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Old 04-16-2022, 10:26 AM   #81
O C Diver
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Quote:
Originally Posted by mvweebles View Post
Can someone provide an objective citation that improved economy comes at the expense of efficiency? Because to my mind it's counter intuitive - efficient combustion of a hydrocarbon produces CO2 and H2O. Overall stats I could find show this is the exception, not the rule. But I couldn't find specific diesel (i could find trucks that show similar trend, though less pronounced). There could be a counter-current within the data, but without a citation, the macro data clearly suggests that efficiency follows reduced emissions which makes sense - extraction of more Btus makes more power and leaves less harmful byproduct (which is why I cited the California program to replace fish boat engines)

See below of what i could find. EPA comparison of actual emissions compared to efficiency. The counterintuitive trend - increased emissions and decreased efficiency- appears to be a 20-year anomaly from 1985-2005. Is it possible the anecdotal comments on this thread are dated?

So does anyone have any empirical citation (vs anecdotal) that diesel engines buck the overall trend that reduced emissions results in improved efficiency? Maybe diesels have a different trend, but hard to support that observation without data. I can tell you from experience that a Willard 40 with an old Perkins 6.354 (135hp) burns around 2.5gph at 7-1/4 kts whereas one with a JD4045T (120hp) burns closer to 1-3/4gph.

I'll say it again. There are several reasons to own an old mechanical engine. Fuel efficiency is not one of them.
Sorry, mine's anecdotal.

I have a 2002 Dodge with the Cummins 6BT 220 HP engine. It's factory original. With 518,000 miles, it still gets 19 MPG in the city and 24 on the highway.

After checking Dodge's latest offerings, the 2022 gets 12 MPG city and 18 highway. Motortrend's test on the 2020 with the same manufacturer's ratings, yielded 20 MPG highway.

So did the economy suffer for cleaner emissions?

Ted
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