markow

just to understand, why that?
peter

MikeBat

Yes, the GT1, and it even had an EVO gen with a different set of 996 headlights. But...it is pretty much a smoke screen to say to say that it was a Carrera, and much less a regular production Carrera.

All this to say, yes, you are right.

But I remain convinced that it is not in Porsche's interest to ever change the engine placement on the car they sell at dealerships as a Carrera.

consolidated

More data, %front/%rear

Porsche 997 38/62
Lotus Elise 38/62
Porsche 991 39/61
Lotus Evora 39/61
Alfa Romeo 4C 40/60
McLaren F1 41/59
Honda NSX 41/59

Lamborghini Gallardo 42/58
Porsche Carrera GT 42/58
Ferrari 430 42/58
Ferrari 458 42/58
McLaren MP4 12C 42/58

Lamborghini Aventador 43/57
Audi R8 44/56
Porsche Cayman 45/55
Porsche 914 46/54

andrewk34

This sounds right to me. But given the fundamental problems with the design, how can a 991 compete with a R8 or even a f430 around most tracks? Why do the others need much more horsepower to get even close to the 911's lap times? It cannot all be down to Porsche just being better. I bet there are some compensating advantages to the rear engine layout.

andrewk34

Bump

Petevb

There are a few ways to answer this.

Generalizing, the advantage of rear engine is traction and hence speed on corner exit. Due to the short wheelbase a rear engined car is going to transfer more weight and hence have more traction than even a mid engined car with the same weight distribution, so there is nothing better at putting power down short of 4wd. Since you'll keep any speed advantage on corner exit the whole way down the straight, even a small improvement in corner exit speed is significant. This is one of the main reasons the 911 could successfully compete in so many forms of motorsports: virtually anywhere traction was a problem the 911 could do well, from high power (ie 935) to slippery surfaces (rally, Paris to Dakar, etc). Is this enough to overcome the inherent advantages of mid engine? In the limit generally no, but in certain circumstances...

As for why the 991 is fast vs a particular car, that gets to be complicated.

The R8 has plenty of traction, but it's hampered by a relatively unsophisticated 4wd system that makes balancing the car well difficult. Vs the 430 age is probably one of the main issues. Porsche's GT3, for example, is dropping lap time at the rate of about .5% per year due technological progression, and other cars are evolving at a similar rate. So in the 8 years between the introduction of the F430 and the 991 you'd expect lap times to drop nearly 19 seconds on a track like the 'Ring.

At the end of the day, Porsche also does have pretty damn good engineers.

chago996

In my opinion, I hope they never fully "dial out" that rear engine bias feel of the 911. Its what makes the 911 a special sports car. Currently I have 997.2 with sport PASM, but I remember the first time I took my first 911, a 996 3.4L, to the twisties up in the mountains. It was then that I got it, how this car likes to turn, how it loves the curves. All as a result of having this engine in the back, having no real engine weight over the front axle, and having a "short" wheelbase compared to cars of its time. At the time, I had traded a very loved e36 M3 (1996). It was the darling of the auto press, and for good reason. It was fast, amazing looks, and felt solid. But it understeered quite noticeably. It was great for the freeway, but not the mountains. The 996 felt like a true sports car, and the 997 built on that, especially with the sport PASM. I haven't driven a 991, but the the wider front track I am sure is a big plus. Not a big fan how much this car grew in wheelbase, the whole car seems really big, but so does the 997 compared to the 996 and it to earlier generations. Driving a 991 may change this perception. Its all about how it feels, and I surely hope they continue with having a manual transmission, and offer one on the GT3 one day

Serge944

It wouldn't be a 911 if it was mid-engined. If you're asking for a mid-engined car that produces the same power as a 911 and costs the same as a 911 - that's not going to happen. If and when that car arrives, but it'll be substantially more expensive than a 911.

sl951

There are two things fundamental to a 911, the core if you will – It’s the rear engine layout and the flat-6 design. Porsche is willing to change just about everything else on a 911 except those two core things.

Since Porsche is unwilling to change the 911 core, the next big evolution will be ‘hybrid’ technology to keep up with the competition. When the 911 GT3-R Hybrid came out a couple of years ago it gave Porsche two important insights. A test bed for technology (the obvious one) and a test bed for the public relations department. The media/public (customers) seemed to be positive about the car with the electric motor add-ons and more importantly they still considered it a 911.

So from Porsche’s perspective a mid-engine will have to come from other projects: 918, 960, Boxster, Cayman, Cayman GT4…
A 911 will always be a rear-layout with a flat-6.

A more interesting question would be.... is Porsche willing to change the "GT" series line-up (GT, GT2, GT3, etc). or does it always have to be a 911??? Can the 960 become the next GT3? or GT2.

Steve

GlengarryGR

Damn guys thanks for the comments. I just learned so much from this post! I owned a Cayman S and now a C2 & C4. The 993 is infinitely more fun to drive but I must say that as a novice driver (I bet my wife is a better driver than I am) I had more confidence in turns in the Cayman S. I did road race motorcycles for 7 years but I found little transfer of skills other than how to enter and exit the apex. Nonetheless, after test driving a 997, I was disinterested. My experience made me realize why the 993 is referred to as the King of Porsche. I will own a 993 until the day I'm dead. Nothing compares. At least to me.

andrewk34

Right. This is a a useful metric for the cost of being rear-engined, and it shows that it isn't all that much---e.g., a few years of regular technical progression. And even then, note the far lower hp for the 911. I guess I'm dubious that we really understand the physics involved well enough to make clear statements about the relative performance of mid-versus-rear engined cars. For example, just this year, Science published an article highlighting that we don't understand why a bike remains dynamically stable after the rider falls off. The usual explanations are (a) gyroscopic precession of the front wheel or (b) by the wheel contact trailing like a caster behind the steer axis. The authors created a bike the cancels both, but it still remains stable. And this is for a bicycle: something that we thought is dynamically well understood. Science is one of the world's leading science journals. It is difficult to publish in it. This article got in because the results are surprising to physicists.

http://www.sciencemag.org/content/332/6027/339
Back in 2011, Car Magazine wrote an article also questing if we really do understand the performance tradeoffs between rear and mid engined cars:
http://www.carmagazine.co.uk/News/Se...t-does-Part-1/

Petevb

Car performance is an incredibly complex topic that at one level no one fully understands. In racing, even in rules that don't change from year to year, you'll get 10 different answers on the grid to the question of how to go quickly. At LeMans we've even seen front-mid engined prototypes make a run at it in the not too distant past (Panoz GT1).

That said, to get very close there are many tools available (such as Adams/Car) that very accurately predict how a car's going to perform before you build it, and on the level of what impact different engine placements have they can tell you with a high level of certainty. In motorsports the question is clouded by rules, performance equalization and aerodynamics that are not applicable to street cars, but the physics is quite clear.

It goes to show that there isn't too much money in figuring out why a bike remains stable after a rider falls off... Not a hard problem to figure out when there is; weigh the couple authors looking at a bike stability problem that has no practical application vs the billions spent on car design and motorsports each year.

By coincidence the bike stability issue is a subject I happen to know something about, being co-inventor as a consultant on a gyroscopic bike training wheel back in the day. It's perhaps a better understood subject than you might imagine from that paper (skip to 26 seconds to see it in action):


Of course the devil's always in the details, regardless of the topic, but the mid vs rear engine stuff is not a mystery. In the automotive field I don't pretend to be one of the guys that understand the most about it, but I do know a couple of the guys that do. On the level above the average author Car magazine there is little question, and you can bet Porsche's CEO wouldn't be admitting the drawbacks of rear engine it if it wasn't both true and pretty obvious.

Again, I'm one of the guys that appreciates those "flaws" and see them as enhancing the experience, but from a purely performance point of view I recognize the drawbacks.

CarManDSL

The OP asked, "Do you think Porsche will ever make a mid-engined 911?"

The answer is a simple NO!
It wouldn't be a 911 anymore then would it.

The "911" in the 911 GT1 came from the homologation rules that stipulated the race car chassis needed to be based on a production car and have been crash tested. They simply took the front of the 911 and graphed on the rear of a 962 like configuration.