Quote:
Originally Posted by Allch Chcar
Hence why Diesel is more attractive to YOU despite only getting better mileage due to more energy per gallon. Diesels powered vehicles need to have a much bigger and heavier engine with displacement/turbo to get the same HP so either you accept half the HP or accept the same FUEL EFFICIENCY as a gasoline car. If you accept half of the HP you're not getting better mileage because it's just more efficient which it is, but because you're running a much lower output engine. It looks fine from a MPG perspective but there's no way we can grown enough biodiesel for anything and Gasoline became more popular than Diesel for certain reasons(not discussing that part here). The production per acre of soybean based biodiesel is worse than corn ethanol and the alternatives are all tropical based just like sugar cane.
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??? Diesel engines are more efficient EVEN VERY LARGE ONES than gas engines of any size under SPECIFIC circumstances.
One example at idle even very large diesel engines use marginal amounts of fuel, my 6.2 idles around .22gph my 3.8buick idles around .44gph. For a hypermiler idle fuel consumption is important in an autotragic vehicle.
Also most diesels DO have a higher thermodynamic efficiency than MOST gas engines, this isn't always the case, choose a 50's 2 stroke diesel and compare to a new honda insight motor for example. But under normal circumstances a diesel is literally more efficient thermodynamically.
Also, a diesel may have lower power output which you claim is the only reason for FE but that also doesn't really hold up, throw a 4 banger gasser of simlar power as my 6.2 into a suburban and compare its FE to my antique 6.2 and the 6.2 will still win. My experience with undersized gassers is that you get WORSE FE than with the larger engine, even driven responsibly.
Things are not as black and white as you make them, the truth is most diesels are built to a higher level of quality than a gasoline motor and generally have a higher thermodynamic efficiency than the cheaper gas motor. Diesels also do not suffer pumping losses which improves low end, low load efficiency, don't underestimate how large these two things are.
Cheers
Ryan