Hi, I'm new here and my cD is .37, can you help me get a .30?

[aerohead]

Here is the Dodge Viper GTS.It's designed for higher speed and you can see what they did at the rear.

[Vman455]

Here's something I just posted in the Corvette thread, but may be of some interest here:

I went searching for more information on this car, trying to find if LMR ever made good on their promise to produce aeromods for the C6. It looks like they didn't, but I did find a more in-depth article on the car and windtunnel. The captions to the pictures give the most information, including the following:

-"The first mod was to seal off openings in the grille, splitter, and fascia.... This is standard practice in top-speed competition and took a solid 18 counts off the drag coefficient."

-"LMR co-owner, Josh Ledford, crafted up some low-tech wheel discs to flush-cover the 19-inch rims, front and rear. We kinda thought this would be a big step and it was, immediately taking off 12 counts of drag while (or perhaps by) reducing overall downforce."

-"The outside mirrors were then folded in from their normal position seen here. This proved aerodynamically effective."

-"Tom Froling then suggested altering the car’s rake by lowering the nose somewhat. Rather than mess with suspension adjustments (nearly impossible with the car on the platform) the crew simply added sufficient ballast weight under the hood and in the cabin footwells to drop the nose by about 12mm. The effect was rather dramatic, lowering drag by 8 counts, and benefiting downforce to the point where the overall lift coefficient was down to 0.001."

-"By now, we were running out of time, so for one final Hail Mary it was decided to extend the baseplate of the front splitter (by about 1.5 inches at the center and tapering back towards the outer corners). By altering the car’s front/rear aero balance, this proved very effective, taking another 4 counts off drag."

End result: .373 down to .307.

[Cd]

Originally Posted by Vman455

End result: .373 down to .307.

What I can't figure out is how that this car had such a high drag coefficient at the start of the test. It appeared to be totally stock on the outside ( no huge spoilers etc.) yet the C6 supposedly had a Cd of point 29.

[razordave]

They didn't even have boat tail!

[Vman455]

Originally Posted by Cd

What I can't figure out is how that this car had such a high drag coefficient at the start of the test. It appeared to be totally stock on the outside ( no huge spoilers etc.) yet the C6 supposedly had a Cd of point 29.

Not in the A2 wind tunnel:



This is from a test by Super Chevy magazine comparing the various Corvette generations, base models. The LMR car has a ZO6 body; for that car, GM quoted .34, but I could easily see that being higher with the different hood, wheels, spoiler, etc.

[AutoDeutchland]

Ok, my first phase is upper grille block, headlight lenses, full under body paneling front to back, and clear wheel well covers (rear only, not just wheels, the whole well.) Any guess as to how many counts I'm looking at here?

[freebeard]

Keep in mind a point is 0.01, not 0.1 as I've seen somewhere lately.

My email notifications flagged a thread that hasn't changed since 20140701, maybe it was so I could point it out to you:

Drag reduction modifications in wind tunnel: Audi A2 from Cd 0.288 to 0.204
http://ecomodder.com/forum/showthrea...-cd-21175.html

[AutoDeutchland]

Yup, and I wanna get to a .30 from .37 so seven points.

[Vman455]

The way I've seen it used is 1 count = .001; so when that Chevy article references "12 counts saved" by smooth wheel covers, they mean a drag reduction of .012. Or, as Hotrod Magazine explains it: "The delta between Cd numbers is often referred to as "counts," or thousandths of a point, so the difference between a Cd of 0.250 and 0.200 is 50 counts."

[AutoDeutchland]

Ok, so I paneled my wheels with clear plastic. Pics to come. I have the materials for the upper grill block. Ill be removing my AC to free up some power and lose the condenser, thus exposing the radiator to more cooling. I will by doing the headlight lenses soon too and I am collecting sheet metal for the under-body paneling. About how many counts am I looking at with the above described first phase?