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Old 12-09-2008, 10:04 PM   #8 (permalink)
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Originally Posted by aerohead View Post
Darin,the SAE considers bearing losses to be so low,they are basically ignored with respect to RR.
Do you know if the same thinking applies to losses in the CV/universal joints, potential brake drag, and differential/transaxle resistance - strictly for the purposes of calculating RR?

I've been using 95 % efficiency for manual-transmission vehicles,as this is a value ascertained by the SAE in early research on pickups and big trucks.Basically,once you've arrived at aero and RR horsepower necessary at the drive wheels,you divide that value by 0.95,and it spits-out Bhp at the flywheel.
Good idea. Currently you can lump that into the "engine efficiency" figure in the calculator, if you're working backward from a known MPG at a certain speed.

Still some refinement to be done, for sure. Thanks for the feedback Phil.
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