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Old 09-23-2010, 07:14 PM   #1 (permalink)
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Join Date: Apr 2009
Location: Arkansas
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The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
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What is MPG penalty for a running radiator fan?

I've started working on my grill block, and so far so good, I can already tell the difference with only half of it blocked. Was getting ready to work on blocking more when the adage of not letting the rad fan come on came to mind.

My question is, how much is the cost of letting the fan kick on at temp as necessary vs the aero drag of a half opened grill? I know the conventional wisdom is to make the fan stay off, but why? Especially if the temp the fan comes on is raised a bit?

RIP Maxima 1997-2012

Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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