|
jdemaris
02-10-2006 17:27:06
|
|
Re: How does a Diesel become 50% fuel efficient? in reply to DanDHA, 02-10-2006 10:04:25
|
|
| |
I think there several issues that are relevant - first being real world experience versus theoretical. E.g. Another poster mentioned higher efficiency due to modern technology. Now, if that held true in the real world, new diesel pickup trucks would be more efficient than they were 20 years ago, and in many cases, they are not. My 82 1/2 Chevy 4WD diesel pickup gets up to 25 MPG. Try to buy a new equivalent truck that will do the same. Our 91 diesel Volkswagen and 81 diesel Chevette both get 50 MPG plus on the highway. What are the best new cars getting? If you want to see some good comparisons of tractor fuel efficiency, look at the Nebraska tests and the "gallons per horsepower hours" ratings. The most efficient tractor tested up to 1985 was a 1983 Yanmar turbo-diesel with the John Deere 1650 name-tag on it. The next most efficient was a 720, two-cylinder John Deere tested in 1956 - obviously old technology. As I understand it, some of the highest diesel fuel-efficiency ratings that have been achieved are in the locomotive industry - if rated by how much fuel does how much work. Even so, they waste much power into heat-sinks. Back in the 80s, Deere Co. G.M. and Ford were all experimenting with super-insulated, extremely hot-running ceramic engines. The idea was, that if the engines did not conduct heat to the outside air, and did not send it out the tail-pipe, then more energy would go towards doing work. I suppose it didn't work, haven't heard about it lately. As already stated, a steady RPM in the peak efficiency curve certainly helps. And with a diesel versus gas - well diesel weighs more per gallon and has more BTUs per volume - so it inherently provides more bang for buck if gas and diesel are in the same price range per gallon. Same reasoning goes to using grease/cooking oil since it weighs more then diesel fuel, and thus has even more BTUs per volume.
|
|
|
