should be positioned in a stream of high velocity air.
Run the pair of tubes back to the cockpit any way you can. Some have gone through the heater box. You could also run it out the cowl exit and up around the fuselage, and under a canopy edge. Duct tape it to the fuselage skin.
Fasten the 1/4" tubing to a 24" x 4" board so it forms a "U" with straight sides. Mark the board with lines straight across every half inch. Mix some food coloring and a bit of dish soap into a few ounces of water. Pour the water into the U-tube until it fills the bottom 10 inches. Now connect the engine compartment tubes to the ends of the U-tube.
Go fly. If the water jumps up and down too much, install restrictors in the lines....plugs with a 0.040" hole bored through them.
Pressure differential is the
difference between the two water levels. Pressure varies with both altitude and airspeed. Email me for a Lycoming cooling air demand chart.