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991 GT3 GT3RS and 911R
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Old 05-13-2019, 02:08 PM
  #16  
Holdens
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Agreed! A spec Miata class with 50 other miatas racing around you is a BLAST! It may not be the fastest in a straight line but it will teach how to drive a car well at its limit....

Love the GT3 but rather track/race a Miata......


Originally Posted by loneregister View Post

Having driven both - the GT3 is Amazing and it is fun to drive and let's face it - it looks and sounds and drives incredibly. But the Miata is funner to hoon around the track and race in groups for many reasons. A major one being that for me, a bump, a spin, a brake job costs $100's of dollars. Not 10k's of dollars.
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Old 05-13-2019, 02:58 PM
  #17  
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Originally Posted by Bobby 911
+1
Neither one of you read the end of my post.
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Old 05-13-2019, 03:10 PM
  #18  
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Originally Posted by Quikag View Post
I think half the people here would have more fun bit*h slapping a Miata around the track sideways than taking their GT3 to 60% of its capabilities, but their ego won’t permit them to drive a lesser car.
If i had a left leg to push a clutch I'd have a Miata or Boxster/Cayman track car. I'd be able to go to the track a lot more and less worry about waddding up one too...thus becoming a better driver.

I do love my .2 GT3...it's fun at the track...boring to me on the street unless i want to go to jail.
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Old 05-13-2019, 03:13 PM
  #19  
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Originally Posted by CAlexio View Post
Neither one of you read the end of my post.
You wrote "So in conclusion (mine)... when you take two 911's with the same engine, with the major difference being a bunch of aero.. an average guy like me can only tell on track the difference."

Interesting comment, I would have thought that the road-going manners (street driving) of the two cars would have been quite noticeably different even by average guys like us. I would have expected the 911R to be more well-mannered (read = compliant) on the street than the .2 3RS. In fairness, this is your opinion and as they say YMMV. you're still lucky to have driven a 911R around Road Atlanta..that's awesome!
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Old 05-13-2019, 04:12 PM
  #20  
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Difference in downforce is immediately apparent to me in a .2 GT3 vs .2 GT3RS. Even off the track.

Look at the diffuser on this 992 mule. Notice how it's not just underneath the car like on the 911R and .2 GT3/RS. It comes up and exits at the bumper's edge right below the exhaust. This adds to my thoughts about center bypass exhausts. The stock center muffler on the GT3 acts as part of the aero. Removing it and replacing with a center bypass exhaust does affect aero to SOME degree since now you just have a big gaping hole there where a flat surface once was. Same goes for side deletes. You've now got two giant holes causing turbulence. Big car companies like Porsche can test their designs in a wind tunnel. You think some small mom-and-pop shop selling center bypass exhausts tests how their products affect aero? Nope. So I've always wondered how a center bypass and/or side deletes affect the aero of the car. It has to, no?

Last edited by FourT6and2; 05-13-2019 at 07:11 PM.
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Old 05-13-2019, 04:44 PM
  #21  
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What we need is downforce graphs so folks understand the downforce achieved at increasing speeds. As GrantG points out, not a lot is going on at slower speeds but it would be great to have the data to show how much/little impact there is a Xmph. Right now it's kind of like looking at torque without plotting it against RPM.
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Old 05-13-2019, 06:40 PM
  #22  
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Originally Posted by ILLCOMM
What we need is downforce graphs so folks understand the downforce achieved at increasing speeds. As GrantG points out, not a lot is going on at slower speeds but it would be great to have the data to show how much/little impact there is a Xmph. Right now it's kind of like looking at torque without plotting it against RPM.
Thank you.. for speaking sane words in the face radical fanboyism. Even Big fat spoilers like on an RS, don't begin to even produce meaningful downforce at anything close to road speeds (below 70mph)... when I read about people "feeling" downforce while driving on the road I have to laugh.. placebo effect and wishful thinking at its very best. I wish those same people actually got on track and felt the difference. And yes, a 911R and an RS are very very similar cars, minus the wings. And yes, at track speeds of 120-150mph on a straight under hard downhill braking, you can feel the aero. But you are absolutely fooling yourself if you think it makes any difference at road speeds.

Luckily.. we have some figures which can help corroborate this to some extent:

https://www.excellence-mag.com/issue...3-aerodynamics

". A more prominent front spoiler and rear wing meant that this 997.1 GT3 RS was the first road going GT-series Porsche to develop a meaningful level of downforce, with 33 lbs in the front and 88 lbs at 186 mph."

That's 33lb on an older RS, at 186mph.. the newer ones 991 go up to 700lb at those speeds, but try and see what happens below 70mph... the downforce is 7.04 times greater at 186mph than at 70mph. (186/70)^2.

I guess an interesting test for RS owners would be to get together with another RS friend, remove the wing off of one car, then do a blinded driving test... if one car feels more sensitive than the other at normal road speeds then you can at least have a semi-objective assessment of downforce at road speeds.

anyway, I'm sure I've raised more fanboy ire with this post than the white knight with the crypts in Game Of Thrones... I'll go grab a bag of popcorn.

I attached a pic of 911 downforce comparing no spoiler (R) to ducktail (nonspoiler Rs?) to fullnspoiler (turbo but close enough)

Name:  photo633.jpg
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Old 05-13-2019, 07:09 PM
  #23  
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FYI, the "downforce" I feel in the GT3RS at road speeds is most likely mechanical grip vs pure aero from just the rear wing. And by "road speeds" I mean hitting triple digits on twisty mountain roads (in Mexico) vs cruising on the highway albeit I'm not hitting 180 on public roads.
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Old 05-13-2019, 07:23 PM
  #24  
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Originally Posted by Quikag View Post
I think half the people here would have more fun bit*h slapping a Miata around the track sideways than taking their GT3 to 60% of its capabilities, but their ego won’t permit them to drive a lesser car.
haha, truth.
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Old 05-13-2019, 07:30 PM
  #25  
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Originally Posted by FourT6and2 View Post
FYI, the "downforce" I feel in the GT3RS at road speeds is most likely mechanical grip vs pure aero from just the rear wing. And by "road speeds" I mean hitting triple digits on twisty mountain roads (in Mexico) vs cruising on the highway albeit I'm not hitting 180 on public roads.
I think that's the point others are trying to make - mechanical grip is different than downforce. What you feel on the road b/w an RS and a GT3 is likely almost exclusively mechanical grip (combined with some placebo effect). GrantG/CAlexio are 100% correct that the downforce in all cars (esp. road cars) is mostly felt at high speed.
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Old 05-13-2019, 07:36 PM
  #26  
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Originally Posted by tstafford View Post
I think that's the point others are trying to make - mechanical grip is different than downforce. What you feel on the road b/w an RS and a GT3 is likely almost exclusively mechanical grip (combined with some placebo effect). GrantG/CAlexio are 100% correct that the downforce in all cars (esp. road cars) is mostly felt at high speed.
Yes, that makes sense.
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Old 05-13-2019, 08:15 PM
  #27  
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If you want to have some really cheap fun get a 125 shifter kart on a tight road course.
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Old 05-13-2019, 10:13 PM
  #28  
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Some data on the APR GTC500 Wing from website. The analysis reflects that most advantage of a large wing, is as expected, in excess of 120mph.
CFD DATA (TABLES)

The following table shows the actual data that were collected from the CFD analysis. The numbers in the table are represented in Pounds.



http://aprperformance.com/racing-pro...ustable-wings/
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Old 05-13-2019, 10:15 PM
  #29  
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Originally Posted by CAlexio View Post
SNIP....when I read about people "feeling" downforce while driving on the road I have to laugh.. placebo effect and wishful thinking at its very best.

Attachment 1303847
I cant tell any difference in my GT3 vs my 2017 GTS on the street as far as downforce. I can defiantly tell at Sebring, especially in Bishops bend at 110-120mph.

Last edited by mdrums; 05-14-2019 at 12:39 AM.
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Old 05-13-2019, 11:38 PM
  #30  
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Originally Posted by FourT6and2 View Post
Difference in downforce is immediately apparent to me in a .2 GT3 vs .2 GT3RS. Even off the track.

Look at the diffuser on this 992 mule. Notice how it's not just underneath the car like on the 911R and .2 GT3/RS. It comes up and exits at the bumper's edge right below the exhaust. This adds to my thoughts about center bypass exhausts. The stock center muffler on the GT3 acts as part of the aero. Removing it and replacing with a center bypass exhaust does affect aero to SOME degree since now you just have a big gaping hole there where a flat surface once was. Same goes for side deletes. You've now got two giant holes causing turbulence. Big car companies like Porsche can test their designs in a wind tunnel. You think some small mom-and-pop shop selling center bypass exhausts tests how their products affect aero? Nope. So I've always wondered how a center bypass and/or side deletes affect the aero of the car. It has to, no?
I'll see the underside of my GT3 in a few days but I don't believe a side delete is going to have much if any impact on the rear aero. The OEM mufflers are mounted high up in the rear bumper so only the piping may be in the air stream, not unlike the side deletes.

I think we can all agree if the diffusor on that GT3 prototype makes it to production it will be bad @ss.
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