343Bhp

You guys are missing the point. Quattro will only be beneficial if you are getting wheelspin in the RWD car. If you rear wheels are not spinning, then your rear tyres are providing enough traction to get the power down efficiently.

If your wheels are spinning then you aren't going forward & a quattro car would be better at that point. Now, I haven't been on any tracks where there are 1st gear corners for me. Even a tight hairpin I will take in 2nd gear. There is no way I can an M3 to wheelspin in 2nd gear by just stomping on the gas. From standstill I can light up the rears by revving & dumping the clutch, but not in 2nd gear. Maybe a car with more low down torque might have more traction issues coming out of tight 2nd gear bends, but not an M3.

Please not I am not talking about sliding yet. I'm just talking about getting the power down & opportunities for quattro to have a benefit on a track. OK, let's talk about corner entry. You are off the throttle as you turn in. Therefore, it makes no difference what your drivetrain layout is if you aren't on the gas. Quattro can't help you to turn in. In fact, the front heavy S4 hesitates to rotate & gets understeer on entry (as does the M3, but not to the same extent).

It's only when you get on the gas that it matters how many wheels are accepting the power. Thus far on all the straights & every braking zone & turn-in points, quattro has not helped you one bit. It's just dead weight to carry around a track. Now when you start applying the throttle too early you will get understeer in a quattro car & oversteer (or understeer as well) in a RWD car. You might be able to get onto the gas earlier in a quattro car as opposed to a RWD car with lots of traction issues. However, an M3 is not one of them. If you rear wheels are not spinning then you don't need the help of another diff to disperse power.

In the wet I always assumed quattro would be much better. Nothing has changed on the straights & corner entry. But on corner exit, you might now get wheelspin when applying the throttle. However, if the surface is not too wet & you have good tyres that are dispersing enough water, & you are progressive with the throttle, wheelspin on the exit might not be a probem. Now, the front heavy S4 wil understeer more on entry due to there being less mechanical grip available on the greasy surface. The M3 should understeer more as well, but you can balance that on the entry by applying throttle & getting the tail out just a little. Thus, you are going to carry more speed into the corner & quattro might not be able to negate that advantage on the exit.

Just my thoughts on the subject. Hope to hear contructive criticism.

Gorobei

I doubt much of it will be constructive

HiTEC

People think that 4wd/awd is something that defies physics. It doesn't really aid in helping your car hold a corner in slippery conditions nor does it help you stop. I always find it funny the first snow of the year when 75% of the vehicles I see in the ditches on my way home are SUV's.

The same applies to the S4 on a wet track

Geza

but everything isn't always so cut and dried.

The fact is exit speed is more important than entry speed. All wheel drive allows more tractive force to be applied to the tarmac earlier in the corner which nets increased exit speed.

I've been able to "hold off" lighter, more powerful cars (911's) on high speed tracks (Watkins Glen) in my stock A4 Avant 2.8 just by acheiving supperior exit speed. I'm at full throttle half way between turn in and the apex (once I know I'm going to make it!).

In a race environment, quattro has better tire wear characteristics under power than FWD or RWD. This enables the driver to "use" more tire during braking, thus out brake the competition. That is why quattros dominated Trans Am in '88, IMSA GTO in '89, the world wide touring car series in '96 and the Speed GT series the last several years.

And when the conditions get slick, the advantage increases.

rtking

Yes, it's true that the Quattro driveline is a liability in terms of weight and drag. But what you're missing is that the Quattro drive line will allow you to apply power sooner in a curve. This translates into higher exit speeds as Geza stated.

At 10/10ths, all RWD, FWD, and AWD cars will have a problem applying power coming out of a turn. The fact that in FWD and RWD cars is that the amount of power you can apply before overcoming the traction available to either the drive wheels or the steering wheels is limited to how much of a slip angle you really want on corner exit.

AWD cars are subject to the laws of physics and the coefficient of friction (measured in Mu) as well. The main difference is that on exit from a turn, you have FOUR tires carrying the load of accelerating and turning.

When you compare understeer on both the M3 and the S4, you're assuming the same point of turn-in on the turn. If you do, then yes... then AWD will not turn in as crisply as RWD. But then again, you're not driving the AWD car properly. The main point is that each platform (AWD, FWD and RWD) will have their own turn-in points, lines and apexes. Finding the proper balance is key. Of course, the driver is a critical aspect as well.

At the big track at Willow Springs in 1994, I attended Ford's SVT press introduction of the Mustang Cobra. Present were both the Mustang Cobra and the F150 Lightning. Randy Bleicher, then chief instructor for Bob Bondurant, drove the Cobra and Tommy Kendall drove the F150 Lightning. I rode with Tommy Kendall. On that 2.5 mile road course, Tommy not only spoke to me throughout each and every turn in a calm voice, but he also reeled in the Mustang Cobra and passed it with a pick-up truck!

My point? Despite the weight and lack of horsepower (compared to the Cobra) Tommy Kendall was able to adapt to the Lightning and balance it through the road course better than Randy Bleicher could in the Cobra. Tommy drove distinctly different lines than Randy and ended-up being much faster in a vehicle that weighed more and had less horsepower.

The same holds true of the S4. Drive it like an M3 and of course, the M3 will win. But if you drive an M3 in the same lines that you would drive an S4, then the M3 will not have a stellar showing (based upon, of course, how judicious you are with the throttle.)

Before anyone flames me, I'll confess: I've driven an E46 M3. It makes you FEEL fast, but to really extract the handling from this car, you had better be an experienced driver because it doesn't reward indiscretion well. My experiences with Audi A4/S4s initially made me think it understeered badly through turns, but as I adapted to the advantages of Quattro, I actually found that the speed was very deceptive. I was exciting turns much faster, but without the dramatic affects of my Mustang SVO or event he M3.

That's my $0.02.

Bob K.

BM3car

For racing quattro cars could just use softer tires, thats why they smoked everyone, that and as you said, tire wear. Better tire wear is why they could run a softer tire, the soft tire, not wear is why they could brake better.

Exit speed is a funny thing, several aspects to it that we just dont have the time and bandwidth to get into. From my exp. I have been able to carry more speed into the corner with rwd than awd due to the initial understeer, however a lot of that will balance out due to the fact that the awd can put the power down a bit earlier. In some respects the M3 needs to be driven this way, at most tracks as soon as I turn in I start to apply throttle, by the apex I am at WOT. This is the only way to get rid of the stock understeer IMO, more throttle If I have more entry speed and get on WOT just slightly later, the exit speeds would be rather close.

And as to what 351 ponies said the M3 does put the power down very well in the wet. Only in 1st gear WOT and during a hard shift to 2nd will I get any wheel spin in the rain. Unless it is just coming down VERY hard.

But if I had to pick a car to drive fast in the rain I would take the S4 over the M3. It just has that nice Quattro saftey net if you will, I would feel better in the S4 if wet.

markbradford

1. Let's agree on this: Corner entry and steady maintenance throttle through the turn = no difference.

2. If you can lay down full throttle in the wet in a straight line with 333 horsepower in a RWD car, I'd certainly like to see it. And if you can, then you're being forced to shift gingerly. I can run the straight through all the gears without even lifting my right foot. =P

3. Where Quattro shines is the ability to put down MUCH more power when you're getting on the throttle through the apex to track out point. You mention that "If you're progressive, wheelspin won't be a problem". That's the whole point - you are restricted in your throttle application, whereas an AWD driver car get on the gas earlier, and harder, resulting in a higher exit speed.

4. You fail to realize that Quattro helps you in the straights because it has afforded you with a few additional MPH throughout that straight.

5. There is a decreasing effectiveness to AWD sytems as teh power levels go down. Less power, less ability to crack the wheels free = less AWD advantage. BUT as power levels go up (and we all know they're going WAY up these days), you are going to see AWD becoming more of an advantage.

ADDENDUM:

6. Next on the menu - make the AWD systems lighter, less parasitic, and add adjustable torque bias.

ryoung

Any g's of acceleration are deducted from the total maximum potential lateral g's of the tire. Assume the tires are capable of 1.0 of lateral acceleration: If you're accelerating (or braking) at 0.4 g, you can only corner at 0.6 g.

<A HREF="https://forums.audiworld.com/racing/msgs/22637.phtml">Corner Weight Revisited</a> discusses this in more detail, and you can see the advantage of an AWD car. If you redid the following table for a RWD car, all the longitudinal acceleration forces would be acting on the rear tires only. The result is obvious -- too much power, too little is left for lateral g's, and the car oversteers. A comparable problem can occur with an AWD -- too much power, too much weight (load) transfers off the front tires, and the car understeers. In neither case is it necessary to spin tires for this to occur.

The result of all this explains why an AWD car use more power sooner. The only question is whether the weight of the additional mechanicals and usually poor weight distribution squanders the advantage. [and I forgot the additional parasitic losses of AWD, thanks Mark.]

<img src="http://pictureposter.audiworld.com/17157/weightdistribution_s8.jpg">

markbradford

If the manufafcturers can learn to make a lightweight, yet effective and robust, AWD system, that also minimizes parasitic driveline loss, the AWD advantage will be much more evident. Adjustable torque bias should be available too IMHO, for varied conditions.

BM3car

let you take my M3 for a ride in the rain. As long as the tires and not dead, 1st gear is the only time I will get wheel spin in the rain, that and if I REALLY try to nail hard the shift to 2nd. Once in 2nd WOT is not an issue. I have done this many times. The shift to 3rd can be as hard as you want, you'll just get a hint of wheel spin but nothing major. Even then wheel spin is a GOOD thing (just not a lot). For most street tires 3-6% slip will give you the max coef. of friction.

And on another side note, I think it may have been in Grassroots Motorsports mag. they did a test of awd cars for accleration in the wet and dry, I think all of the AWD cars were FASTER in a straight line in the wet over dry. In the wet they could all get slight wheel spin, and not bog down. Wish I could find it, it was a good read.