mjdcolo

I know the subject of this topic drew you in because you're saying, "What idiot would ask that question? Clearly aero makes a difference." While that is true, and we all know that, I can't help but ask myself, "Is it really going to make that much of a difference to my stock 911 or Cayman during a HPDE weekend when the average speeds are 80-90mph?"

If you look at some of the graphs of downforce versus speed you're not really seeing a massive amount of downforce until you hit rather high speeds; above 120mph. I've seen a few graphs over the years (certainly when researching my last p-car, the GT3), and I can't pin point them right now, but I hope most of your know what I'm talking about. So what happens in the corners where speed and grip are most important? Certainly the downforce is at a minimum, and now I'm relying on the tire grip, the camber, the entire suspension setup - not the aero. And if most of my time is spent in turns around a 1.5-3.0 mile track, then is the aero that important?

You can see where this is going for me: Buy a Carrera S, or Cayman S, and mod the engine and suspension only, so I don't have crazy aero as I drive it around daily, OR break the bank on a another GT3 (manual this time of course) or GT4?

Side Note: I sold the GT3 because the PDK did not have enough engagement with the car for me. And now, sadly a manual GT3 is way too pricy.

Thanks in advance for those that wish to give comments to this topic,
Matt

lcrain

If you don't want aero, don't buy a car with aero. But it absolutely makes a difference. Even sub 100 mph it can make a huge difference. And it isn't just grip in the corners. Performance under braking is massively improved with proper aero.

Sounds like you don't really want aero, which is understandable for a street car. If you can live with not being the fastest, then who cares? Do what you want and enjoy it.

stownsen914

Tough question to answer, really. On a modern sports car, aero is a lot more than a wing and a splitter, it's also 100 other small details all designed to work as a package (which of course includes a wing and a splitter). So back to back comparison would be tough. Not to mention, to do a proper and fair comparison, you'd have to set up the car after the aero is removed, which might include changing suspension parts etc. A big job that most might not bother to tackle.

Honestly, modern sports cars have such high limits, I'd guess the vast majority of drivers aren't pushing the cars enough to need the aero

LuigiVampa

A couple of stories about aero:

944 STORY

A bunch of years ago I was experiencing a really severe vibration on my 944 when I was driving somewhere north of 80mph. We looked at everything and could not figure it out.

I was at WGI, and was still experiencing the vibration, when my car was black flagged. The flagger called in that my splitter (Joe Toth) was oscillating on the front passenger corner.

Initially, when we felt the splitter it seemed to be firmly attached, but if we really pressed down on the splitter, it would move. What was happening is that the splitter would catch air, push the splitter down, which would dump the air, causing the splitter to pop back up. Rinse and repeat and that is what was causing the vibration.

The bottom line, is that even in a little ole 944, the amount of pressure pushing down on this splitter was enormous. It was absolutely pushing the nose down and working as designed.

DAYTONA

I was at Daytona in a Gen 1 Cayman with a big GTB1 type wing. During practice my crew realized that the wing was in high downforce position that we had been using at LRP. They made it more flat and I instantly picked up a second or so. Aero can also hurt, which is why the F1 teams use small wings at high speed tracks such a Monza.

Nowanker

Another 944 story... 300ish HP & 2500lbs
Turn 1 at Laguna is really nothing but a slight bend at the crest of the hill on the F straight.
No wing: The tail dances briskly(!) to the right, at 100+
Wing: Rock steady.

Olemiss540

Matt,

I don't understand how aero has anything to do with your decision making process on gt car versus non-gt car.

You can add aero fairly cheap if needed or you can spend coin on a serious track day GT car that has it already.

You have already owned the GT cars, are you worried the non-gt car is going to be too slow for you due to lack of aero?

Give me the keys to a 911 and I'm going to have a blast on track. Give me the keys to a Cayman and Im going to have a blast on track.

If I can easily afford the upcharge for costs (insurance, purchase price, consumables) for a GT3/4, hell yea Im tracking those instead.

I'd say you can't go wrong. Get what you can easily justify that will make sure you spend as much time on track as possible without costs effecting your decision to signup for events. There's always going to be faster cars but the fun is in dicing with similar cars,l and self improvement, not in winning the HPDE.

I have an extremely fast racecar that has absolutely HORRIBLE aero. Never have I thought I would have more fun with aero improvements. I have a project to improve my aero just because I am the tinkering type/hobbiest type though.

Zhao

Couple stories: Closed wheel car, 100kph corner, car was a loose on the edge. cranked the rear wing up a tiny bit more, instantly 100% stable in that corner. Open wheel car, A hole friend cranked the aero settings (technically a big more than just aero too) to close to max wonkiness to see how it affected it. 70ish+ kph corners turned into massive understeer. Cranked them the other way. Then 70ish+ kph corners turned into full drifts.

At the edge of grip, minute changes make big differences. So I would say aero at low speeds is still significant. Not necessarily in making you go fast, but making sure you aren't going slow. Or mentality fatiguing you.

Aero affects cooling too. We have a theory on why subaru's always seem to boil their brake fluid at one track I instruct at, and our theory is because the ones that do always seem to be equipped wiht stupid rally armor mudflaps. we think it messes up the airflow in teh wheel wells and traps the heat.

Gt3/GT4 factory aero probably does next to nothing though for lap times though. Factory aero shouldn't be a negative either. Home brew aero mods might make you worse though.

mjdcolo

All great points, and stories. Thank you all for sharing. Even at low speeds aero is making a large difference; not so much in terms of grip but in stability. I'm not going to be able to drive upside down in a tunnel at 50mph, but it will keep my front and/or rear from getting out of control. And I'm pretty sure Porsche designs their non-GT cars with stability in mind, even without the massive amount of aero that we see on the GT models.

mjdcolo

It does when I ask myself, "Am I going to want to put aftermarket aero on a non-gt car because I'm not finding the grip and stability I want, or better yet what I'm used to?" Tracking that GT3 around Mid-Ohio, PItt, and Road America has now spoiled me. So much so that I think the only way to go is to dive into a dedicated track machine (Cup Car, or mod the hell out of a 911 or Cayman S). That way I can also get a simple Porsche for the road (maybe even an old G-series), and it doesn't have to be some extreme model.

ProCoach

Aero for street driven GT cars makes little difference below 65-70 mph. People confuse adding d/f with reducing lift, which is what is present in most street driven GT cars. Have seen a lot of add-ons for GT cars hurt more than help.

For example, not much aero effect in WGI turns 7-8-9, significant in T5 and T10, borderline in T11.

Hardly any at VIR T1, T4A, T12 and T14, starts working in T3, more in T10 and through T16, a lot in the Uphill Esses.

Braking from terminal velocity at the initial hit through the first half of most high speed brake zones is a big help with aero, but can turn into ice pedal if you don’t bleed off as the d/f goes down.

Bottom line is that aero TUNING for balance achieves a good deal. Front splitters, dive planes improve stability in the front with little cost in drag, rear wings adjust to balance the front, with more exacting significant penalty in drag.

I’ve got tremendous amounts of data for everything from 911 Carrera RS up to and including 986/987/996/997/991/981/982 and 992 GT cars, plus older sports racing cars up to and including 908/3 and 917’s.

991.2 GT3 RS and 992 GT3’s with good track day drivers at 1:57 at ViR and the Glen, plus race cars (981 GT4/718 GT4 ClubSports, not 4-liter) at better than that. The last ten years of Cup cars will REALLY spoil you. THAT is about the best GT aero in something approaching all out GT3 cars like the GT3 R.

It’s all about comfort with the balance of the car. Anything you can do to enhance the balance and stability front and rear working together will cause drivers to have greater comfort and confidence, which allows commitment. That’s where lap times come from.

Do it, OP! You’ll never regret it, especially in T7, the Carousel, the Kink and at Turn 13!

Cory M

It sounds like you are doing track days and not competing in a race or time trial series. How important are your laptimes relative to the other cars in the track? Do you care more about how you stack up to others, or how your laptimes compare to your own personal best? The fact that you're asking the question here makes me think you should just get the faster car with aero. This is Rennlist, so if this thread continues it will inevitably end up with a unanimous recommendation for a brand new cup car and toterhome

If you decide to get the car without aero just promise you won't use it as a qualifier before talking about lap times and put it in the title of your YouTube videos

mjdcolo

Lap times are important to me when comparing them to my personal best. I'm always looking to improve - to me that's the fun of doing them.

And you are right about Rennlist! Everyone will say "Go for the Cup Car!"

LOL! I promise!

ParadiseGT3

Trying to speak to your vehicle history, with pb lap times relevant to your decision --

If you go the modded Carrera or Cayman route you'll likely never match .2 GT3 times. Unclear if you're content forgetting .2 GT3 performance/lap times (and engine?) and just maximizing a different platform.

Find base .2 GT3 aero noticeable as compared to a base 992 Carrera, for example. Believe the cars are similar enough that that variable can be isolated among all of the other component differences.

.2 RS aero definitely noticeable as compared to base .2 GT3. Mostly in the first half of high speed brake zones, procoach spot on per usual. Later on the brakes and more control with + aero.

Do you need it? Not if you don't know what it feels like... Would you miss or really notice absence of GT3 aero on another, completely different platform? Probably not, particularly if it's not a 911 and you're at a much reduced pace.

So, maybe best approach would be a Cayman with some reasonable mods (no aero), then back into a GT car with factory aero when budget permits?

Zhao

Improving by improving the car isn't improving though IMO. If you're fighting your past lap times only (which is how I got fast at HPDE's), go buy one of the 'slower' car that comes out to pca events, do whatever it takes to get -2.5 to -3.0 camber in the front, whatever that number is less .5 in the rear, put some 200tw tires on it, light duty race pads, and go.

To me that's a 987 or a 997.1, 996, or even a 986 if you go real cheap. Now you have a consistent car to learn on and it has enough power to pass a lot of cars it shouldn't if you take corners better. It'll also be cheaper on consumables, both from cost for rotors/pads/tires/wheels, and not wearing out the edge of tires from lack of camber. Those cars are also more raw than something new so it'll be you doing more of the work.

New or fast cars can be nice on the track, but they have barriers to going faster such as being worth too much to risk, or too fast on the straights to take the corner properly, and consumables on newer Porsches can be ridiculous. 10 sets of tires on my GT4 is the cost of an entire 987,

mlct

All the reviews of the new GT3 RS and GT4 RS suggests that factory aero makes a difference. I agree with those above that say the more advanced suspension, horsepower for some, and lighter weight for some (911 Cups in particular there) street 911's may be what you are looking over.a modified Cayman. My experience below is with a track only modified 981 Cayman Clubsport for HPDE sessions so if you are going that route it might be relevant. For me aero works.

Procoach is doubt correct about the effects of added aero. While I have not attacked any brake zones yet to feel that difference mentioned I definitely have more grip overall with the various Verus Engineering products now on my 981 Clubsport. Note: the car was already modified by its previous owners (thanks!) with vented front venders, dive planes, JRZ 4 ways, a 997 RSR style rear wing, a 4.25l Deman engine (500+ HP), and various other items so not a stock Clubsport at all.

Briefly:

Last year I added the Verus Front Splitter and Rear diffusor, lowered the ride height and put on stiffer springs needed to stop the car from bouncing off the track. I felt more grip but didn't set any dramatically faster lap times at Lime Rock (down .2) and nothing really at Watkins Glen (still roughly a second slower than I had down in my old GTB1ish car before I wrecked it at WGI back in 2000).

This year the Verus dual dive plans and swan neck rear wing went on and wow.

- I set a new personal best at Lime Rock in my first few laps out and was not driving particularly well (IMHO) or very aggressively. The shocks were rebuilt over the winter but I think that is due to the new rear wing as I don't think my..uh..private parts got any bigger over the winter! That new best is a 56.1 down from a 57.08. A pro did a 54.8 that day so more to go... .

- a personal best in my first visit to Watkins Glen this year and, once again I don't think I was on the apexes as I should be. That was a 2.00.62 down from 2.03.17 (2.02.4 in my old car back in 2019). This was with the same high downforce setting (9 degrees angle of attack which is on the high side for the Verus wing) I used at Lime Rock. I will try less rear wing at the Glen soon to see if I pickup more speed on the straights. There is a video on YouTube of pro Jan Heylen doing a 1.51 in a Clubsport from a few years ago so lots more time to go. Other non-pros in the 1.50's too so under 2 min is a reasonable goal for me.

So far the Verus products are well designed and built. Very happy with them.

Good luck,

Mark
P.S. now you might ask why modify an already great car. A silly thing to do I agree and would not work for racing as the car is on the heavy side. I blame iRacing and rFactor2 as driving the 911 RSR (the "old" GTE car) "felt" awesome so I decided I wanted some aero but didn't want to go the Cup Car or non-Porsche route. Also tried the old Williams or the new Mercedes F1 cars in iRacing. You hardly brake or lift at Lime Rock. I could develop some bad habits driving those F1 cars too much.