[s-cars] Belly pan blues (95 S6A)

[Taka Mizutani]

I agree about using the OE pan. I've never had a problem with the OE pan.

Now if other listers want to make a metal belly pan for whatever reason,
well
so be it. I doubt that it would cause any aerodynamic issues due to the
nature
of the UrS, but that is an educated guess. I think rather than lift, the
more important
thing to consider are the cooling issues:

1. the belly pan affects intercooler efficiency w/ the stock intercooler
2. the belly pan may affect oil cooler and radiator efficiency
3. the belly pan may affect airflow through the engine compartment, hence
points 1 and 2

Cleaning up the air underneath the car would, IMO, actually improve gas
mileage. This
has been proven with the WRX and the STi, using the OEM aero pieces from the
later
model on the earlier cars. I know that these pieces were definitely tested
in a wind tunnel,
but they are basically completely flat.

My hypothesis is that by cleaning up the airflow underneath the car, you
would be able to
reduce drag enough to see a 1-2 mpg improvement on the highway. Rather than
reinventing
the wheel with the belly pan, I'd look at fabbing some flat-bottomed pieces
for the rest of
the floorpan and cleaning up the undercarriage on the back end of the car.
With the brick-like
aero of the STi (big hood scoop and big wing) seeing a big improvement, the
much slicker
UrS should see an improvement- some STi owners were reporting as much as
4mpg difference
on the highway, which would result in a halfway respectable 26-27mpg.


Taka


On 1/11/07, Dave Forgie <forgied at ae.ca> wrote:
>
> Taka: You are taking this beyond all belief. It was a causual comment
> meant to suggest, there are consequences of lift and that the metal
> belly pan designers should consider that because I can guarantee that
> the plastic belly pan designers did.
>
> I like said, just use the OE plastic pan. It is well designed and will
> be
> proven to be reasonably priced after the aluminum pan design is
> completed and installed. (The is an OPINION)
>
> Dave F.
> >>> "Taka Mizutani" <t44tqtro at gmail.com> 01/11/07 11:36AM >>>
> Dave-
> What is your evidence that a belly pan made of metal would cause
> excessive
> lift?
>
> At what speeds?
>
> How much lift?
>
> What is the differential between the OEM plastic belly pan's generated
> lift/downforce vs. the metal one?
>
> How do you know that lift is even generated and if so, that it is due
> to the
> belly pan?
>
> Did you or did you not take into consideration the fact that the MBZ
> race
> car generates downforce?
> That said downforce being disrupted by the bumpy road caused excessive
> air
> to flow underneath the
> car, something that apparently was not anticipated?
>
> Audi UrS cars do not generate significant downforce. Your hypothesis
> that a
> metal belly pan would
> cause lift at all, much less lift significant enough to lose control of
> the
> car is not based on sound
> principles.
>
> Taka
>
>
> On 1/11/07, Dave Forgie <forgied at ae.ca> wrote:
> >
> > I knew somebody would take exception to my "back flip" hyperbole.
> My
> > point was if you go out and reinvent the wheel without the proper
> > tools,
> > e.g. a wind tunnel, then there could be bad consequences.
> Admittedly,
> >
> > not as extreme as in my example, but nevertheless, added lift can,
> in
> > no
> > way, be a good thing.
> >
> > On the Mercedes thing, who do you think said "OH, SH*T!!" first, the
> > driver or the engineers?   I think the engineers watching the race
> live
> > or
> > on TV. They would see what was happening earlier than the poor
> > driver who was very likely very confused why there was no road noise
> > and the steering suddenly became very light while the rev limiter
> was
> > being hit.
> >
> > Dave F., P.Eng.
> >
> > >>> "Taka Mizutani" <t44tqtro at gmail.com> 01/11/07 10:32AM >>>
> > I think equating a metal belly pan to the back flip action of the
> Benz
> > you
> > mention
> > is a little bit beyond hyperbole and is overly alarmist.
> >
> > I agree that the OE belly pan is probably the best solution, esp.
> > taking
> > into account
> > cost.
> >
> > Taka
> >
>