Actual fuel efficiency of combustion engines
Posted: 22 July 2006 05:11 AM   [ Ignore ]
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Gasoline-electric hybrids are weird, I don’t get them at
all, why combine the motor/battery with the combustion
engine?  Sure regenerative braking makes it more efficient,
but the part where they saddle down the car with an engine
used primarily to recharge the batteries is just weird,
and reduces the motor’s efficiency down to something
similar to a normal car because the motor/battery is now
dependent on the efficiency of the engine.

On the other hand, some more sensible prototype cars do
exist.  In idealized race conditions they achieve as much
as from 473 km/l (1,112 mi/g) to 2,560 km/l (6,021 mi/g).
But the record is:

  "The awesome fuel efficiency record, of 3,836km/l
  [9,022mi/g], set at last year’s European Shell
  Eco-marathon remained unbroken as participants struggled
  against challenging weather conditions in southwest
  France."

http://www.shell.com/home/Framework?siteId=eco-marathon-en&FC2=/eco-marathon-en/html/iwgen/leftnavs/zzz_lhn1_0_0.html&FC3=/eco-marathon-en/html/iwgen/welcome.html

  - steve s.

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Posted: 22 July 2006 05:11 AM   [ Ignore ]   [ # 1 ]
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Actual fuel efficiency of combustion engines

Gasoline-electric hybrids are weird, I don’t get them at
all, why combine the motor/battery with the combustion
engine?  Sure regenerative braking makes it more efficient,
but the part where they saddle down the car with an engine
used primarily to recharge the batteries is just weird,
and reduces the motor’s efficiency down to something
similar to a normal car because the motor/battery is now
dependent on the efficiency of the engine.

On the other hand, some more sensible prototype cars do
exist.  In idealized race conditions they achieve as much
as from 473 km/l (1,112 mi/g) to 2,560 km/l (6,021 mi/g).
But the record is:

  “The awesome fuel efficiency record, of 3,836km/l
  [9,022mi/g], set at last year’s European Shell
  Eco-marathon remained unbroken as participants struggled
  against challenging weather conditions in southwest
  France.”

http://www.shell.com/home/Framework?siteId=eco-marathon-en&FC2;=/eco-marathon-en/html/iwgen/leftnavs/zzz_lhn1_0_0.html&FC3;=/eco-marathon-en/html/iwgen/welcome.html

  - steve s.

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Posted: 22 July 2006 05:54 AM   [ Ignore ]   [ # 2 ]
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I wonder about the same thing. Additionally, the added cost and complexity (both in production as well as in the form of increased likelihood for the need of repairs and an increased cost of repairs) involved in having two different type of engines trading off on the powertrain, seems to me would offset the potential benefits of a hybrid.

A more cost-effective appraoch to sustainable energy needs and environmental impacts would seem to me to be to specialize in one or the other approach.

I personally prefer the electrical car aroach.

Take a look at the Tesla Motors luxury sports car that apparently has power enough to accelerate from 0-60 in 4 seconds, and a 250 mile range per charge:
[url=http://blog.wired.com/teslacar/]http://blog.wired.com/teslacar/ [/url]

If the technology is available to make an all electric high performance sports car . . . I would think we could mass produce a cost efective all electric vehicle for the rest of us; I know I’d buy one, even if it only had a 50 mile range between charges. Centralized electrical production is more efficient to generate and more cost effective to make clean than mass producing thousands of individual mobile high-tech combustion engines for public use.


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Posted: 22 July 2006 11:22 AM   [ Ignore ]   [ # 3 ]
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There are a number of other issues, like acceleration potential (nobody wants a car that goes 0-60 in twelve minutes) and the availability of recharging or refueling stations (if we’re going to use hydrogen power, for example, we need hydrogen fueling stations nationwide).

But that said, these are clearly very important R&D efforts.

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Posted: 22 July 2006 02:23 PM   [ Ignore ]   [ # 4 ]
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Great story in Scienec Friday Recently on this topic and the electric car . That said we have everything here: Steep mountains, long highways, city traffic (excluding very long distances), and I own a Smart Car ForTwo . 3 Cylinders and very very very low emissions. Plus for us plenty of room. We use public transport for work and such and only use the car to go to the country parks or golfing on off days, or when we need to take the dog somewhere. And we switched from a Subaru WRX 5 door sports car to this and still have just as much fun driving! But I am always so surprised by how many big 4 wheel drive type rigs we have in Hong Kong! I think humans could have a dramatic impact on the environment if we could just agree that a big car doesn’t = a big… :oops:

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Posted: 22 July 2006 06:34 PM   [ Ignore ]   [ # 5 ]
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Well the point of that first message was that when they
tall about 40 MPG, that is a joke!  Where are the three
digit numbers of MPG for todays efficiency cars?  But to
achieve thousands of miles you’ve got to lean up, no trunk,
no passenger seats, no steal body and frame, etc.

I ride a bicycle and was so sad and driving rage-mad when
I owned two combustion engines, one that drove four tires
and one driving two.  But I’m much happier now-a-days,
you would be amazed if you could experience that change
as I have.  Not to go into bicycle issue here.

The ideal laboratory table power efficiency of motors is
around 90% and for combustion engines around 70%, with a
lot of tolerance for those numbers to change depending
on the exact motors and engines tested.  In the real
world those numbers drop, the motor efficiency drops
a little and the engine efficiency drops down hard.
I expect that a real world engine in a car that is six
years old is probably down around 30% (imagine soft tires,
junk in the trunk, worn spark plugs, a leaky head gasket,
stop-and-go traffic, heated seats in the winter and AC is
the summer, etc.)  I can only imagine, but I imagine motors
staying up in the 80% area in the real world.  The point
is that hands down, the motors own the efficiency feature.

I don’t know how the efficiency holds up once you charge
your motor battery up from the power grid system which
burns coal, spins in the wind, spins under the water from
a damn, and boils water with refined uranium to spin the
steam turbine generators.

Acceleration?  That a different feature from when I was
talking about efficiency.  But we can talk acceleration.
Basically these hybrids start the engine when needed and
stop it when not.  Parallel, serial, and combination
hybrids’ designs vary, but basically the engine is
deactive at stop lights and low speeds, and active during
acceleration (boosting the torque) and high speed cruising
(charging the battery).  (I’ll bet that all those restarts
are hard on the engine, which is another reason why hybrids
are weird.)

I’ve learned something important about acceleration
while bicycling, though.  You see a bicycle is human
powered, so I have a good feel for how much effort it
takes to cruise, accelerate, and to stop.  Do you know
how my bicycle acceleration compares to car traffic?
When the car drivers accelerate normally and casually,
and so do I, we match acceleration rates!  Although, I
admit that when they seem angry at me for daring to assert
my rights to the road (How dare he ride a bicycle on MY
road!!), and gun their engines hard, then they do beat me.
But they have to gun their engines quite hard to beat me.
And, as you can guess, the cruising speed of the cars is
higher than that of bicycles.  So when my acceleration
tops out at a cruising speed between 12 and 18 MPH, then
they begin to pass me.

So my point is that normally the cars don’t need all that
much acceleration.

Oh but you doubt that the excitement about cars can exist
without that exciting adrenaline rush during acceleration,
don’t you?  But I can argue that the romance that the
automobile advertising promotes is just fantasy that
doesn’t even reach most drivers.  I can say that because
the used car market is so large.  The used car buyers
are probably not buying a particular model based on some
romantic ad, especially not when that car has sixty,
one-hundred, or even one-hundred and fifty thousand
miles on it.  They are probably just bargain hunting for
a vehicle that gets them from here to there reliably.
Romance has little or nothing to do with that choice.
Acceleration ads on the TV and the magazines don’t reach
many of the used car drivers.  And nor is the dangerous
excessive addreneline rush a goal for most drivers,
thankfully, as I see them accelerating as fast as me on
my bicycle most of the time.

And I know that people want to accelerate fast when merging
on the highway (55 MPH).  But it only takes some driving
skills, patience, discipline to discover that if you
wait for a big opening in traffic, then there is no need
to accelerate fast.  I drove on a worn out clutch for a
few months (extremely worn out!) and had the acceleration
of molasses, that provided the discipline and forced the
patience and skills to follow.  Likewise the skills and
patience can be learned in order to understand this point,
or can be easily forced with a car that doesn’t give you
a choice to accelerate so fast.  The point is that you
don’t actually _need_ to accelerate fast to merge at 55
MPH, nor higher.  If you discipline yourself and drive a
hybrid with low acceleration, then you’d hardly use the
engine at all, and it would just serve as dead weight
loading down your efficiency.

So again, the hard focus that the auto-manufacturers have
on acceleration, hard enough focus that they’ll have you
lug around a spare engine, is a weird way to focus their
time and our money.

Now I know that the production electric cars in the
past have had their limitations.  I already handled
the acceleration limitation topic.  I’ve also heard
of the range limitation, and that is an other fantasy.
I saw some guy from the automobile industry saying that
electric cars can’t work for people until they can go
for three-hundred miles on one charge.  What a load of
phony boloney, three-hundred miles!  Who needs to take
a three-hundred mile round trip on a charge?  I realize
that people un-regularly go for a far drive, but that
isn’t normally why people drive, and you can simply rent
a long driving car for those un-regularly long drives.
Perhaps the rural people take some long drives regularly,
but I’ll bet that the majority of drivers can do fine with
one-hundred miles per charge.  So again, the engine in the
hybrid cars makes little sense if people could do fine with
todays batteries and electric cars, thus making hybrids’
engines weird.

And I know that electric cars need some charging outlet,
and people living in apartments probably can’t have one
installed near where they’ve parked today.  There are
certainly some ways around that, we pay the meters that
time our parking, why not pay a meter for some electricity
supply?  Not that I’m pushing electric cars, just that I
want to make the point that hybrids are weird.

And we could have efficient combustion engines cars today
as that Shell race shows, but you’ve got to give up some
weight to achieve it.  Do you really need four or five
spare passenger seats?  Do you really need all of that
trunk space?  Do you really need that steel cage?  I know
you’ll react to disagree saying that you need the steel
cage for safety, blah blah blah.  Not that I have anything
against safety, just that it’s a argument with no wind
behind it.  It has no wind because if the world were full
of fuel-efficient light-weight cars (the opposite of SUVs)
then the safety cages could be a lot lighter and do the
same job, or a better job.  And eliminating the cages and
thick bodies can also inspire some more good discipline
into your driving habits, by the way.  I know this
because I’ve been riding an open vehicle since June, 2003,
a bicycle.  And I’m not crazy to put down safety cages,
because more safety can be achieved with driving skills
and disciplines (prevention) than can be with safety cages.

And I know that driving behavior can achieve a lot of
efficiency, but as those tests results of the race show
the excess weight of todays cars is a big factor as well.
And I know that expecting people to behave disciplined
when driving is ridiculous, that’s why I mentioned forcing
a little discipline above.  Maybe forcing was a harsh word
for what I meant, I simply mean establishing a environment
that gives people the help that they need to deal with
the boring routine of daily driving which occasionally
becomes deadly.  Then again, maybe forcing discipline was
the proper phrasing.

And again, hybrid cars are weird.

  - steve s.

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Posted: 26 July 2006 02:06 AM   [ Ignore ]   [ # 6 ]
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There is a documentary out called “who killed the electric car”  If you have a torrent program like Azeures I highly recommend a site called   Its not directly related to chomsky, it really is a haven for educational documentaries on society, religion and reason.

If you go to the search box and type in “electric car” the torrent will appear and you can download it from there.

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Posted: 29 July 2006 11:19 PM   [ Ignore ]   [ # 7 ]
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You’ve got lots of great comments and unique perspectives, Steve. However, again we run into the issue that you’re sort of preaching to the choir.

Why did vehicles get bigger and bulkier in the first place? Ego. People define themselves by their purchases, especially with the cars they drive. Automobile companies are simply trying to deliver the products that are in highest demand. It almost doesn’t matter what the ideal scenario would be since most people aren’t willing to make the sacrifices needed to reach an ideal situation on practially any topic. It would take billions of dollars in advertising/educational campaigns just to make a dent in the current conception that you’ll achieve a higher social status when your car is bigger, faster, stronger, etc.

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Posted: 30 July 2006 12:41 AM   [ Ignore ]   [ # 8 ]
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Oh that? That’s the Grand Canyon behind me, taken from Bright Angel lookout…one of natures wonders.

LOL

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Posted: 10 September 2006 06:12 AM   [ Ignore ]   [ # 9 ]
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hybrid cars

I have the Honda Civic hybrid.  It’s 2 years old and has 13000 miles on it.  I like gadgetry and wanted to do a little for the environment.  I bought the shop manuals for the car so I could understand the technology.

I don’t think it is wierd, but it is complex.  Everything is controlled by computers and there is a backup circuit for the critical things to enable the car to be driven even when a major component fails.  Even the critical hydraulic circuits in the automatic transmission have these emergency circuits built in.

My car’s hybrid system is called Integrated Motor Assist (IMA).  The electric motor is geared to the gas engine crankshaft, so I can’t use the electric independent of the gas.  There is no alternator - all electricity is generated by the IMA motor at 144V and stored in the IMA battery.  There is an electronic DC - DC converter that charges the 12V battery, which supplies power to the lights, radio, etc.  The engine is normally started by the IMA motor:  I just turn the key to “start” momentarily and the engine starts.  I never even touch the gas pedal to start it.  The computer controls the power input to the IMA motor and the fuel injection and ignition timing and the car always starts - hot or cold.  There is a 12V starter in case the IMA battery and circuits malfunction.

It is complex, but it is well made and has been trouble free.  All of the IMA components are warranted for 80000 miles.  And, my actual MPG has averaged out to 39.75.  This is city and highway combined and I am not afraid of using the gas pedel when it is needed.  smile

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Posted: 23 January 2007 08:29 AM   [ Ignore ]   [ # 10 ]
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original question

To the original question of why both gas and electric?

Its easy really.  We can do electric power for about 30 miles at a reasonable speed and acceleration.  If you have stop and go and stop, stop stop city traffic, the electric excells greatly. grin

But DARN it, they you want to drive 50 miles more without recharging!  Darn you. :-(  That is where the gas motor comes in.  It recharges the batteries as you drive so you can keep going. 

Also, the gas motor on these units runs at a constant speed, one that is selected for the best fuel efficiency, not off and on, up and down, like you normally drive.  Gearing and all are set to one optimum ratio.

By best alternate is a hybird that focus more on the electric.  Sun roof solar cells built in.  Mandatory road side and work electric rechargers (coin operated) .  Going on a long trip?  When you stop for lunch, pull into the recharger station, put in 75 cents and plug in. 

By making better use out of the battery, over all milage goes up to about 50 to 75 miles a gallon or better.  To and from work, the electric works down to say 25 % of full charge before the motor kicks in.  Recharge on the plug at work, etc.  OH yes,  I would like batteries to be better integrated better, like down the “hump” style, so you could service them and replace them much easier.

Hope this makes sense.
Elder Norm

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Posted: 24 January 2007 03:10 PM   [ Ignore ]   [ # 11 ]
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And on a related subject, I find the whole concept of using ethanol insane.  Since it’s already partially oxidized it will require more gallons of fuel to travel an equivalent distance so we’ll probably introduce even more carbon dioxide into the atmosphere by switching to it.

The only value it will have is to increase the profits of the large agricultural companies that produce corn.

Occam

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Posted: 25 January 2007 01:11 AM   [ Ignore ]   [ # 12 ]
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[quote author=“Occam”]The only value it will have is to increase the profits of the large agricultural companies that produce corn.

Yep. That and the sugar subsidies that make high-fructose corn syrup salable. Bad stuff.

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