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Old 09-10-2009, 05:03 PM   #17 (permalink)
bwilson4web
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Location: Huntsville, AL
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Quote:
Originally Posted by some_other_dave View Post
Why would high throttle settings have any impact on highway FE? When you're at a steady speed on a flat highway, your engine is only generating about 10-15 HP. That says a very low throttle setting to me. . . .
This graph includes the power curve for my NHW11 and is not far off from the NHW20 and ZVW30:


You'll notice that:
70 mph -> 25 hp
75 mph -> 30 hp
But that assumes flat land and most roads, even on river bottom, have small dips and rises. These variations push the power requirement up quickly and that is where the inefficiencies come it.

At 10-15 hp, I'll be in the 45-55 mph range, which is great for performance but not what the EPA nor the most reviewers are actually driving. In fact, there are dead stops in the Euro, 'intra-urban' cycle, and though I don't have the EPA profile handy, I thought it had at least one dead stop.

Quote:
Originally Posted by some_other_dave View Post
High throttle settings would be useful in getting up to a given speed, so they would be used more frequently in stop-and-go driving. Like in a city with lots of stop signs and traffic lights.
A good theory, it seldom works out in practice. Too much of the energy goes to heating the brake pads.

Bob Wilson
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2019 Tesla Model 3 Std. Range Plus - 215 mi EV
2017 BMW i3-REx - 106 mi EV, 88 mi mid-grade
Retired engineer, Huntsville, AL
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