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.

David

--
****** David Round - EMail Tel (01248) 382416 *****
*****These are my own views, I represent nobody (Well maybe myself)*****
***********I guarantee nothing - Particularly the spelling**************

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.

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


--
****** David Round - EMail Tel (01248) 382416 *****
*****These are my own views, I represent nobody (Well maybe myself)*****
***********I guarantee nothing - Particularly the spelling**************

(D.P.Round) wrote in message ...

(Electric motors don't *have*
to suffer transmission losses because they can be designed to pretty
much any set of torque and speed specifications.)

Which is fine if you want a particular torque speed combination only.
In an application like a car, where you need to have power delivered
across a large speed range, efficiency considerations may well require
a gearbox. And anyway, unless the motor(s) are built into the driven
wheels, there will still be transmission losses.

Ian

Apparently on date 13 Apr 2004 05:37:26 -0700, (Ian
Johnston) said:

(D.P.Round) wrote in message ...

(Electric motors don't *have*
to suffer transmission losses because they can be designed to pretty
much any set of torque and speed specifications.)

Which is fine if you want a particular torque speed combination only.
In an application like a car, where you need to have power delivered
across a large speed range, efficiency considerations may well require
a gearbox. And anyway, unless the motor(s) are built into the driven
wheels, there will still be transmission losses.

Not wanting to support electric vehicles particularly, there are some features
which make perfect sense. Your energy comparison is ok, but the 48000 Kj of
energy in the petrol would have to then be converted into kinetic energy of the
vehicle. A petrol engine won't deliver 48000, it won't even deliver 24000, it
will end up more like 12000 Kj of vehicle motion, what with one thing and
another.

Of course, if taxed at the same rate, mains electricity would then cost four
times as much as the petrol, so it balances out much the same anyway.

And the electricity, that's already useable energy so you can use it to power
something like linear accelerators acting on the disc brakes where better than
90% of the energy does turn directly into forward motion, saving any
transmission losses which you do definitely have with a combustion engine
design.

There are also some other gains from the petrol engine, notably the heat which
most of the energy ends up as, can be used to keep the passenger compartment
warm, whcih saves carrying around large amounts of insulation and having to
spend some significant portion of your electricity in heaters, or making the
humans suffer from the cold of a metal box passing through cold air at speed.
This isn't a trivial matter, either, although in hot summer days I daresay it
would be a mere inconvenience and sometimes even an advantage.

The real strength of an electric vehicle is that the motor will be a fraction
of the weight of an equivalent combustion engine, and doesn't need to be
started, you just pump electrical energy into the motor and get instant torque.

The real weakness of it, is how you carry about enough energy. Batteries weigh
far too much for their capacity, and cost a lot more than a fuel tank as well
as needing to be replaced a lot more regularly. Electric motor designs cost a
lot more over the life, because of this, as well as not being able to have
decent range.