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Old 11-21-2014, 10:03 AM   #4 (permalink)
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Originally Posted by Daox View Post
The radiator fan can pull some decent power, and alternators aren't that efficient. So, the fan should be avoided. However, if it only comes on 1-2 times on your trip, I'd just leave it.

On my Prius, I run a full grill block all winter unless I'll be going on the highway. Then, I remove one of the pipe insulation strips from the grill. That allows for plenty of cooling.
I have a variable speed fan that keeps the coolant returning from the radiator 10 degrees C below the thermostat opening temperature thus allowing the thermostat to mix warm and cool coolant and keep the engine temperature constant.

In normal running the fan stays off for 10-15 minutes and then runs slowly, if I go up a steep hill it speeds up. The amount of power used is typically 15W while the grill block appears to be saving several KW. So even though alternators aren't 100% efficient it doesn't matter as long as I save more than I use...

Originally Posted by Sven7 View Post
I'm almost positive there are threads that discuss this. Look up "bottom breathers" like the Corvette. It uses the high pressure zone in front of the air dam to shove air into the radiator.

Or just punch a 25 square cm hole in the lower middle of your grille block, since it won't affect that much.

Or rig up a flap in the lower middle of the block, with a hinge so it can open when you need it. Actuate by cable or solenoid.
Thanks for the search tip, helps to know what to search for.

They still seem to have the intake in the high pressure area though, and in a place my car doesn't have. The obvious places to put a hole and maybe flap on my car are in the lower grill block or in the undertray in front of the radiator which is a low pressure area so would need some extra effort from the fan possibly in return for gains in aerodynamics.
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