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Old 04-15-2018, 03:31 AM   #44 (permalink)
Cyborg ECU
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Join Date: Mar 2011
Location: Coastal Southern California
Posts: 4,913

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 59.41 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
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Originally Posted by mpg_numbers_guy View Post
Yep. Hoping the box cavity helps the kammback eek out maximum possible mpgs. What do you think of the aerodynamics of the design, especially the box cavity? Should it be enclosed? I know a full boattail is better but that's waayy too impractical....
Well I am no authority. But I have seen studies that show box cavities can work. I totally agree about how it seems more practical than a boat tail. Beginning with post #3 in my modding thread for my car I describe show my adandoned effort at a box cavity. The devil is in the details. Something else for you to consider is that a kamm is probably less useful on our Civics because the rear window and deck lid were already optimized quite nicely. It might be konda easy to build a kamm that makes the wake worse, not better on our cars. The box cavity and kamm can work, but it takes precision and luck. Check out my box cavity failure. It should have instructive detail on studies and such you may or may not have already seen :

See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

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