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Old 12-06-2009, 11:23 PM   #31 (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 roverdriver View Post
That kind of increase in speed could not be created purely from improved aerodynamics- don't forget that streamlining only helps after about 60 mph anyway.
It's a common misconception that aero drag becomes an issue only at highway speeds and above.

Have a look at this tool: Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com

The default numbers provided are for my vehicle in stock form, and with its drag area (CdA - product of frontal area and Cd), it shows that over half the power required to go just 30 mph is spent overcoming aerodynamic drag. And this is for a modern vehicle with a dramatically lower (ie. better) CdA figure than a Model T.

It also happens to show that 13.8 kw / 18.6 hp are required to get a vehicle with its rolling & aero resistance figures to 70 mph.

So a sufficiently streamlined car with a 22 hp engine could do it.

I suspect you may have the figures for the T at your fingertips, which you can input into that tool. You could even work the figures backward to find out just what change in CdA is needed to get to 70 mph from the stock starting point.

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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
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