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post #7 of Old 01-19-2003
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Gas Vs. Deisel (are we crazy?)


Several years ago I took a diesel mechanics course at orange coast college in southern california. The instructor was a guy named Terry Brown who was a local diesel mechanic. He seemed quite knowledgable. I was impressed enough to remember his name after 12 years.

One of the things he told us was that diesels are much more efficient than gasoline engines for two reasons.

1. the temperature of diesel exhaust is about 2000 degrees cooler than on gas engines so a lot of the energy generated in a gas engine is pushed out in the exhaust.

2. the energy content of diesel fuel is higher than for gasoline. The following paragraph is pulled from the web site "How things work"

Diesel fuel has a higher energy density than gasoline. On average, 1 gallon (3.8 L) of diesel fuel contains approximately 155x106 joules (147,000 BTU), while 1 gallon of gasoline contains 132x106 joules (125,000 BTU). This, combined with the improved efficiency of diesel engines, explains why diesel engines get better mileage than equivalent gasoline engines.

My experience with the atomic 4 has been different from yours. While the 2gmf diesel on my NorSea 27 gave me a cruising range of about 400 miles on 20 gallons, a friend of mine had somewhere between half and 2/3 of that on his ericson with an atomic 4. His boat was much lighter than mine and he was not pushing it when we cruised together. I was always the one playing catchup under power.

The engine on my norsea used less than 1/4 of a gallon an hour unless I really pushed it.

Diesel cars and trucks also get a lot more miles per gallon than similar sized gas powered vehicles.
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