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Old 03-29-2013, 05:31 PM   #36 (permalink)
brucepick
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Outasight - '00 Honda Insight
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Quote:
Originally Posted by IsaacCarlson View Post
...
I am thinking a gear swap would put me too low on the power curve. I would literally be idling down the road. I don't want it to downshift to go up every hill do I?
Don't be afraid of a downshift. In this situation, I think it's a good thing.

At highway speeds, you pretty much want the engine running at low rpm so it's at maybe 60-70% load when cruising. Not super light throttle and 25% load, that would give you some engine braking constantly. The high loading puts you in the good part of the BSFC chart. Since it's running at kinda close to maximum output for its rpm, you will need more power if you want to maintain speed on a significant upgrade, or for acceleration. So you'll need a downshift for that.

If you don't need a downshift, you're running a lot more engine and/or a lot more rpms than you need. And your fuel economy will suffer.

Shucks, its an automatic. It will downshift for you. Now worries! With the tall gearing, the downshift won't bring the huge fuel economy penalty it would on a "normal" automatic.
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