LocostUSA.com

These articles on diffuser design are extremely helpful:

http://porschecarshistory.com/wp-content/old/lib/magazines/RE/2014/RE2014-10.pdf
http://www.trackcarperformance.com/2017/08/willem-toet-explains-motorsport-diffusers/

The first article starts on page 56 of the magazine PDF (I wish I could afford a subscription to that magazine, every time I look through one I learn stuff).

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Those are two great articles. Thanks!

well i closed off the whole underside of my car but am slowly removing panels, before this i cut a rectangle out of the panel under the tunnel just before the diff and added a lip of about 1" hanging down in front of the cutout to try and create some turbulance under the car to suck air out of the back of the tunnel as the tunnel was getting very hot, of course it starts very hot here in AZ at about 150 degrees on the road surface.
now though i have just removed the panels from under the tunnel and the rear of the car to give an open path to the air, this has reduced the temps of the tunnel inside the car, now i can actually touch the hand brake after a long drive, well all my drives are long anyway you look at it.

to be honest though i don't think that aero has much effect with anything under 100 mph and really does have an effect at 150 mph, that is unless you start with something that is aerodynamic to start with like some of those sun racers, or your car is barn door shaped, then you would be wasting your time

the weight of defusers and the like do counter act the improvements in aero as far as gas milage and you need a lot of aero on a slow moving car to get any positive advantage in grip.

i sometimes wonder when you see slalom or hill climb cars with aero wings and think that just the placement of the weight of the wings and associated bracketry is where the added benefit lie, not the aero at all, like adding a bar full of lead in the front wing location may help the grip just as much without hindering the straight line speed that the wing does.

perhaps Adrian Newey could answer this question, i'll see if i can get my son to ask him as he has now left Renault and is working at Red Bull.

i know for a fact that my sportsman dragster behaved differently above 150 mph with and without the wing and that adding aero to your average boy racer box sedan helps grip in no way at all even if the car can do 80 mph.

just my ramblings

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