^Good job posting the picture. It's even funnier the second time, no really, it is.

I see what you're saying Mafia. But, nobody just adds awd hardware to a rwd car. I realize how Speed GT balances the cars with penalty weight. As I mentioned, the Audi's are carrying the extra weight of the AWD, plus near maximum penalty weight last season, and they still were near or at the top. If RWD is so superior, why was audi winning with so much of a weight penaly?

 

Not to detract from the excellent technical argument in play here, but it'd be interesting to see Porsche come out with a GT34 with some more power to even things up, wouldn't it? Then we might see a decent comparison that makes sense. That would also serve as a nice homologated version of an AWD P-car racer to go after the RS6's on track. Just think how much more Henzler would kick tail (if that's possible).

And, what happens when Porsche see's Rick G and other privateers converting TT's to race cars?...They did run turbo race cars in the past...A GT3-esque turbo would be mighty interesting as well.

Ben's mention of purpose and target for the AWDTT was correct IMO, and few could argue that the TT was meant for a performance/luxury cruising buyer and not a racer, at least in it's OE form. It was smart for them to create cars that could bring more buyers in. That's not degrading Porsche purism, it's good rev-generating business. I doubt Porsche could survive on "pure" sports car sales alone. If selling more cars and diversifying to attract and sell to a greater market share allows continued development of serious sports cars "on the side", I'll be the first to support that tact and be happy that the sports cars are still being built at all.

I've been on track in RWD and AWD cars, but haven't been in a true race-prepped AWD car, so I can't extoll the virtues of one over the other. The apples-to-apples comparo opportunity just hasn't surfaced yet.

Let's watch Rick and other privateers this year, and see how their home-grown AWD racers fare. In the meantime, it's great to have variety to enjoy (and argue over!). With the Boxster, C2, C4, TT, GT2, GT3 and CGT, I think Porsche's sports car soul is very much intact.

 

big D, you're back! hopefully you can stay off these boards, get your biz for tomorrow done today, and...

 

I don't think it works that way in racing. Audi's don't carry the extra weight of the AWD because they are or should be at the lowest weight limit for their class just like everyone else. Other cars might run more ballast though to get up to that minimum. The extra penalty weight they do, of course, carry indeed as it is extra weight in every sense of the word. As far as winning - not sure why they won more than others. More power? Maybe. Better power delivery? Maybe. Better handling? Also maybe. We're not comparing the same cars here. If there was an AWD RS6 and a RWD RS6 then it would be closer to the true comparison.

996TT X50 and 996TT GT2 is sort of that comparison. GT2 is lighter but that is mostly accomplished by ditching AWD hardware - makes sense. Other things are more or less equal or could be equal and GT2 comes out on top. That's basically my point as to why RWD config is preferential. That said there are obviously some very fast AWD cars on the track - EVO's just one example. So one can go fast in many different ways, but if the only variable was the drivetrain config - AWD is at a disadvantage IMHO.

 

Yep, I'm trying to, dammit!

 

I agree. I don't think I was clear before. Here is what I meant: say you have X units of friction available, then you can spend 100% of X on braking. But if you'd like to turn using 10% of X, then you have to decrease braking such that it would be using only 90% of X otherwise the available friction will be exceeded. The way 10% of X relates to actual reduction in braking forces is something I didn't really intent to address, it's probably more complicated than a 1 to 1 ratio. Basic idea is that you can't ask a tire to do too much, if you want to do more of one thing (braking) you have to do less of another (turning) - and that's the important part.

 

yeap, very much agreed.

 

On the friction circle argument, the fact some of you are forgetting is that it's a CIRCLE. IOW, mathematically, if X is acceleration (or braking), and Y is Left/Right, and you're in a 1g capable car (and let's keep aero out, and assume it's 1g in all directions), then X squared + Y squared = 1. Or, if you're at the 45 degree point on the circle, X=Y, and when you solve for X, you get 2 X squared = 1, or X = the square root of 0.5, which is about 0.7. So, in trail-braking, you could brake at 0.7g, and turn at 0.7g, and still only be working at 1 g total.

This is why you don't take corners at max lateral acceleration, in a perfect constant-radius arc all the way round the corner, straighten the wheel, then hammer the throttle. You get on the throttle at (or before) the apex, and straighten the wheel gradually, feeding more throttle as you go. By symmetry, you do the opposite on the way in (i.e. trail-braking). This is where the piece-of-string-connecting-steering-wheel-to-foot visual comes from.

Obviously, there are exceptions. Trail-braking is not always the best approach to a given corner, but often it is. It's just really hard to do it perfectly every time, which is why Schumacher does it, and I don't.

As for what that has to do with AWD vs RWD, I'm not sure it has much to do, other than being a way for us to boil down the behavior of 4 tires to one picture. In reality, the friction circle is much more complex, as you would need to think about each wheel individually, its respective loading at any point in time (which influences yaw angles, which changes the characteristics of the circle for that tire at that moment...), and blah blah blah.

I have to believe that a properly programmed AWD system could be made to be faster than RWD, simply because RWD is a special case of AWD (with a 100/0 torque split), that could be redistributed in situations when an alternate balance is optimal.

Whether that's enough to overcome the intrinsic weight penalty, I haven't got a clue.

As for fun factor, that's a subjective thing. RWD cars are clearly more responsive, and more given to throttle steering and all the things many driving enthusiasts treasure. Some people like the cornering-on-rails and stability AWD cars tend to have. Different strokes, as they say.

 

But if one is trying to analyze awd vs. rwd, then I think the point is not simply a discussion re friction but rather a discussion re "does putting some accelerative torque into the front tires reduce their cornering capability on a 1 to 1 ratio with the amount of such torque". If it does, then awd should not improve things...if it does not then it may. I do not believe that it does. Further...if putting accelerative torque causes a 1 to 1 loss in cornering, then putting in deaccelerative torque should as well should cause the same 1 to 1 loss. And if this is the case then trail braking should not be effective, except in circumstances where you are trying to drive around understeer.

 

Look at WRC for example.... there's a situation where AWD is needed... why? Because even on straights, the tires have problems harnessing the power and get'n it all to the ground. Likewise, any slippery condition will see the benefits of AWD. But, in dry conditions, with two identical drivers in two similar cars of RWD and AWD, the RWD should win out.

Look at road-going versions of money-is-no-object sports cars... McLaren F1, Enzo, CGT, F40, F50, Saleen... outside of the CGT, these cars all have very rich racing heritages... notice that none of them have AWD. If it really is advantagous, certainly at least some of them would have it.

The Porsche Turbo is a GT through and through, and prehaps the AWD will make 90% of its owners faster at a track than in a GT2... that is as a result of a lack of skill in a RWD platform more than anything else... the Turbo will save your *** every time with its sheer power, grip, and safetly margin that the AWD allows for dancing around the limits of adhesion. With the GT2 and like cars, driver skill plays a much bigger role.

I''d be interesting to see F1 go with the option of AWD... I'd suspect you won't see a single team go that route... with success.

 

yes i agree that in theory awd should allow you to maximize every available bit of traction out of each tyre. BUT, it comes at a cost:

#1 it's extra weight you have to lug around
#2 it's extra drivetrain loss you have to put up with
#3 it's extra possibility of a mechanical break down
#4 it doesn't get you anywere if the system is not dialed in close to perfection. i think awd is really hard to trully dial in properly for each and every situation. to perfectly harness every bit of potential traction available you'd have to run a very sofisticated traction control system that might actually be illegal in the series you're running.

i think advantage of the AWD is outweighted by it's disadvantages given "enough" traction already. that's why these systems are not more widespread.

in a well dialed in RWD car with "enough" traction already a good driver can do what the AWD car would be trying to do (max available traction) without the extra penalties. it's no doubt in my mind that a ham fisted driver will be faster in an awd car but that's not the point.

 

BTW...I do not think the 996tt is a very good example of optimal usage of awd capabilites. Frankly I think it is a pretty poor handling car at the limit...it understeers when you try to drive it hard out of the corner. Stock that is...I am still working on making it work through mods.

 

Obviously this is fun to discuss but the only way you could really judge this is on the track. It would be great to take a driver with a tt and have him run a track say 10 laps and get his best time. Then disconnect the front driveshaft and run the same track getting a best lap out of 10 to see the difference.

 

the diff would not be nearly as large as it normally would be since they'd still be carrying around all the weight from the AWD if it were just disconnected. in fact, it might (probably would) be worse since the weight, balance, suspension, etc are all set up for the AWD which would still be there but completely unoperational.

 

True, so maybe a GT2 and a tt with X50 and GT2 suspension. Same driver, same track. Doubt this would happen so what's the point?