Re: da numbuz-

["Rich Wagner" <drsavage@xxxxxxxxxxxx>]

Zamani wrote:

>My car produces 150 bhp @ 5500 rpm and 160lb/ft of torque at 3800 rpm.
>So does it mean that it has around 185 bhp and 200lb/ft of torque at the
>flywheel.

If the 150 hp was measured at the wheels, then yes, it's producing
significantly more power at the flywheel.  I believe that figure could be
anywhere from 185-200 hp.  Assuming that the engine is generating 185 hp at
5,500 RPM, that would mean it's producing 177 ft-lb of torque.  It would
produce even more at its 3,800 RPM torque peak.  If you have the power
produced at 3,800 RPM, and we can agree on a figure for transaxle
efficiency, I can tell you what the torque is at that speed.


>Is 22% a good figure for driveline drag? 

Good question.  I don't know for sure, but I think that's in the ballpark.


>Does the Alfa
>driveline setup produce more drag than other RWD setups (ie compared to
>a BMW)?

I doubt it.  Most of the power loss is in the meshing of the gears. 
Straight cut gears waste less, helical cut gears waste more.  I'd bet that
most contemporary, roadgoing gearboxes and final drives have about the same
efficiency.  Don't take that as gospel, though.  I don't have any good
references here to back me up.  I'm just going on my own engineering and
gearbox design experience.


Rich
Montrose, CO
'82 GTV6 Balocco

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