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Old 03-07-2012, 01:23 PM   #8 (permalink)
mort
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Quote:
Originally Posted by Bobux View Post
I guess a turbocharger will not help efficiency much, right?
Hi Bobux,
On a Diesel, especially something like you have, a turbocharger will improve efficiency substantially. At high power the Diesel engine is injecting fuel through most of the power stroke, and that fuel burns slowely so the equivalent expansion ratio is quite low. For a compression ratio of 16:1 at full power, (but not black smoke - does it do that?) the expansion ratio is about 4:1. Although the mechanical efficiency of the turbine is lower than the piston engine, there is a lot of power there. Using that power to increase combustion pressure and temperature is like increasing the compression ratio. So you waste less and improve thermodynamic efficiency win - win. Right up to the point that something blows out...
Roughly, the thermodynamic efficiency of a Diesel with 16:1 CR and 4:1 ER is 53% Increase the ER to 15:1 and efficiency goes to 66%

-mort
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