4wd Mechanics

[Dave Eaton <dave.eaton@minedu.govt.nz>]

hi all,

a little while ago we were having a discussion about differing 4wd technologies
with regard to engine packaging.

well, i was reading up about the german class 1 racers, 2 types of which are
4wd. the mercedes racers are rwd with a fancy diff, but both the opel calibra
and alfa 155 are 4wd.

for those of you not familiar with the series, the fia class 1 is for
"production-based" saloon cars of no more than 2.5 litres (normally aspirated)
displacement.  to all intents, it's a silhouette formula with fully race egines
generating in excess of 450hp, active diffs and suspension, carbon fibre sheels
and semi-automatic steering.

anyway, all contestants have longitudinal drivetrains, front mounted.  the alfa
has it's v6 ahead of the front axle with the front diff in the gearbox (aka
audi).  this gives it good stability with a penalty of a higher polar moment. 
the opel was interesting because it's drivetrain was initially offcentre with
the front diff alongside the lh side of the engine and the rh driveshaft
traversing the sump.  this years racer has the front diff embedded in the
bellhousing ahead (!) of the clutch and flywheel.  drive from the diff exits
both sides of the bellhousing and is transferred via 3 transfer gears in a
"ear-like" housing running on each side of the engine. the front part of this
housing has the mounting for each front drive shaft.  all in all a very neat
arrangement which means that the motor can be mounted lower and further back
which improves the polar moment and the weight distribution and well as
lowering the c of g.

seem like a good alternative for audi ?  what do you think?

-dave.