Cowling Pressure Drop

[dirkverdonck]

Hi,
I added the new Onex lower cowl lip and increased the outlet area and also copied/pasted the B-model side outlets.
Hopefully, this will solve the cooling issues!
Apparantly, with side outlets, electric flaps, etc, I'm probably building a B-Onex!
Dirk Onex117

[Onex107]

I have a question about cowling pressure. I suspect that I have an over pressure situation because,------after a flight there is a small amount of oil that streaks back from the top center of the cowl, behind the prop hub. I think the source of the oil is the filler and vent caps on top of the engine. They don't leak but they are wet. The air would have to be exiting to the front to carry oil up on the top of the cowl. My Onex has the standard Aerovee with oil cooler on top with the new design exit hole in the bottom cowl. I don't like the way the fins on the heads are arranged. There isn't enough through holes to do a decent job of air cooling. If all this is true, the cowling opening is larger than necessary for the cooling flow at cruise speed.
Second question. Has anyone ducted the oil cooler exhaust down over the intake manifolds? I suspect that warmer intake manifolds would result in more even cylinder temp. AKA Lycoming. They pass the intake tubes through the crankcase so they see oil temperature.

Onex 107
Tri Gear
Aerovee
181 hours