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Old 09-30-2017, 03:18 PM   #306 (permalink)
Merlyn2220
Deep Lurker
 
Join Date: Sep 2016
Location: Central Florida
Posts: 53

Creepy Van - '95 Ford E150 Cargo
90 day: 14.45 mpg (US)
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If I'm reading the truck data correctly:

Cd = 0.435 with everything and the joints taped up on the bed cover (aka Tonto)
Cd = 0.458 as above without the tape (+5.3%)
Cd = 0.357 removed the bug deflector (-22.1%)
Cd = 0.338 removed the air dam (-5.3%)
Cd = 0.450 stock (no Tonto, bug deflector, airdam) (+33.1%)

Is that an accurate summary of the truck data? I ask because there's a prevailing sentiment that the front end geometry isn't as important as the rear end geometry. I recall reading a post about Bonneville testing where they said that extensive front-end changes made little to no difference in speed. The bug deflector seems to be a huge hit to Cd performance, negating the advantages of all the other aero details. So clearly the front end matters a lot. I wonder how bad it is with the bug deflector and nothing else...

Maybe the right way to look at front vs rear is, "don't do anything really bad on the front, or you'll lose all the work you've done on the rear."
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