Speed Holes for MPG?
 

The "speed holes" are a fad in the tuner circles. Basically, they just cut a bunch of holes in the rear bumper. Supposedly, by ventilating the rear bumper, it reduces the aero drag.

Has anyone tried such a thing on an "ecomodded" car? And was there any measurable benefit? I have my doubts, but wanted to ask anyway.

The premise is faulty and the execution is usually even worse.

...they make the car go faster...

http://www.youtube.com/watch?v=XVV_COOey0E

I haven't seen "holes" but I've seen some cars like this

http://www.bodykitsuperstore.com/ima...nda/890179.jpg

If they want to make a difference on cd they should have boat tails. And if they're racing I'd love to see the faces on the other people who are racing them haha :eek:

holes
 

Opening holes in the rear bumper would increase the drag,not lower it.The bottom of the rear bumper should be close to the elevation of the underside of the car.You want it to pool dead air up where all the naughty bits are,allowing the air underneath to flow smoothly to the rear.
If you're having a problem with wheelspin at high speed,then perforating the rear would allow low base pressure of the wake to communicate forward under the car to provide downforce and traction.It would cost you speed though.
A rear spoiler would be better.

Assume anything the ricers do is wrong, no matter what the intended goal is.

I spent an afternoon with a guy who was head mechanic fora Le Mans team which won its class. He was backed by a BIG factory which spent a LOT of money on windtunnel testing.

Any air which gets under the car slows the car down by causing drag. More air, more drag. This is known by ANYONE who races, and front spoiler height is heavily regulated by every sanctioning body.

Once the air gets under the car, get it OUT at the back. Run the highest possible bumper with the most amount of the biggest holes.
Any amount of restriction in getting the air out the back of the car causes upforce and drag.

These rules apply to any car which can't run aero tunnels, which are defined to be any car with a ride height of over 2 inches (you can't make very effective tunnels with 2 inches of ride height.)

we are not talking about fully built race cars... we are talking about the punk ass ricers civics with fart cans.

I don't see any "racing holes" in this, or any other, Le Mans car I've looked at.

http://upload.wikimedia.org/wikipedi...1981-08-15.jpg

Le Mans cars can sometimes have too little aerodynamic drag. They turn into lifting surfaces, to the detrement of their drivers.

http://thatcarblog.com/wp-content/up...rn-300x291.jpg http://i213.photobucket.com/albums/c...05338251_o.jpg

Pure drivel. :rolleyes: