I saw a 911 Turbo Cabrio today and that got me wondering ....

Does anyone know the numbers for the 718 Boxster, 718 Cayman (any difference between plain and GT4?), and while we're at it, the 911 Cabrio and 911 hardtop?

TIA,

 

Check out the link to the discussion. I don't know the numbers for the 911 though.

https://rennlist.com/forums/718-gts-...l#post17138925

 

I don’t know the numbers in detail or all the facts. It’s my understanding that the 982 chassis was improved over the 981 in the rear, I suppose this was done for the 4.0. As for the Spyder vs GT4, I believe they’re equal in rigidity — but a side note fact is that the Spyder produces the same downforce as the GT4 which is no easy feat! I know very little about the 992 and don’t really have any interest in that model. I’d love to learn more nonetheless as well hopefully another member will post more details.

 

when the 718 was introduced there was no 4.0L engine, and I’m fairly certain the spyder generates some downforce but it is not the same as the GT4

 

THIS!!! The Spyder does NOT produce the same amount of downforce.

 

True but as a product manager that scale would have been considered, typically. I’ll fish up the videos with the structural additions in the rear.

 

The Spyder by nature of having its top cut off does not have the same rigidity as the GT4. It's a little less than half. Please refer to the link I shared above.

Also, the Spyder does not produce the same downforce as the GT4.

Per Excellence November 2019, the GT4 in the standard setting has "22 lbs front and 117 lbs at the rear at 125 mph. In the performance setting, these increase to 35 and 141 lbs, respectively."

Per Excellence December 2019, the 982 Spyder is the first Spyder to instead of reducing lift actually creates downforce. "With the Spyder's smaller front splitter and electrically operated rear spoiler, it generates 8.8 lbs of downforce while the front has 66 lbs of lift."

 

Tell that to Andreas. He specifically points out they both share the same downforce and it was extremely challenging. He would know, right!? (shrug, marketing?)

 

I think you are misinterpreting what he is saying. At no time does he say the Spyder has the same amount of downforce as the GT4. He says that they worked hard on the Spyder and it had its own unique challenges, but does not say they achieved the same amount of downforce.

Also, see halfmoney's link and reference.

 

Thanks for pointing that out, definitely misinterpreted.

Great link as well. Thanks, again.

 

Actually, you have it reversed, the Cayman (GT4) has its roof added, the Boxster (Spyder) was engineered as a roofless car 😜

Cheers,
Harry.

 

It is difficult to fathom that with 'nearly' identical aero from the windshield forward that the GT4 and Spyder can have such different figures up front... I just don't see how decreasing the depth of the front splitter could 'add' 88 lbs of lift!

 

I'm not an aerodynamicist but I will say that when watching some closed car racing (vs open wheel such as F1), the front lip is large. For example, cars racing up Pikes Peak have huge front splitters so there has to be some truth to the splitter aiding in creating downforce. Now whether or not it's creating enough to go from lift to as much downforce as Excellence is quoting is lost on me without seeing actual data from PAG but I have no reason to doubt this information so I'll just take it.

I will add though that all cars at "speed" generate lift and the car has to be cleaned up aerodynamically for it to create downforce. Whether or not a manufacturer will spend the wind tunnel hours to create downforce depends on the car. Obviously, a Honda Accord has no need for downforce. With the Spyder having a small extending wing, I believe that it's not going to create much downforce (as Excellence states only 8lbs of downforce (doesn't say at what actual speed) and to balance the front end with some lift seems about right for the goal of the car whereas the GT4 has a large rear wing and so the front has to be balanced with the rear downforce.

 

Not arguing just discussing , the front of the Spyder and GT4 are identical save for about 1" greater depth on the splitter, the side curtains and the under body flaps are the same as well, IMHO it doesn't account for the difference in figures... I think they are closer to the same, magazines don't always get it right.

Additionally, regarding the bolded, there would be no reason to want to induce lift at the front of the car, in fact with any amount of downforce being generated out back the need would be to balance that with downforce up front, not lift! AP comments that the Spyder is "slightly downforce... very neutral... doesn't have any lift", his words not mine. The video below is queued to begin right after he finished talking about the GT4 then describes the Spyder.

 

Sorry if you took my words as defensive or combative. Not meant to be. Also, didn't take your words as argumentative. Just sharing and responding with my "knowledge" on the matter. I do agree that it seems a lot of downforce for about 1" of extra lip but again, I'm not an aerodynamicist so I don't know how efficient their design is of the front end where 1" could affect lift/downforce that much.

I'm not tracking my car so it does't affect me and quite frankly, I don't notice it and don't know any better as I'm cruising down the freeway. As long as it's giving me many miles of smiles, it's all good.

Cheers. We're good.