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Old 01-15-2008, 04:23 PM   #5 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,530

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 62.14 mpg (US)
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Quote:
Originally Posted by Daox View Post
Is there a generally agreed upon relief angle (rear window angle off the roof) which should not be passed as far as aero is concerned?
I've read the initial transition shouldn't exceed approx. 10 degrees. You can exceed the angle, after the initial 10 degrees, if it's done gradually.

As for overall rear angles, I can't find the reference at the moment. But there is definite agreement that up to a certain overall (average?) angle is OK, then there's a zone past that where drag increases significantly, and beyond that, it's reduced again. I'll have to dig it up.

Books: you could look for Hucho or R H Barnard.
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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
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EcoModder
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www.MetroMPG.com - fuel efficiency info for Geo Metro owners
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