Re: Let's talk handling - Why is the 911 so great?
My choice: An M3 daily driver/family car and a Manthey-tweaked 997 GT3 fun/track car.
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AUM said:
I would rather hit a mid-bend bump in an autobahn sweeper at 250 kph in an M3 than a 911. Although almost any 911 is a more engaging and faster track car than an M3, the intrepid beemer does everything well. The e46 M3 is the most balanced all-round sports car of our time.
My choice: An M3 daily driver/family car and a Manthey-tweaked 997 GT3 fun/track car.
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GA997S said:
Grant, I guess this is something you'll have to think about for a while to understand it. Maybe go to an engineer or physics professor and let them illustrate it.
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frayed said:
You guys are getting too hung up on layout and design and not focusing enough on execution. Porsche has had years to fine tune the rear engine 911 and turn it into what it is today; a predictable engaging communicative and intensely desirable sports car. It is also an engineering feat to overcome what is fundamentally an unstable and inferior design.
I've a fair bit of track experience, front engine, rear engine and mid engine layouts. Certainly mid engine cars are superior from a *design* perspective, but that's only part of the story. The newest 911s are incredibly well engineered and are absolutely stunning to drive.
My Ferrari is a badass car, but it is twitchy. Much more so than any 911 I've owned including my 996 GT3. When the rear end goes, it goes in a flash. In contrast, the GT3 was very tractable and you could carry pretty amazing slip angles on track. My 997S has this trait as well, but even more stable and predictable. The 997S in particular begged to be driven hard and brought to the edge. The ferrari is finnicky and twitchy and the limit; it is more of a white knuckled driving experience and you always keep things dialed down a notch for fear that it'll get away. It is, however, a more passionate car and very intense.
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nberry said:
[...] you have a greater comfort level driving rear engines cars. You probably "cut your teeth" in them. As a result, you prefer them to mid-engine or front engine cars. [...] the problem with the CGT is its power.
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Ferdie said:
the Smart two-seater vehicle there seems to be no other car with a rear-engined concept - the later not really well-known for its superb handling.
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nberry said:
Have you had an opportunity to drive a 430? It is superior to the 360 in so many ways including handling.
My impression is you have a greater comfort level driving rear engines cars. You probably "cut your teeth" in them. As a result, you prefer them to mid-engine or front engine cars. As I wrote earlier, it all depends on what you are used to.
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sws1 said:
I've now had my C2S for a little over a week and thought I'd throw in some random commentary.
First off, I love this car. I'm only posting this to get an intelligent discussion going.
In the past, I've generally driven rear-wheel drive, front engine performance cars (M3, M5). Given the engine in the 911 is in the rear, I was expecting a handling difference, but I don't think I would have thought it would be as noticeable. Let me explain.
In corners, it is VERY easy to feel the balance of the car change based on how much trottle is provided. It's not subtle IMO. I'm still in the break-in period, and at 3000 RPM, I can feel the front end "lighten" in mid corner with even a little gas. With the cars I came from, you didn't get that much sensation of balance change.
So, that would lead me to believe right there that to maximize the potential of the 911, one must be a more skilled driver. Correct?
If I perfect my driving skill, will the 911 handle better a M3? I'm assuming this would be case, otherwise we have a more difficult car to drive that, when perfected, isn't as good.
Is the analogy between the 911 and front engined cars like the difference between a short surfing board and a long surfing board? A long board is easier to handle, particularly for the beginner, but the short board will allow you do maneuver better.
Does a race car have similar handling tendencies? What about other high-end cars? Ferraris?
Again, I'm not antagonizing. I'm truly seeking comments from folks who are good drivers / racers on their reactions.
Dec 12, 2006 9:09:19 PM
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The yaw axis - the one that matters most when steering. It is centered on the midpoint of the wheelbase. Since 911 has so much of its weight behind rear axle, alot of mass is well aft of this axis - mid-engined cars have most mass concentrated near this axis.
Dec 12, 2006 10:11:17 PM
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Carlos from Spain said:Quote:
The yaw axis - the one that matters most when steering. It is centered on the midpoint of the wheelbase. Since 911 has so much of its weight behind rear axle, alot of mass is well aft of this axis - mid-engined cars have most mass concentrated near this axis.
That is my understanding as well, and what I have read in books like Vic Elford's Porsche High Performance Driving.
In fact the "pivot point" in the 911 is not only not more rearward, but rather on the front of the car over the front axle, the reason being that the rear placement of the engine cause a "pendulum effect", hence the tendency to oversteer of the 911. While a mid-engine car has the enigne/tranny "mass" very close to its pivot point located in the middle of the car, hence a lower polar moment of inertia. Its like a dumbell with the weights at the ends of the bar, and another with the weights closer to the center of the bar, which is easier to spin? therefore the mid-engine car turns over its yaw axis with less effort making it more nervous handling and easier to spin, but for skilled drivers and racecars it yields easier turn in and aglility in changes of direction.
Dec 12, 2006 10:41:47 PM
Dec 13, 2006 12:47:11 AM
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Carlos from Spain said:
ahh... no... of course not, just like to waste time typing senseless lines
No really, I gave you a reference that you can look up and read on about it if you like, and if you don't know who Vic Elford is, you can check him out in google.
I think I may have introduced some confusion with introducing the pivot point concept that is more related to rotation in the limits of driving with tire slippage, control, and negotiating the turn when racing.
But its is very easy if we keep it very simple; the closer the mass of the car is to the center b/w the four tires of the car, the lower angular moment of inertia is, and therefore the less effort is needed to rotate the car through its tires. Mid-egine =lower polar moment, rear and front engined = higher polar moment.
Imagine a ball of pizza dough, you flaten the dough into a small disc and start to spin it an flaten in succesively to make flater and larger in diameter for the pizza, as it grows in diameter while you spin it, it gets harder to spin because its mass is farther away from its axis, i.e. higher angular moemnt of inertia.
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Jim48 said:Quote:
sws1 said:
I've now had my C2S for a little over a week and thought I'd throw in some random commentary.
First off, I love this car. I'm only posting this to get an intelligent discussion going.
In the past, I've generally driven rear-wheel drive, front engine performance cars (M3, M5). Given the engine in the 911 is in the rear, I was expecting a handling difference, but I don't think I would have thought it would be as noticeable. Let me explain.
In corners, it is VERY easy to feel the balance of the car change based on how much trottle is provided. It's not subtle IMO. I'm still in the break-in period, and at 3000 RPM, I can feel the front end "lighten" in mid corner with even a little gas. With the cars I came from, you didn't get that much sensation of balance change.
So, that would lead me to believe right there that to maximize the potential of the 911, one must be a more skilled driver. Correct?
If I perfect my driving skill, will the 911 handle better a M3? I'm assuming this would be case, otherwise we have a more difficult car to drive that, when perfected, isn't as good.
Is the analogy between the 911 and front engined cars like the difference between a short surfing board and a long surfing board? A long board is easier to handle, particularly for the beginner, but the short board will allow you do maneuver better.
Does a race car have similar handling tendencies? What about other high-end cars? Ferraris?
Again, I'm not antagonizing. I'm truly seeking comments from folks who are good drivers / racers on their reactions.
Great discussion that you started with your comments.
After driving my 911S for nearly ten months, I find myself using the throttle increasingly to get through turns, especially if I have some previous familiarity with the tougher ones or I can see the full turn (with tree leaves having fallen, it makes it possible to see around more turns and thus use more throttle to get through). I now feel a lot more comfortable when applying extra power in a turn.
At least to me, as relatively inexperienced as I am compared to most Rennteamers, I find that the car sticks to the road as if it were on rails. The handling is predictable and, in a word, incredible!!
Every time I take it out for a brisk drive, I know I made the right decision in getting one.
Jim
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Jeannot said:Quote:
Ferdie said:
the Smart two-seater vehicle there seems to be no other car with a rear-engined concept - the later not really well-known for its superb handling.
I think the smart handling has nothing to do with where the engine is. I had one for a year, and this thing is freaking scary on the wet.....but that would be the same I am sure with no engine, an engine in the front, a sail on the roof, a electric motor in each wheel or even 2 rugbymen pushing it...
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ADias said:
Now... dynamically the assymetric distribution of mass produces what Carlos correctly described as the pendulum effect. THAT happens when slippage starts and not until then.
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Gnil said:Quote:
Jeannot said:Quote:
Ferdie said:
the Smart two-seater vehicle there seems to be no other car with a rear-engined concept - the later not really well-known for its superb handling.
I think the smart handling has nothing to do with where the engine is. I had one for a year, and this thing is freaking scary on the wet.....but that would be the same I am sure with no engine, an engine in the front, a sail on the roof, a electric motor in each wheel or even 2 rugbymen pushing it...
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frayed said:
You guys gotta get a grip. Here's my very technical, PhD explaination:
There's a heavy azz anchor behind the rear wheels. Only the 911 has this layout in all of sportscardom. Like a tomahawk, the heavy part will always want to be in the front. However, PAG has done a marvelous job engineering such a fundamentally flawed car into one of the most engaging (and reasonably stable and tractable) sports cars ever.
Now, go out and drive!!!
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ADias said:
Guys... I stand for what I wrote. If no slippage, the car rotates around a vertical axis (sitting inside the curve on the center of rotation) which forms a plane with the horizontal rear axle. Both rotated front wheels' axis point inwards to the point where the vertical axis of rotation intersects the rear axle (the outer wheel always rotates more). This is straight geometry for all cars (not rear wheel steering) without slippage. Now... dynamically the assymetric distribution of mass produces what Carlos correctly described as the pendulum effect. THAT happens when slippage starts and not until then. In normal driving conditions (without slippage) the proverbial car on rails, no pendulum effect takes place.
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John H said:Quote:
ADias said:
Guys... I stand for what I wrote. If no slippage, the car rotates around a vertical axis (sitting inside the curve on the center of rotation) which forms a plane with the horizontal rear axle. Both rotated front wheels' axis point inwards to the point where the vertical axis of rotation intersects the rear axle (the outer wheel always rotates more). This is straight geometry for all cars (not rear wheel steering) without slippage. Now... dynamically the assymetric distribution of mass produces what Carlos correctly described as the pendulum effect. THAT happens when slippage starts and not until then. In normal driving conditions (without slippage) the proverbial car on rails, no pendulum effect takes place.
What happens when the titchepalio loses compatibility with the fibbly-fobbly?