Pick-up Air Dam Frontal Area vs cd
 

I'm looking to extend the air dam on my 2006 Dodge Ram. Currently the bottom of the air dam is 16 inches off the ground, but I am curious as to what point the additional frontal area outweighs the drag reduction. I am also planning to do a belly pan on the truck at some point in time. I figure I'll start at the front and work my way back. Any research or experience that can be shared so i can get a starting point for building and testing is appreciated.

Some say go as low as you can stand it- with all the scraping. Others (me) suggest going down to the same level as the lowest undercarriage bits. The optimal solution is probably somewhere in-between.

Following, aiming to do this to my F150 as well. Thinking about pushing the ends out to better push air around the tires too and adding a half pan from the radiator support back to about the swaybar, which would make the belly pan really complicated to clear the bar and links.

In my opinion, if you are going to put on a belly pan don't extend the existing chin spoiler at all.

However, if going chin spoiler alone as I have done on my S-10 pick-up truck (see link in signature below), I have found 7-1/4" to be the magic clearance height for most shallow curb stops, raised sidewalks and snowfall in my region.

7-1/4" happens to be the height of a nominal 2x8 piece of lumber which you may want to use as a guide.

It depends on the use case. Off-road much?

You need to lose about 10". You could airdam to the chassis bottom, like Frank Lee suggests and then lower it the rest of the way.

Lowering > airdam

Unfortunately a 10 inch wide air dam would look a little ridiculous on the front of the truck and I still have to keep it appealing for the misses. I probably won't do a full belly pan due to all the other stuff under the truck so I figured an additional air dam would help. I don't do any off-roading the ground clearance is only a minor issue.

Alrighty then!

http://farm3.static.flickr.com/2694/...3e2a959d32.jpg
Flickriver: VonGerman's most interesting photos

You could cut the roof and rear hatch off a junkyard Dodge Magnum and make a lift-off cap out of it. It has really nice lines.

I still need to clear more than a penny. I currently have a shell on the bed, but want to create an aerocap when I have the time. Foam shaping and fiberglass molding take a while. Not to mention if I want a window so I can see behind me, but I'll probably resort to a camera for that.

Anyway, back to the air dam

airdam
 

Faisel Ahmed did a master's thesis analyzing the drag of a 2WD Dodge pickup.
He found a limit at 6" ground clearance,after which drag increased as the dam went lower.
At 3" there was a 1% drag reduction,but it was only for the race track.
Brett Herndon (aka bondo) built a beautiful 'lower' composite airdam for his F-150 and found it to hurt his mpg,and had to raise it back up,closer to the actual bottom of the truck to get his mpg back.
Hucho says to not 'add' frontal area.There are exceptions (race track,and the original aero-modded 'Crisis Fighter Pinto' of May,1974,CAR and DRIVER).

I defer to Ahmed and aerohead.

I'll let this go, but compare the Magnum hatch width and the truck bed. I'll bet you could get some nice taper.

http://www.motorsportscenter.com/upl...ailgate_up.jpg

You could use a Magnum for a male mold. Okay done now.