quattro Digest, Vol 10, Issue 86

[Larry C Leung]

Mike,

The energy goes into various places besides making the car go 
forwards (or backwards!), mostly due to what is generally called
frictional losses. Potential energy sinks:

Heat (into the drivetrain parts, air, lubes in the driveline, etc. -
largest of the losses)
Sound (all that whirring noise, that's losses!)
Vibration (essentially work that's wasted in making parts vibrate up and
down or whatever)
Hysterisis (flexural absorbtion in the tires)
Other mechanical losses (now we're getting into minor bits, shock
absorber heat, spring flex, etc)

Since there are more bits to absorb in an AWD car vs. 2WD, there tends to
be greater losses. 
Don't know what losses are caused by the diffy fluids that shall remain
nameless in the center of post
'89 quattros......, although my understanding of those particular diffs
(also known as Quaiffe's) is it's
mostly a mechanical set-up, with lot's of little bits, allowing for much
of the same losses as the overall,
just on a much smaller scale....

LL - NY - a.k.a. the Physics Teacher


> ------------------------------
> 
> Date: Thu, 26 Aug 2004 08:27:17 -0400
> From: Mike Arman <armanmik at earthlink.net>
> Subject: drive train losses
> To: quattro at audifans.com
> Message-ID: <4.2.0.58.20040826073546.00ad7bb8 at mail.earthlink.net>
> Content-Type: text/plain; charset="us-ascii"
> 
> 
> 
> I have to take issue with the idea that you can "lose" 100 hp in the 
> drive 
> train.
> 
> Where does this energy go? 100 hp is (at 33,000 ft. lbs per hp) over 
> 3 
> million foot pounds, at 746 watts per hp, it is 74.6 KW, enough to 
> run your 
> whole house, central A/C, big screen TV and all. This energy simply 
> does 
> NOT "disappear" in the drive train.