More and more companies are proudly incorporating all wheel drive features in their cars (i.e. lamborghini, 911 turbo, Audi, subaru), which clearly contrasts other cars and companies that have consciously excluded awd as a feature (i.e. 911 GT3, GT2, Ferrari, Mcalren). So what is the reason for all of this. I am aware of the advantages of AWD in dirt, ice and snow, but why would cars never meant to touch dirt have AWD. If it is such a great feature then why have some cars and practically all of road racing stayed away from it. I have heard some people say that AWD cars handle better. I can't see why they would. Is it True? If two identical cars, one AWD and one rear wheel drive, were on a track which one would put up faster times. Is the difference really just driving style?


And on a side note wich would you choose if performance figures were equal:
911 turbo, gt2, gt3, carrera 4s (don't take asthetics into desicion)

(in other words which combination of engine type and drive line whould you prefer) Turbo vs Naturally Aspirated and AWD vs RWD

 

If you put a C2 and C4 on a track, the C2 would run faster lap times, at first. After a few laps, the C4 would start gaining and eventually pass the C2 even thought it is heavier and has the same hp. Why, tire management. Both cars speed is going to be limited by adhesion, once the C2 starts stressing the rear tires (temperature), the 4wd will provide the benefit of evening out the power down and temperature.

That being said, I like driving the C2 better. 4wd is a bit numb for me (and I own a Turbo)...

Just my .02 worth...

Roy

 

Is 4WD safer on the tracks as well?

Let's say one of your rear wheel catches a little bump (like the edge of a rumble strip) and got lifted. With 2WD, there is only one wheel left pushing the car and you could spin easier than with 4WR where the power is spread across the rest of the 3 wheels.

Some people talk about 2WD cars turn better because the front wheels don't have to pull and can concentrate on turning. This may be advantagous when powering out of a corner.

 

Porsche got burnned with a major law suit ala La Jolla. They starting with the AWD to limit the oversteer and the liability that is inherent for novice drivers on city streets.

 

On a dry surface, particularly at high speeds, if the traction limits of the rear tires are exceeded and the car commences the action of rotation, there are two scenarios that can unfold:
A two wheel drive vehicle can not exert enough energy to overcome the angular momentum of the rotating vehicle since the front axle is not powered. The vehicle then spins out.
A all wheel drive Porsche 996TT, for example, in the same circumstances overcomes the momentum of the rotation by exerting a frontal force [energy] sufficient to pull the vehicle forward which will true the vehicle vector and decrease the angular momentum, of the rear of the car, therein. The vehicle direction is corrected and the race continues.

 

but if the lateral acceleration is enough to overcome the adhesion of the rear tires would it also be enough to overcome the adhesion of the front, renderiong the forward push on the front wheels obselete? or does it not work that way?

which type of drive is faster on the track? ( given equal weight, power, ect..)

 

Typically the angular momentum of the vehicle moves the rear of the vehicle in a left or right rotation when the traction limits of the tires have been surpassed. To have all four tires lose traction and not have enough energy to overcome the angular momentum may occur if the front tires could not re-gain traction to pull the car forward. This could happen in a very severe rainstorm or if there was a large oil slick which would inhibit traction.
The other way the car could very rapidly move in a tangential direction to the driver's intended direction is if the vehicle was bumped by another car.
Dirt track drivers may identify with this scenario.

 

FWIW

Audi "cleaned up" in the Trans Am with a 5000 Quattro a few years ago. These were full race, tube frame cars running on slicks. They were banned after 1 or 2 years. With the exception of rallying, most sanctioning bodies have banned AWD. When properly applied, AWD is faster than RWD. Whether it is faster on a track on street tires in the hands of a novice is another matter.

Cheers,

 

Just trivia..........1989 was 1st 911 (not counting 959) and Lambo has been doing it almost as long.

Obviously 2 or 4 is a personal choice, and has alot to to with the particular car, your ability, and what you use it for. I've tracked 911s for some time (just recreational, say 25 track days a yr) and personally I'm not good enough to manage a rear-engined car with 5-600 HP driven to only 2 wheels (and go as fast as I like to go) .

 

Good news for me that Porsche makes an AWD vehicle. I live in NYC and as most of you know the weather can be somewhat brutal (rain, snow, ice) so a RWD car is not an option for me. As many of us, I'm sure, have owned or own a BMW you know that it didn't leave the driveway if it looked like rain. I think the M5 is a terrific car, but I wouldn't take it out if it was cloudy.

So Porsche tapped a market for people that love to drive in all weather conditions - smart.

If I lived in Arizona I doubt I would buy an AWD Porsche (excluding the turbo of course because you don't have the option).

Rob-

 

AWD is safer on many high hp cars for the novice drivers as well. It can transfer a certain percentage when it feels the back breaking loose. I have heard the statistic that something like 25% of all GT2's have been in an accident lready. If you are a novice driver too much throttle application in turns can cause you to lose the back end. In an expert's hand (ala Hurley Haywood, or Walter Rohyl) the GT2's and GT3's are probably much faster as they know how to control the cars much better. For the average daily driver (myself included) I would probably get the 911 TT.

 

This is a question I've had for a long time. People who are race enthusiasts seem to be partial to 2wd. I agree with the awd being much more forgiving (my turbo is still in one piece!!). I wonder what things would be like if there was a dedicated rally or race series for awd. Historically, race cars have enough trouble finishing in one piece. The engineering and technical advances have provided us with fairly reliable hardware for today. Maybe awd would be faster if given time for R&D and possibly safer. My 2c. anyone have any thoughts on this?