aerodynamic effects on drag cars
 

hi guys, well after spending some time time searching, and not coming across anything of value, thought i would ask :)

most of us are over 100mph, for over 50% of the track, which i can`t help but think there are some significant gains to be found from an aerodynamic point of view.
obviously i have seen the cars with holes in the rear bumper, and sheet ally under the car, closed mouth front bumpers, taped seams etc etc, what im looking for has anyone done any real back to back testing (i.e standard rear bumper vs holed bumper etc) to see the effect on trap speed.

i realise ET wont be effected much, as thats more driven by the 60` and 330`, but im guessing mph would show improvments found, are there large gains to be had, or is it very minimal? is it worth spending some time and money on...

im limited to a minimum weight in my race class 1039kg, so cannot simply make the car lighter, and were trying some things with the motor, but i just want to hear about aero tweeks, and findings here.


cheers team :)

Re: aerodynamic effects on drag cars
 

i remember reading about the effects of a stock rear bumper acting like a parachute when you get up to speed. thats where the rear diffusers came from. but i can not remember anyone doing side by side testing.

i know in the supra community people have seen 1-3 mph gains on removing the rear spoiler. so im sure that doing some undercar aero would surely help the mph. not too sure about e.t. like you said.

Re: aerodynamic effects on drag cars
 

We had a diffuser setup on a EP3, that we tested, with and without, and then with the whole bumper cut out. Back to back testing didn't provide us with anything solid, but I'm sure the car needed to be more consistent to really take anything from it.

Again the same kind of thing with a rear wing, changed the angle of that a couple of times, and then took it off and there wasn't anything conclusive to take away from the tests.

I was talking to a guy from Mugen about a certain wind tunnel experiment with one of the BTCC Honda's, on paper, effects of the shut lines between the headlights, bumper and wings do show up, and a simple bit of tape does solve it, but again on the track, little things like that don't really show up as there are so many other things that affect consistency.

I would always aim to get some ally underneath the front of the car, get it all flush with the front bumper. Catch pans should be mandatory over here anyway, so i like to combine the 2 into 1.

And cool ally drag wings just look plain cool :P

Re: aerodynamic effects on drag cars
 

trust you to find my thread lou ;)

yeah i guessed that real results would be hard to find, as most cars are not consistant enough for any results to really count as evidance, but trap speed is quite consistant, more so than ET anyway, and i think most people would notice if they jumped 4mph + for example.


in for more input please guys :)

Re: aerodynamic effects on drag cars
 

You wont be jumping 4mph from making small changes to your stock body EG :P

Re: aerodynamic effects on drag cars
 

I have read something interesting in an article a while back. It was something like a one square foot in the vertical position takes 9hp to push at 100mph.

Like I said, this is internet reading so I don't know how accurate that is.

Re: aerodynamic effects on drag cars
 

You are absolutely right there are not many places to find information about this for our type of racing. I have done a lot of digging this off season as well . .

A good thing to do is read all of the research done on increasing gas mileage on commuter cars for highway use. . There is a plethora of tests about how to increase your MPG by changing the aerodynamics of a normal car.
The first thing that is always mentioned in every study is to seal off the front of the car as much as possible . . . Food for thought . .

I figure that if it is working to help cars cut through the air better on the highway at 65mph to increase MPG, it might be worth a shot for cars like ours on the track . .

Do i think there will be any crazy gain by trying any of this stuff? No not really. Most cars are above 100mph ( at least NA cars lol ) only after the 1/8 mile. From The 1/8 mile to the traps it is barely 4 seconds so I will set your expectations that you wont see anything too impressive but every little bit helps . .

Check out a book called Aerodynamics for Competition Cars by Simon Mcbeath . . you can order it online. Its pretty extensive and has a lot of math in it but has some very good info in it . . .

Just my 2 cents . . . Good luck in your search

Re: aerodynamic effects on drag cars
 

Re: aerodynamic effects on drag cars
 

one of the first things done for hypermiling, i e mpg, is to seal up the front end, which is really easy.

There have been a few people that have tested different body additions and one that has made a good size difference is a boat tail or kammback design.

if you want to see a car that gets crazy gas mileage, it might not be the most beautiful but im sure it could be made to look good if someone could refine the design a bit

http://www.aerocivic.com like i said, not pretty but proven to work really well

Re: aerodynamic effects on drag cars
 

thanks for the input guys :)