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Print 27 comment(s) - last by YashBudini.. on Aug 24 at 6:17 PM

Porsche's 991 911 is the next step in the evolutionary line

It may be hard for the untrained eye to spot the differences between the older 997 and new 991 versions of the 911, but people have been saying that for years when it comes to Porsche's most famous model. The 911 may have not changed significantly when it comes to styling, but there's enough going on under the flesh to justify it being called an "all-new" model.

First of all, in a move that is sure to anger some purists, the 911 is growing in size yet again (the last big jump came with the 996 introduction). The rear-engined sports car is now 3.9" longer overall bringing total vehicle length to 179.5". However, Porsche counters with the fact that the body weight weight of the vehicle is down 100 pounds thanks to the use of lightweight steel, aluminum, and composites.  

Also new to the mix is a “world first” 7-speed manual transmission for those that prefer to row your own gears. For those that would rather have a computer micromanage your shifting, the 7-speed Porsche Doppelkupplungsgetriebe (PDK) is available. Porsche has also installed an automatic start/stop system in the 911 which will help to improve fuel efficiency while driving around in the city.

Although Porsche has not revealed U.S. EPA numbers for the new 911, the company says that fuel consumption is down 16 percent compared to the outgoing model using the New European Driving Cycle (NEDC). 

The engines are mostly carryover this time around, but power is up for both the Carrera (3.4) and the Carrera S (3.8). The 3.4-liter flat-6 is up 350hp (an increase of 5hp) while the larger 3.8-liter flat-6 jumps to 400hp (up 15hp). 

As in previous models, 911s with the PDK transmission will be faster on the track than the manual-equipped cars. The Carrera with a PDK can hit 60mph in 4.4 seconds and reach a top speed of 179mph. The Carrera S with PDK and Sport Chrono Package can do the dance in 3.9 seconds and reach 188mph.

However, all of this fun is going to cost you a serious amount of coin -- the base MSRP for the Carrera is listed at $82,100. Stepping up to the Carrera S will set you back a whopping $96,400, and that's before the option overload that greets you when it's time to order your new 911.



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RE: A lot has changed
By corduroygt on 8/23/2011 8:28:50 AM , Rating: 1
quote:
The longer wheelbase with especially the rear wheels having been moved back so the engine is much less behind the wheels is a big deal. In fact some say this car may look like a 911 but feels more towards a mid-engine car (which is good and bad).

Why is it bad? It's all good since we all know the MR configuration is superior from a performance and handling point, however considering the 911's rear-engined heritage, this was a good compromise, 1/2 rear engine-1/2 mid engine...


RE: A lot has changed
By BZDTemp on 8/23/2011 11:14:12 AM , Rating: 3
It's bad because the car looses some of it's unique character.

As for performance being better with an MR I'd say that is into an area where driving style/talent makes more of a difference since most people will never get the last bits of performance from any super car. Or to put it differently who was the prettiest back in the day - Audrey Hepburn or Marilyn Monroe :-)


RE: A lot has changed
By amanojaku on 8/23/2011 6:56:35 PM , Rating: 2
quote:
Why is it bad? It's all good since we all know the MR configuration is superior from a performance and handling point, however considering the 911's rear-engined heritage, this was a good compromise, 1/2 rear engine-1/2 mid engine...
That's a matter of opinion, and it even varies from car to car. Some people like the Porsche feel. I generally prefer an RMR, not having driven a mid-AWD yet.

Here is my layman's knowledge of drive layouts and their performance characteristics.

FF
* High drive-wheel weight/grip at low speeds
* High steering-wheel weight/grip at low speeds
* Eliminates drive shaft weight
* Center of mass shifts with changes in acceleration
* High moment of inertia

Acceleration - Poor
Steering - Great
Build - Simple, inexpensive
Tires - Fronts burn out very quickly

Analysis
* Excellent for low speeds and low traction environments (snow, mud, wet surfaces, etc...)
* Transverse engines limit engine size and increase turning circle radius
* Best for typical consumer cars (e.g. Ford Taurus), not good for towing or racing

FR
* Medium drive-wheel weight/grip at high speeds
* High steering-wheel weight/grip at low speeds
* Has drive shaft weight
* Center of mass shifts with changes in acceleration
* High moment of inertia

Acceleration - Good
Steering - Good
Build - Slightly complex, slightly expensive
Tires - Rears burn out relatively quickly

Analysis
* Good overall acceleration and steering in high traction environments (tarmac, asphalt, etc...)
* Lack of a forward transaxle allows for larger engines and decreased turning circle radius
* Best for sporty consumer cars (e.g. Ford Mustang, Nissan 350Z) or trucks, good for towing and racing

RR
* High drive-wheel weight/grip at high speeds
* Medium steering-wheel weight/grip at low speeds
* Eliminates drive shaft weight
* Center of mass shifts with changes in acceleration
* High moment of inertia

Acceleration - Excellent
Steering - Poor
Build - Simple, inexpensive
Tires - Rears burn out very quickly

Analysis
* Excellent for high straight-line speeds and high traction environments (tarmac, asphalt, etc...)
* Rear-mounted engines lead to both understeer and oversteer
* Best for exotic sports cars (e.g. pretty much anything from Porsche), not good for towing, good for a skilled racer

FMR
* Medium drive-wheel weight/grip at high speeds
* High steering-wheel weight/grip at low speeds
* Has drive shaft weight
* Center of mass shifts with changes in acceleration
* Medium moment of inertia

Acceleration - Good
Steering - Good
Build - Slightly complex, slightly expensive
Tires - Rears burn out relatively quickly

Analysis
* Good overall acceleration and steering in high traction environments (tarmac, asphalt, etc...)
* Lack of a forward transaxle allows for larger engines and decreased turning circle radius
* Best for sporty consumer cars (e.g. BMW Z4, Honda S2000), good for towing and racing

RMR ("MR")
* High drive-wheel weight/grip at all speeds
* Medium steering-wheel weight/grip up to medium speeds
* Has virtually no drive shaft weight
* Center of mass essentially does not shift with changes in acceleration
* Low moment of inertia

Acceleration - Excellent
Steering - Good
Build - Somewhat complex (except for race cars), somewhat expensive
Tires - Rears burn out relatively quickly

Analysis
* Excellent acceleration and good steering in high traction environments (tarmac, asphalt, etc...)
* May need a front spoiler to improve high-speed cornering
* Engine layout at the expense of passenger comfort
* Lightest weight, along with FF and RR
* Best for exotic sports and race cars(e.g. Ford GT, Formula One, Group C, Le Mans Prototype), good for towing and racing

4WD/AWD
* Comes in front, mid, and rear engine configuraions, with similar characteristics
* Front and rear axles are driven, splitting traction (front/rear ratio can vary from 50/50)
* AWD can allows front and rear axles to move at different speeds and is used all the time
* 4WD is turned on for slow-speed, low grip situations and can damage the drivetrain otherwise
* Extra weight from drive shafts, differentials, etc...

Acceleration - Better than a car with similar engine placement
Steering - Better than a car with similar engine placement
Build - Very complex, very expensive
Tires - Fronts burn out quickly, unless the engine is rear mounted

Analysis
* Everyone does it differently, sometimes within the same family of car
* The best AWD system can send any amount of power to any combination of wheels (e.g. 4x25% or 1x100%), like a Humvee
* Best for many cars, but particularly cars where price and weight are of no concern (e.g. Lamborghini MurciƩlago, Porsche 959 and 911, AM General Humvee)


RE: A lot has changed
By YashBudini on 8/23/2011 11:35:19 PM , Rating: 2
quote:
FF
Steering - Great

Huh? Am I missing something here? What about torque steer?

In a RWD setup taking a turn too fast results in understeer. The natural reaction is to brake, which brings things back in line.

In FF setup take a turn too fast and you get understeer, but isn't the proper response no to brake but slight acceleration? Brake too much and you can end up with oversteer. What are the odds an average driver will recover from oversteer?

Worst handling vehicle I driven in 35 years in the snow? A 1980 GM X car.


RE: A lot has changed
By BZDTemp on 8/24/2011 4:44:19 AM , Rating: 2
Torque steer is only really a problem with high power cars but then you're right.

quote:
In FF setup take a turn too fast and you get understeer, but isn't the proper response no to brake but slight acceleration? Brake too much and you can end up with oversteer. What are the odds an average driver will recover from oversteer?


With FF the proper response to understeer is simply to put less pressure on the gas pedal little unless you're going way to fast in which case the right way is to get of the gas and maybe brake. Lifting of is because then you use less of the available grip for acceleration and there will be more for steering eg. reduce understeer.

Not counting 4WD then FF is really the better solution for anything but sports cars and cars/trucks meant to carry loads. The reason is FF is cheaper and more importantly the car reacts safer in emergency situations - like you hint the average driver will have a hard time recovering from oversteer.

For most drivers the instinct reaction to a problem is to get off the gas and if that is not enough then go for the brake. In a turn with an FF car going to fast(but not crazy to fast) that will mean understeer so getting off the gas will save the day without further skills needed while going to fast in a RWD abruptly getting of the gas can cause the rear end to oversteer in a big way.

Putting it differently front wheel drive is safer because most peoples instinct reactions will not cause further loss of control while with rear wheel drive it is another matter. Of course RWD is more fun because you can use oversteer actively where as understeer is just boring.


RE: A lot has changed
By lagomorpha on 8/24/2011 7:44:42 AM , Rating: 2
"* Best for sporty consumer cars (e.g. Ford Mustang, Nissan 350Z) or trucks, good for towing and racing"

I was under the impression Nissan's Front Mid-ship platform was an FMR.


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