Lower the speed limit to 55

[jspande]

Rusty, you're absolutely right - there are more issues to the question than fuel mileage.

I'm a bit preoccupied by the fuel mileage because of the physics questions. It is a pet-peeve of mine that wishful thinking so often trumps science in the public mind. 10% - 20% better mileage at 70 -80 mph compared to 55 mph is absurd, and indicates something wrong either with the measurement (very likely, since such measurements under matching conditions are extremely difficult) or the vehicle.

I remember back several decades (before widespread use of fuel injection) when it was widely believed that there was a carburetor design (which the oil companies had bought up and hidden) which would improved the mileage of the existing cars (generally getting less than 20 mpg) to 100 mpg! The fact that this would totally violate the Laws of Thermodynamics mattered not at all to those who found such nonsense completely believable.

[melvonnar]

If you took a car; any car, tuned the engine RPM and given the proper gears, to run at 70 MPH;
Took the same car,tuned the engine to run at 55 MPH. and give it the proper gears.
That car would give much better milage at 55MPH
Why?
Wind and rooling resistance.

If your vehicle is tuned for a higher speed you; possibly could get better milage.

[melvonnar]

Most gas motorhomes engines sweet spot is right around 2500 RPM.
oil burners some where around 1600 to 1800 RPM. the bigger the oil burner engines the lower the RPM.

[jspande]

Another thing to remember is that the sticker on new car windows gives EPA fuel mileage ("Highway") which I believe is still a 55 mph estimate. Nowhere does a customer see a 70 mph figure. Yes, I know the EPA measurement is very flawed, but that's beside the point.

Not all customers worry too much about that number, but some do, and it's pretty unrealistic to think that manufacturers would put their engineering effort into mileage at 70 when it's the 55 value that's going to be visible.

Now an exotic with 500+ HP and design speed 150+ mph, and for which an EPA estimate down around 5 mpg is practically a badge of honor may be an exception.

[RustyJC]

EPA Highway test cycle:



Except:

New method (2008 and later)
It's common knowledge that EPA fuel economy estimates do not reflect real world mileage, and are particularly advantageous for hybrids. Because of these known discrepancies, the EPA decided to revise its testing methods. Tests will continue to use a dynamometer. Changes will include:

Higher speeds - up to 80 MPH on the highway cycle

Colder temperatures - tests will now start at 20 degrees Fahrenheit rather than 75

More rapid acceleration

Use of accessories - the air conditioner will be operated 13% of the time

Results of the new method:

The new testing methods will drop city fuel economy estimates by 10% to 20%, with hybrids taking the highest percentage. Highway estimates will drop by around 5% to 15%.

The new methods -- which will be accompanied by a new fuel-economy label on the car's price sticker -- will apply to 2008 model year cars manufactured after September 1, 2007. Through June, automakers will be allowed to attach an additional label showing what fuel economy estimates would be using the old test methods.

Current regulations only include vehicles with a GVWR (Gross Vehicle Weight Rating - the maximum permissible weight of the vehicle, fuel, and payload, including passengers) of up to 8,500 lbs, which excludes many large SUVs, vans and pickups. By 2011, manufacturers will be required to apply EPA fuel-economy ratings to medium-duty vehicles with GVWRs of 8,500 to 11,000 lbs.

Rusty

[Ray,IN]

Originally posted by jspande:
Rusty, you're absolutely right - there are more issues to the question than fuel mileage.

I'm a bit preoccupied by the fuel mileage because of the physics questions. It is a pet-peeve of mine that wishful thinking so often trumps science in the public mind. 10% - 20% better mileage at 70 -80 mph compared to 55 mph is absurd, and indicates something wrong either with the measurement (very likely, since such measurements under matching conditions are extremely difficult) or the vehicle.

I remember back several decades (before widespread use of fuel injection) when it was widely believed that there was a carburetor design (which the oil companies had bought up and hidden) which would improved the mileage of the existing cars (generally getting less than 20 mpg) to 100 mpg! The fact that this would totally violate the Laws of Thermodynamics mattered not at all to those who found such nonsense completely believable.

Read this article- original blueprints found for 200 MPG carburetor, then follow the links to view the blueprints.

[melvonnar]

I remember back several decades (before widespread use of fuel injection) when it was widely believed that there was a carburetor design (which the oil companies had bought up and hidden) which would improved the mileage of the existing cars (generally getting less than 20 mpg) to 100 mpg! The fact that this would totally violate the Laws of Thermodynamics mattered not at all to those who found such

nonsense completely believable

And there are those that believe that putting moth balls in your gas tank will improve gas milage

[hamguy]

From the article - "Mr Davies has had the patent number on the plans authenticated, proving that they are genuine documents."

If the patent was applied for and issued, it would be public information. And it would have
expired so it would be public domain. Note, he doesn't give the number.

Sorry, but as a patent attorney, I will call all of this Pure-D BS!

Also, I would like to see the physics formula that shows friction increases as the cube of the speed.

And my final comment would be that if the environment was the biggest concern, then ban the use of fossil fuels altogether.

PS, we humans are every bit as much of the environment as a penguin. we have the same rights. We cure more problems than all other critters put together. Why are cattle not cleaning up their own flatulence?

[melvonnar]

Why are cattle not cleaning up their own flatulence?

Question?
I read somewhere that cattle produce more methane than anything man has produced.
Does anyone know if this is true?

[RustyJC]

Originally posted by hamguy:
Why are cattle not cleaning up their own flatulence?

More than you ever wanted to know about this subject may be found HERE - compliments of your tax dollars!

Rusty

[historyljc]

Originally posted by robert h:
...

Question?
I read somewhere that cattle produce more methane than anything man has produced.
...

My DW will have a difference of opinion on this.

[Canuck]

For those who think that they will use MORE fuel by slowing from 65mph to 55mph here is some info working against that idea.
Canuck

[GRV]

O.K. If it's truly about fossil fuel and environment preservation, why not make ALL ships "sail" power, stop all air traffic (those big planes really waste fuel), and go back to horse and buggy...

[melvonnar]

O.K. If it's truly about fossil fuel and environment preservation, why not make ALL ships "sail" power, stop all air traffic (those big planes really waste fuel), and go back to horse and buggy

There is a hole bunch of people in Ohio and Pennsylvania doing just that.