Quote:
Originally Posted by jared1970
I was wondering, on a car like a Chevy Lumina, how much of a difference would blocking off the grill make? Would it even be noticeable? It seems like a pretty easy first step toward aerodynamics and I'm thinking about trying it.
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Every vehicle is different and cooling system drag numbers published in past research reflect a 'fleet' average for the aggregate of vehicles tested.
A loose rule of thumb would be that the Lumina's entire cooling system drag constitutes about 12% of the cars overall aerodynamic drag.
In loose numbers,if you were to completely block off the grille,you'd be shaving 12% off drag,and at 55 mph this would equate to a 6% improvement in highway mpg.(With a melted engine of course!) City mpg would essentially be unaffected,aerodynamically speaking,however,a quicker warmup can add thermal efficiency to the power plant.
Racing cars may have fully ducted and 'tuned' airways which can add as little as 2% to the cars overall drag.
It's been mentioned a number of times,that the cooling system of North American Aviation's P-51 Mustang actually produced a modicum of thrust do the the thermal expansion of the air coming off the heat-exchanger.
You wouldn't expect to see this in a car.