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Old 04-21-2021, 12:23 PM   #1 (permalink)
aerohead
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engine 'power' and cooling load

Example:
2012 Tesla Model S
* original Cd 0.26
* frontal area= 25.8333-sq-ft ( 2.4 meters -squared )
* 4,197- pounds, EPA test weight
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* @ 155-mph, aerodynamic load is 170.7366- hp ( top speed )
* @ 155- mph, rolling-resistance is estimated 26.8693- hp
* @ 115- mph, total road-load horsepower is est. 197.6059-hp
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* @ 85-mph, aero load is 28.1571-hp ( fastest legal speed in USA )
* @ 85-mph, R-R is estimated 14.7348-hp
* @ 85-mph, total road-load horsepower is est. 42.8919- hp.
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* @ top speed, the 'engine' power requirement is 460% higher than at maximum legal speed.
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* @ top speed, 'engine' heat flux is 460% higher than at maximum legal speed.
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* @ top speed, 'engine' and battery cooling load is 460% higher than at maximum legal speed.
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Had the Tesla Model S been specified for a lower top speed, it follows that, if it requires an 8%-drag cooling system for 155-mph, the Model S could easily have an adequate cooling system, with a fraction of 8% drag.
Ditto for Porsche's Taycan Turbo, and Turbo S, of 161-mph top speed.
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And since modern cars have ' multi-stage active cooling management of cooling...' , one would want to assign a 'spectrum' of cooling system drag, rather than a fixed value, like 8%.
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Additionally, as already mentioned by members, back-to-back comparisons between ICE and BEV variants of the same vehicle, offer the greatest insight into the difference in drag, including cooling drag, between any models of interest.
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Finally, I'll leave 33.333% of the argument unmentioned for the time being. Just to see if any of the 'experts' pick up on it ( be careful who you trust ).

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