I know the mudflaps are a drag, but without them the wheels throw crap all over the back fenders. Maybe I could design more aero friendly ones. Without them the car ends up looking like an off roader. The plan is to add some to the front as well. The door and rocker panels get the junk there now. It was worse before I went to wheels with an increased offset. I previously had custom wheels which set the wheels out 3/4" further on each side. I went back to stock wheel this Summer, which not only look nicer to me now, but the car handles better. And now I read that setting the wheels in further improves the airflow. When I was into racing I regretted the semi wheel skirt design of these rear fenders as they limit the size tire you can put on the back. Now I admire them.
The gurneys actually do angle in slightly, and are curved at each end. I could angle them a bit more. Because of the cutout on the bottom of the belly pan for the wheel, you end up with limited material to mount it to. It would be simple though to angle it a bit more. The question is angle it in or out? Out runs the air into the wheel. "In" puts the air into the mess under the car. These were made from an old trash can. I could find one with a more curved side I suppose. I will keep my eyes open at the market. This can was just what was sitting in my garage.
One of the goals of the airdam was to NOT change the appearance of the car much. I feel like I accomplished this. No one has ever mentioned it at a car show. But in order to make it less noticeable I had to keep it inside the lower edge of the front fenders. This does limit its effectiveness. If you click on the photo you can then scroll through my car album on photobucket and see and older version which was smaller in every way. The old one used a Ford Ranger airdam as a starting point, the new one uses a full sized Chevy pick up air dam.
I have actually added the inner lining as suggested. I suppose I could make it deeper. There was nothing there before. Here is a photo of that fabrication. I used the inner wheel well from a Cadillac for that one.
Thanks much for the ideas. They are all going in the mind and churning around. I do not know much about diffusers and how they work or are designed. I also have a BMW 328, and there is a stock M series rear diffuser available for it, and was considering adding that to that car. Can you supply a link or explanation for what a diffuser is please? Thanks again. I am all ears and learning every day. I feel I can fabricate anything I can imagine as long is it is not too visually distracting.
Sam