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> Fun facts, kinda OT, for the bored
lapuwali
post Aug 23 2005, 05:10 PM
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1 US gallon of gasoline contains 104,000 BTUs of energy.
1hp = 2,540 BTU/hour of energy consumption.

A typical car requires about 9hp to cruise at 60mph, given aero loads and rolling resistance from tires.

So, if engines were 100% efficient at extracting energy from gasoline, you'd get 273 mpg at 60mph in a typical car. Since most cars actually get less than 30mpg, most engines are extracting roughly 10% of the energy in the gas and applying those to actually propelling the car. Most of the energy is being thrown out as waste heat directly out of the exhaust, or in heating up the coolant, the engine itself, the gearbox, and the tires.

btw, hydrogen has 180,000 BTU/US gal, so if a liquid H2 fuelled engine were produced that only had the same efficiency as a 27mpg gasoline engine, you'll see 45mpg typically.

Pure ethanol has only 70,000 BTU/US gal, for only 18mpg. E85 would bring this up to 20mpg. Britt noted E85 where he lived was $2.10/gal v. $2.58/gal for gasoline, meaning E85 costs 81% as much, but only takes you 74% as far...

Now, as for the efficiency of a Mr. Fusion powered car...
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Sammy
post Aug 23 2005, 08:21 PM
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Last time I heard this same thing it was 15% to move the car, 25% for friction, and 60% lost to heat.

Not very efficent except that gas is sooooooooo darn cheap considering, even at today's prices.
Anyone want to guess at what a gallon of liquid H2 costs? Hint, you doan wanna know.


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Posts in this topic
lapuwali   Fun facts   Aug 23 2005, 05:10 PM
SGB   Its like- http://www.914world.com/...   Aug 23 2005, 06:13 PM
SLITS   my head and stomach hurt. and that's a Flux C...   Aug 23 2005, 06:16 PM
scottb   gaaaaahhhhh!!! it gets into that conv...   Aug 23 2005, 07:59 PM
sgomes   Jives with numbers I've seen before. Good stu...   Aug 23 2005, 08:01 PM
Sammy   Last time I heard this same thing it was 15% to mo...   Aug 23 2005, 08:21 PM
Cap'n Krusty   And to the cost of the Hydrogen, add the cost of m...   Aug 23 2005, 08:22 PM
lapuwali   Cost is an interesting issue, actually. There are...   Aug 23 2005, 08:42 PM
lapuwali   http://www.914world.com/bb...   Aug 23 2005, 09:12 PM
lapuwali     Aug 23 2005, 09:26 PM
sgomes   ...   Aug 23 2005, 09:30 PM
jkeyzer   entropy!   Aug 23 2005, 09:36 PM
Flat VW   ...   Aug 23 2005, 09:41 PM
SGB   entropy is my copilot.   Aug 23 2005, 09:41 PM
lapuwali     Aug 23 2005, 10:40 PM
grantsfo   I dont much about the energy held in various fuels...   Aug 23 2005, 10:48 PM
trekkor   Let's enter diesel. I can get as good as 16 m...   Aug 23 2005, 11:27 PM
TimT   I get 22 mpg out of my F250 when unladen, when Im...   Aug 24 2005, 07:27 AM
!   87 went down 3 cents at the corner this morning......   Aug 24 2005, 08:25 AM
Cap'n Krusty   <...   Aug 24 2005, 09:01 AM


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