Engine Quiz

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30 out of 30 in less than 2 minutes.

I actually expected it to be harder - there were only a couple of questions in that quiz that required even reading or thinking about all the multiple choice answers.

Otto was one of them Kraut engineers - ya' know, like Porsche, and Wankel, and Goddard, and that Einstein feller... (just to name the first 4 that come to mind)

And it's OK for me to call 'em Krauts - cause I'm about half German myself. :D
 
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29 out of 30. I don't think a diesel engine contains more energy than a gas engine. The fuel might, but the engine doesn't. I object to the form of the question. It was a phrased poorly. "Energy" has a very specific meaning, and it wasn't used correctly. What if the gas engine held 1 gallon of gas, and the diesel held half a gallon of diesel. Wouldn't the gas engine then contain more "energy" based on the way the term is used in the question?
 
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Kernel Crittenden said:
29 out of 30. I don't think a diesel engine contains more energy than a gas engine. The fuel might, but the engine doesn't. I object to the form of the question. It was a phrased poorly. "Energy" has a very specific meaning, and it wasn't used correctly. What if the gas engine held 1 gallon of gas, and the diesel held half a gallon of diesel. Wouldn't the gas engine then contain more "energy" based on the way the term is used in the question?
Click to expand...
Actually the exact question was "Why does a diesel engine get better mileage than a gasoline engine?"

Gasoline = 114k BTUs per gallon
Diesel = 130k BTUs per gallon

Diesel has 16k more BTUs per gallon = roughly 14% more energy per gallon. More energy per gallon = more miles per gallon. And that is assuming the two engines have an equal overall efficiency.

Generally diesels have a slightly higher overall efficiency percentage than gasoline engines - primarily due to higher compression ratios and better volumetric efficiency.

So diesels get more miles per gallon due to more energy per gallon in the fuel AND greater efficiency of the engine itself.
 
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Kernel Crittenden said:
How was the answer worded? Including the little explanation.
Click to expand...

Correct Answer:
because it contains more energy
Additional explanation:
Diesel has a higher energy density than gasoline, meaning that each gallon burned makes more power.

I can see where you said the correct answer was poorly worded, because it was. HOWEVER, the other two answers, which were:
because of coal rolling
or
actually, it doesn't

are both so obviously wrong they could be dismissed out of hand.

Rolling coal refers to black smoke pouring out of a diesel's exhaust pipe. Most of that smoke is unburned fuel. Unburned fuel = worse mpg, not better mpg.

And to say a diesel engine doesn't get better mpg than a gasoline engine is patently false - as the EPA sticker on any diesel vehicle will show anyone who cares to examine one.

If they didn't get better mileage then locomotives, tractor trailer trucks, and cargo vessels - all of which can only maximize their profits by operating at maximum efficiency - would be running on gasoline instead of diesel.

So once you eliminate the two totally wrong answers, the partially right (though poorly worded) answer was the only one left. Process of elimination.
 
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