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Old 04-22-2009, 02:10 PM   #6 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,527

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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Frank: didn't SAAB's use a movable head somehow?

rkcarguy: no image, but a pretty good description from the GCC article:

Quote:
The piston structure has an inner and an outer piston. The outer piston sits atop the inner piston, and constitutes the combustion chamber against a cylinder head; the inner piston has the function of a piston skirt, a lifter mechanism, and a lock mechanism....

Honda installed a small pump separate from that of engine lubricating oil pump. Oil passage was constructed from the external pump through the crankshaft and connecting rod to the piston.

To switch from low to high, the hydraulic pressure is turned on. This acts on the pin of a lock plate, freeing the outer piston. The outer piston rises the 3.5 mm by the resultant force of the piston inertia force and the cylinder pressure force. To go from high to low, the hydraulic pressure is turned off, the lifter plate rotates out, and the out piston lowers over the inner piston by the resultant force.
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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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