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Old 02-27-2017, 12:25 AM   #46 (permalink)
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Originally Posted by aerohead View Post
*Adding a conventional spoiler on top of a full tonneau may have no effect as far as drag goes.The tonneau provides for the captured-vortex,reattached flow and, kills the rear lift.An additional spoiler might provide downforce at the expense of higher drag.We have no data from research on this topic.
The only OEM-designed spoiler on a tonneau that I know of was available on the 2005-06 Ram SRT-10. It differed slightly from the spoiler designed for the open bed:

Dodge claimed 150 lbs of downforce for the initial spoiler; I don't remember ever seeing a quoted figure for the tonneau spoiler. The open-bed spoiler also has a trough on the underside that Dodge claimed reduced drag, but they didn't specify by how much.
UIUC Aerospace Engineering
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