In article , "Doki" writes:


D.P.Round wrote:
WHAT ON EARTH ARE YOU ON ABOUT? YOU ARE OLIVER KEATING AND I CLAIM
MY FIVE POUNDS.

Your typical yank engine has 8 cylinders, pushrods and is stifled by
a load of emissions gear. Because of the extra cylinders there are
much bigger frictional losses, and the emissions gear the engine is
less efficient. They will burn more fuel to produce the same amount
of energy as a decent 4 or 3 cylinder engine. And an electric car
doesn't get any more efficient just because it's in Europe rather
than America.

Facts please not hot air. Find me the efficiency of an European 4 pot
engine and we shall see. The laws of thermodynamics are pretty
inflexible.

Google gives me figures for the efficiency of the Prius' engine at 34%.

The website you gave is: http://www.electroauto.com/info/pollmyth.shtml
That page claims the efficiency of a car as 15%, however it doesn't explain
what car this is, or how the figures were arrived at (efficiency of the
engine? efficiency including air and tyre resistance?). As the website's
advocating electric powered vehicles, I wouldn't be surprised if the figures
are plucked from the crap end of the spectrum.


Excellent. I accept that the data I found was poor but that is all I
could Google up quickly. I'm pretty sure I said that at the time.

Anyway running with your figure. Since that is the engine only we
should take into account transmission losses which are, I've always
thought, surprisingly high. There is a figure bandied around by the
rolling road sort of dyno chaps. Anyone? (Electric motors don't *have*
to suffer transmission losses because they can be designed to pretty
much any set of torque and speed specifications.)

If we accept that most EVs will use an identical transmission to the
ICE option (given very small production) then the conclusion is that
the efficiency with a conventional power station is almost exactly the
same as an ICE vehicle.

On "urban cycle" presumably the efficency of the ICE drops significantly
whereas an electric motor's efficiency will be almost unchanged (and the
battery will do better).

David


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