Why are 911 so fast around N-Ring?
10-31-2018, 03:53 PM
#46
The rear engine layout actually is an advantage on braking and corner exits. Simple physics, on acceleration the weight transfer to the back, and with the engine back there too there is a ton of weight acting one the rear tires pressing them firmly on the ground. On braking, the weight transfer forward. Front or mid engine cars, will have all their weight on the front axle, basically the car is stopped by only the front brakes. In a 911, with the engine behind the rear axle, the weight is also transferred to the rear axle, thus utilizing the rear brakes, and better braking performance. With the front brake less loaded, it heats up less and the brakes won't be affect by brake fade, this is in addition to the extra brake cooling details done by Porsche. When is the last time you heard someone cook their 911 brakes? Never.
Forgot, one other point about 911s being great performers in racing.
It's all about the corner exits. As I said, 911 have better traction out of corners, it means drivers can put the power down earlier, and accelerate quicker out of corners onto the straights. Other cars may have HP advantage for the absolute top speed, but they are useless on corner exits and they don't have the traction out of corners. That translate to 911 leading the first half of straights while the other cars are playing catch ups. Most will reach higher top speed near the end of the straight but since they have inferior brakes and higher speed, they will have to brake sooner.
In the braking zone before turn in, any racers worth their salt can and will adjust their line to prevent a passing maneuver, so even if the car behind is faster down the straight and caught up, it is still hard to pass a 911.
Forgot, one other point about 911s being great performers in racing.
It's all about the corner exits. As I said, 911 have better traction out of corners, it means drivers can put the power down earlier, and accelerate quicker out of corners onto the straights. Other cars may have HP advantage for the absolute top speed, but they are useless on corner exits and they don't have the traction out of corners. That translate to 911 leading the first half of straights while the other cars are playing catch ups. Most will reach higher top speed near the end of the straight but since they have inferior brakes and higher speed, they will have to brake sooner.
In the braking zone before turn in, any racers worth their salt can and will adjust their line to prevent a passing maneuver, so even if the car behind is faster down the straight and caught up, it is still hard to pass a 911.
None of this of course matters on a road car and yes, being rear engined gives the 911 it's own USP as it at least feels different to drive in today's world despite Porsche's best attempts to turn it every more into behaving like a mid engine car over the years but the layout is not one that is going to give it any sort of performance advantage.
10-31-2018, 04:46 PM
#48
I think we can all agree on certain advantages of RR layout, weight transfer, exit speed etc. the question is can you get the better side of the two worlds by moving the weight center of engine slightly forward like right on the rear axle or just a few inches before. I mean would there be a sweet spot between RR and MR?
https://www.roadandtrack.com/motorsp...rank-walliser/
https://www.roadandtrack.com/motorsp...rank-walliser/
10-31-2018, 08:22 PM
#49
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And that explains why Porsche GT cars ride in general considerably worse than say a Ferrari nevermind Mclaren I guess....?
911s were great race cars..... in the dim and distant past. Modern racing regulations have very much prioritised cornering speeds, especially where there isn't BoP to attempt to equalise the disadvantage of a rear engine. And even where there is BoP, Porsche have seen fit to turn their most advanced road homologated race car from a rear engined one to being mid engined. When is the last dedicated ground up race car Porsche have built that hasn't been mid engined?
None of this of course matters on a road car and yes, being rear engined gives the 911 it's own USP as it at least feels different to drive in today's world despite Porsche's best attempts to turn it every more into behaving like a mid engine car over the years but the layout is not one that is going to give it any sort of performance advantage.
911s were great race cars..... in the dim and distant past. Modern racing regulations have very much prioritised cornering speeds, especially where there isn't BoP to attempt to equalise the disadvantage of a rear engine. And even where there is BoP, Porsche have seen fit to turn their most advanced road homologated race car from a rear engined one to being mid engined. When is the last dedicated ground up race car Porsche have built that hasn't been mid engined?
None of this of course matters on a road car and yes, being rear engined gives the 911 it's own USP as it at least feels different to drive in today's world despite Porsche's best attempts to turn it every more into behaving like a mid engine car over the years but the layout is not one that is going to give it any sort of performance advantage.
Where rear engine screws things up a bit is aero, and that may be the main reason Porsche had to go mid-engine for RSR. Just compare aero of the current RSR with the previous generation.
Old:
New:
That underbody aero is super powerful and is more efficient than the wing. Significantly more downforce in the rear allowed to proportionally up downforce at the front as well. That's what gives a big boost to cornering speed rather than changes in handling. When Porsche announced the reversed RSR they said exactly that - huge aero benefit that others in the series were taking advantage off already, and only 1-2% change in front-rear weight distribution, depending on ballast requirements.
10-31-2018, 08:37 PM
#50
If you look at club and state level the prevalent cars are non-GT, probably the most common are Caymans (various generations).
There maybe certain DE events where GT cars dominate - they are the exception rather than the rule.
When it comes to timed competition I don't see many 991 GT3s at all. Older heavily modified variants are there in abundance.
The fundamental issue is tires, wheels and clearance - to put it simply a Porsche on 18 inch wheels with soft rubber will easily knock off something on Cup 2s. Thus a well setup and worked over 997 Series 2 is a good proposition.
In regard to other high end cars it's more to do with access to parts and servicing e.g because of my location I have to order everything from a dealer on the east coast for my 720s - which incidentally has zero problem dispatching any Porsche I come across including two of my own.
By by the same token, I most commonly use my Porsches for timed events - simply because they are less fuss and if you bin one (which I have done) then it's no drama to fix them up eg local dealers and parts.
When it gets to more serious timed events - there are plenty of cars that best Porsche - largely because deficiencies get fixed through modification. Which is the deep pockets solution - in fact at this point Porsche become an expensive proposition because of the high cost of crate engines and gear boxes.
I think its its important not to conflate timed competition with DE type track days - its very different as are the costs and outcomes.
There maybe certain DE events where GT cars dominate - they are the exception rather than the rule.
When it comes to timed competition I don't see many 991 GT3s at all. Older heavily modified variants are there in abundance.
The fundamental issue is tires, wheels and clearance - to put it simply a Porsche on 18 inch wheels with soft rubber will easily knock off something on Cup 2s. Thus a well setup and worked over 997 Series 2 is a good proposition.
In regard to other high end cars it's more to do with access to parts and servicing e.g because of my location I have to order everything from a dealer on the east coast for my 720s - which incidentally has zero problem dispatching any Porsche I come across including two of my own.
By by the same token, I most commonly use my Porsches for timed events - simply because they are less fuss and if you bin one (which I have done) then it's no drama to fix them up eg local dealers and parts.
When it gets to more serious timed events - there are plenty of cars that best Porsche - largely because deficiencies get fixed through modification. Which is the deep pockets solution - in fact at this point Porsche become an expensive proposition because of the high cost of crate engines and gear boxes.
I think its its important not to conflate timed competition with DE type track days - its very different as are the costs and outcomes.
10-31-2018, 08:43 PM
#51
Rennlist Member
There maybe certain DE events where GT cars dominate - they are the exception rather than the rule.
At DE’s GT3’s mostly rule.
The occasional tuned car may be be faster for a few laps, but eventually they get cooked and passed.
And IMHO it’s more the exception then the rule when a Porsche GT car doesn’t set fastest lap.
In other words, if they go flat out, they win their DE ;-)
10-31-2018, 08:56 PM
#52
Lol it's bad enough paying an event fee and pit crew to win a 50 buck plastic trophy. 😀
I have to say I avoid DE days - to many poorly managed events - Europe is full of them
True to say Porsche is a great bridging car to competitive Motorsport largely because of the research and development put into them.
By by the same token - it's always the quickest driver that shines through, not the quickest badge/marque.
For example if if you go to a Ferrari owner invitational track event more time is spent talking and drinking great coffee than tracking. I quite like this approach 😀
I have to say I avoid DE days - to many poorly managed events - Europe is full of them
True to say Porsche is a great bridging car to competitive Motorsport largely because of the research and development put into them.
By by the same token - it's always the quickest driver that shines through, not the quickest badge/marque.
For example if if you go to a Ferrari owner invitational track event more time is spent talking and drinking great coffee than tracking. I quite like this approach 😀
10-31-2018, 09:13 PM
#53
"MacLarens and V8 Ferraris typicaly weigh in 42/58 and the last GT3 I saw corner-balanced was 39/61. That's hardly a difference."
But weight distribution does not tell the whole story. A bumbbell has a 50/50 distribution with its weight perfectly centered, but the rotational mass is completely different from a football and still different from a soccer ball, given they all have the same total mass. The center of rotation of a 911 is different from either car, and with that should be respected for its distinct physics.
But weight distribution does not tell the whole story. A bumbbell has a 50/50 distribution with its weight perfectly centered, but the rotational mass is completely different from a football and still different from a soccer ball, given they all have the same total mass. The center of rotation of a 911 is different from either car, and with that should be respected for its distinct physics.
10-31-2018, 09:33 PM
#54
Engine location impact on handling is overestimated in modern 911m particularly in street cars. It is truly practically a mid-engined car. Yes, the engine is further back compared to a typical mid-engined car, but the gearbox is much more forward, and modern PDK boxes are quite heavy. It's important to keep in mind that ear engine is NOT shifting the gearbox and engine pair back by a foot or two but rather swapping them around and actually moving the whole assembly slightly forward. As a result, weight distribution is hardly different from mid-engined cars. MacLarens and V8 Ferraris typicaly weigh in 42/58 and the last GT3 I saw corner-balanced was 39/61. That's hardly a difference. In addition, with rear wheel steering (active or even passive), the pivot point of the car is actually behind the rear axle. Contrary to popular belief, the pivot point is never in the middle of the car - that would require rear wheels to turn opposite to the front wheels by the same amount.
Where rear engine screws things up a bit is aero, and that may be the main reason Porsche had to go mid-engine for RSR.
That underbody aero is super powerful and is more efficient than the wing. Significantly more downforce in the rear allowed to proportionally up downforce at the front as well. That's what gives a big boost to cornering speed rather than changes in handling. When Porsche announced the reversed RSR they said exactly that - huge aero benefit that others in the series were taking advantage off already, and only 1-2% change in front-rear weight distribution, depending on ballast requirements.
Where rear engine screws things up a bit is aero, and that may be the main reason Porsche had to go mid-engine for RSR.
That underbody aero is super powerful and is more efficient than the wing. Significantly more downforce in the rear allowed to proportionally up downforce at the front as well. That's what gives a big boost to cornering speed rather than changes in handling. When Porsche announced the reversed RSR they said exactly that - huge aero benefit that others in the series were taking advantage off already, and only 1-2% change in front-rear weight distribution, depending on ballast requirements.
i agree underbody aero is much more efficient than fixed wings.... However, the performance benefit of extra downforce wasn't imo really the main reason on the RSR but rather the effect on rear tyre wear. BoP in theory would have adjusted for any lack of downforce not being able to run a huge diffusor and assuming BoP does it's job properly, the variables in sports car racing are more fuel efficiency and tyre wear than absolute performance.
10-31-2018, 09:47 PM
#55
Rennlist Member
McLaren had always been top for street car in their trick hydraulic suspension. I had one before and I had been praising them since. But McLaren street cars were never good track performers, they might have a wonder lap or 2, but they were not well developed like Porsches and always breaks down. They simply cannot last forever on track like a Porsche. Pretty much mirror McLaren's racing efforts, they can't last a single race.
I have tracked all my cars, From Porsche all the way down to McLaren, with Ferrari, Lamborghini and even Alfa 4C I ninth middle. McLaren has the problem of overheating, Ferrari, Lamborghini have the problem of cooking their brakes, but the little Alfa, it's the little Alfa that could. Not much power, superb fun on track, but it also has the problem of brake pedal going soft, not as quickly as Ferrari or Lamborghini though.
Our race track had been running for 2 years now, so we have a very good idea on which brand of cars perform well on track. Vipers, Corvettes and McLaren's all overheats. Bimmers and Audi, Ferrari and Lamborghini love to cook their brakes. GT-R destroys their tires unbelievably fast. Porsches are the only brand that can track all day in 30-40 degree heat with problem.
911s were great race cars..... in the dim and distant past. Modern racing regulations have very much prioritised cornering speeds, especially where there isn't BoP to attempt to equalise the disadvantage of a rear engine. And even where there is BoP, Porsche have seen fit to turn their most advanced road homologated race car from a rear engined one to being mid engined. When is the last dedicated ground up race car Porsche have built that hasn't been mid engined?
None of this of course matters on a road car and yes, being rear engined gives the 911 it's own USP as it at least feels different to drive in today's world despite Porsche's best attempts to turn it every more into behaving like a mid engine car over the years but the layout is not one that is going to give it any sort of performance advantage.
None of this of course matters on a road car and yes, being rear engined gives the 911 it's own USP as it at least feels different to drive in today's world despite Porsche's best attempts to turn it every more into behaving like a mid engine car over the years but the layout is not one that is going to give it any sort of performance advantage.
Shall we give you a lesson in physics?
Mid-engine cars have the lower polar moment of inertia. Meaning they don't require much effort to change directions, which is a good thing for race cars, hence grounds up designed race cars are all mid engined.
Front engine and rear engine have their heaviest component out at the ends of the car, they have higher polar moment of inertia, so they resist changing direction and not easy to turn. Porsche's 911 is stuck with that design in their street car, but somehow, they made that weird layout work, and work well enough to be the most successful manufacturer in racing, and variations of 911 race cars are the most successful race car also. Tells you something about the dedication and skills of Porsche engineers over say Ferrari, McLaren.
The current 911RSR flipped the engine forward in order to gain a bigger rear diffuser like all their competitors, their rear engine layout prevent them from putting in a meaningful one before, even Aston can have a giant one as their engine is in the front. It is well within the rules for them to do it. Rules only state that engine location cannot change, but that's only with respect to the driver, not the axles. So a Front engined Aston cannot move the engine to behind the driver, but Porsche with the engine in the back can freely move it forward, and if Ferrari is crazy enough, they can also move it all the way backwards.
With the engine moved, another side benefit is reduced rear tire wear. Something that's beneficial too.
Oh, and the engine move didn't changed the weight distribution that much, it still retains most of the weight in the rear and keep the corner exit advantage. And foul weather. Have you not noticed the RSR are exceptional quick in the rain? That's the rear weigh bias in action. It pressed the rear more firmly on the ground vs the mid engine cars and hence they can shot out of corners quicker and maintain that advantage down straights.
10-31-2018, 10:12 PM
#56
You forgot the default mode in Ferrari is stiff and the optional mode is bumpy road setting? It soften the car to comply better on street roads, but it also ruins the handling of the car. And Ferraris like to cook their brakes on track, they were not engineered for heavy tracking, period.
Are we talking about dedicated grounds up race cars? Or Race cars based on street cars? You are mixing them up dude.
Shall we give you a lesson in physics?
Mid-engine cars have the lower polar moment of inertia. Meaning they don't require much effort to change directions, which is a good thing for race cars, hence grounds up designed race cars are all mid engined.
Shall we give you a lesson in physics?
Mid-engine cars have the lower polar moment of inertia. Meaning they don't require much effort to change directions, which is a good thing for race cars, hence grounds up designed race cars are all mid engined.
10-31-2018, 10:45 PM
#57
RL Community Team
Rennlist Member
Rennlist Member
I don't think its correct to say that Porsche GT cars are the end-all-be-all of track cars.
What is safe to say is that Porsche GT dept. tunes their cars specifically for the 'Ring, as well as their drivers. Nothing more, nothing less. And it's really hard to extrapolate Porsche's prowess at the 'Ring beyond just that "Porsche cars are really good around the 'Ring"
Because if a rear-engine car from Porsche was like **** that smelled like perfume, then why doesn't Porsche GT cars dominate, say, the DTM series?
What is safe to say is that Porsche GT dept. tunes their cars specifically for the 'Ring, as well as their drivers. Nothing more, nothing less. And it's really hard to extrapolate Porsche's prowess at the 'Ring beyond just that "Porsche cars are really good around the 'Ring"
Because if a rear-engine car from Porsche was like **** that smelled like perfume, then why doesn't Porsche GT cars dominate, say, the DTM series?
10-31-2018, 10:55 PM
#58
Drifting
Forgot, one other point about 911s being great performers in racing.
It's all about the corner exits. As I said, 911 have better traction out of corners, it means drivers can put the power down earlier, and accelerate quicker out of corners onto the straights. Other cars may have HP advantage for the absolute top speed, but they are useless on corner exits and they don't have the traction out of corners. That translate to 911 leading the first half of straights while the other cars are playing catch ups. Most will reach higher top speed near the end of the straight but since they have inferior brakes and higher speed, they will have to brake sooner.
In the braking zone before turn in, any racers worth their salt can and will adjust their line to prevent a passing maneuver, so even if the car behind is faster down the straight and caught up, it is still hard to pass a 911.
It's all about the corner exits. As I said, 911 have better traction out of corners, it means drivers can put the power down earlier, and accelerate quicker out of corners onto the straights. Other cars may have HP advantage for the absolute top speed, but they are useless on corner exits and they don't have the traction out of corners. That translate to 911 leading the first half of straights while the other cars are playing catch ups. Most will reach higher top speed near the end of the straight but since they have inferior brakes and higher speed, they will have to brake sooner.
In the braking zone before turn in, any racers worth their salt can and will adjust their line to prevent a passing maneuver, so even if the car behind is faster down the straight and caught up, it is still hard to pass a 911.
11-01-2018, 02:24 AM
#59
See below for a couple of examples
and another
I feel its important to never under rate the opposition. There are some fantastic machines out there. Its true Porsche are great out of the box, however, even with a modicum of work so are others. Tracks are humbling places and respect is often rewarded
11-01-2018, 03:46 AM
#60
I think it comes down to development. When I think about buying a Porsche, I think about buying a car with a lower performance ceiling than cars with bigger engines, mid engine layouts, etc., but one that has been honed more than the other cars. My guess is that, to some degree, Porsche knows the 911 and its idiosyncrasies more than other manufacturers know about their cars. More importantly, I'd venture that the R&D budget with most cars goes into designing and making the car (with room to profit) rather than producing something less exotic that has had engineering personnel take their time to hone its road and its track manners and durability.
What's my evidence? Germany and the UK seem to present very different challenges for manufacturers. Germany has the autobahn which means the cars have to have strong, durable powertrains that can be held at WOT for extended periods without breaking or losing performance. The UK seems to have some of the world's most appalling roads which requires a compliant suspension that can deal with bumps. In all of the journalist reviews I've read, I've never heard of a 911 failing to produce decent power (and consistent power) or that doesn't have good body control. The NRing is essentially a blend of these, plus a stress test on brakes. Porsche excels in all fields because while it's not featuring 5 valves per cylinder or active aero, it's putting power to the ground in a bloody hurry.
I'd like someone to fact check this next statement, but I think Porsche probably uses better components throughout the car (via its suppliers) than other brands, some of which are more expensive and exotic. I believe one of our forum members who no longer posts here for unfortunate circumstances indicated that the same **** suspension components that go into a stock, nonperformance model Corvette at a price point were also put on some of the mid engine Ferrari models. I couldn't believe that but I have done a bit of research and it was indeed true. Again, happy to be corrected, but perhaps Porsche is also going the extra mile with its suppliers, including tire suppliers, to provide a product that is more complete than the likes of its competitors.
Finally, in GT racing, the 911 hasn't dominated the world like it used to generations gone by. Bigger factory budgets, more competition and interest from different brands, but more importantly cars with bigger displacements, longer wheelbases, room for upgraded aero, and different engine layouts are giving the P-car a tough time. Take the R8 as an example. IIRC, Audi's first generation R8 was much closer to the street car in terms of parts sharing than the comparable 911. Audi can also afford to disconnect the FWD in the R8 and have a more balanced car (mid engine) with extra torque (which is additionally beneficial when restrictors cap max power), descent aero, and good structural rigidity. If you were building a car to go racing from scratch, you'd build something more like the Audi than the 911. But when Audi makes a car for the road, it isn't bothering to spend time making sure its street cars have steering feel, good brake feel, durable brakes, suspension that modulates body roll and controls body movement.
One more thing. Porsche already ran a relatively stock GT3 RS at the NRing 24 ( https://www.auto-motor-und-sport.de/...-rs-rennwagen/ ). They have faith in the cars they produce. Oddly though, Nissan did the same thing with the GTR and despite what has been written on this and other forums, it lasted and even won its class (FWIW): https://www.autoblog.com/2012/04/09/...f-nurburgring/ .
What's my evidence? Germany and the UK seem to present very different challenges for manufacturers. Germany has the autobahn which means the cars have to have strong, durable powertrains that can be held at WOT for extended periods without breaking or losing performance. The UK seems to have some of the world's most appalling roads which requires a compliant suspension that can deal with bumps. In all of the journalist reviews I've read, I've never heard of a 911 failing to produce decent power (and consistent power) or that doesn't have good body control. The NRing is essentially a blend of these, plus a stress test on brakes. Porsche excels in all fields because while it's not featuring 5 valves per cylinder or active aero, it's putting power to the ground in a bloody hurry.
I'd like someone to fact check this next statement, but I think Porsche probably uses better components throughout the car (via its suppliers) than other brands, some of which are more expensive and exotic. I believe one of our forum members who no longer posts here for unfortunate circumstances indicated that the same **** suspension components that go into a stock, nonperformance model Corvette at a price point were also put on some of the mid engine Ferrari models. I couldn't believe that but I have done a bit of research and it was indeed true. Again, happy to be corrected, but perhaps Porsche is also going the extra mile with its suppliers, including tire suppliers, to provide a product that is more complete than the likes of its competitors.
Finally, in GT racing, the 911 hasn't dominated the world like it used to generations gone by. Bigger factory budgets, more competition and interest from different brands, but more importantly cars with bigger displacements, longer wheelbases, room for upgraded aero, and different engine layouts are giving the P-car a tough time. Take the R8 as an example. IIRC, Audi's first generation R8 was much closer to the street car in terms of parts sharing than the comparable 911. Audi can also afford to disconnect the FWD in the R8 and have a more balanced car (mid engine) with extra torque (which is additionally beneficial when restrictors cap max power), descent aero, and good structural rigidity. If you were building a car to go racing from scratch, you'd build something more like the Audi than the 911. But when Audi makes a car for the road, it isn't bothering to spend time making sure its street cars have steering feel, good brake feel, durable brakes, suspension that modulates body roll and controls body movement.
One more thing. Porsche already ran a relatively stock GT3 RS at the NRing 24 ( https://www.auto-motor-und-sport.de/...-rs-rennwagen/ ). They have faith in the cars they produce. Oddly though, Nissan did the same thing with the GTR and despite what has been written on this and other forums, it lasted and even won its class (FWIW): https://www.autoblog.com/2012/04/09/...f-nurburgring/ .