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Old 07-29-2008, 11:21 AM   #5 (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: 52.8 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 73.57 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)
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My home-made water pump belts were enough of a pain in the butt that I hadn't been doing much alternator-less driving since last summer (2007). The belts would work for several hundred km, and then fly off or fray and wear out (and then fly off).

I once missed hearing the belt fly off, and pegged the temp gauge. So I was looking for a way to electrically shut off the alt, and leave the reliable OEM belt on to drive the water pump.

But because the Metro uses a "1 wire" alternator (senses battery voltage and feeds current through a single fat wire), there's no easy external way to tinker with the "control" wiring to shut down the field.

So I took the plunge yesterday and simply cut the output wire. Put two golf cart batts into the back of the car, and headed to Ottawa for the EVCO meeting. (I'll add a switch in the wire later.)

Predictably nice results - and one of those super rare situations where I had a tail wind on both directions (moderate on the first leg, light on the return)!

78 mpg (US) on the way there, strictly DWL with an avg speed of 36 mph, (that speed includes city driving at both ends, and passing through one town in the middle). My "target" highway speed was around 45 mph.

84.5 mpg (US) on the return trip, DWL again with an avg speed of 37 mph, max of 57.

Compare that return leg to a previous winter trip on the exact same route where I got 75 mpg (US), with an average speed of 28 mph, using 3rd gear pulse and glide the entire way. The winter differences being: alternator on, no Kammback, no tail wind, wet/slushy roads, and it was 2 C instead of 19 C.
Latest mods test: 15 mods = 15% MPG improvement: A-B test, 2007 Honda Civic 1.8L, 5-speed
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Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L

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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