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Old 05-06-2018, 12:15 PM   #131 (permalink)
Cyborg ECU
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Join Date: Mar 2011
Location: Coastal Southern California
Posts: 5,219

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.37 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
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Originally Posted by mpg_numbers_guy View Post
What about when approaching a stop and you've coasted to below 15 mph and the mpg readout is 30 or under? Is it okay to turn it off and coast the last few feet?
If RPM is still over the minimum threshold, usually about 1500/1600 in my experience but sometimes lower, then the computer should have cut off fuel entirely if your foot is totally off the throttle. That would be "infinite" gas mileage. Can you select gears at all? Is the a "L1" and L2" choice on your gear selector?

Originally Posted by mpg_numbers_guy View Post
Wouldn't the gains from that be negligible with the air dam?

Originally Posted by mpg_numbers_guy View Post
... wouldn't the reduced weight reduce coasting ability? Like, when going down even a slight downhill my MPGs jump to like 85...wouldn't the weight reduction require the generation of more momentum in cruising, thus cancelling out the benefit from the lighter weight?
It all depends on your driving conditions. For example, if you drive in traffic where both somewhat hard acceleration from a stop is frequently as unavoidable as friction brake stops, then weight reduction is a good idea. If you have lots of opportunities to coast off all or almost all of your speed, then weight reduction is probably not much of a benefit.

Originally Posted by mpg_numbers_guy View Post
I generally take turns at 15-25 mph (when safe) to reduce acceleration, wouldn't this make that impossible due to the increased steering difficulty?
Above 5 or 10 mph, most people cannot tell much difference between PS and non-PS, in my experience. It's most useful in parking and such.

Originally Posted by mpg_numbers_guy View Post
Aren't the batteries expensive, and isn't their lifespan short enough to where there is no ROI?
Yes, they are more expensive. My Odyssey 1200 with the metal jacket coast over $200 and it lasted 7 years. If you buy the right charger and plan not to draw down the charge very much, using the alt once you get down to 50% charge, then the battery will last ages. I think I killed mine prematurely because I started charging devices on it and not always remembering to plug in at night anymore. If I were doing it again, I would go for lithium batteries. More charge cycles. I jsut could not justify the outlay for a new charger when I have a great one for the Odyssey battery, so I bought another odyssey battery (lead acid). My alt delete is probably worth about 3 mpg. Maybe more. Impossible to measure. I have no idea if it is a great ROI measured directly. But if I think about how much I learned and how these mods and my fuel savings encourage me to keep the car, and then if I remember the cost of Prius in depreciation and insurance... well, every mod to "Black & Green" has pretty good ROI.


See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

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