Is the Porsche Carrera GT Too Dangerous?

Hugh Pickens DOT Com writes "CNN reports that the 600 horsepower Porsche Carrera GT is notoriously difficult to handle, even for professional drivers. Known as the car actor Paul Walker was riding in when he died, there is no suggestion anyone was to blame for Walker's crash but Top Gear's Jeremy Clarkson says drivers are on a 'knife edge' handling the car and described it as 'brutal and savage". 'It is a phenomena — mind blowingly good. Make a mistake — it bites your head off.' Todd Trimble, an exotic car mechanic in Las Vegas, says the Carrera GT is a 'very hard car to drive.' It's (a) pure racer's car. You really need to know what you're doing when you drive them. And a lot of people are learning the hard way.' The sports car has a top speed of 208 mph, a very high-revving V10 engine and more than 600 horsepower says Eddie Alterman, editor-and-chief of Car and Driver magazine. 'This was not a car for novices,' says Alterman. Having the engine in the middle of the car means it's more agile and turns more quickly than a car with the engine in the front or in the rear so it is able to change direction 'very quickly, very much like a race car,' adds Alterman. The Carrera GT is also unusual because it has no electronic stability control which means that it's unforgiving with mistakes. 'Stability control is really good at correcting slides, keeping the car from getting out of shape,' says race car driver Randy Pobst. Alterman concludes that learning to drive a car like a Carrera GT can be extremely tricky. 'Every car is sort of different. And this one, especially since it had such a hair-trigger throttle, because it changed directions so quickly, there is a lot to learn.'"

Re:When you have a bad driver ...

[0123456]

Can anybody give me a reason not to have stability control where that reasons does not contain “fun” or “because”? (which might be sufficient – just looking for any other reasons.)

'Cause, uh, it's a sports car designed for racing?

Mid-engined cars are designed solely to get around corners fast, and they're extremely unstable compared to your average Ford or Honda. The problem is that many are bought by people who have no clue, and end up in a ditch the first time they take their foot off the gas in a corner.

Re:No, it isn't

[Anonymous Coward]

The Porsche has a very counter intuitive trait which helps to make it dangerous in the hands of an untrained driver. They exhibit oversteer when you lift your foot off the throttle. This means that as you begin to slide taking your foot off the throttle is exactly the wrong strategy as it will make the slide worse leading almost immediately to loss of control. At the point where the tires begin to bite again you will either dart quickly in a random direction or roll the car.

Yes.

[yoduh]

As someone that's driven 1,000+ HP cars, worked over a decade around high performance cars ... yes.

There are some cars that have a reputation of trying to kill you, but the Carrera GT is on the far side of that spectrum. Clutch engagement range compared to a light switch and no ground clearance makes this car difficult to drive on the street.

This isn't a 911, or anything remotely streetable. Many crazy high performance cars come with very advanced stability controls and AWD for a reason.

Re:Stability Control

[adolf]

Because it is designed to be a simple car, and traction control is != simple.

And a car of this caliber, if driven in a fashion typical of how most sane people drive, would be operating so far below its limits that traction control would be unnecessary.

Furthermore, in its purest form, traction control only helps grip on acceleration, and the only actions it can perform is reducing engine output and/or selectively applying braking. It does not help grip when in a four-wheel drift. It does not help grip when braking. It does not help when ... [I could go on, but why?].

Re:No, it isn't

[Scootin159]

Lift off oversteer isn't exclusive to Porsche - pretty much any car that adheres to the laws of physics will do it. It stems from the weight transfer off the rear wheels when you lift off the throttle (due to less forward acceleration pushing the body of the car "back"), this decreases the normal force on the rear tires, causing the total grip to decrease in the rear (while the exact opposite is happening at the front end), and shifts the grip balance towards the front.

The only reason most "other" cars don't exhibit this behavior as strongly is that they aren't setup (from the factory) with such a neutral balance - they're setup to understeer so strongly that the balance window you play in goes from "more understeer" to "less understeer" - not "understeer" to "oversteer".

Re:When you have a bad driver ...

[bleh-of-the-huns]

That is incorrect. There was never a reason to ban an aid that allows a vehicle to go faster, it is racing after all, the point is to go faster.

The primary reason many of the driver aids were banned was to level the playing field between race teams. It literally all came down to money, where some teams (like Williams back in the day) had 10 to 20 times more money for R&D. Other teams just did not have the finances to develop all the advanced functions that some teams were coming out with. Traction control for example was banned, which is a shame as that would have saved Senna's life (traction control is different from stability control). At the time the cost of the system put it out of reach for many teams, so FIA decided to ban it.

The "news for nerds" on this....

[Scootin159]

Since Slashdot is supposed to be a place for nerds... and nerds like to know the technical details more than just sensationalizing the latest headlines (or at least like to think so).... here's some technical information on why cars like the Porsche Carrera GT is so difficult to drive. I unfortunately don't have time to write out all the details here, but here are some basic principles of automotive suspension tuning to keep in mind:

• There's nothing special about it being a "Porsche" in this scenerio. It's more a factor of being an aggressively tuned high-performance sportscar. Your Toyota Camry will have a VERY different handling profile than the ones you see circling at the Daytona 500 - despite both being "Toyotas". To lump the precieved "dangerous" handling of a Porsche 930 (the car that started the sensationalizing of being a "dentist killer") with a Carrera GT, just because they're both "Porsches", is almost equally absurd.
• There's nothing unique about the Porsche Carrera GT that could cause these crashes - other than perhaps that they're headlines when they happen. It's more a factor of it being an agressively tuned chassis than anything unique to "Porsches". Most of the top-level modified "race cars" you'll see at any amateur racing event will have much the same "issues" of being hard to drive.
• Pneumatic tires require a "slip angle" to work properly. This is defined as the angle between where the tire is pointing, and where the car is heading. Even when you're driving your Prius at 20mph around a casual bend, there will be some flex between the angle of the tire and the angle of the car (this is why your Prius tires don't last forever) - it's a very, very small angle in that case, but it critically exists.
• In any suspension design, you'll have something resembling a basic bell curve that describes the ratio between slip angles and the amount of grip available. As you increase slip angle, you'll have more grip in your Prius... to a point, at which it will start to fall off
• The more aggressively you tune a suspension (stiffer components, stickier tires, etc), the higher the peak of this bell curve will be.... but at the same time the steeper the drop offs on either side of that peak will be as well. This bell curve is how drifting works, and why drifting isn't the fastest way around a corner. At very high slip angles you'll have much the same grip level as at very low slip angles - meaning that your cornering speeds at large yaw angles will be very similar to our casual Prius driver.
• Aggressive race cars will want the absolute highest peak possible, even if that means sacrificing the area under the curve. Drift cars conversely will look for maximum area under the curve, as it will allow them a larger window to play in. Street cars will be tuned for a very flat curve, as it's the most natural to the average person - they'll also need to compromise total area under the curve in the quest for comfort.
• The stiffer components in a suspension will improve the suspension's consistency (input x = output y) and responsiveness. This increased responsiveness will also make things happen quicker (duh), so you had better have a quicker reaction time if you hope to "catch" any mistakes. In high-strung race cars (open wheel formula cars for instance), this responsiveness can become so quick that you almost have to predict the mistakes as you can't move your hands quick enough to "catch" them if you wait for them to happen before trying to adjust. Likewise, your "catches" need to be more precise, as you've got a smaller peak in that bell curve above to aim for.

As you can see... the more aggressive you tune a chassis (which the Carrera GT was designed to be very aggressive, as that's the market they were after), the less compliant the car will be, and the more apt it will bite you if you make a mistake. Is this unsafe, or just a fact of the physics involved that you can't drive an aggressive sports car and expect it to handle like your Camry?

Re:When you have a bad driver ...

[contrapunctus]

The point of ABS is to give you control at the cost of stopping distance.

Re:When you have a bad driver ...

[Khyber]

WRONG. DEAD FUCKING WRONG.

http://www.design911.co.uk/blog/index.php/2012/06/27/pasm-psm-or-sport-what-does-it-mean/ [design911.co.uk]

My 944 had it, and that's WELL THE FUCK BEFORE 2005.

It wasn't known as ESC, it was known as PSM on a Porsche.

Have you even driven a Porsche, n00b?

Re:When you have a bad driver ...

[Wookact]

He was in the passenger seat and the car was being driven by a "pro" apparently. Try not to leap to conclusions.

Re:Stability Control

[drinkypoo]

Furthermore, in its purest form, traction control only helps grip on acceleration, and the only actions it can perform is reducing engine output and/or selectively applying braking. It does not help grip when in a four-wheel drift. It does not help grip when braking. It does not help when ... [I could go on, but why?].

While that's true, most cars are now required to have yaw control, and not just traction control and ABS. And the traction control system is part of the same system that handles yaw control, typically built straight into the PCM.

Re:When you have a bad driver ...

[zyzko]

Yeah, every *novice* race driver claims that they can stop faster without ABS.

This has been debunked even on 20 year old ABS systems. In Finland - with professional rally drivers. Yes - on perfect conditions when the driver has the power to start whenever he likes - the non-ABS braking distances were a little bit shorter. But when you introduce even 1 unknown variable (not knowing when to start braking, unknown traction below the wheels, distraction during braking) even the professionals failed to stop faster on non-ABS car.