Cold air intake for 912is

[JoeRuscito]

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!

[efwd]

Under the maximum power capability of the 912iS you would expect 100hp. Most of the time the engine produces less due to DA. 3% of say 90hp, I don't think you would even be able to notice that IMHO.

[jrevens]

Joe,

25-30 deg. is pretty considerable. I believe that an increase in intake air temp of that amount would result in a HP loss of approximately 5% due to decreased density, everything else being equal. That's based on a rough rule-of-thumb (5.5 deg. = 1%). I hope someone corrects me if that's wrong. I'm partially blocking that lower opening with my landing light and it seems just fine, but I'm unsure how much effect re-purposing much more of that opening would have.

[JoeRuscito]

John how much of the opening does your light block?

[jrevens]

Roughly 1/3?


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[Shadowrider]

I think if I where spend the effort, I would make a intake duct that attaches to your intake manifold and route it to cool air. So many variables of trying to route fresh air back to your filter and hoping it gets drawn in unless you box it. Maybe that’s what your thinking? I would get some silicon ducts and and route the intake to get fresh air. I remember seeing a picture that edge performance had posted that someone made a carbon duct routing it to front of engine. The back side of the engine I have to imagine air is swirling?