RPM at 70% maximum

[dachshund]

I've read this in several websites including http://john1701a.com/prius/prius-advice02.htm .
Is this informatation available from the car, as is (without adding extra dials)? I have a 2006.

"A gasoline engine works more efficiently when running at higher RPM, about 70 percent of maximum."

Thanks in advance.

[Ichabod]

No, as of yet, that info is not available without finding a way to rig up a tach yourself. What you do have is ears though! You can learn to hear and feel what "about 70%" feels and sounds like.

But I have a feeling you're in the same boat with me right now: We're both better off driving our new cars like they're just regular cars. We'll figure out all the subtleties of improving our MPGs through a lot of experience.

I've been using pulse/glide a bit, and it's fun to feel more in-tune with the car, the way I used to feel driving a manual-transmission. But I also don't pretend to be better at overall balance of the system than the computers.

[hdrygas]

Well I don't know about 70% of max, I will look into that over the next few weeks, but I will tell you something you can get at on any Prius, It appears to me that when the car is between 20 and 38 mpg during acceleration you are in the grove for pulse and glide. I will pay more attention to the RPM's for the next few days.

[priusenvy]

<div class='quotetop'>QUOTE(dachshund @ Sep 4 2006, 05:21 PM) [snapback]314236[/snapback]</div>

I've read this in several websites including http://john1701a.com/prius/prius-advice02.htm .
Is this informatation available from the car, as is (without adding extra dials)? I have a 2006.

"A gasoline engine works more efficiently when running at higher RPM, about 70 percent of maximum."
[/b]

That sounds about right, althought I think it's usually expressed as a percentage of throttle opening rather than RPM. But you need to know what "efficiency" means. It doesn't mean maximum MPG. It means the ratio of useful work produced at the crank compared to the amount of fuel consumed. You wouldn't drive your car around at 70% max throttle to get the best mileage. But if you had to pick an engine size to produce X horsepower using as little fuel as possible, you'd pick an engine that could produce X horsepower at around roughly 70% max throttle. 70% max throttle in a Prius might be the most efficient speed for turning fuel into horsepower, but you'd be producing way more power than is needed to drive at legal speeds (at least on a level road).

IIRC, diesels are much more efficient than gasoline engines at small throttle openings, which is why diesels get very good mileage on the freeway. Well actually, I guess they don't have throttles like gasoline engines, which is why the pumping losses are low at lower RPM.

[hobbit]

70% of *RPM*?? That does *not* sound right. Load, yes. Not RPM,
especially where over-the-road efficiency is concerned.
.
John? You might want to nose around on cleanmpg.com, and rethink
this statement a little.
.
_H*

[dachshund]

<div class='quotetop'>QUOTE(Ichabod @ Sep 4 2006, 05:33 PM) [snapback]314239[/snapback]</div>

I've been using pulse/glide a bit, and it's fun to feel more in-tune with the car, the way I used to feel driving a manual-transmission. But I also don't pretend to be better at overall balance of the system than the computers.
[/b]

Yes - the pulse/glide works well driving around town, and it's fun to work that in where I drive less than 40mph. I think it's a "new owner" condition to think the gas engine is "bad" and to avoid using it. I keep trying to accelerate slowly from a stop to use the electric motor. So when I read about using the gas engine more efficiently, I wanted to look into that. I don't know anything about car mechanics, so I'd have to go by what my ears tell me, as you said. But I don't have the sound of the car shifting into 2nd, 3rd, 4th, like my old car.

They have that big display - they could embed a digital readout of RPM in the picture of the gas engine in the Energy Monitor.