[SGVLUG] Fw: [OT] Cummings paper on efficient driving

[David Lawyer]

On Fri, Sep 07, 2007 at 11:26:16AM -0700, Tom Emerson wrote:
> given some recent [and some "long ago..."] discussions, I found this
> PDF to be interesting reading...

> While not stated directly, I'd imagine the authors would cast a
> doubtful eye on "pulse driving" a big-rig...

[they do state this indirectly by mentioning that "rapid variation in
speed" causes the highest loss of efficiency, and that "driving
technique" can account for as much as a 30% variability of efficiency
between different drivers]

If you vary speed by cruising for a while at one speed and then for a
while at another speed, it's inefficient as compared to cruising at
steady speed.  But if you pulse and glide with a big-rig you'll save
some energy.  Not as much as you would save for a gasoline engine
since the diesel doesn't drop as much in efficiency at low
torque as the gasoline does.

I've got Russian efficiency maps for diesel-electric locomotives and
they are more efficient at high load.  In fact there a whole Soviet
Russian book about improving the fuel economy of diesel-electric
locomotives.  I have a lot more to say about all this but have got
more pressing things to do.

> 
> ----- Forwarded Message ----
> From: Robert J. Wilson <bwilson4web at gmail.com>
> To: Prius_Technical_Stuff at yahoogroups.com
> 
> http://www.everytime.cummins.com/every/pdf/MPG_Secrets_Whitepaper.pdf
> 
> Long haul truckers share our interest in fuel efficient driving.

Do they have the brake specific fuel consumption maps?  If not, they
really don't know what they are talking about.

			David Lawyer