Discussion
When the stock wing is not enough...
Verus Engineering are developing a range of aero parts for the GT4, with dive planes available now and rear wing and splitter to come. The link below from Verus describes and illustrates aero effects and describes their thinking and design processes.
https://rennlist.com/forums/gt4/1103179-verus-engi...
Added link https://www.verus-engineering.com
Verus Engineering are developing a range of aero parts for the GT4, with dive planes available now and rear wing and splitter to come. The link below from Verus describes and illustrates aero effects and describes their thinking and design processes.
https://rennlist.com/forums/gt4/1103179-verus-engi...
Added link https://www.verus-engineering.com
Edited by gtsralph on Wednesday 17th October 19:33
I'd like to see someone get through the road legal test with that rear wing. And imo diffusors are a bit of a non event on road car ride heights. Ok perhaps they can clean up some of the air behind the car but it's not really going to generate significant downforce as people always seem to think without putting the car on the floor literally. There's way too much emphasis placed on downforce on road cars I think.
isaldiri said:
I'd like to see someone get through the road legal test with that rear wing. And imo diffusors are a bit of a non event on road car ride heights. Ok perhaps they can clean up some of the air behind the car but it's not really going to generate significant downforce as people always seem to think without putting the car on the floor literally. There's way too much emphasis placed on downforce on road cars I think.
Tend to agree - and manufacturers are playing the marketing game... 'because, race car'isaldiri said:
I'd like to see someone get through the road legal test with that rear wing. And imo diffusors are a bit of a non event on road car ride heights. Ok perhaps they can clean up some of the air behind the car but it's not really going to generate significant downforce as people always seem to think without putting the car on the floor literally. There's way too much emphasis placed on downforce on road cars I think.
Not really , lift in a road car is not very nice at speed.My golf is the 1st golf not to have lift, and look at the Audi TT , they had to fit a spoiler to stop you crashing it !
Take your spoiler off the 4.0 and report back at 140mph on hanger straight.
Take the diffuser off the 911r you prob kill yourself.
Any down force is better than lift and any extra is better in the wet.
But I'm not talking about lift am I? Merely that the recent emphasis on road cars supposedly producing huge amounts of downforce is imo total nonsense. And funnily enough for years the 911s before the 991R didn't have a diffuser, even those without a large rear wing and people didn't all kill themselves.
Edited by isaldiri on Thursday 18th October 22:24
isaldiri said:
But I'm not talking about lift am I? Merely that the recent empashsis on road cars supposedly producing huge amounts of downforce is imo total nonsense.
Certainly with Ferrari where SportAuto no longer tests them in the Mercedes wind tunnel, just repeating Ferrari's claims. The Porsche, well Mr GT3's claims are not matched by SportAuto tests. Generally diffusers have little to no effect but splitters and wings will.Faux aero bits are the similar to using carbon fibre, a light weight stronger material as trinket jewellery. However using carbon in body structure and having effective aero provide useful benefits.
Porsche911R said:
isaldiri said:
I'd like to see someone get through the road legal test with that rear wing. And imo diffusors are a bit of a non event on road car ride heights. Ok perhaps they can clean up some of the air behind the car but it's not really going to generate significant downforce as people always seem to think without putting the car on the floor literally. There's way too much emphasis placed on downforce on road cars I think.
Not really , lift in a road car is not very nice at speed.My golf is the 1st golf not to have lift, and look at the Audi TT , they had to fit a spoiler to stop you crashing it !
Take your spoiler off the 4.0 and report back at 140mph on hanger straight.
Take the diffuser off the 911r you prob kill yourself.
Any down force is better than lift and any extra is better in the wet.
R you are growing antllers like a moose,kill your self!,spoiler off the 4.0 ltr down hanger would be a peice of cake and probably quicker.
Try 165 in a 1971 st with no spoilers let alone a rear diffuser,front end lift was minimal.
But look at the rear window.
isaldiri said:
But I'm not talking about lift am I?
yes, in fact you are !The term "lift" is used when talking about any kind of aerodynamically induced force acting on a surface.
This is then given an indicator, either "positive lift" (up) or "negative lift" (down)
Negative lift, pushes the car onto the track.
the 911R created negative lift with the use of the diffuser and pop up rear spoiler, all though the pop up spoiler causes more drag.
it's the movement of air where design in cars has moved 10 fold, My GT3 as an example has the same negative lift as your massive rear Spoiler on the 997 4.0 as an example, and In my Golf in the front end it's the 1st time a Golf has not produced positive lift.
Lotus has again made big advances In the Elise and Exige in air flow on the same design car to combat positive lift.
The term "downforce", is the negative force as the word lift can get confusing as lift means up...
isaldiri said:
I'd like to see someone get through the road legal test with that rear wing. And imo diffusors are a bit of a non event on road car ride heights. Ok perhaps they can clean up some of the air behind the car but it's not really going to generate significant downforce as people always seem to think without putting the car on the floor literally. There's way too much emphasis placed on downforce on road cars I think.
Every mini SUV has a faux diffusor these days. It's de rigeur...
I'm with Yellow on this one. I've tried my 964 with the spoiler up and down on the track. Its quicker and no more difficult to drive with it down - so i dont bother with it now.
When I was racing 911 cups, I always set my rear wing on the lowest downforce setting. I think that aero is pretty irrelevant until you are looking at RSR level of motorsport - whatever that is nowdays. For a road/track car? not an issue
As i recall the 991R had no downforce at very high speeds and could be unstable as a result..This is the reason the Gurney lip was added to the Touring to counteract this,,The Touring has some downforce at high speeds although exactly half as much as the winged GT3 at all speeds.A high mounted wing is far more effective at generating downforce compared to an upright pop up spoiler.A pop up spoiler produces less downforce yet also creates more drag compared to a wing.
Its for this very reason that the Touring has a 3MPH lower top speed compared to the winged manual GT3..
Its for this very reason that the Touring has a 3MPH lower top speed compared to the winged manual GT3..
Taffy66 said:
As i recall the 991R had no downforce at very high speeds and could be unstable as a result..This is the reason the Gurney lip was added to the Touring to counteract this,,The Touring has some downforce at high speeds although exactly half as much as the winged GT3 at all speeds.A high mounted wing is far more effective at generating downforce compared to an upright pop up spoiler.A pop up spoiler produces less downforce yet also creates more drag compared to a wing.
Its for this very reason that the Touring has a 3MPH lower top speed compared to the winged manual GT3..
But it's not needed Porsche should take all aero off and have positive lift :-) not need for any pop up Spoilers then and the racers can go faster …..Its for this very reason that the Touring has a 3MPH lower top speed compared to the winged manual GT3..
Porsche911R said:
yes, in fact you are !
The term "lift" is used when talking about any kind of aerodynamically induced force acting on a surface.
This is then given an indicator, either "positive lift" (up) or "negative lift" (down)
Negative lift, pushes the car onto the track.
the 911R created negative lift with the use of the diffuser and pop up rear spoiler, all though the pop up spoiler causes more drag.
it's the movement of air where design in cars has moved 10 fold, My GT3 as an example has the same negative lift as your massive rear Spoiler on the 997 4.0 as an example, and In my Golf in the front end it's the 1st time a Golf has not produced positive lift.
Lotus has again made big advances In the Elise and Exige in air flow on the same design car to combat positive lift.
The term "downforce", is the negative force as the word lift can get confusing as lift means up...
I thought it is rather obvious when i said lift, it meant, well lift and downforce when the net overall 'lift' on the car was negative. The term "lift" is used when talking about any kind of aerodynamically induced force acting on a surface.
This is then given an indicator, either "positive lift" (up) or "negative lift" (down)
Negative lift, pushes the car onto the track.
the 911R created negative lift with the use of the diffuser and pop up rear spoiler, all though the pop up spoiler causes more drag.
it's the movement of air where design in cars has moved 10 fold, My GT3 as an example has the same negative lift as your massive rear Spoiler on the 997 4.0 as an example, and In my Golf in the front end it's the 1st time a Golf has not produced positive lift.
Lotus has again made big advances In the Elise and Exige in air flow on the same design car to combat positive lift.
The term "downforce", is the negative force as the word lift can get confusing as lift means up...
And you do understand how a diffuser actually works right? The 991R diffusor is most certainly not one that is going to generate a lot of downforce as it's limited in length due to engine location and again at road car ride heights diffusors do not do a lot. The issue with the 991R was keeping the rear aero more or less in sync with the front as they mainly kept the gt3 front spoiler. It was a balance issue rather than an outright downforce issue. not producing lift is obviously ideal (not that it seemed to hurt a 458 which as gtsralph mentioned SportAuto found to have positive lift on the front though) but the recent ever increasing focus on road cars producing large amounts of downforce is completely nonsensical.
Taffy66 said:
As i recall the 991R had no downforce at very high speeds and could be unstable as a result..This is the reason the Gurney lip was added to the Touring to counteract this,,The Touring has some downforce at high speeds although exactly half as much as the winged GT3 at all speeds.A high mounted wing is far more effective at generating downforce compared to an upright pop up spoiler.A pop up spoiler produces less downforce yet also creates more drag compared to a wing.
Again, i reiterate the issue is one of a balance, there's net overall downforce and there's the split front to rear (you want some form of rear bias most of the time). A standard 991 will hit almost similar speeds and doesnt have wings, diffusors or whatnot without this so called instability but the R is a bit different as it has a gt3 spec front spoiler. I believe SportAuto found the R to more or less have zero downforce, a bit of lift on the front offset by a bit at the rear. Now their test is at 200 km/h, I'm not sure if rolling road. Unless there is a significant change due to some extra turbulence at speed etc, I can't really see how a car with those figures will become 'unstable' at very high speeds.I remember when Audi first launch the TT there were a series of high profile accidents where drivers crashed their cars and the Audi stuck a lip spoiler on the boot lid to solve the 'problem'. Crashing a 250hp hairdrier because of a 2" lip spoiler wasnt fitted is laughable but the rediculous 'Palcebo' solution seemed to shut everyone up. A road car weighing 1500+ kg really doesnt need anything to help hold it onto a road surface. The same goes for a 911. If an early car doesnt need it, a new one certaily doesnt.
Road cars have been mimicking race cars for deccades. But if a GT3 cup doesnt respond that much to areo, it's lost on a road version. I've seen a Carrera cup race where a car lost it's rear spoiler completely in a shunt and went on to get a podium. it wasnt any slower without it. The areo effect on these cars is mainly asthetic.
Road cars have been mimicking race cars for deccades. But if a GT3 cup doesnt respond that much to areo, it's lost on a road version. I've seen a Carrera cup race where a car lost it's rear spoiler completely in a shunt and went on to get a podium. it wasnt any slower without it. The areo effect on these cars is mainly asthetic.
isaldiri said:
Again, i reiterate the issue is one of a balance, .
balance is all down to positive and neg lift though !No getting away from the fact, it's all about lift.
air flow is Key with Porsche and Lotus atm, hence why when you click the GT4 spoiler a notch you also have to change the front air restrictors.
Guess what it's all "lift" be it positive and negative.
The balance between the front and rear with regards to downforce/lift is imperative..Its needs to mimic f/r weight distribution which in the case of 911s 60 to 70% more downforce or negative lift on the rear..As Isaldiri points out the R's problem with instability arose from the front splitter reducing lift at the front which was out of kilter with the rear, hence why Porsche added a Gurney lip on the Touring's rear lid.
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