Quote:
Originally Posted by MobilOne
I have a question. Take a Ford 4.6 and a 5.4. IIRC the 5.4 is a stroked 4.6. How would they compare, mpg wise with the same set-up? Then, how would they compare if the 5.4 had a taller rear end? Just thinking.
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Fuel economy by swapping in a taller rear end can be roughly guessed at by the rule-of-thumb that a percentage change in gear ratio will give you about half that percentage change in fuel economy. For instance, going from 3.92 to 3.64 (which is a 7% change) should give roughly a 3.5% increase in fuel economy.
Don't know about the change in displacement, though. Couldn't even venture a guess on that one.