Well, I'm definitely putting the "experiment" in the Experimental Aircraft category! Just opening the inlets to 5.5" and blocking off the side vents only gave my a slight improvement. I noticed on the flight test video tuft test that there is still a tremendous amount of turbulence as the air comes off the edge of the side vents. So... I've opened up the bottom exit as much as possible, used cardboard to "fair" in the abrupt edge, and used aluminum sheet under the exhaust pipes and cardboard to fair the bottom exit another 10" further aft to see if that will smooth the exit air and allow an efficient cooling air flow through the cowling. Hopefully I'll get to flight test it tomorrow. Check out my new YouTube channel, "Savannah S" to see a video of the result. Here's the link to copy and paste: https://www.youtube.com/channel/UCqsik5IjeMAqJRCsf75vGRw
