Speed Holes for MPG?

[Frank Lee]

Originally Posted by wdb

Just wanted to quote the pix again

[aerohead]

Originally Posted by drmiller100

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.)

I basically agree with your comments with respect to the context of dedicated racing vehicles,however none of this is germane with respect to the fuel economy of daily drivers operating on public roads and streets.

[Gone2]

A great deal of the items that ricers use to improve performance of their cars is actually counterproductive (evident in the amount of black smoke that comes out of the tailpipe of these fart can mufflers). If you have holes on the back of your bumper, you would actually encourage more airflow to your rear bumper and create a drag. I would be curious to see this theory tested in a wind tunnel. I imagine that the rear bumper area would do the same as a pick up bed only upside down. Instead of drilling holes, why not just remove the bumper?

[mcrews]

or just seal up the bottom!

[JasonG]

But then where would you mount the expanded metal ?????

[oil pan 4]

Whats the difference between this:

Originally Posted by mcrews

from the driver side rear:

And this (besides the top one really working)?

Originally Posted by Blacktree

Here's a picture of what I'm talking about.

The top one doesn't make your car look faster.

[Sven7]

Yes- why modify your car in an effective but invisible way when you can look faster and go slower? The great thing about ecomodding is you can be effective and visible without spending lots of money.

Just imagine in the future if teenagers did stop-light MPG runs instead of 1/4 mile races.

[Frank Lee]

I suppose a new way to visually identify retarded high school car modifiers was needed (as if the sub-woofers and fart cans weren't enough ) since back in the day everybody jacked the rears of their cars about a foot up in the air so as to look like fast Funny Cars, but now that most everything is fwd that doesn't make sense.... hey, wait a minute, it doesn't have to make sense. They could still do that!

[mcrews]

Originally Posted by Sven7

Yes- why modify your car in an effective but invisible way when you can look faster and go slower? Just imagine in the future if teenagers did stop-light MPG runs instead of 1/4 mile races.

lol

[Sven7]

Originally Posted by Frank Lee

I suppose a new way to visually identify retarded high school car modifiers was needed (as if the sub-woofers and fart cans weren't enough ) since back in the day everybody jacked the rears of their cars about a foot up in the air so as to look like fast Funny Cars, but now that most everything is fwd that doesn't make sense.... hey, wait a minute, it doesn't have to make sense. They could still do that!

One of my life goals is to install hydraulic suspension in my '81 VW Rabbit. Three wheeling in a FWD economy car doesn't make sense, but it would be fun as hell.

And after all, isn't car modification supposed to be fun?