Porsche...I don't get it

sars said:
In the 911 as you accelerate the mass of the engine moves further behind the rear wheels giving you less grip and significantly lightens the load at the front (see saw effect)
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Despite the Z4MC having the advantage of the engine (a relatively heavy cast iron lump) mounted directly above the front axle and well forward of the rear wheels, when the car accelerates hard, the front end lifts significantly, which makes the steering floaty. :wink: This doesn't happen in the later 911s. I do agree that having the engine out at the back is not ideal, but Porsche aren't going to start changing their icon (Golden Goose), and why should they?

Surely, the answer to the problem lies within the suspension design in order to minimise the shifting of the polar mass of inertia under acceleration, braking and cornering? Does it matter that Porsche have used "substantial trickery" or even Black Magic to get the design to work? The proof of the pudding...
 
sars said:
You just have to look at that posted article to confirm all the points from my previous comments, that there is substantial trickery involved to make the best of a bad job and I openly admit that what they have done is miraculous.

There is absolutely no advantage in having the engine situated behind the rear wheels, apart from internal ergonomics. In every other high performance car the engine sits before the rear wheels, so that when you accelerate the mass transfers backwards to the rear wheels giving you better grip when you need it. In the 911 as you accelerate the mass of the engine moves further behind the rear wheels giving you less grip and significantly lightens the load at the front (see saw effect)
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The new 991S it timed at 7.37 at the 'ring' better than a few mid engine cars with larger capacity engines, 991 now corners where you want it to unlike before.

I guess you either like 911 or you don't, unfortunately there's usually a reason why some people dislike a 911
 
tomscott said:
Never the less its a great car and the drive is like no other. You are correct that the steering is lighter under acceleration
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Not any more it isn't :)
 
Kryton said:
Stark said:
What I didn't get, is why would you pay £20k more and buy a 991?
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Well Nick possibly because they look like this?

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Not getting away from it Kryton, it's a fabulous looking car, and if I had £85K to spend on a Porsche it would be a 991. But if I had only £60K....I would be foolishly dismissing it in my head that it wasn't value for money as I have been doing. Perspectives on value and costs etc change depending what end of the scale you're at.

I wonder if there are any Porsche drivers with a £100 k budget to spend on a car, who decided to buy the Boxster because it was better value for money....

In BMW terms, a guy with a £55K M3 buying capability who decides to buy the 1M instead.....
 
I had a passenger lap around The Ring last year in an expertly driven GT3 RS. It was nothing short of truly amazing! We flew past all manner of exotica, and the way it went through the Karrusel was astonishing. The car remained flat at all times: no pitch, squat or roll, which gave the tyres the optimum geometry for grip under acceleration, cornering and braking. If only all cars handled /rode that well!
 
exdos said:
Surely, the answer to the problem lies within the suspension design in order to minimise the shifting of the polar mass of inertia under acceleration, braking and cornering? Does it matter that Porsche have used "substantial trickery" or even Black Magic to get the design to work? The proof of the pudding...
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As scotty said, ya canna change the laws of physics, what they have done is mask the effect caused by the shift in CofG under acceleration

Kryton, as i have said many times before I love the styling of your car, I just don't aspire to own it
 
exdos said:
I had a passenger lap around The Ring last year in an expertly driven GT3 RS. If only all cars handled /rode that well!
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It's a good job they don't Exdos otherwise we wouldn't be so exhilarated when they do!
 
Sorry kryton I was meaning a 997 with lift.

I can tell there isn't a way of altering your view but if you get the chance to drive one do. It's just a great experience, maybe then perception may change :)

I like Porsche because they are the underdogs to the Italian finesse. And the working mans supercar although maybe not quite working man now haha!

Plus I just love the style it's iconic and after aspiring to M cars the only real affordable upgrade for me is the 911. As i think M cars are very hard to beat. I would feel I left myself short buying a Cayman or Boxter. No denying they are great cars but I would just feel like they aren't the real deal and would certainly not love it as much, neither would it mean as much, which to me defies the point I owning such cars.
 
This might be slightly controversial (and I do really, really like the 991) but I think the new Boxster is a better looking beast. Bodes well for the Cayman.
 
If the renderings of the future cayman are anything to go by then it will be a very desirable car.

I do wonder though, what with the economy nose diving if we'll ever see as many new boxters/Caymans as the thousands of 986/987's that are rolling around. Surely they cant match those numbers again??? Not unless they can make one that does 60+mpg i fear :(
 
sars said:
As scotty said, ya canna change the laws of physics
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True.

sars said:
what they have done is mask the effect caused by the shift in CofG under acceleration
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What do you mean by "mask the effect"? In OEM guise, my Z4MC had lots of lifting and pitching under acceleration and braking. Now that I've fitted an aftermarket suspension kit and uprated the ARBs, the lifting and pitching has been almost completely eliminated (with its present settings for road use). Are you suggesting that I've only "masked" the effects of the movement of the polar moment of inertia, rather than actually restricted the movement to a smaller area by stiffening up the suspension at the front etc.?
 
One of the guys I work with at my main account has had a number of 911s and raced them. His view is the Cayman S is a better drivers car and on a track would see off any stock 911 other than a GTx. In a straight line the 911 is faster, and for day to day use, he'd stick with a 911

Don't shoot the messenger!
 
original guvnor said:
It's a good job they don't Exdos otherwise we wouldn't be so exhilarated when they do!
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Yes, better to be wanting for something than taking it all for granted with nothing left to look forward to and excite you.
 
If I wasn't so frightened by potential hidden repair costs I would have an 80's 911 turbo in a heartbeat. Boxsters and most other recent Porsches look quite boring to me these days.
 
exdos said:
What do you mean by "mask the effect"? In OEM guise, my Z4MC had lots of lifting and pitching under acceleration and braking. Now that I've fitted an aftermarket suspension kit and uprated the ARBs, the lifting and pitching has been almost completely eliminated (with its present settings for road use). Are you suggesting that I've only "masked" the effects of the movement of the polar moment of inertia, rather than actually restricted the movement to a smaller area by stiffening up the suspension at the front etc.?
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A gyroscope is the classic example of the principles of the polar moment of inertia of mass, I am unsure how this effect relates to mass transfer under acceleration and giving extra grip to the rear wheels with a rear engine layout which was your original point, please enlighten me

Mass transfer occurs under acceleration and thus the C of G moves, if you upgrade the springs and increase the overall stiffness it is blindingly obvious that you will have less deflection, however the mass transfer still occurs....ergo the original problem remains.
 
sars said:
A gyroscope is the classic example of the principles of the polar moment of inertia of mass, I am unsure how this effect relates to mass transfer under acceleration and giving extra grip to the rear wheels with a rear engine layout which was your original point, please enlighten me

Mass transfer occurs under acceleration and thus the C of G moves, if you upgrade the springs and increase the overall stiffness it is blindingly obvious that you will have less deflection, however the mass transfer still occurs....ergo the original problem remains.
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Try something like this: http://ironduke7.tripod.com/vehicledynamics101.htm

I repeat: does it matter that Porsche have used "substantial trickery" or even Black Magic to get the design to work? The fact is that Porsche has overcome the inherent weakness of the original design concept of a rear-engined car: their latest cars are superb. With the passage of time, the handling has progressively improved with each version of the 911 and does it matter to most Porsche drivers if this has been achieved by the use of electronically controlled active suspension and other "wizard" technological solutions etc.?

The OP's point was why would anyone pay £20k to buy a 991 rather than a Boxster. I think the answer probably lies in the fact that most Porsches are bought new as status symbols, and their 911 range fits in the market for cars now costing circa £100k.

Here's an interesting read: http://www.caranddriver.com/feature...ne-debate-porsche-cayman-r-vs-911-gt3-feature
 
exdos said:
I repeat: does it matter that Porsche have used "substantial trickery" or even Black Magic to get the design to work? The fact is that Porsche has overcome the inherent weakness of the original design concept of a rear-engined car: their latest cars are superb. With the passage of time, the handling has progressively improved with each version of the 911 and does it matter to most Porsche drivers if this has been achieved by the use of electronically controlled active suspension and other "wizard" technological solutions etc.?]
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I quite agree, the latest 991's have PDCC and Dynamic engine mounts (both options) and as I said before they now handle like a mid engine car, indeed the 991S is faster than a track based GT3 around the ring which says everything about the 991's handling

Sars needs to attend a Porsche track day at Silverstone driving 996's 997's and 991S's to see the massive leap forward, theory is one thing practice is another.
Before I drove I was taken around by my instructor for the morning in a 991S at max speed, and I can tell you the handling is fantastic, and I could also drive their car way faster into corners than I could in a 997 and my old E89 :)
 
The first article has been written in simple terms so that the laymen can appreciate the effects and importance of the Fiero's engine position and whilst correct it is too simplistic and thus the proviso at the end. Interestingly though the one article you found explaining polar moment of inertia of mass, reaffirms my continued point on the 911 engine position.

And so the Boxster has its engine in the right place, it has a great foundation in producing the best possible drive without all the trickery of the 911 and as so many journalists and aficionados have commented on, the latest Boxster is probably the best driving Porsche in production.

It would seem our conversation has now come full circle, the OP stated that he did not understand why someone would spend the extra £20k on base 911 and not buy a Boxster S, my original comment that the only reason, apart from snobbery, might be for the 2+2 configuration, the raison d'être
 
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