Originally Posted by the_buch
(Post 15394511)
Weird - you'd think Porsche would want to reduce drag in the sportier modes? Plus, how much difference could that bit of drag make at average speeds more typical of running in Normal?
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Originally Posted by JR956678
(Post 15399142)
I would think it would be a small effect, but these days manufacturers have to operate within a number of sometimes conflicting regulations (CAFE, emissions, etc) where even small effects make a difference when combined. For what it's worth, this link https://www.porsche.com/usa/models/911/911-carrera-models/drive/active-cowl-flap/ is what I alluded to having read where Porsche says they do this with louvers for drag reduction purposes. While drag reduction is certainly valuable in sportier modes, the engine is more likely to be generating higher output and oil cooling would be more important in sportier modes. In addition to what happens in Sport or Sport+, this is also an "on demand" situation in Normal - based I would suppose on oil temperature.
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Originally Posted by JR956678
(Post 15399142)
For what it's worth, this link https://www.porsche.com/usa/models/911/911-carrera-models/drive/active-cowl-flap/ is what I alluded to having read where Porsche says they do this with louvers for drag reduction purposes.
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Originally Posted by the_buch
(Post 15399717)
The only question I still have is what oil temperature is better for wear and tear on the engine itself - higher oil temp=less friction=lower wear (though probably slightly higher oil consumption) ... or ... lower oil temp=lower heat stress on components?
The indicated temperature is where the temperature sensor is which may not necessarily be the hottest point. This link suggests the range is 180-210 and also explains this relationship between oil temperature and engine life. |
Originally Posted by JR956678
(Post 15401703)
I think it's a range rather than any specific temperature. You want the oil to get hot enough to vaporize any water that has accumulated in the oil which means that at some point in the engine it has reached 212 or higher, and that defines the lower limit. As temperature increases the viscosity decreases and the oil film gets thinner, increasing wear on the engine; the lowest acceptable viscosity for proper lubrication defines the upper limit.
The indicated temperature is where the temperature sensor is which may not necessarily be the hottest point. This link suggests the range is 180-210 and also explains this relationship between oil temperature and engine life. |
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