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db
Dodge Dakota
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8/10/2005
14:31:13
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 Subject: Aerodynamics, drag coeffieient,
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The results of my forum search.
"Your search for aerodynamics, ground effects, drag coefficient did not return any matches (80388 documents were searched):"
Did I spell them wrong?
We are driving trucks. So much discussion about every ounce of hoursepower and so little about physics.
Recently I staged my 99 R/T next to a Mustang GT at a stop light. We nodded politely at each other (we were both over 60) agreeing to a short drag race. I noticed the other guy reach over and turn off the air conditioning. After the light turned green I could hear the Mustang pulling hard two car lengths behind me in a desperate attempt to catch up. U n t i l, I seemed to hit a wall at 50-55 MPH (55 MPH zone for all you street racing police). He grabbed the next gear and passed me so I shut down.
I figure that wall I hit was mother nature pushing back. Wind resistance. So my question to the racing community is: What can I do to reduce the drag, increase the aerodynamics, on my Dakota? Please keep it simple and realistic. All I really know how to use are hand tools.
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me
Dodge Dakota
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8/10/2005
15:27:37
| RE: Aerodynamics, drag coeffieient,
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a tonneau cover.
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modain47
Dodge Dakota
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8/10/2005
15:39:34
|  RE: Aerodynamics, drag coeffieient,
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It's nice to see that advancing age doesn't slow some of us down. We still like to have a good thrill now and then no matter the age...
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GraphiteDak
GenIII
8/10/2005
21:09:34
| RE: Aerodynamics, drag coeffieient,
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Damn Straight!
Just have to remember to decide where is and isn't the proper time/place.
School Zone/ Residential area. No no.
I try to street race on areas like GRAND AVE around here that have LONG areas of straight divided road without cross traffic. Can run 60 to 80 easily and have plenty of room to watch for other people.
Then you have monkey fukks like this guy in a V6 Mustang last week (when we came out from watching the Dukes of Hazard) and he passed people TWO TIMES using th middle left turn lane (Suicide Lane) in congested traffic!
IDIOT!
And about 3 miles down the road low and behold I got a red light with him once other traffic turned off.
I blew his doors off. He shoulda got a V8!
But yeah. I don't mind some street racing myself :)
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gen1dak
Dodge Dakota
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8/10/2005
23:38:26
| RE: Aerodynamics, drag coeffieient,
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The aero question is a a peculiar one. When the new RAM fullsize truck hit the scene in the early 90's, according to Mopar, it actually had better aerodynamics than the Dakota then in production, despite being considerably larger. They also pointed out that while previous Rams benefitted from the use of the tonneau cover, the new more aero profile actually did worse with the cover due to the turbulence caused with one in place. Now, the new, much cleaner Dakotas from the late 90's are pretty clean. What you ran into db, was the weight and HP wall, more than anything else. The 'Stang is lighter, and typically has more power, especially if you had an automatic, and he had a stick. Granted, it's gonna be a bit cleaner with aerodynamics, but the late 90's Dak is no slouch. You need more power, especially in the mid and upper rpm range. As for aero, you can lower the Dak, get extended ground effects to limit air under the truck, wax the Hell out of it, shave the mirrors.......See where I'm headed? There's onlt so much you can do legally, or practically. You can, however, do quite a bit on the HP front, and a shift kit for the tranny always helps.
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db
Dodge Dakota
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8/11/2005
11:11:14
| RE: Aerodynamics, drag coeffieient,
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gen1dak
Your response was most helpful and practical. While I can think of a dozen reasons that Mustang passed me, including driver skill, I was most curious about aerodynamics. Horsepower/weight at mid to high range is a very good point. I'll work on that.
As for aero, Ground Force lowering kit, Street Scene front valence and mirrors, and rear roll pan are on order.
The tonneau cover is contraversial. Best to just remove the tailgate and loose the weight as well.
I have Mopar PCM which extends the shift range and has a pretty good kick in the butt when shifting. That's about all I can do there.
I'd still like to know what the drag coefficient is. Published numbers for trucks and SUV's average .45. A specific number for the factory Dak would be nice to know. It figures into simulation software calculations.
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Pointer
Dodge Dakota
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8/11/2005
14:17:06
| RE: Aerodynamics, drag coeffieient,
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If you're handy with auto bodywork, you could make the front end more pointy.
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gen1dak
Dodge Dakota
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8/11/2005
23:58:42
| RE: Aerodynamics, drag coeffieient,
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TransGo has a kit that'd make it even better. It compliments what the PCM does.
Keep the tailgate. The added weight helps traction on aggressive launches.
Curious about some numbers? Scroll to the bottom of this page. Keep in mind it's the worst of the recent Daks with 4x4 being an issue.
http://www.darklair.com/cd.html
A great read on making the Dak more aero:
http://www.bankspower.com/Banks_Sidewinder/dodge_dakota_platform.cfm
Keep in mind, a '96 was at 0.48
http://www.theautochannel.com/vehicles/new/reviews/hg_dak.html
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db
Dodge Dakota
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8/12/2005
10:51:16
| RE: Aerodynamics, drag coeffieient,
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Great links gen1dak. I knew there must be something online. I just couldn't find it.
The Banks article confirms we are on the right track though we didn't get a published Cd for the stock and modified configurations.
That Mustang GT had a Cd of .36 while mine was closer to Dakota Sport 96 at .48.
.45 would not be a bad number to work with since the rumor is the 99 is slightly better than the 96.
It will be a couple weeks before I have my 99 trimmed down but I will try to determine the Cd after modification and publish it here.
Anyone know how to determine Cd? I have the PDA Dyno software for data collection.
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db
Dodge Dakota
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8/14/2005
10:38:04
| RE: Aerodynamics, drag coeffieient,
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More info:
http://www.insideracingtechnology.com/tech102drag.htm
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