One of the aero changes I wanted to make involves the fender vents. I'm planning on a splitter and pan under the engine compartment. So I need to evacuate the under hood air that comes through the radiator and reduce high pressure air under the hood that causes lift. Many have experienced the effect called "float" at high speeds (over normal highway speed) in regular cars and some models are worse than others. The 2nd gen TA fender vents help reduce that and I want to maximize the benefit.
So I began by doing some tuft testing on the stock vent with the screen removed to see how it performed. Then I made cardboard modifications to the vents and tested again. I spent more than a day on this process testing various configurations and came up with a couple modified vents that should help keep the air pressure lower under the hood. For a more detailed version of the testing and how the modified vents were made see this thread which just covers my aero mods.
http://transamcountry.com/community/...?topic=71522.0
The stock TA vent has a hole with surface area about 15 sq. in. The screen in the stock vent blocks off about 5 sq.in. reducing it to 10 sq. in. and creates turbulence as the air tries to exit through it. As I went through the testing process I changed the angle of the leading edge, added wicker bills of varying heights and expanded the opening. The modified vents now have openings about 3 times the sq. in. with steeper leading edge and the design of the housings seem to draw a lot more air from under hood. One set will be used for Land Speed racing type events (less drag) and the one with the wicker at the leading edge will be for road course use (more drag but also more evacuation).
As I mentioned it was a long process and lots of variations were tuft tested. Here's a few pics to show a couple of the differences.
Stock vent with screen removed.
Modified vent below with steeper leading angle and stock opening.
Modified vent with wicker and extra slot opening below.
This version seemed to get the best results for evacuation with reduced turbulence. But it wasn't enough "better" to warrant all the extra effort I'd have to put in to incorporate strakes into my design.
