Quote:
Originally Posted by mwebb
10% improvement .... not very likely
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I did a little Excel heat energy calculation, using a specific heat of 1 kJ/(kg K) for air, and 2 kJ/(kg K) for gasoline. The air was assumed to be at 30 C (86 F), and the gasoline was assumed to be heated up to 90 C (194 F, and presumably heated up by engine coolant). A 14.7:1 mass ratio was assumed, too.
(1 kJ/(kg K)) * (14.7 parts air) * (30 C + 273.15 C) + (2 kJ/(kg K)) * (1 part gasoline) * (90 C + 273.15 C) =
(1 kJ/(kg K)) * (14.7 parts air) * (303.15 K) + (2 kJ/(kg K)) * (1 part gasoline) * (363.15 K) =
4456.305 kJ/kg + 726.3 kJ/kg =
5182.605 kJ/kg
Now, to find the final temperature of this mixture:
5182.605 kJ/kg / (1 kJ/(kg K)) * (14.7 parts air) + (2 kJ/(kg K)) * (1 part gasoline)) =
5182.605 kJ/kg / (16.7 kJ/(kg K)) =
310.3 K
or
37.2 C (98.9 F). This is a 12.9 F difference between the initial and final temperatures.
Given that my documented HAI gain of around 5% is done with an intake air difference of about 45 F, I would have to agree that 10% improvement with fuel heating seems rather unlikely.