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Old 12-02-2017, 08:18 PM   #2 (permalink)
Master EcoModder
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Join Date: Dec 2014
Location: Butte, Montana
Posts: 674

little jona - '91 Dodge D 250 first gen cummins LE
Team Streamliner
90 day: 23.4 mpg (US)

Little Jona airo modded - '91 Dodge RAM 3/4 TON D 250 24 AUTO
Team Cummins
90 day: 18.5 mpg (US)

The Salted Hound Jenny. - '87 Dodge Ram 50/D-50 5sp 4X4
90 day: 20.24 mpg (US)

Jona Allison aero - '91 Dodge Ram D-250 Le
90 day: 20.6 mpg (US)
Thanks: 198
Thanked 374 Times in 244 Posts
What went wrong withV1/2 and were Im going with V3/4

Most moddern cars use a Spat. A small 1-2 tire width mud flap looking thing 1-2" vertically angled slightly to the outside 1/3 tire. This softens the angle of impact, and redirects the air to go around the front tire with the smallest protruding wake(hence they stop short of the edge of the tire). This reduces the increases of frontal aera to the smallest number with the maximum effect. At some point the increases in frontal area (A)offset the improved side flow(Cd)
Coefficient of drag down, Aera up at equal percentages will net a zero change. In my cace I changed the A from a poor flow open suspension, to no flow solidthis increeced the frontal aera. As well as I went the same size as the bumper... yhis wound up 4"widerthan the tires.
Hear are some pictographs to further explain were I see my desine was for V1 , V2 and were I'm headed with V3
Some of verious situations I got into by reducing my aproch angle too much. (Moderators the system is fliping images agen)

And what the broken off part looked like.

Hears one I scalped from a car lot gave me some ideas. A Toyota Tacoma pickup.

they (Toyotas aero team)solved some of my problems .
1 they taper up on tbe corners.
2 they moved air dam back under the bumper closer to the tire. Improving the approach angle ( less likley to experience a ground strike)
3 they kept it low full with to and used the center section as an intake duct for cooling. The air dam has a crease running horizontally were the loical stall poit is located(the point that the air has to go up and around or down and under).
4 not so good
Setting the air dam back and under like this will cause lift as the air( being pushed like a snow plow) builds high presure on the under side of this bumper. There is alredy low pressure at the front of the hood were the air separates at the transition to horizontal flow.
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1st gen cummins 91.5 dodge d250 ,HX35W/12
ehxsost manafulld wrap, Aero Tonto
best tank: distance 649gps mi 24.04 mpg 27.011usg
Best mpg : 29.3mpg 97mi 3.311usg 7/27/16

'83 GMC S-15 Jimmy 2door 2wd O/D auto 3.73R&P
'79 Chevy K20 4X4 350ci 400hp msd custom th400 /np205. 7.5-new 14mpg modded befor modding was a thing
87' Hyundai Excel
83 ranger w/87 2.9 L FI2wd auto 18mpg on the floor
04 Mitsubishi Gallant 2.4L auto 26mpg
06 Subaru Forrester XT(WRX PACKAGE) MT AWD Turbocharged 18 plying dirty best of 26mpg@70mph
95Chevy Blazer 4x4 auto 14-18mpg
04 Chevy Blazer 4x4 auto 16-22mpg

Last edited by gumby79; 12-02-2017 at 08:21 PM.. Reason: Fix mixed up pictures.
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