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Car Forum / Driving, Maintenance, Tuning / General Car Topics / October 2007Most drivers do not coast down slopes, produce CO2 unnecessarily.
I try to convince others to coast like I do. Does any1 here do this ? Manufacturers can fit small & light air compressors on each axle to ( during braking ) use cars' momentum to compress air , to be released into air intake ( during acceleration ) as cool & forceful air, to increase torque. This design.will save fuel & reduce CO2. Nitrogen in tyres reduce rolling resistance & save fuel, yet very few people ( even lorry companies ) know this fact. Govnmnts can force cabs, buses & vehicle manufacturers to use nitrogen in tyres, petrol stations & tyre shops to offer nitrogen to customers. > I try to convince others to coast like I do. Does any1 here do > this ? Most current fuel injected cars turn off the injectors when you are coasting, so there is no CO2 generated when coasting. > Manufacturers can fit small & light air compressors on each > axle to ( during braking ) use cars' momentum to compress air > , to be released into air intake ( during acceleration ) as cool > & forceful air, to increase torque. This design.will save fuel > & reduce CO2. Well this might work. What sort of savings do you expect? Why not just get a Prius. It already does this. except it does it electrically. I believe the electric motor used by the Prius is much more reliable and efficient than the air compressor system you are describing. > Nitrogen in tyres reduce rolling resistance & save fuel, yet > very few people ( even lorry companies ) know this fact. > Govnmnts can force cabs, buses & vehicle manufacturers to > use nitrogen in tyres, petrol stations & tyre shops to offer > nitrogen to customers. This is total BS. The difference in rolling resistance between a tire filled with dry air (80% nitrogen) and pure nitrogen is trivial. I challenge you to find a single reputable study that will show any measurable increase in fuel economy from using pure nitrogen in tires. Ed | Most current fuel injected cars turn off the injectors when you are | coasting, so there is no CO2 generated when coasting. Impossible, engines will stall w-o fuel. Engines with manual gear box can be switched off & restarted by changing gear from neutral to e.g. 3rd gear ( depends on road speed ), before coasting ends, but engines with auto gearbox cannot. | What sort of savings do you expect? no idea | Why not just get a Prius Not sold in msia yet, not cheap either. | The difference in rolling resistance between a tire | filled with dry air (80% nitrogen) and pure nitrogen is trivial. Only in very low profile tyres. The higher is profile, the bigger is a drop in rr. | I challenge you to find a single reputable study that will show any | measurable increase in fuel economy from using pure nitrogen in | tires. I don't need any study to tell me ; I could feel a drop in rr right after nitrogen* replaced air, every time ( in 3 cars already ). If toe-in is not zero, or ( cheaper ) tyre walls are stiff or very low profile, or brake pads bind discs, then driver may not feel any drop in rr. Lorries' tyres are big, a drop in rr from * should be very significant. I & my relatives have no commercial interest in manufacture / sale of machines which extract * from air. >| Most current fuel injected cars turn off the injectors when you are > | coasting, so there is no CO2 generated when coasting. [quoted text clipped - 3 lines] > but > engines with auto gearbox cannot. I am talking about cars with automatic transmissions. The PCMs are smart enough to turn the fuel back on to keep the engine running if the rpms drop too low. > | What sort of savings do you expect? > no idea > > | Why not just get a Prius > Not sold in msia yet, not cheap either. Yet you are willing to suggest a new system that is not sold anywhere? > | The difference in rolling resistance between a tire > | filled with dry air (80% nitrogen) and pure nitrogen is trivial. [quoted text clipped - 11 lines] > in rr. Lorries' tyres are big, a drop in rr from * should be very > significant. Given identical tires, filled to the same pressure, there is zero chance you can detect the difference. > I & my relatives have no commercial interest in manufacture / > sale of machines which extract * from air. Ed > | Most current fuel injected cars turn off the injectors when you are > | coasting, so there is no CO2 generated when coasting. > Impossible, engines will stall w-o fuel. Funny, fuel injected engines have been doing just that for over 25 years. > Engines with manual gear > box can be switched off & restarted by changing gear from neutral > to e.g. 3rd gear ( depends on road speed ), before coasting ends, but > engines with auto gearbox cannot. Foolish. > | What sort of savings do you expect? > no idea Finally, an accurate statement. > | Why not just get a Prius > Not sold in msia yet, not cheap either. So plant a few trees to compensate. > | The difference in rolling resistance between a tire > | filled with dry air (80% nitrogen) and pure nitrogen is trivial. > Only in very low profile tyres. The higher is profile, the bigger > is a drop in rr. You don't get it. There is no difference in rolling resistance based upon whether an inert gas is used to fill the tire. > | I challenge you to find a single reputable study that will show any > | measurable increase in fuel economy from using pure nitrogen in > | tires. > I don't need any study to tell me ; I could feel a drop in rr right > after nitrogen* replaced air, every time ( in 3 cars already ). Placebo effect. > If toe-in is not zero, or ( cheaper ) tyre walls are stiff or very low > profile, or brake pads bind discs, then driver may not feel any drop > in rr. Lorries' tyres are big, a drop in rr from * should be very > significant. I dated a Lori once, she could deep throat a can of hairspray. > I & my relatives have no commercial interest in manufacture / > sale of machines which extract * from air. Still doesn't mean your not wrong. >> I try to convince others to coast like I do. Does any1 here do >> this ? [quoted text clipped - 26 lines] > > Ed I think the only real advantage to nitrogen is that as it doesn't leak out like air does the tires don't get soft, so that would give a slight mileage increase... unless you check your tire pressure once in a while like your supposed to and don't let them get low. Jeff DeWitt > I think the only real advantage to nitrogen is that as it doesn't > leak out like air does the tires don't get soft, so that would give > a slight mileage increase... unless you check your tire pressure > once in a while like your supposed to and don't let them get low. Regular old air is already 79% nitrogen. The difference in leakage rates is trivial. But even if true, after a few "refills" with regular air it seems like you would end up with a much higher percentage of nitrogen in the tires (if the oxygen really leaks out at a significantly higher rate). I think this nonsense with "pure" nitrogen got started when people heard race cars use pure nitrogen in their tires. For a racer, tiny changes in air pressure are used to adjust handling to gain hundredths of a second in lap times. Tire pressures change as tires heat up under use and "pure" nitrogen is slightly more predictable than regular air (mostly because there is no water vapor present). While this difference may make the use of "pure" nitrogen justifiable for racers, it is irrelevant for normal street usage. The companies that make the nitrogen generating equipment have been promoting the use of "pure" nitrogen in tire with dubious claims. You might be able to sell me on the idea that using "pure" nitrogen in large truck tires that may be recapped at least once, and go over a 150,000 miles is sensible. You will never sell me on the idea that the average driver gains any measurable benefit from the use of "pure" nitrogen in their tires. It is a borderline scam. Another thing - the machines use to generate "pure" nitrogen, are actually just changing the concentration from 79% Nitrogen to somewhere around 96% nitrogen. So you still have some of those evil other gases (mostly oxygen) to worry about. And one more thing - when the tire is mounted on the rim, it is not mounted in a "pure" nitrogen environment, so somewhere around 25% of the stuff in the tire will be regular old air even if you pressurize it with the "pure" nitrogen. This means that the "stuff" in a freshly mounted tire, pressurized with "pure" nitrogen will still only be around 91% nitrogen (versus the 70% in regular air). And almost certainly, anytime you add air to your tires to replace leakage, you will be adding regularly air. I'll wager you that a year after filling a tire with "pure" nitrogen, if you check the composition of the air in the tire, you'll find it is at least 12% oxygen. Is it really worth worrying about the difference? Ed <nitrogen in your tires> We should use helium. That would make the car lighter, and therefore get better gas mileage. Plus, you could suck some of it out of the spare and make funny voices at parties.  SignatureLife is too short to play cheap guitars. > I try to convince others to coast like I do. Does any1 here do > this ? Just the ones with repeat clutch/transmission failures. > Manufacturers can fit small & light air compressors on each > axle to ( during braking ) use cars' momentum to compress air > , to be released into air intake ( during acceleration ) as cool > & forceful air, to increase torque. This design.will save fuel > & reduce CO2. And the storage tank for all this compressed air, how much does -it- weigh and where exactly are you going to put it and who's footing the bill to have it inspected as required? > Nitrogen in tyres reduce rolling resistance & save fuel, Nope, not even close. > yet very few people ( even lorry companies ) know this fact. > Govnmnts can force cabs, buses & vehicle manufacturers to > use nitrogen in tyres, petrol stations & tyre shops to offer > nitrogen to customers. The latest scam. You think this all up on your own? Plain old air in tires is 78% nitrogen anyways. hardly worth paying extyra for pure N2^ >> I try to convince others to coast like I do. Does any1 here do >> this ? [quoted text clipped - 23 lines] > > You think this all up on your own? > I try to convince others to coast like I do. Does any1 here do > this ? It's illegal in most places. Graham
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