Thanks for your comments.
How would this benefit more than just having a 2x25" opening in the bottom grill.
If I don’t do this, that is exactly what I will do. I don’t know that this would be better, just different. I already have my aluminum grill cover made, so if I put some lexan or black coroplast behind it I can have a decent looking (to me) 100% grill block with little effort. I have not yet thought of a good easy way to incorporate a 2”*25” radiused opening into the lower grill area without completely changing my design and starting over on all my grill blocks. (Yes, I care a little how it looks.) Anything I do under the car can look like whatever it wants, doesn’t have to be pretty if it is hidden.
Also after reading some about the airflow under the car, I thought it wouldn’t be a bad place to “rob” the cooling air from. My way of thinking it should give similar effects to having a small air dam.
I would think smoothing out the belly completely and just having a small opening in the front would be more beneficial, but you got the holy aero bible, so you would know better.
If I thought that I knew better, I wouldn’t be asking questions.
Most things I have seen put the intakes low on the front nose of the car. My way of thinking about it, this intake would still be on the front of the car, and even on the nose of the car, it is just below where the other styling features of the car stop. It is almost like dropping the nose 2” (like an air dam) and then putting the inlet right on the bottom.
Also after previous experiences I won’t be smoothing the belly completely, just partially. I will leave the exhaust components out in the open.
Although, you may benefit even more if you do what you say in your diagram, but instead of an opening with an angle (which creates a parachute), you could have a completely flat belly with NACA ducts. That is my plan for my belly pan, whenever I get around to it.
I had considered making it NACA like, but you have to have smooth flow on a surface for the NACA to work properly, I don’t know I have smooth flow right there. I am thinking of my design more like a normal grill opening, utilizing the high pressure at the front of the car to ram the air in.
In your diagram, you have the air escaping out the bottom, but why can't you exhaust out the top, up and over the windsheild like Hucho mentions (other than having to cut the hood open)?
Can’t say I didn’t consider it, but I don’t really want to cut my hood open. Hucho also warned about the heated air going into the fresh air intake on the cabin. Others have warned about dirty water getting on the windshield. It would be interesting to test if I happened upon a spare hood.