Ill be the first to admit I'm no engine expert, never have been, so I want to see if this idea has any validity. As OATs start to rise I've been looking at the difference between my OAT and manifold temps. I've seen pretty consistently 20-25 F degrees higher at the manifold which got me thinking about if lowering those temps would increase engine performance. Now I believe I'm correct in thinking colder intake temps will generally increase performance all else equal (denser air, more oxygen = more fuel = more power). From my research it looks like a 10C decrease in temps (assuming a normally aspirated engine like the 912is) can give a 3% increase in HP. This is significant! Depending on the OAT I'm seeing a delta of 10-15 C.

So. I want to avoid cutting into my cowls to add a naca duct by the air filter, but will if this makes the most sense. Im wondering if simply adding a pipe that routes air from half of the lower cowl opening (below the prop spinner) to the air filter area would be worth it? Also I think the upper two opening provide most of the head cooling but I dont want to restrict additional cooling provided by the lower opening if needed. My engine already runs cool, I have half the oil cooler taped off with OATs at 75F and I still barely get the oil to 212 F.

Any and all info appreciated. Thanks!