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Old 10-29-2012, 07:04 PM   #29 (permalink)
aerohead
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gears

Quote:
Originally Posted by Vekke View Post
If I remenber correctly you also need to make your gearing same amount taller that you can save fuel on your aero mods. Secret for this relates that BSFC maps... Other option is to use P&G technigue and gearing is not that big problem.
Yes,both Gino Sovran,and Wolf Hucho emphasize proper gear-matching after streamlining in order to maintain the same load as before.It protects the engine from over-speeding,and keeps the engine operating on the same 'island' of it's BSFC map,yielding the biggest bang for the buck.
Sovran claimed that up to 60% of the streamlining benefit to mpg could be lost without it.
Carl Breer's streamlining team ran into this with the Cd 0.244 Chrysler DeSoto Airflow test mule.
I do believe that modern EFI technology may mitigate some of the loss,as manifold vacuum no longer controls fuel metering as in the carbureted-engine-cars with which early research was conducted.
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