Quote:
Originally Posted by oil pan 4
I have seen plenty of test that show diesels get better fuel economy with cold air intakes until the ambient air starts to get around freezing.
In my diesel the air is heated to 1100'F adding more heat will waste power compressing the air and forcing the heat through the piston and combustion chamber.
Also adding more heat to the combustion process will increase NOx.
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. . . is a term I jot down next to my notes during data gathering. It means exactly that. One variable change on one side of the equation results in a change X on the other side of the equation.
I have seen dyno test after dyno test that shows how cold air in the diesel engine's exhaust produces better fuel economy. But, what are the changes in the SYSTEM due to the introduction of cold air? How does the system react? Also, what is the loading you are testing at? Pin all your variables except for air temperature and test at low cruising loads to test your BSFC (brake specific fuel consumption ). If you run a pressure sensor into your combustion chamber, you can see that the time delay between injection point and heat release is reduced with added heat and it can reach the point that injection timing advance will need to be reduced to take advantage. It is a small but measurable advantage. And yes, NOx is increased as a side reaction, but that is an aside, not the main point at hand.