[Jamesons Viggen]

Originally Posted by 300hp

Has anyone considered that at each gear change the awd has the advantage of putting the power down more efficiently than the rwd. Since the transfer of power happens after the quarter, both cars, which were MT, are now in 6th gear and as everyone expects the rwd then gains it's much needed victory. Drivetrain losses and weight start to weigh in on the awd as it has no more traction cards to play. Isn't this the variable we were missing all along?

Again I am no expert on this but I am just taking a wild guess here

Not the case unfortunately.

300hp is a very modest power level(for a 3500lb RWD car). So is 400.

On cars equipped with 255mm rear tires, in dry weather, you should have traction briefly interrupted in the 1-2 shift, and MAYBE the 2-3 shift with the 8spd.

When you start breaking traction at over 40-50mph in higher gears you are likely seeing DOUBLE the power of a stock N55.

[300hp]

Originally Posted by Jamesons Viggen

Not the case unfortunately.

300hp is a very modest power level(for a 3500lb RWD car). So is 400.

On cars equipped with 255mm rear tires, in dry weather, you should have traction briefly interrupted in the 1-2 shift, and MAYBE the 2-3 shift with the 8spd.

When you start breaking traction at over 40-50mph in higher gears you are likely seeing DOUBLE the power of a stock N55.

Not surprised about the 2-3 shift since even on xdrive with the staggered 19s for a very brief inconsequential moment, you can hear the tires let loose under WOT. That's why I had assumed gear changes may play a role.

I stand corrected then

[Jamesons Viggen]

Originally Posted by 300hp

Not surprised about the 2-3 shift since even on xdrive with the staggered 19s for a very brief inconsequential moment, you can hear the tires let loose under WOT. That's why I had assumed gear changes may play a role.

I stand corrected then

It is more of an issue with 6mt cars, as you can be more aggressive in the shifting and basically shock the driveline a bit into brief wheelspin.

Stock, N20, 255mm rear S001's, I could spin on the 1-2 shift, and chirp on the 2-3 shift. So imagine what the added power of the N55 would do.

[335BOY]

110 posts about +/- .20 of a second.........................

[300hp]

Originally Posted by Jamesons Viggen

It is more of an issue with 6mt cars, as you can be more aggressive in the shifting and basically shock the driveline a bit into brief wheelspin.

Stock, N20, 255mm rear S001's, I could spin on the 1-2 shift, and chirp on the 2-3 shift. So imagine what the added power of the N55 would do.

You are being modest you know the answer since you have another beast you don't talk about often

[Jamesons Viggen]

Originally Posted by 300hp

You are being modest you know the answer since you have another beast you don't talk about often

Wheelspin in that car is not very relevant to this conversation lol. But when I was talking about much higher power levels causing wheelspin at higher speeds, I was talking from experience.

I will say- this week someone from a turning lane went to go straight and bully me from a greenlight as I was going straight. This led to a noiseless smoking burnout in first at a 20mph roll, then into second where I tipped into it a bit more and again smoked the person out as I fishtailed a bit and took off. Twas fun :P

[NISFAN]

Originally Posted by 300hp

I never disagreed about this, that's why I was making the point that it takes almost an eternity to break the small 0.2s lead. This 0.2s lead is maintained through the 1/4. I jokingly implied that by the time the lead goes to the rwd both cars are about to hit their speed limiter ( unless you have the speed limit increase option)

However you still seem to be ignoring the rolling start numbers (45-65mph) for the ATS awd vs rwd and the 335i xdrive with PPK vs the 335i rwd no PPK. It does not appear the rwd has more grunt at 45mph than it did at 0mph. (Remember the theory was it's all over for awd when it's a rolling start). I will jokingly suggest that it appears any race that begins in the 0-45mph range will have to head toward the 100mph zone for the transfer to be made. It's a race to that speed limiter all over again.

When one says at some stage the lead is transferred its generally a forgone conclusion that the lead was being eaten away until that point. It goes without saying. If I told my toddlers that I will catch up with you I think they understand that I mean even if they start to run I am faster than them. It's common sense

You are getting yourself all muddled up, you cannot compare two drag times done at different events and be satisfied that they are directly comparable.

Lets look at this....

The information you rely on states that a 335iX gets to 60mph 0.2 seconds faster than a 335iS. Sounds about right to me given AWD traction in the first 15-20mph range.

....but then the heavier, more power loss through the drive train 335iX maintains it's 0.2 second lead all the way through the 1/4. A 335i typically traps at around 103-105mph. So the suggestion is that the heavier 335iX has no disadvantage from 60-105mph. Clearly the RWD is not powerful enough to spin the wheels at 60+mph so what the heck is happening here?

Then miraculously, the 335iS goes from say 104mph (typical 1/4mile trap speed) to 120mph in a whole 0.6 seconds faster than the xdrive, even though it couldn't gain any time the 20mph before this. (0.2 seconds behind at the 1/4 then 0.4 seconds ahead at 120mph). What was it wheel spinning at 80mph?

It doesn't take a genius to realise that other factors are at play here, and therefore the figures are NOT comparable.

[NISFAN]

Originally Posted by Jamesons Viggen

It is more of an issue with 6mt cars, as you can be more aggressive in the shifting and basically shock the driveline a bit into brief wheelspin.

Stock, N20, 255mm rear S001's, I could spin on the 1-2 shift, and chirp on the 2-3 shift. So imagine what the added power of the N55 would do.

It is commonly understood that maximum traction occurs with between 10-30% wheel slip, depending on tyre type. It is only rampant wheel spin that causes poor traction.

On a fast MT gear change, it is drivetrain inertia chirping the wheels, not engine power. i.e a heavy flywheel, and I'm sure you'll find a 328 has a similar weighted flywheel to a 335i

[Jamesons Viggen]

Originally Posted by NISFAN

It is commonly understood that maximum traction occurs with between 10-30% wheel slip, depending on tyre type. It is only rampant wheel spin that causes poor traction.

On a fast MT gear change, it is drivetrain inertia chirping the wheels, not engine power. i.e a heavy flywheel, and I'm sure you'll find a 328 has a similar weighted flywheel to a 335i

Like I said, it is more the function of shocking the driveline. It is not the fastest way to get things done. People often associate wheelspin with power/speed. I had friends with V8 Monte Carlos and Camaros that would spin wheels all the time, then go run high 15/low 16 second 1/4 mile times.

Same thing with drifting, it looks cool, but it is not the fastest way around the track

[Elk]

Originally Posted by Meeni

AWD has better traction in inclement weather, but DSC and other electronic controls mean that with proper tires, RWD is not the animal it used to be, and can confidently be used on the snow nowadays. Given the mpg hit, I'd rather pass on the AWD except in a place where it snows most of the year...

Speaking of pure performance, AWD does have a traction advantage at corner exit (and could post quicker 'figure' times), but it will understeer more and detract confidence on entrance. It is a matter of weight distribution. AWD is heavier from the front, which is bad. RWD also offers better throttle control mid-corner, one can oversteer the car with the throttle, which is (often, depends on bias) not possible with AWD.

Excellent points.

I note however that for the F30 the AWD does not have an advantage on corner exist as it possesses insufficient power to brake the rear tires loose other than in a very slow corner, or if driven in a deliberately ham-fisted fashion.

[F32]

Originally Posted by NISFAN

It is commonly understood that maximum traction occurs with between 10-30% wheel slip, depending on tyre type. It is only rampant wheel spin that causes poor traction.

Exactly.

It's a shame one can't learn this through reading a magazine.

[Elk]

Originally Posted by 300hp

I threw in the towel on this a while back

That is, you now recognize xDrive inherently understeers more than RWD?

If not, perhaps you will now address the points I raised such as the xDrive using more of its available cornering traction than RWD on the same corner, and xDrive ability only to reduce the understeer the xDrive system itself directly causes, etc.

[NISFAN]

Originally Posted by Elk

That is, you now recognize xDrive inherently understeers more than RWD?

If not, perhaps you will now address the points I raised such as the xDrive using more of its available cornering traction than RWD on the same corner, and xDrive ability only to reduce the understeer the xDrive system itself directly causes, etc.

xDrive unfortunately cannot undo the understeer it causes. However there is a driving technique used on very powerful AWD racing cars that exploits the drive traction of an AWD.

This technique involves getting the rear end of the car out during the braking phase to a position that points the nose of the car at the apex. Power is then applied to drive the car towards the apex. All 4 wheels are pointing straight ahead in this position. Very similar (not as aggressive yaw angles) to Rally and Ice racing. This is used by professionals only in an attempt to neutralise AWD under-steer.

[300hp]

Originally Posted by NISFAN

You are getting yourself all muddled up, you cannot compare two drag times done at different events and be satisfied that they are directly comparable.

Lets look at this....

The information you rely on states that a 335iX gets to 60mph 0.2 seconds faster than a 335iS. Sounds about right to me given AWD traction in the first 15-20mph range.

....but then the heavier, more power loss through the drive train 335iX maintains it's 0.2 second lead all the way through the 1/4. A 335i typically traps at around 103-105mph. So the suggestion is that the heavier 335iX has no disadvantage from 60-105mph. Clearly the RWD is not powerful enough to spin the wheels at 60+mph so what the heck is happening here?

Then miraculously, the 335iS goes from say 104mph (typical 1/4mile trap speed) to 120mph in a whole 0.6 seconds faster than the xdrive, even though it couldn't gain any time the 20mph before this. (0.2 seconds behind at the 1/4 then 0.4 seconds ahead at 120mph). What was it wheel spinning at 80mph?

It doesn't take a genius to realise that other factors are at play here, and therefore the figures are NOT comparable.

You are answering a scenario that is in your own head here. I pretty much made it clear that the rwd is catching up and suggested its around the quarter mile (in terms of time not speed) where this happens. Its a suggestion since C&D never gave us the trap speed of the xdrive. Weren't both cars tested on the same day by the same driver. How are the two situations not comparable?

On the other hand I suggested that the advantage of the rwd from a rolling start at 45mph is overblown and gave some examples.

[300hp]

Originally Posted by Elk

That is, you now recognize xDrive inherently understeers more than RWD?

If not, perhaps you will now address the points I raised such as the xDrive using more of its available cornering traction than RWD on the same corner, and xDrive ability only to reduce the understeer the xDrive system itself directly causes, etc.

I threw in the towel because as I read more of what you guys have to say I realize that maybe the new awd systems are not yet properly understood. I will not stand in the way of your creative juices here

[StealYourFace]

I live in the so called snow belt- I have never been stuck. If I went to ski country a bunch, I might concider an xi but probably not. It's not worth giving up fuel economy and handling for the 30 or 40 days a year we actually get snow. The car is awesome with a set of blizzaks.

[btbossman]

Can you do 80mph in a downpour with RWD? Thought not. Cruise muddy(steep) terrain? Nope.. All better reasons to get X drive than strictly for snow. Even then, you may be okay in most conditions, but snow tires wont help going up an icey hill.

[NISFAN]

Originally Posted by 300hp

You are answering a scenario that is in your own head here. I pretty much made it clear that the rwd is catching up and suggested its around the quarter mile (in terms of time not speed) where this happens. Its a suggestion since C&D never gave us the trap speed of the xdrive. Weren't both cars tested on the same day by the same driver. How are the two situations not comparable?

On the other hand I suggested that the advantage of the rwd from a rolling start at 45mph is overblown and gave some examples.

Nope the scenario I posted is very close to the sum of figures listed in your magazine articles. Whether it is time, speed or distance a given car will achieve consistent comparable numbers between all 3. Take 10 identical spec 335i's, run them down the quarter mile and guess what, they all trap in a tight range, at a similar ET.

[NISFAN]

Originally Posted by btbossman

Can you do 80mph in a downpour with RWD? Thought not. Cruise muddy(steep) terrain? Nope.. All better reasons to get X drive than strictly for snow. Even then, you may be okay in most conditions, but snow tires wont help going up an icey hill.

Why would going 80mph in a downpour be difficult in a RWD?

[300hp]

Originally Posted by NISFAN

Nope the scenario I posted is very close to the sum of figures listed in your magazine articles. Whether it is time, speed or distance a given car will achieve consistent comparable numbers between all 3. Take 10 identical spec 335i's, run them down the quarter mile and guess what, they all trap in a tight range, at a similar ET.

I think we are agreeing then that the rwd catches up around the quarter. Trap speed of around 103-105mph? Once we agree or somewhat agree I am done with this. Whoever created this thread should then be banned for life

[Jamesons Viggen]

Originally Posted by btbossman

Can you do 80mph in a downpour with RWD? Thought not. Cruise muddy(steep) terrain? Nope.. All better reasons to get X drive than strictly for snow. Even then, you may be okay in most conditions, but snow tires wont help going up an icey hill.

Yes, 80 in a downpour. Muddy steep terrain? Where the hell are you driving lol. If it's that muddy and steep you should not be driving an Xdrive car either lol.

[Meeni]

Originally Posted by btbossman

Can you do 80mph in a downpour with RWD? Thought not.

And you should not, even with AWD. False sense of security leads to catastrophic outcome.

The problem with downpour is visibility and lack of braking traction (and possible hydroplaning), all of which has nothing to do with AWD or not.