My motor seems to stay pretty cool during these summer months. My bottom of the cowl is maybe a 3.5 x 3.5 square cutout with the two front openings open. Really my issue is cracking around my cutouts through vibration and by connecting the glow plug ignighter every time I start it up. Right now i have pretty much fiberglassed everything now to keep things together. The tape VF used to join the 2 cowl halfs on the bottom have pealed off on my second flight, so that is now fiberglassed together.