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Old 03-06-2009, 04:04 PM   #77 (permalink)
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Join Date: Mar 2009
Location: Rochster, NY
Posts: 2

Tomato - '08 smart fortwo Cabrio
90 day: 41.46 mpg (US)
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Your grill block mechanism looks very nice! I've noticed this winter that the coolant temperature in my Smart swings wildly when the ambient temperature is low - a perfect application for a grill block.

I'd suggest basing its control algorithm on ambient temperature rather than on coolant temperature (perhaps with overrides at low and high coolant temps). For example, the shutter might be fully shut at 30F and fully open at 100F, varying in between. The exact calibration would require experimentation. That way the grill opening would always be "just right" for the ambient temperature rather than being oversized at everything other than the maximum expected air temperature.

One could even consider a vehicle speed input so that the shutter gradually closes as speed increases.
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