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In the very high and hot summer temperatures here in Idaho my oil and CHT temps seem to run a little warm creeping up into the yellow range as specified by Rotax.. Last summer I added an air scoop to the NACA duct for the oil cooler - dropped the temp very slightly, but it did decrease. Also added an air scoop to the radiator (vertical ULS) which again helped slightly. Picture attached.
Now am fabricating a "lip" for the bottom of the cowl to increase - maybe - air flow through the cowl. Read that this will decrease the pressure at the cowl air exit thus more air flow.
Question - how much lip in height do I want and also should the height of the lip follow all the way around to the juncture of the fire wall?? Attached picture of my rudimentary efforts - please ignore the mess in my shop - the flare and lip will be better finished when done.
The lip seem high and at a large angle to me. My understanding is that you need to have a low pressure but laminar flow. If it gets too turbulent the air will not come out of the cowling.
Have you tried to make the hole for the landing gear bigger instead of adding a lip?