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Old 12-06-2010, 01:56 PM   #154 (permalink)
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One site I checked was 124k BTU for gas and 139k BTU for diesel, so that's 12% higher BTU content per unit of volume for diesel.

I wonder what the dyno figures would be in difference between gas and diesel engines at the load that would run both at best efficiency.

I think under those close to identical situations the difference is about 34% for typical gas engine and 40% for typical diesel, give or take a coupe percentage points for either.

Adding 12% to 34% would get you to 38% which is why I thought the most significant difference would be due to energy content in the fuel, with the rest due to other factors.

Pumping losses are something else I would like to see others opinions as to sources, but it would probably be better to start a different thread on that subject.

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