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E-M:/ Re: Automatic transmissions



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Enviro-Mich message from "William Tobler" <williamtobler@critterswoods.org>
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The question has many, many variables that changes the complexion of the answer depending on the situation.

The quick answer first.
When driven over an EPA certification cycle like the "highway" cycle, a typical automatic transmission has an overall efficiency over the cycle of about 80%.


A manual transmission over the same cycle should be better than 95%.

The torque converter works as Alex described, although almost all modern torque converters have a "lockup clutch" built inside that mechanically locks the converter to eliminate slip under certain driving conditions. This is typically top gear cruise and mild accels. As such, the torque converter efficiency varies from zero as you are idling at a stop light, to 99% (bearing losses) under locked conditions. If you do a lot of city driving, the torque converter efficiency will be pretty low, maybe like 50% averaged over some kind of local cycle. But this number can be lower or higher depending on those details (like hills). The benefit of the torque converter is that it eliminates the need for a human controlled clutch (as in manual tranmission) to provide either convenience, or for those that have never bothered to learn how to drive a manual which seems to be a majority today. Also, the torque converter gives a torque multiplication of about 2.0 during the driveaway, eliminating the need for an extra low first gear ratio.

Another big energy hog is the transmission oil pump which is there mainly to provide muscle to actuate the shifting clutches to have "automatic" shifts. Several horsepower goes right down the drain for this purpose. This pump also provides the lubrication flow, and the flow to the cooler in order to get rid of all the heat churned up by the torque converter. A third factor is the "windage" losses. There are lots of parts flailing away inside of the automatic transmission. And lastly, there usually are more gear meshes carrying torque at any one moment to add additional losses with about 1% loss per mesh.

In the manual transmission, there is no torque converter. Typically there is no oil pump. Lube is handled by splash. The energy lost in the clutch depends more on on well you can drive, and can be very small especially under highway conditions. Windage is comparitively small. It is relatively easy to have a direct power flow in a manual transmission, so the number of gear meshes carrying torque might be two or three (about 1% loss per mesh). Older manuals could have zero meshes carrying torque in top gear and have unbeatable efficiency.
The EPA numbers for manual transmissions aren't so attractive. This is because of the nature of the test and the unnatural test requirements imposed by the EPA. Personnally, I'm more concerned by "customer fuel economy" than "EPA fuel economy".


The California "highway" cycle is not exactly what I would consider highway. Lots of stop and go. Maybe like going down US12 Michigan Avenue in the Dearborn Livonia area. The city cycle is much slower with lots of stop and go, where the convenience of the automatic is high but the overall efficiency is low.

Another big factor is "How People Drive". I know people who are always in and out on the accelerator pedal - nervous foot, and/or who also tailgate, requiring a nervous foot. This will keep the torque converter unlocked, keep the transmission in a lower gear, and put the engine operation at less than ideal conditions.

One way to train yourself how to drive for better economy is to borrow a car with a typical trip computer. You usually can read out either the instantaneous fuel economy, or the running average over your last few minutes of driving. Our F250 farm truck gets only about 14mpg average, but out on a decent paved road goes up to about 23mpg. You can see a big impact by learning to routinely coast up to a stop, rather than drive up to a stop and then brake.

Conceptually, CVT transmissions should deal with a lot of the downside that I've described. But they have their list of problems too. They start with a "theoretical" benefit of around 20% over a 4 speed automatic, but by the time all of the realities are added together, every CVT that I have seen real data actually got less fuel economy than an equivalently modern automatic transmission, sometimes 10 to 20% less. Hence the German designed ZF cvt in the Ford 500 gets less EPA fuel economy numbers than the alternative automatic.

I personally much prefer manual transmissions for my own driving.

Other killers for fuel economy, especially on smaller cars, are air conditioning and power steering and those horrible boom boxes that some kids mount in their cars to entertain us at 3am.

OK. Bottom line. A 1.9L Escort with automatic transmission and the other conveniences got about 30mpg.
A 1.9L Escort manual w/o AC and PS on my commuting route gave me about 45mpg, and around 52mpg on interstate trips.





----- Original Message ----- From: "Alexander J. Sagady" <ajs@sagady.com>
To: <enviro-mich@great-lakes.net>; <williamtobler@critterswoods.org>
Sent: Thursday, July 27, 2006 2:10 PM
Subject: Automatic transmissions



William, as you are the resident Enviro-Mich auto engineer
you should be able to answer this question:

About how much is the energy/fuel penalty for using an
automatic transmission with the fluid clutch/torque converter
in a vehicle compared to use of a manual transmission with the
traditional pressure-plate clutch?

I realize the answer could vary somewhat based on
driving habits, but is there a rule of thumb for a general
determination on the energy loss from an automatic transmission?

For the uninitiated.... all
of the mechanical work-energy used to drive your
automatic transmission-equipped vehicle forward is
transferred mechanically through a fluid between
torque converter surfaces.  This allows an automatic
transmission to shift between gears through limited
slippage.  However, transferring work through a fluid
like this heats the fluid through friction, causing energy loss,
that is released by your transmission oil cooler.

All of that heat dissipated by my transmission oil cooler came
from burning gasoline in the engine to produce work.

As a self-identified Greenhouse Gas Polluter
going through self-evaluation for my effect on the planet, I'd like to
figure out how much additional carbon dioxide I'm
generating toward global warming solely because I drive a
car with an automatic transmission.

Regards, Alex Sagady



At 12:58 PM 07/27/2006, William Tobler wrote:
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Enviro-Mich message from "William Tobler" <williamtobler@critterswoods.org>
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The legal requirements for car certification are different between Europe and the US.
So it is not necessarily easy to import to the US a model designed for European market.
Never cheap.


The Ford Contour was the US version of the Mondeo (I prefer to think the reverse).
Ford spent a huge amount of money on the Contour and the sales were very disappointing, so it was
discontinued after a few years. The Mondeo continues in Europe and is regularly updated.
So for two very similar cars, one is successful in one place and unsuccessful in the other.


Ford Fusion and Focus are cars "about" the same size as the Mondeo.
The 4 cyl and 6 cyl versions provide completely different driving experiences.


I have never been to Europe, but I continue to hear "wonderful" stories about the Autobahn and
fuel conservation and driving habits.




----- Original Message ----- From: <Craig_Riley@URSCorp.com>
To: "Rita Jack" <rita.jack@sierraclub.org>
Cc: <enviro-mich@great-lakes.net>; <owner-enviro-mich@great-lakes.net>
Sent: Thursday, July 27, 2006 12:27 PM
Subject: RE: E-M:/ FW: Nothing to celebrate while gas prices so high


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Enviro-Mich message from Craig_Riley@URSCorp.com
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I would say it certainly has curbed their driving and consumption.

For anyone who has traveled overseas we need look no further than the vast
amount of mass transit they have, walkers, bikers, and most obviously (to
me as a Detroiter) are the models of cars (size factor) on the road. One
can easily notice a certain absence of some of the Big 3 models that you
would normally see here (a Ford Explorer looks like an urban tank), while
at the same time notice some Big 3 models on European roads that are not
available here. For example, I recall a Ford Mondero (???) I saw
frequently in Spain.


Their driving habits and types of cars are far different than here.



           "Rita Jack"
           <rita.jack@sierra
           club.org>                                                  To
           Sent by:                  <enviro-mich@great-lakes.net>
           owner-enviro-mich                                          cc
           @great-lakes.net
                                                                 Subject
                                     RE: E-M:/ FW: Nothing to celebrate
           07/27/2006 12:00          while gas prices so high
           PM


Please respond to "Rita Jack" <rita.jack@sierra club.org>






------------------------------------------------------------------------- Enviro-Mich message from "Rita Jack" <rita.jack@sierraclub.org> -------------------------------------------------------------------------

Lest there be more confusion, please note I was only passing on the
Governor's press release, and I didn't add my own opinion to it!

Though it hits me square in the pocketbook because I do a LOT of driving
for
the work I do (tomorrow to Menominee County, this past Tuesday to Huron
County), I also still agree with the need for higher gas prices, or rather,
higher taxation, that reflect the true cost. I've not researched it, I
admit this, but I understand that Europeans pay much more for their fuel
that we do. Can anyone share if that's curbed their driving and other
consumption over the years?


-Rita

<><><><><>><><><><>
Rita Jack
Water Sentinels Project, Sierra Club Michigan Chapter
tel:  517-484-2372

Make all Michigan's waters fishable and swimmable.


-----Original Message----- From: owner-enviro-mich@great-lakes.net [mailto:owner-enviro-mich@great-lakes.net] On Behalf Of jmgear@acd.net Sent: Thursday, July 27, 2006 11:54 AM To: enviro-mich@great-lakes.net Subject: RE: E-M:/ FW: Nothing to celebrate while gas prices so high

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Enviro-Mich message from jmgear@acd.net
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I don't understand.  High gas prices are the _only_ thing
that has ever worked to reduce gas consumption, which is
one of the most important goals to be desired by
environmentalists.

I may not _like_ high gas prices, but then I don't _like_
tetanus shots.  But I certainly celebrate the freedom from
deadly illness provided by tetanus resistance, and would
gladly celebrate gas priced at something approaching its
true costs--which is something closer to $10/gallon rather
than $3.

People who want to claim to be environmentalists need to
recognize what an opportunity the imminent peak in oil
production provides--if we tax oil and gas consumption
appropriately, we could eliminate all other taxes, keep
much more of Michigan's wealth in Michigan, help preserve
an irreplaceable resource, and clean up the environment.

Oil is one of the most underpriced substances in the
universe . . . which is why we waste so much, and cause so
much environmental havoc as a result.  At $84 a barrel
(about $4 a gallon for gasoline), oil is only 50 cents a
quart, the cheapest liquid in the world, and the gasoline
made from it is only $1 a quart, less than the $1.50 I see
kids plugging into the machines to buy a PINT of sugar
water.


=========================================================

"Rita Jack" <rita.jack@sierraclub.org> wrote:

From: gov_office@MICHIGAN.GOV
[mailto:gov_office@MICHIGAN.GOV]
Sent: Wednesday, July 26, 2006 5:44 PM
To: GOV-NL@LISTSERV.MICHIGAN.GOV
Subject: Nothing to celebrate while gas prices so high



Bush Administration and Congress Toast Energy Bill
Anniversary While
Consumers Get Roasted at the Pump



LANSING - One year following passage of comprehensive
federal energy
legislation, Governor Jennifer M Granholm today criticized
Republican
leaders in Washington for celebrating the new law's first
anniversary while
gasoline prices and oil companies' profits soar to new
record highs.



"The President and our congressional leaders ought to
postpone celebrating a
policy that's hurting average families and instead pass new
legislation that
gives consumers meaningful relief.  Filling champagne
glasses in Washington
while Americans empty their wallets at the pump is just
plain wrong," said
Granholm.



Granholm pointed out that with average gasoline prices
passing $3.00 this
week, Americans are paying almost 60 percent more than they
were in May,
2004.  At that time, the White House said that the
President "believes, like
Americans do, that gas prices are too high."  The White
House blamed high
gas prices on the fact that Congress had not yet passed the
President's
energy bill.  In early 2004, the average price of gas was
$1.76 per gallon.



"I challenge President Bush and Republican congressional
leaders to take
meaningful federal action to reduce record-high gas
prices.  Almost 300,000
Michiganians joined me in asking for the President to act
by signing my gas
price petition to lower gas prices and cap corporate oil
profits," Granholm
added.



Granholm has taken several actions to protect consumers
from rising gas
prices in addition to calling on the President to cap oil
profits in
September 2005 and again in her 2006 State of the State
message.  Over the
past three years, Granholm has:



. increased gas pump inspections and called for legislation
to require gas
station operators prove their pumps have been calibrated
and are working
properly when they apply for renewal of their operator's
license - state law
requires that licenses are renewed annually;



. sent a letter to the federal Commodities Futures Trading
Commission
requesting they conduct an inquiry into all contributing
factors in price
spikes, including any role speculators have played in
driving the
inflation-adjusted price of oil and gasoline toward
historic high levels;



. signed executive orders temporarily suspending state laws
restricting the
supply of gasoline and increasing the diesel fuel supply
and called on
Marathon Oil Corporation to reduce the price of gas for
Michigan customers,
an action that resulted in an immediate drop in the price
of gas by the
company - steps taken in the wake of Hurricane Katrina;



. directed the Michigan Department of Agriculture to
conduct routine surveys
of gasoline prices and directed the department to refer
information about
potential unfair pricing practices to prosecutors for
possible legal action
- a step that led to the felony conviction of a Macomb
County service
station caught defrauding customers;



. supported legislation to add a legal cause of action to
the Michigan
Consumer Protection Act that would expressly ban the
practice of price
gouging during states of emergency declared by the Governor.



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Postings to:  enviro-mich@great-lakes.net      For info, send email to
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==============================================================
ENVIRO-MICH:  Internet List and Forum for Michigan Environmental
and Conservation Issues and Michigan-based Citizen Action.   Archives at
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Postings to: enviro-mich@great-lakes.net For info, send email to
majordomo@great-lakes.net with a one-line message body of "info enviro-mich"
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==============================================================
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and Conservation Issues and Michigan-based Citizen Action.   Archives at
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========================================== Alex J. Sagady & Associates http://www.sagady.com

Environmental Enforcement, Permit/Technical Review, Public Policy,
Evidence Review and Litigation Investigation on Air, Water and
Waste/Community Environmental and Resource Protection
Prospectus at:  http://www.sagady.com/sagady.pdf

657 Spartan Ave,  East Lansing, MI  48823
(517) 332-6971; (517) 332-8987 (fax); ajs@sagady.com
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