Quote:
Originally Posted by dcb
I don't know about that whole tap dance there, glad I could clear up how bsfc charts are used for you.
But weight is a much more consistent unit of measure when dispensing energy, as you can see from that scatter plot, hydrogen at various pressure (or temperature) levels contains the same energy content for a given amount of weight. Hopefully that is intuitive.
And it is also interesting to note that your 200-250 bsfc numbers (which was NOT power/gallons, in case there is still confusion there no thanks to mech) clearly put the improved efficiency of diesels in a new light. Despite gasoline having slightly more energy by weight, gas engines are frequently found with %25 worse fuel consumption at peak bsfc, per unit of power output.
Brake Specific Fuel Consumption (BSFC) Maps - EcoModder
What the bsfc charts are telling you is that, for essentially the same ENERGY input, diesels are still more efficient. You need to rethink your diesel assertions. |
I think that's an artifact of comparing older powertrains because the diesels tended to have more lenient NOx emissions requirements (if a certain group of engines can run leaner they'll probably exhibit lower fuel consumption). Now that all engines have to comply with the same standards they're pretty much equivalent in terms of efficiency, at least AFAIK.
Edit-I think taller gearing/displacement on demand is easier than running multiple small engines and firing them up as more power is needed.