Joee75. I run an OS46AX in my beasty and it has more than enough grunt to pull the Lancair around like a pylon racer. Ive not had any overheating issues with my AX, but I do tend to run it a bit richer than I normally would for this motor. My AX is completely covered by the cowl - not even the head is exposed and I access the glow plug through a small hole in the cowl and a long glow plug. I also start up in or near the pilot area to eliminate long taxiing to the strip to keep the engine cool. Once in the air there seems to be enough air flow to keep things running O/k