376.59 MPG Automobile

[Newbian]

Originally posted by: mugs

and secondly the engine and operating conditions must be chosen so that power requirement is met with minimum fuel utilization."

My Civic could get 377 MPG with that constraint, but it probably wouldn't be drivable once it hits the ground.

:laugh:

 

[SagaLore]

Originally posted by: Quixfire
300 mpg defies physics, there isn?t enough energy in a gallon of gasoline to move a vehicle that far.

Most of the energy in the gasoline is being converted into unused heat and noise, through friction and vibration, premature cooling due to limitations in alloys, catalytic conversion of unburnt waste products, etc.

The problem is in practicality of manufacturing perfect engines, not that they can't be made. The day you can put your hands on a running engine and not get burnt, only feel a slight hum, and the immediate exhaust from the engine is nothing more than a cool breeze, is when we'll achieve 300+ mpg.

 

[Jeff7]

Originally posted by: Quixfire
300 mpg defies physics, there isn?t enough energy in a gallon of gasoline to move a vehicle that far. If there was we would have motorcycles doing 600-900 miles per gallon let alone 300 mpg.

Using gasoline alone like they would have in 1949, 1968, & 1973.

My university competes in SAE's Supermileage competition. From the college's website:

At the May 30-31, 2003 competition the Penn State Erie team came in ninth of twenty-seven collegiate teams in the mileage competition, with the winning car registering 1,343 miles per gallon.

Teams are given a Briggs and Stratton engine, and are allowed to modify it from there. The cars are quite small though, not really a practical transport means. I think they run at 23mph during their test runs.

Still, there is a lot of energy in gasoline. The problem is converting chemical energy into kinetic energy. The efficiency losses are huge, due in part to restrictions in materials. Running engines with hotter combustion temperatures would increase the base thermodynamic efficiency, but then you have other problems, such as increases in ductility of metals at high temperatures. There is work being done to create ceramic engines, but the big problem with ceramics is surface defects - in ductile metals, tiny surface cracks aren't much of a problem. But with ceramics, very tiny cracks can lead to a complete failure. Solve that, and you've got yourself a damn fine engine.

Originally posted by: redly1
If GM or Ford had a 365MPG car in their back pocket...I'm thinking they would have played that card... right about now

Why go for broke? If the competition is at 40mpg, and you can do 300mpg, why do it? Release a 50mpg model instead.
Unfortunately, that's how it works.
Capitalism is about profits, not progress.

 

[OokiiNeko]

And modern engines can run consistently leaner air/fuel ratios than could have ever been possible with old carb'ed engines.

No. The problem is that smaller engines needed to rev higher, so they needed lighter components. One of those components is the exhaust valve. The problem is that using less material to make a lighter valve creates a heat dissapation problem.
The answer to this was to program in x amount of fuel specifically to NOT get burned in the combustion process and help cool the exhaust valve. This is the fuel that gets burned by the catalytic converter.

Theoretically, you should be able to lean out the fuel/air mixture until almost NO FUEL is present in the engine`s exhaust. That would mean that your engine is burning almost ALL fuel in the combustion process. Unfortunately, you will end up sucking an exhaust valve.

The very fact that cars have catalytic converters means the engineers have already planned to NOT burn all fuel during combustion.

Of course, I may be wrong

 

[Zenmervolt]

Originally posted by: Quixfire
300 mpg defies physics, there isn?t enough energy in a gallon of gasoline to move a vehicle that far. If there was we would have motorcycles doing 600-900 miles per gallon let alone 300 mpg.

Using gasoline alone like they would have in 1949, 1968, & 1973.

Motorcycles have huge amounts of aerodynamic drag. They are also almost invariably geared for power and not for economy because they manage to achieve good economy even when geared to run 0-60 in 4-5 seconds. Hell, my little old 450cc Honda (standard, not a sportbike) will outrun a good number of cars to 60. It tops out at 80 from drag, but it gets to 60 pretty quickly.

Short of fitting a fairing over both the bike and the rider, there's not much that can be done to make a motorcycle more fuel efficient. The aerodynamics just kill it.

ZV

 

[jhu]

just drive slower. you'll get better fuel economy. to get better than that, you'd have to alter your regular driving habits.

 

[AyashiKaibutsu]

Originally posted by: SagaLore

Originally posted by: Quixfire
300 mpg defies physics, there isn?t enough energy in a gallon of gasoline to move a vehicle that far.

Most of the energy in the gasoline is being converted into unused heat and noise, through friction and vibration, premature cooling due to limitations in alloys, catalytic conversion of unburnt waste products, etc.

The problem is in practicality of manufacturing perfect engines, not that they can't be made. The day you can put your hands on a running engine and not get burnt, only feel a slight hum, and the immediate exhaust from the engine is nothing more than a cool breeze, is when we'll achieve 300+ mpg.

I suspect an engine like that would require a method other than internal combustion.