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Old 26-04-2006, 08:42   #91
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Efficient cars

Ford, Citroen, Peugot, Mercedes and others make thrifty small cars. Their adds often claim 75 mpg, that is the big gallon at 4.546 liters. Some folks will get that mileage while others will not.
I would buy one of these things except I prefer something a bit better for driving over the mountains in the winter, which means larger diameter wheels. My car has a claimed 47 mpg on the highway. I get that if I keep the speed down on mostly flat roads, but in BC we do not have mostly flat roads, we have mountains everywhere we go, so my highway mileage is a bit less. But as Wheels said, you have to think 1000cc engines in 1500 pound cars with good wind resistance. 750cc motorcycles used to do about 70 mpg at around 60 mph, due to the affect of wind resistance. It is no easy task to get really good fuel economy and there are not short cuts that I know of. It is a huge amount of work moving vehicles or anything that has mass. Sailboats sailing is about the best deal going in my opinion. Our local dump is now producing electricity from the methane created. We have the technolgy to make other brews of fuel, we are just using the cheap stuff first. Unfortunately it polutes, but the new vehicles are getting better.
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Old 26-04-2006, 11:18   #92
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"750cc motorcycles used to do about 70 mpg at around 60 mph, due to the affect of wind resistance. " My barber had too many golf magazines so I was reading one on motorbikes recently. They were looking at 250cc bikes and even there, only a few made 70+mpg these days. I'd call that a good alternative for urban commuting but, as the article said (and as my friends who once rode bikes ALL say) "first buy good medical insurance". Traffic can be a bit rough here, as are the roads.

The car makers...I've worked both sides of that desk.<G> The public wants conspicuous consumption, wants pigmobiles, so the car makers "must" build them. Folks who proudly spend $500/month to lease SUVs (three or four for the family please) then bitch about $3 gasoline...hmmmm...Dunno, I bought a riceburner years ago because Detroit just wasn't building decent compacts. And the price of gasoline STILL hurts. Personally I'm planning to fight that buy replacing the O2 sensor in my car, apparently they wear out and that very much affects mileage--but nobody replaces them until they fail totally. Go figure, too many parts.<G>
I look at the new cars that will do 40mpg against my 25-28 and the only consolation is that an extra $20k for the newer car still costs a lot more than gas. For boat owners, I guess the bright side will be that rising oil prices will make fiberglass more expensive (as it has in the past) and used boat prices will RISE in the next five years, as the new boat prices get forced up.
"Unfortunately it polutes," As does life. The good news is, many geologists think our polluting ways have saved use from the "normal" state of ice age that we should be in. I don't condone pollution, just note that sometimes knee-jerk propriety needs to be tempered with years of dull and expensive research, which no one wants to fund either.
How high does gas have to go before it keeps the jetskis off the water anyway?<VBG>
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Old 26-04-2006, 13:41   #93
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Hmmmmm, a row of holes along each side of the hull. I team of rowers and an oar sticking out each hole. Now ya thinking.
But here is my out there dream, the means of riding magnetic rivers in the earths field. You could be drawn along or be propeld by the magnetic fields that are moving the immense flows of molten rock below our earths surface. These flows are what the continents are floating and riding along.
I hereby on this day register that idea in history. In a hundred years from now, I could go down in history as a man ahead of his time, or a compleate nut case. One thing for sure, right now I am probably considered a nut case.
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Old 26-04-2006, 15:36   #94
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You maybe a nut case, Alan?

Only history will figure out whether you are or not!!
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Old 26-04-2006, 19:12   #95
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Most of the great thinkers were thought to be lunatics, or heretics in their time, but who would call Socrates crazy now? I like the concept Wheels. No clue how to procede with it. What about a large, chemical expansion engine? Mix two chemicals in an injector, and let them create an expanding gas to push a piston. No combustion, no heat. Slow turning due to the speed of the reaction, but if the expansion was sufficient, it could produce plenty of power to turn a geared drive, and spin a prop fast enough to drive a boat. I am no chemist, so I have no idea what chemicals might be practical for such a purpose, but I remember from school seeing this type of rapid expansion from something.
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Old 26-04-2006, 21:59   #96
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Quote:
Originally Posted by Kai Nui
I agree that the energy in sea water should be able to be harnessed to produce mechanical power, but how?
E=MC^2 - separate out the heavy hydrogen and use a fusion reaction to extact some energy. The only problem is that nobody has found a way to let out just a little bit of energy at a time...

You could use water as the oxidizer for some other fuel. For example, pure sodium (a soft metal) releases a lot of energy when it comes in contact with water. But then your fuel is sodium, and your expense and hassles far exceed any oil based solution.

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1.2 liters per hour is pretty impressive. Is that at hull speed?
The 1/3 gallon per hour is a verbal claim by somebody connected with selling the boat. I just remembered the approximation. I never bothered to measure it myself. It applies to "cruising speed", which was defined in terms of engine RPM - 2800, 3000, something like that. This is below hull speed.

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I had forgotten about flywheel technology. It is probably one of the oldest technologies applied to mechanical propulsion, but has been replaced in the search for lighter, faster spinning engines. For a sailing vessel, it is very logical technology.
The problem with a flywheel that can store a substantial amoutn of energy is that it will act as a gyroscope. It resists rotating any direction except around the axis. I think that would yeild very "interesting" handling that varied with the amount of energy stored in the flywheel.

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Originally Posted by Alan Wheeler
You can build cars even higher than 70mpg. It just depends on the size, weight and CC rating.
How many here are old enough to remember the Energy Crisis? Volkswagen was running a commercial on TV about how they achieved 80 mpg with a modified Beetle. They took off all the doors, body panels, windows, etc - everything that wasn't necessary to make the car go. Then they found somebody who weighed 90 lbs to drive it, and they didn't drive very fast. It was a hack, but it still got pretty good mileage with an engine originally designed in the 1930's.

I'm not really sure what they were selling...
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Old 26-04-2006, 22:20   #97
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Kai, the chemical reaction one is easy. All you need is a conventional engine, or a steam engine or what ever, and place a meash of Platinum on the piston top. Now squirt hydrogen peroxide into the cyclinder. It instantly reacts and turns into a form of steam. You know those jet packs that you strapped to your back that they tried back in the 60's or 70's. Well that was the "rocket fuel" the things ran on.
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Old 26-04-2006, 22:24   #98
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Ah, Volkswagen.<G> Back in the early 70's my girlfriend had a superbeetle and I had a 289 Mustang. She got 28mpg on the highway and I got 21mpg, as I recall. When you figured out how much more my car weighed, and how much more powerful it was...it turned out the legendary Beetle was simply a lightweight POS with a tiny engine and that was all. Among the things VW has changed over the years are that the old VWs were all air-cooled engines, which are thermodynamically inefficient but cheaper and simpler--a good way to build "folks' wagons" for Hitler and an impoverished posterwar Germany. Knock any 3000lb. car down to 1800lbs. and gear it up for economy instead of performance, and you can do great things for mileage. Except...people keep buying the cars with more hp and more speed.
I once heard someone say the best definition of a psychotic society was one where you sold people cars with 140mph speedometers, and put 55mph speed limits on the roads. Hmmmm.....

For here and now with ON the shelf technology, diesel engines burning waste oil (frier oil) or steam engines (which have come a long way since the Stanley Steamer beat old man Ford every way except in public relations and false explosion scares) are both good technologies. Check out greasecar.com for what can be done here and now, if you have a diesel engine, space for a second fuel tank, and a spare thousand dollars. Oh, wait....that would subsidize an awful lot of diesel fuel for most casual sailors.<G>
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Old 26-04-2006, 22:32   #99
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Miniature fusion engines. No there's an idea
I can not imagine the gyroscopic effect being an issue while motoring. It would take a pretty large flywheel to have any real effect on a boat. As for the VW add, they really used to have a sense of humor didn't they
Wheels, Now we're talking real horsepower
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Old 26-04-2006, 22:42   #100
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Thanks for that link. Good info on the greasecar. So if higher compression increases horsepower, at what point does the compression start to reduce horsepower on a diesel?
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Old 27-04-2006, 01:10   #101
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The point where the piston gets a hole blown through the top or the head lifts off.
There is no theoretical limit, more of a physical limit. You may get more power, but you also expend energy to compress the air/fuel in the cylinder. The higher the compression, the more energy it takes to do so. The energy is heat whichis what makes the fuel ignite in the first place.
The physical limits are set by stroke and bore sizes and component mass to deal with the greater pressures and lastly, the flywheel to keep the engine kicking over smoothly. Thus the more compression, the heavier the engine, so once again, the power achieved is robbed. Hence why the ratio's that are arrived at on the designers table.
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Old 27-04-2006, 21:19   #102
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Nitrogyn cooled titanium heads with O-Rings. So, now we can keep the engine cool, and the compression in. Too much flywheel. HMMM? That is a difficult one.
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Old 27-04-2006, 21:49   #103
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Oh OK, if we are going high tech then, the flywheel aint a problem. You use a centrifugal balance system that as the engine idles, which is where it needs the flywheel weight, the flywheel has it's greatest weight on the outside. Then as the engine increases in RPM, the counter wieghts pull the flywheel into a smaller diameter, thus allowing you to use a light weight wheel and simply change it's diameter.
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Old 27-04-2006, 23:25   #104
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A mercury weighted flywheel could accomplish that pretty easily.
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Old 28-04-2006, 09:00   #105
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Still chasing

Still chasing the better engine when more results will come from reducing the load. Constant speed is fairly easy to tune for, the stop start is the hard part. That's why we now have computers in the cars. Here's another novel concept, if your car does 40 mpg with one person in it, it would get 80 mpg with two people in it, or it would half your fuel bill, whichever way you like to count. Stop start is changing the speed of mass, and that uses a lot of energy, reduce the mass and you reduce the energy required. A 250 cc motorcycle weighs about 300 pounds so it gets very good fuel economy around town, it suffers at highway speeds because of wind resistance. If you install a fairing you will improve the fuel economy. There are many fuel efficient engines, but there are many more inefficient habits. I own a belch mobile for the farm, but it uses less fuel per year than an efficient car, because it sits most of the time. It has used zero fuel for the past two months.
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