Petevb

There are no part changes up front between the Touring and winged car that I can see on the PET, so it is likely down to the back. Rear aero does have a big effect at the front, often in unexpected ways.

Typically when you add a large, high mounted rear wing to the back of a car you'll see rear downforce increase (as expected) and front downforce decrease. There are lots reasons for this, but the main one is simple. Imagine sitting on a car's rear bumper: the back goes down, obviously, but the front goes up because the rear wheel are acting like the fulcrum of a seesaw. A big wing mounted out back applies a similar downwards force which reduces load on the front wheels slightly. This is then compounded because you've changed the car's rake: the front's ridding a little higher while the back's sitting lower, so the whole under-body is tilted tail down slightly compared to no wing, and that change in angle means the splitter and floor are not functioning as effectively to make downforce. So in a simple aero package more rear downforce equals less front downforce, and that's likely what's happening when you increase the 991.2 rear wing angle.

There's another way that a wing can interact with the underbody, however, and that can produce the exact opposite effect. Keep in mind that a wing functions by redirecting the air in its wake. To make downforce a wing takes the air flowing over the car and throws it up and back- we'd see a big rooster tail following a GT3 if we could visualize the air, and that rooster tail would be bigger for the winged car vs the Touring's spoiler. Done correctly this redirected air leaves a big hole of low pressure behind the rear bumper, and that low pressure effectively sucks air out of the diffuser making it much more effective. Of course the air feeding the diffuser needs to come from somewhere, so an effectively sucking diffuser can turn the entire underbody from the splitter on back into a low pressure area, making highly efficient downforce that's centered closer to the front of the car than the back (because on a raked car that's where the underbody is closest to the ground, and hence where the air's moving fastest).

So wing energizes diffuser energizes underbody and splitter and increases front downforce. That's likely the difference in front downforce between the Touring and Wing at the standard angle. Of course for that to work properly a delicate balance must be maintained between ride height, angle, etc, and the higher rear wing angle likely upsets that balance and is "too much of a good thing" as far as the front is concerned.

Or something like that. Even pros won't claim to fully understand all of the nuances of aero interactions.

Footsoldier

WernerE

^ Interesting comments, thanks. Reassuring words for the Touring at higher speeds, in contrast to reading the 911R felt less planted.

TRAKCAR

Brian Himmelman

Brian Himmelman

evilfij

C.J. Ichiban

You guys realize that any downforce quotes at 186mph are basically irrelevant for any track other than the ring, and that any downforce amounts less than 100lbs on one end are basically negligible on a 3200lb car at 120mph right?

So if the difference between two cars is 5-20lbs at one end of the car at 150mph that's not going to effect the car as much as fresh sport cup 2's...

This is from my daily driver GTS at Laguna Seca (with lame corsa oem fit tires)

928cs

It was possible to order a GT3 without PCM, in Europe at least. I still haven't seen one without it.

nszombie

My Touring has radio-delete (sorry for the bad quality). That was pretty much the only decision I never changed and so far no regrets.

928cs

Vow, Touring, no PCM, no leather dashboard and no sport-chrono!

Gravs

Yes awesome spec. Still have the AC though

evilfij

_fletch

This!

Oldmxnut

Oh to cut laps at over 1.5 G in a road car. Nice going sir.. I think we forget how advanced this latest generation is. Can any of us name a "touring" race car from the 90s, let along a road car that was able to do this...