In the process of geeking out about 928s with interesting options, and collecting all the Exclusive department brochures, I thought I had a pretty good handle on what was available, options-wise. Then this guy rolls into the local Cars & Coffee yesterday with a '94 GTS with frickin' NACA ducts in the hood.




Ok, fine, aftermarket NACA ducts, not my taste, free country, whatever. But then he pops the hood, the workmanship is pretty good:



Really pretty good:



And it's sporting these Speedlines with 235/265-18 P Zeros on Speedlines with a really high offset. And because my GTS was parked right next to it, it became obvious that it has 18s on it, because it has F50 brake calipers and larger rotors. I had left my ruler at home, not sure how much larger.




I hate the connotation of the word 'stance', but in this case I'll make an exception:





Euro rear end:



Left rear suspension, clean clean clean.



The interior has a number of interesting bits, note the console work around the stereo EQ:


Still sporting a 300 kmh speedometer:



Driver's door panel:




So- 1994 German market 5-speed GTS, when I pull the VIN options, a couple of interesting things come up, it's a C99 market car, and it's an X38 car, so the front fenders are ostensibly wider (if they are, it's really subtle when compared to my GTS in the next parking spot)

But then you look at the options sticker in the trunk, and one of the 5-digit codes is 09971. Never seen that code before, a little Googling reveals three levels of prep for cars with Exclusive options.

09991- Made for the exclusive program - Exclusive option that could be installed on the standard production line
09981 - Vehicle inspection to VRS for the installation of "Exclusive" parts - Exclusive option that required the whole car to be transported to the Exclusive Department facility
09971 - Exclusive options that are unique to that given car.

So the story is that this GTS was built especially for Helena Suková, a Czech tennis star who was sponsored by Porsche at the time. And that it came off the line and got the X38 fenders and NACA ducts, then went to Porsche Motorsports and the engine was modified (I have no details on 'how', externally it looks like a 94+ configuration GTS motor, besides the strange air intake ducting), got Speedlines and big brakes, and the special interior pieces.

I wasn't very good about suppressing my enthusiasm about the car with the owner- he offered to bring some of the documentation that came with the car, so I'm hoping to learn more about the mods to the car. Hopefully more to report later!

 

Very cool. Beautiful car.

 

 

Those ducts look great. Neat car.

 

There’s something very ... strange about the air box. At first I thought the filter was just missing. Then I realized that the whole air box is shaped strangely.

Factory r134a.

Jump post cover dangling

 

Great looking car - has had a good life. Did you happen to see the mileage? Helena was 6'2" (1.88 m). Kinda surprised she had a sunroof

 

I think that I heard about this car, last year.
Are the initials of the owner MK ?

 

Those NACA ducts are located in an area of positive pressure gradient, or in other words where the local static pressure is less than ambient (location 6 below). This location is providing less air for the intake than the stock intakes which pull from the higher pressure air coming from the under the front lip. Properly placed NACA ducts should always be placed in an area of high pressure.



NACA ducts orginal purpose were to be a low drag intake, not necessarily an efficient high volume air intake, like say a ram air scoop.

 

This is my new favorite 928

 

I agree...

... Except that these ducts are not configured to feed the engine with air. Note that the air tubes to the air box still connect to the fan shroud. These ducts are 'open' to the engine compartment.

These ducts were the first thing on that GTS I stared at for a while.

These ducts *might* serve to extract air from the engine compartment. Except that, IIRC, if that was their intended purpose they need to be flipped 180 degrees.

I'm not about to pull-out and revive my 30-year-old 'book' knowledge of aero... but, I seem to recall that NACA ducts could serve either as low-drag intakes or extractors.

I'm left with the conclusion that these ducts were installed because: Cool (looking.)

 

I agree, but I’m not convinced that Porsche installed them. The reason is because Porsche engineers the cr*p out of every single detail. To add a functional duct that doesn’t serve a real purpose is antithetical to that. For instance, they could have gone to the air intake or to the brakes and actually served a purpose, but they don’t. And it seems it is not found on a single other 928. Anyway, just my two cents at the moment and it’s worth probably less than that!

I have seen great builds where super chargers or turbos were added to high end cars where the non essential added bits were professionally boxed in and painted so the hood and bumper look completely factory to those that don’t know the car. So that also adds to my thinking on this car.

 

Not anymore.

 

The lack of an emissions decal make me suspicious as well unless German market cars didn't have them?

Whether they were installed at the factory or not, it's a very cool car!
Can't wait to hear more about it.

 

You may be surprised to hear then that Porsche installed what seems to me the exact same NACA duct on the passenger side of the 968 turbo S/RS bonnet for an aesthetical reason, as the driver's side duct is purposed to feed fresh air straight into the single entry, front-mounted airbox. The passenger side however feeds air dust straight onto the PS bottle.

I cannot tell exactly from the pictures but it seems that the ducts on this GTS feed straight into the openings of the two inlet tracts.

As for Porsche possibly over engineering every detail on their cars, I'm curious if they went all the way to drill the pistons on this GTS motor...

 

If anyone absolutely falls in love with the NACAs, you can find them here (I have absolutely no idea if they are what’s on that car though):

http://www.sportwagen-zuerich.ch/con...nsaxle-models/