05-31-2018, 01:43 PM
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#21 (permalink)
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Master Ecomadman
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This will get you to work in a hurry...
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- Tony
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Other popular topics in this forum...
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05-31-2018, 02:22 PM
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#22 (permalink)
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Rat Racer
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Sadly, I live more than 1/4 mile from work...
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Quote:
Originally Posted by sheepdog44
Transmission type Efficiency
Manual neutral engine off.100% @∞MPG <----- Fun Fact.
Manual 1:1 gear ratio .......98%
CVT belt ............................88%
Automatic .........................86%
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05-31-2018, 02:35 PM
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#23 (permalink)
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Human Environmentalist
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Quote:
Originally Posted by Ecky
My understanding is that the island of efficiency is more like ~75% rather than 30-50%.
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Yeah, usually around 75% of peak torque, but about 35% of peak power. You'd want an aero car that at 100 MPH is producing 35% of peak power. I base that off of the BSFC chart I studied to understand how they work:
This assumes most of the driving done is at this speed. No sense optimizing the car to that speed if it's only occasional.
Really though, I'd probably get a used EV as a commuter and a nice ICE for longer trips. EVs are efficient at most any speed, and excel when stuck in traffic.
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05-31-2018, 03:47 PM
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#24 (permalink)
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Not Doug
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This is way too complicated! I will just keep under 100 KPH!
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05-31-2018, 05:07 PM
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#25 (permalink)
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Human Environmentalist
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Quote:
Originally Posted by Xist
This is way too complicated! I will just keep under 100 KPH!
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There are online calculators where you can enter the vehicle Cd and frontal area, and it will calculate HP required for a given speed. Find a car with an efficient aero shape, and then plug the numbers in to find the required HP. The amount of power needed at the target speed should be 35% of max horsepower, and the gearing should be such that the horsepower is achieved at 75% of peak torque.
Yes, fairly complicated.
EVs operate between 85-95% efficiency throughout the range, so they are good for just about any speed or operating condition. |
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05-31-2018, 06:45 PM
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#26 (permalink)
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Master EcoModder
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Quote:
Originally Posted by Fat Charlie
Sadly, I live more than 1/4 mile from work...
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That's ok, how long does it take to coast down from 300mph?
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05-31-2018, 07:38 PM
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#27 (permalink)
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Not Doug
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Quote:
Originally Posted by Fat Charlie
Sadly, I live more than 1/4 mile from work...
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That is good. Otherwise you would pass at 300 MPH.
Quote:
Originally Posted by ksa8907
That's ok, how long does it take to coast down from 300mph?
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I think I can coast a mile from 60 MPH. Two miles from 120 and three miles from 240? |
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05-31-2018, 08:47 PM
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#28 (permalink)
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Master EcoModder
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I'd start with a Prius, and boat tail it. I've only had mine up to 85, but it was surprisingly smooth at that speed.
Here's a video of a 2007 at 108 MPH
and here's a prius at 195 KPH |
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05-31-2018, 09:05 PM
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#29 (permalink)
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Human Environmentalist
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I find my Prius (and most cars) over-report speed by about 3%. Still, the fine for doing 105 MPH in a construction zone wouldn't be pretty.
The Prius is an excellent choice given the great aero, and variable gear ratio which will keep the car in the most efficient RPM and load range for the given power demand.
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05-31-2018, 10:10 PM
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#30 (permalink)
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Not Doug
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"Sir, do you know how fast you were going?"
"This is a Prius! She can barely do seventy-five!"
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