Aero mods

[J-Dub]

What have you done to make your car more aerodynamic? Less lift, more down force or simply less drag?

I have a 718 Cayman GTS and am looking at what the GT4 and GT4RS have for inspiration. I see they each have panels under the rear side of the front wheel wells to evacuate the pressure and reduce lift.

The GT4RS parts are readily available and relatively affordable. Highly considering.
https://www.suncoastparts.com/product/sku718rsubs.html


There is a similar part for the 991 chassis.



Edit: the 4 piece kit that I ultimately purchased is PN is 9GT-807-913

The 6 piece kit can been seen with this link:
https://www.suncoastparts.com/product/pkrsscoops.html

The two extra pieces separately are available here:
https://www.suncoastparts.com/product/s ... guide.html

[blueline]

What have you done to make your car more aerodynamic? Less lift, more down force or simply less drag?

I have a 718 Cayman GTS and am looking at what the GT4 and GT4RS have for inspiration. I see they each have panels under the rear side of the front wheel wells to evacuate the pressure and reduce lift.

The GT4RS parts are readily available and relatively affordable. Highly considering.
https://www.suncoastparts.com/product/sku718rsubs.html


There is a similar part for the 991 chassis.

Not sure on your car, but if you increase the angle of attack on the rear wing on a GT4, you are instructed to remove the diffusor ducts in front of the front wheels to compensate for the increased downforce on the rear of the car, so I would imagine that you'd need to figure that situation out before adding any aero bits under the car. It will make a difference.

I've attached my GT4's "Driving On the Race Circuit" factory manual that I managed to acquire in pdf and renamed. (See page 5 of the Race Circuit manual.) The pictured parts might be the same as one of the ones in the kit you're contemplating.

Also, the bottom of a GT4 is completely covered which might make a difference too. Not sure how the bottom of your GTS is configured.

Then there is the rear wing to consider. Are you thinking of adding one? There is added benefit on track. For mine, I switched to RSNV's wing risers that I got from Soul to get the wing higher so it would have a better chance of catching the air slipstream from the roof.

2021 Porsche 718 GT4 'Driving On The Race Circuit' Factory User Manual.pdf

(5.54 MiB) Downloaded 111 times

[J-Dub]

Hey Tim,
On the GTS models we don't get the front of the front wheel air dams or the fixed rear wing so no adjustment opportunities there. We also have the same flat bottom as all of the other 718 models short of the rear diffuser area. I am mildly considering the GT4 rear diffuser, but more likely fabricating my own filler panel between the rear brace and the rear valence as the GTS has a open area there. Not sure how the base or S models look there.

I am definitely more interested in reducing lift than I am at adding drag and excessive down force. Of course keeping a good balance is paramount however I don't have much experience.

[blueline]

Hey Tim,
On the GTS models we don't get the front of the front wheel air dams or the fixed rear wing so no adjustment opportunities there. We also have the same flat bottom as all of the other 718 models short of the rear diffuser area. I am mildly considering the GT4 rear diffuser, but more likely fabricating my own filler panel between the rear brace and the rear valence as the GTS has a open area there. Not sure how the base or S models look there.

I am definitely more interested in reducing lift than I am at adding drag and excessive down force. Of course keeping a good balance is paramount however I don't have much experience.

After ragging on Porsche's software on the other thread I will happily now bend over backwards in praising the beyond awesome job the engineers have done at Porsche mastering aero. I think Porsche does it better (or as well as) any other car company, including the 7-figure super cars. (My Porsche bias!)

Figuring out aero is tough - waaaay beyond me. Too many variables that require big brains, big computers, big wind tunnels, big experience, big trial and error, and more!

I'd just be sticking stuff on there hoping it works while creating Frankenstein's monster.

191zq9oyypo4njpg-1801177952.jpeg (367.49 KiB) Viewed 1145 times

[J-Dub]

After further review we do have little spats in front of the front tire. They are not adjustable or removable like on the GT4. They do look cut-able thought I will review some of the GT4 and GT4 RS next week end.

@blueline , the part I am mentioning here is the part the article you linked called "inserts from the diffuser duct" in the front wheel well. Have you removed yours? I just reviewed the @JetFuelOnly YouTube video on this. I see opportunity here.
See @ 4:06

[blueline]

Yes, removed when I adjusted the wing per the Porsche sub-manual that came with the car, "Driving on the Race Circuit". (That's the pdf I attached.)

[J-Dub]

Today I installed the GT4RS strakes to my GTS, I got them from Suncoast in the link I originally posted. There is a 4 piece kit but you can add two additional pieces for a total of six if you wish.

I opted for the 4 piece kit, two pieces per side, a larger piece and a smaller piece. I was surprised how easily they installed. Each piece attaches with 4 screws, all required hardware was included or re-used from existing screw locations.

The larger piece requires a small square to be cut out and a small hole drilled. Since all 718s have the same underbelly tray, the square and the hole are already marked and perforated so this is a simple job. The square is so you can install a uclip over the hole and this is the 4th hole for the large piece, the other three holes reuse other under-body pannel fastening holes.

The small piece replaces one found on a GT4 however the GTS does not have one at all. If you have a GT4 two of the three needed holes are already there. I had to add three new holes to the wheel well liner, the 4th is reused from where the fender liner attaches to the side skirt area. The kit comes with plastic anchors to attach the three holes, they don't look to be super sturdy however i decided to give them a try. They are the type that you put them in the hole and then insert a screw and the little fingers expand locking them in place like a drywall anchor.

Bottom splash tray where you need to cut out a square and hole:


Two of the three holes you need to make for the small piece, note that the locations area already marked from the factory:


general pictures:





Reference:
Installing them on a GT4

installing them on a 911
https://rennlist.com/forums/991-gt3-gt3 ... gt3-7.html

[blueline]

I'm going to have to check that out further Jeremy - will watch the video. It looks interesting but I'm wondering how everything is affected. Aero is a hidden engineering art imo, relying on every bit and piece along with the car's natural dynamics all working in concert. Will it unbalance what's already set up? And if not, will it make a difference? I haven't a clue.

[J-Dub]

Agreed, it would be hard for the mortals like us to prove or disprove. The Gt4 got little ones, the GT4RS got bigger ones. Manthey racing offers the GT4RS ones in their kit. Bigger is better maybe?

[blueline]

Agreed, it would be hard for the mortals like us to prove or disprove. The Gt4 got little ones, the GT4RS got bigger ones. Manthey racing offers the GT4RS ones in their kit. Bigger is better maybe?

That's always been a good fallback in my book!