I cant explain it, just telling You how it acts in real life.

The reason You dont see people racing is what You see here in this thread. Even when presented with evidence they work well(C4s) people still generally wont accept it.

I know the reality, I drove the reality, I modded the reality and the AWD car was better, combine that with bigger brakes and wider/bigger footprint it was the hands down winner.

I built the car to literally prove the point to a friend who said that if it were better the factory would have done it that way...it was a fun project and worked very well. The TT conversion later was ridiculously easy and what I would do to any 993 I had now if I was looking for the best bang for the buck mod on the 993. We did it in the barn at my house in just a few hours....good times!

 

OK, so this is how I thought it worked. If your car is understeering, then the front wheels will be spinning faster than the rear wheels, in which case the power goes to the rear wheels (exactly like RWD). It could be worse (i.e., not transferring fast enough), but it could not be better since the power is already to the back wheels.

The real advantage that AWD theoretically offers over RWD only occurs in an oversteer situation, where the rear wheels are spinning faster than the front wheels. In a RWD car, you can't send power to the front, so you have to modulate the throttle. In an AWD car, the car can send power to the front so you can get on the gas faster.

For a car that has a lot of HP, that can be a real advantage. For a car that doesn't have as much HP, the advantage is not as important. As such, it becomes a balancing act between the advantage and the extra weight and complexity of the AWD system.

My original proposition is that, for a n/a bone stock 996, the added weight of the C4S is not worth the marginal advantage of the AWD system in a relatively low HP car.

What am I missing?

OOOPS: I posted before I saw your post above Glen.

 

thanks Ray. I must have missed that.

 

I agree with TD on this point.

- In dry conditions a 300-320hp 996 C2 does not have any problem putting the power down (even with the open diff). So the C4S sending power to all 4 wheels is of little advantage, however the added weight is a significant disadvantage.
- The wider rear end doesn't provide any real advantage (you can get 315's on a NB C2). However it also increases weight and adds aerodynamic drag.
- The bigger brakes don't really help (but they do add to unsprung weight) because the stock C2 brakes have proven to be more than up to the task in race conditions.

Even if one concedes than you may be able to get on the power a smidge sooner on corner exit with a C4 you would also have to concede that the lighter C2 should be able to brake later, and carry more speed into the corner.

The C4S is a great car (one of the best looking 996's made) and is obviously a great choice for bad weather. However, if I were building a 996 race or DE car (non GT3, GT2, turbo) I would start with a C2.

 

Yes. I don't see what would be so different about a 996 or 997 variant compared to the 993.

 

The C4S's are relatively rare cars compared to C2's. I am not 100% sure but could the GT3 be homologated if it was AWD? I think that would be an issue for the racing series since they would not be raced as they were produced.

IMO the advantage of the AWD cars like the C4S is that they can get on the throttle much sooner.

 

There are a TON of 996 C4Ss. I "think" it was one of the best, if not the best, selling 02+ 996s. My question is that if they have such an advantage over C2s, then why aren't more guys racing them in PCA club racing? It can't be money, because the price wasn't all that different . . .

 

Just to clarify for those who asked, I no longer own the car, sold it several years ago but it is still in the same configuration basically as when I sold it. The gears have been changed, turbos updated etc.. and its no longer AWD I guess. Otherwise its very close to how it was when I sold it.

 

Your question about why no body races C4 probably has more to do with the classing of cars in PCA that the cars themselves. Most of the complaining about stock class rules is in classes where your "free" C2 or C4 would run. IIRC, many people complain that 996C2s are not competative where they are classed. FWIW, 964C4 is F car and 964 C2 is in E because of weight difference.
And yes I know, you only are talking about 996/997. Why don't you look at the weight difference in those cars. I bet they are less than a 100 lbs which given the differences in driving ability at a club race, is not insurmountable (sp).

 

Nader,

when I looked at the PCA classes, I believe that all 996s (i.e., C2 and C4S) are in the same class. There is approximately 250 lb difference between the cars IIRC. If the C4S had such a decisive advantage over the C2 despite the weight difference, I would expect to see more C4Ss racing than C2s.

TD

 

According to Porsche, the 996 C2 laps the Nurburgring in 8 minutes 20 seconds. The 996 C4S in 8 minutes 16 seconds. Unless you believe that Porsche fabricated the numbers for marketing purposes, there should not even be a debate going on as to which is more capable in stock form.

Perhaps you could argue that it takes a very talented driver to take advantage of the C4S and that most mere mortals would be faster in a C2, but that's a driver issue and not an issue with the platform.

 

Link please to the official Porsche Nurburgring time.

I have seen so many lists, and some list the C2 as faster and some list the C4S as faster. Let's see your link.

 

Glen,

I posted on purpose the C4 (NOT the C4S) vs. C2 in earlier post.

I completely buy your argument about the technical advantages of AWD over RWD and how it will be superior in practice. However I've always found it to be more of a handicap when taking a stock C4 vs. C2. Using same footprint, brakes and suspension, but the added weight and the rather simple AWD. +50kg? That's actually quite a lot...

If talking about C4S, a standard C2 is not comparable I believe. Due to the other advantages that for example a 993 have, giving it better stopping power and being able to utilize a wider set of tires.

I believe the correct question would be - would two similar Porsches, with the same weight, suspension, tires and engine, give the one with the stock AWD an advantage?

 

Ring times are all different from day to day. Driving conditions are just too different.

It's also not possible to determine if it's caused by the AWD. A C4S is 1470kg and runs on 225/295, that's different from a C2.

 

but you see, that is a very different question. My intent here has nothing to do with proving that AWD is inferior. Not at all.

It is an engineering question. My assumption is that, when it comes to track performance, lighter is better. As such, if something adds weight, it should not be included in the car unless it decisively improves performance.

The same with brakes. Big brakes are not always better. I really do not understand why people are saying that the Turbo brakes on the C4S are "better" than the standard brakes on the C2. Both cars have the same engine. The C2 brakes do not suffer fade issues, they can repeatedly lock up the tires, and they have perfectly fine modulation characteristics. As such, bigger is overkill, and it just adds unnecessary weight. If two cars can both lock up the tires at will, modulate well, and do not fade, then the car with bigger and heavier brakes is at a disadvantage.

Same with AWD. If AWD gives you a decisive advantage in putting power down, then sure, the extra weight may be worth it. BUT, for a normally aspirated 996, is it really necessary at the expense of an extra 250 lbs?

Finally, the slighly wider stance? I really doubt that makes any appreciable difference at all.

But then again, I do not know it all, and I learn more every day, so I am willing to keep an open mind.