I’ve been contemplating this. Its gets very hot here in AZ.
The ducts would be twofold. One, to bring in fresh air. (This would be with the foot box blocked off from the radiator)
2) To fill the cockpit with air, creating a positive/high pressure area. For air to flow out of the cockpit and not into it. So as to help eliminate air flowing backwards from the engine compartment. Its difficult to explain in a few words, so sorry for being long winded here.
The windshield deflecting air over and around the open cockpit creates a parachute effect. (Low pressure behind it) If you can direct some air flow into the cockpit, say the footwell area, it can help keep the air moving over and around the windshield (fast moving high pressure air) and keep from dumping/tumbling into the cockpit. It won't have the low pressure area it wants to flow to. How much air we'll need to do this is the unknown part.
See the upper pic and you can see the green trail of air heading into the cockpit towards the knees. Note the air coming over the short windscreen/deflector, skimming the top of the helmet. It doesn't seem to be a lot of air to do this.
George, I also think you had mentioned somewhere in your posts about building a diffuser. Have you given that a try yet?
I'm thinking that sealing the area underneath the engine/subframe, from the firewall back behind the engine could help as well.
Just putting ideas out there.
I'm not an aerodynamis' by any means, but I did sleep at a Holiday Inn!
