Highway acceleration - sharp pulse or gradual throttle

At least two ICE RPM-related dropoffs in efficiency have been described: 2400 and 3000. Lacking a tachometer, keeping instantaneous MPG above half the vehicle speed will generally keep RPM below 2400. The result is what you might call modest acceleration, though terms like "modest," "gentle," etc. are subjective -- which is why I like an objective criterion like engine speed or the iMPG/MPH relationship.

 

My recommendation in most fuel efficient to least is:

1. Wait for a down slope and accelerate then (gravity assist)
2. User your cruise control to "pat up" the speed
3. Keep your engine rpm under 2,700 rpm
4. Especially keep your engine rpm under 3,150 rpm
5. Drive safely so you burn gas in the ICE instead of a flaming wreck

GOOD LUCK!
Bob Wilson

 

I'm working on building a chart to lay out just what you are asking, then program it into a thermometer in either Ken@Japan's program or the mycanscan. Hopefully I'll have it built by the end of the summer or even better hybridfest.

Anyhoo, my thought is that there is an acceleration range to stay within, the minimum is the RPM which will hold the speed you want to go. For example, if 2200 rpm will hold 70 mph on flat smooth ground and you're at 65 holding 1900 rpm, gradually increase rpm to 2200 and let the car do its thing and get there when it gets there. If you want to get there faster, the high range would be the low + 200-400 (capped at the suggested 2400 max).

In general try to avoid sending the "I MUST GO FASTER RIGHT NOW" message to the computer, and stay in the suggested ranges with smooth adjustments and you'll be fine. The consumption screen is helpful here, don't want to see the bar bouncing down to 10 then back up to the JimboK suggestion level of 1/2 speed, increase rpm to the 1/2 level without a large move past it.

 

Feel free to use anything from Prius Power Study.

Also, some these may help:
http://hiwaay.net/~bzwilson/prius/
pri_power.html
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pri_power_Brindley.jpg
pri_power_ICE.jpg
pri_power_MPG.jpg
pri_power_climb.jpg
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pri_power_force_charge.jpg
pri_power_fuel.jpg
pri_power_injector.jpg
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pri_power_throt_010.jpg
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pri_power_watt_fuel.jpg

Bob Wilson