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Can Your Car Get 1,700 MPG?
Xaroth writes "Given all the hubbub over EPA mileage ratings, I'm a little surprised that this one hasn't come up earlier. SAE apparently holds a contest each year to encourage students to design single-person, fuel-efficient vehicles. This year's winner achieved 1,747.4 MPG, with the press release that tipped me off pointing out that third got a 'measly' 1,194. There are more details on the competition over at SAE's site about the competition. Now, if only they could make these street-legal..." However, even the winner has nothing on top entries we mentioned in Shell's competition a few years back.
What kind of gas mileage will they get when they are loaded up with 1000+ pounds of DOT required safety equipment?
1. When the pin is pulled, Mr. Grenade is no longer your friend.
2. Do not eat iPod shuffle.
My bicycle.
I win.
How about the most fuel efficient 4 door seating for 4 w/ trunk space, radio, air conditioning, that meets federal safety and crash tests?
Than watch those MPG numbers plummet. Add to that must have respectable performance numbers (ie it must not be so slow accelerating as to cause a hazard on public roads)
That's a real contest.
> Fred Flinstone, with infinite miles to the gallon.
Laugh if you will, but we'd all be a lot healthier if we followed Fred's example and ran to and from the office, instead of hit cruise control after rolling drive-thru.
The dangers of knowledge trigger emotional distress in human beings.
40 miles each way, to and from work, 50 weeks a year (2 week vacation), with a 500ft altitude change and see what kind of milage/reliability results the bloody thing gets. My guess is that it wouldn't last a week before some major malfunction. Optimization in one area often degrades performance in others.
When I can buy a car with that kind of effencieny I'll look into it, but until then, a walkin' I a' go.
Must be a bitch to take that shiny new 21 inch monitor home from the store.
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It's important to note that MPG has a lot to do with driving style. While my car cannot get 1700 MPG, a bit of predictive driving (i.e. know when to start slowing down, when to build up momentum) will greatly increase the MPG.
It depends on where you are, but in the US the NTHSA and the DOT would strongly disagree with you. Vehicles sold in the US have to meet certain standards of crashworthiness in order to be allowed to be sold here for street use. This has kept a lot of cars from being imported here, because they would require significant modification. It is a result of all the big old cars (and big new cars) we have on our roads, of course. In Japan, where large vehicles are relatively rare (you have delivery vehicles, and tiny vehicles, and not much in between) you can have lots of little beer can vehicles because they can't do nearly as much damage to one another, whereas here in the US you have scads of two-ton-plus vehicles, even passenger cars with that kind of weight.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
There's one catch. Nitrogen is very stable. Almost any chemical reaction will take more energy than it releases. When it comes to engine efficiency, this is Not Good.
Ideally, what you'd want to do is separate the oxygen and nitrogen, so that the oxygen ratio in the engine is much higher. Since you're losing less energy through the nitrogen, you would (by implication) get more useful energy out.
Ok, so how to do this, without reducing the energy you're getting from the oxygen at the same time?
That's tough. However, it may be possible. Nitrogen, as mentioned, doesn't react easily. The electrons in the outer shell are tough to displace. With oxygen, the reverse is true. Oxygen reacts very easily, and electrons are displaced with considerably less effort.
You can certainly use this to separate oxygen and nitrogen. Just set up an electrically charged grid, such that the charge will convert O2 into O2+, but leave nitrogen (N2) electrically neutral. Set up a second grid, with the reverse charge. The oxygen will be attracted towards it, the nitrogen won't.
If you picture the first grid at the entrance to a y-shaped tube, and the second grid at the fork splitting off of the long section of tube, you can see how the nitrogen will travel straight on, whilst the oxygen will be diverted.
Now, here's the tricky bit. The oxygen is one electron short (it's charged), and you've got to put quite a bit of energy into a device like this to charge the grids up enough. Will you get a net gain in efficiency?
That part, I can't answer.
Would it be worth doing anyway? Maybe. Well, it'll cut out a major air pollutant. The oxides of nitrogen that you get off will react with water to produce nitric acid. Not really something I want to be breathing in, if I don't have to.
Are there better solutions? Not using a conventional piston engine. We're almost at the limits for those, given a standard air mix. A rotary engine might get you a better theoretical limit (you don't have to keep reversing mechanical devices), but they're costly to make (they develop far higher pressures) and you have to develop one that's large enough that the increased surface area to volume is no longer a factor.
For ultimate fuel efficiency, I suggest a small fusion reactor. Though you may need to wait a while for them to be approved for use in cars.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
It's not really a fair question, as aircraft are so very different from cars. Their handling and common behaviors are different, as are the tasks to which they are put- An airliner may be less efficient than a car on paper, but if you try to move 300 people across the US with both of them, the plane may still come out on top.
Also, planes can use propulsion systems much more exotic than a reciprocating mechanical engine.
<rant>
Fuel cells are only batteries. The theoritical best is getting back what you put in them. Even assumming a 99% efficiency you'll still be running off how efficient the original power source was.
Although hydrogen is essentially everywhere, you can't just dig it out of the ground. I can think of two ways (I'm sure there are more) to get usable hydrogen, electricity (split the atom off from an existing molecule), and heat (burn the atom off an existing molecule, or seperate it from a compound). Since about 75% of the country's electricity is fossil fuels, and heat is usually generated with fossil fuels or electricity using hydrogen doesn't solve anything.
I'm truly ashamed for people who think that hydrogen fuel cells will solve all of the world's fossil fuel problems. Sure, hydrogen fuel cells will make for extremely low exhaust cars, longer laptop battery life, etc, but they won't solve the fossil fuel crisis.
If you think that modern automobiles are getting close to their efficiency limit, then you've been looking the other way when people talk about TDI and hybrid cars. TDI increases fuel efficiency by redifining how diesil engines work (turbo charged, fuel injected, etc). Hybrid cars increase fuel efficiency by having a (almost always more efficient than ICE) electric motor do the actual driving, and using braking power to regenerate their batteries.
Using a hydrogen fuel cell car is almost exactly like using a hybrid motor. The only differnce being in the type of battery, and where the battery gets its energy reserve from.
People (especially in America) tout hydrogen as the best way to "rid ourselves of foreign oil," when it really just puts us in a stranglehold for the next 10+ years. Sure, 10 years from now, when fuel cell cars roam the highways, there's a possibility that we won't be using any foreign oil, but I doubt it. We will likely be using a large amount of oil to create hydrogen and even more to power massive ICE generators (just like we do today). If you really want to "rid yourself of foreign oil" go Nuclear. It's technology that, in 5 years time, could power 100% of any countries electrical needs. How? It only takes that long to build 1 reactor, 2 reactors, or more. The fuel for nuclear reactors, though not highly abbundant, is available in large enough quantities to suffice any demand.
Ten years from now I don't want to be seeing a world where 10% of the automobiles run on fuel cells, 15% are hybrids, and 75% are SUVs that are exempt from fuel efficiency standars. Stop the madness now.
</rant>
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The SAE competition in the link requires a four cylinder engine. This kind of rules out other types of power such as steam, fuel cell, and stirling engine. Although, I suppose with enough modification, the provided Briggs and Stratton engine could be converted into a steam engine (not that this is necessarily more efficient). Let's see, new camshaft, a means to adjust the valve cutoff, maybe one of those cool looking fly-ball governors... Since a steam engine can apply power in each cylinder on every revolution, this makes it equivalent to a V-8. If you seal off the crankcase into a separate compartment for each cylinder, you can use both sides of the piston and make the equivalent of a V-16. Of course, details like, how to water from condensing in the oil will have to be addressed.
Also, since the peak horsepower of a car is rarely needed except in rapid acceleration, I would think that the key to reducing engine size, and thus, improving efficiency would be to use a small engine with some kind of storage system. Since batteries are bad for the environment, maybe two flywheels rotating in opposite directions (to cancel out precession) under the floor can be used, along with an electric motor/generator to transfer power to/from them. Extra power generated by the engines, as well as from braking, can be used to accelerate the flywheels. This would also improve handling because the gyroscopic effects would keep the car perfectly level on fast turns.
Also, I would think that the car would be cheaper to engineer and produce if you could eliminate most of the mechanical parts. How about a gasoline fired generator, a flywheel battery, and an electric motor on each axle?
Unknown host pong.
The Bush administration announced today that all US military personnel in Iraq would be either returning home or shoring up the neglected war on terror within the next month.
White House spokesman Scott McClellan said, "It turned out Iraq wasn't really ever a threat to our national security, so we couldn't really justify keeping so many troops over there, what with real threats like Al Qaeda out there needing attention." He added, "You may not know this, but it was actually Al Qaeda and not Saddam Hussein who's been attacking us all along! Even September 11th, we're starting to understand, had nothing to do with Saddam Hussein!"
Vice President Dick Cheney denied any link between this latest move and the recent availability of super-fuel-efficient vehicles: "Listen you pig #*$^@%ers, the war in Iraq was not about oil. So drop it if you want to stay out of Guantanimo, alright? I've got some explaining I need to do to Halliburton's shareholders, so I can't stay long."
I've always thought it was odd that crashworthiness tests in the US don't look at the damage the car will do to the other car. Having large protruding eye-level spikes will make the car even more crash-worthy, as they will slow the car before impact (by skewering the passengers of the other car).
The most compelling argument for buying an SUV is that in one you are most likely to survive a crash with an SUV. However, that's also a pretty compelling argument for banning the whole bloody lot.
We even give tax brakes to SUV's above 6 thousand pounds. 6 Thousand pounds!
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Some students do something cool in a contest and all most people are saying is "yeah, call me when it's really a car." Criminy. Articles on case mods get friendlier comments than this, and this is something that I would have thought geeks would have found interesting. Or nerds. Or whatever we are.
http://www.rootstrikers.org/
Um... calm down there big guy.
You can use gas directly in a fuel cell.
Fuel cells CAN be very efficient.
The original poster was simply saying that to get more efficiency out out gas as an energy source, you need to look at other methods besides internal combustion.
Note that your points are all good, just off topic.
The Carnot engine is the basis of the 3rd law of thermodynamics. I think you can put that in the theoretically sound category.
The actual efficiency is 1-Tc/Th. From wikipedia.
In this equation, Tc is the temperature of the heat sink, and Th is the temperature of the engine's heat source. For a 40% efficient engine, your hot engine gases have to be about 1.75 times hotter than the atmosphere that you discharge your exhaust into.
That doesn't sound like much - but remember you have to use absolute temperature. Room temperature is about 300K. So you need a 500K heat source - which is 230C, which is actually fairly hot. And of course you have all kinds of non-idealities in a real engine.
The only way to get anywhere near 100% efficiency is to get the hot part really hot and the cold part really cold. That is why metal-cooled reactors are fairly efficient - you have liquid sodium metal (very hot) coupled with river water (reliably cold).
If you run the math backwards it tells you what the maximum efficiency of an air conditioner is as well. As the temperature difference between hot and cold grows the efficiency drops accordingly. Of course, in real life you also have to deal with the fact that as delta-T grows your walls also start leaking heat like a sieve...
I'm truly ashamed for people who think that hydrogen fuel cells will solve all of the world's fossil fuel problems. Sure, hydrogen fuel cells will make for extremely low exhaust cars, longer laptop battery life, etc, but they won't solve the fossil fuel crisis.
Very true, but they do provide an easier means of transition once better energy generation comes on line. It is a lot easier to just convert over/build new electricity generation plants and use that electricity to charge all the fuel cell powered gizmos (especially cars), than it is to stick with gas powered cars and then have to suddenly convert them to something else.
Basically by going to fuel cells you are setting up all the required infrastructure (no small feat) for an easy transition. You simply charge your fuel cell car at a suitable charging station - where and how that electricity is generated (via fossil fuels now, or something more efficient later) is irrelevant. Changing the infrastructure is a huge step towards moving away from fossil fuel dependence.
So no, fuel cells aren't a cure for the fossil fuel crisis, but I would suggest that they are an extremely useful means to take preliminary steps and smooth the eventual transition.
Jedidiah.
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The dark black smoke is usually caused by too much load on the engine. The blue smoke you see is usually a problem with the injectors leaking. The fuel is leaking into the cylinder and not being burnt and thus coming out like a vaporized oil. Sadly, most of the time both of these are due to lack of maintenance on the engine, especially when it comes to locomotives. About the only time a locomotive should be smoking is when they are climbing steep grades (for a locomotive) over a long distance, and even then should be very little.
I can see where a diesel locomotive is not the efficent for moving passengers (at least in populated areas where it must stay slow) because passengers way so little. However, when it comes to moving heavy freight, a locomotive should be far more fuel efficent then the trucks used to move most freight now.
Reserved Word.
Very fuel efficient; on average, light aircraft generally use less fuel per mile than most cars.
That said, they do different things. Planes fly stright lines, at fairly constant speeds. This benefits fuel economy. Cars really get hurt by stop/start driving.
You are missing the point - hydrogen fuel cells aren't intended to by themselves negate the need for fossil fuels, they are a means to the end though. 10 years ago you couldn't really have an electric car...batteries weren't good enough. Even now, they aren't all that great - long-ish charging times and low capacity, high weight to stored energy ratio etc. Granted they are improving greatly as of late and that is certainly one path to take.
Another path is to have a better (different) means of storing electricity. Hydrogen fuel cells may be this way. Once we have proven the technology to run a car (or whatever) in this manner, we can then concentrate on ways to get the hydrogen without fossil fuel...maybe a nuclear generator providing the electricity for elecrolysis, or perhaps everyone with their own little windmill on top of their house. Or maybe a fancy new catalyst that allows the reaction to proceed with very little energy input.
Hydrogen fuel cells might not be the answer to fossil fuels, but they might - can you think of a better alternative beside each car having their own little nuclear reactor?
. The fuel for nuclear reactors, though not highly abbundant, is available in large enough quantities to suffice any demand.
And 640K ought to be enough for anyone...
and there is the matter of waste heat heating up lakes and that little matter of the nuclear waste - not exactly an ideal solution.
If it was something like "SAE contestents achieve 1,700 MPG" then I would think that these comments would be much less.
I'm a machinist, and I've dealt with automotive engine blocks before. I think the big problem is going to be manufacturing costs. When machining a ceramic, it tends to chip very easily, which could raise costs due to high waste, and special manufacturing procedures that hamper productivity. However, since it's non-ferrous, you can use diamond tooling instead of the traditional carbide tooling, which will save a fortune on tooling costs
Ceramics are also very abrasive, which might drive up maintenance costs due to the need to frequently replace piston rings. The engine block itself should wear much more slowly than a normal cast iron block, however.
Ceramics can be pretty resilient even when faced with temperature stresses, but I don't know how well a car that needs to be running one moment, and parked the next would fare. I doubt people would put up with the need for a 5 minute warm up period, especially if failure to do so would destroy their car.
Another issue is that a ceramic block would be impossible to repair, and would probably be a good deal larger than a regular cast iron engine to provide strength at every location on the block that feels stresses. But, if it's possible to build ceramic handguns, I'm sure it's possible to build a durable ceramic engine block.
I doubt there's very many manufacturing experts who read slashdot, but I would be very curious to see solid numbers on the costs of ceramics manufacturing compared to traditional cast iron. I haven't done much work with ceramics, so much of the above is just educated speculation. Treat it as such.
Come on, this is lame. No, your car isn't going to get 1000+ mpg because it isn't 80 pounds and powered by a 3 hp motor.
Yeah, they made neat toys. Wahoo.
While I agree that cargo capacity can be important to have every now and then, when was the last time that you drove to a brick-and-mortar computer store to buy a 21" monitor?
Hell, when was the last time that you bought anything besides a cable or adapter at a brick-and-mortar computer store?
May we never see th