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Old 11-28-2007, 09:20 AM   #1 (permalink)
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 53.56 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 57.23 mpg (US)
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Expanding, sprayable foam as an aero construction / shaping material

Had a thought recently after reading about the shaped foam board construction of an aerodynamic prototype which was used to make a mold. ... Ever since I made the Kardboard Kammback, I've been thinking about foam/fiberglass construction approaches.

I went up to the Home Depot and picked up an $8 pressurized can of high expansion urethane foam this evening.

"Cured foam dries rigid and can be shaped, sanded, trimmed, painted or stained."


I'm going to try this stuff out making a couple of things on the car:

- shaped deflectors ahead of all 4 wheels/tires

- radiused transition at the aft edge of the front wheel arches (I've got lots of space between the arch and the tire to do this)

- possibly also boat-tailing behind the front wheels/tires

- this might make a good grill block plug material - custom fit! - though I've already got a "bra" on that does that job.

Tin foil taped/pressed in the area that will serve as the base of the object being created makes a decent non-reactive "release agent", and will protect the paint.

It'll be a bit of an experiment to see how well it adheres to vertical & upside-down surfaces, and whether I need to approach it in layers, or do it all at once.

Then of course the big issue will be discovering how nice or not it is to shape/smooth & what techniques work best.

Latest mods: 3-cylinder Mitsubishi Mirage. EcoMods now in progress...
Ecodriving test:
Manual vs. automatic transmission MPG showdown

has launched a forum for the efficient new Mitsubishi Mirage - fuel efficiency info for Geo Metro owners - electric car conversion on a beer budget
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