VW Vortex - Volkswagen Forum banner
1 - 20 of 21 Posts

· Registered
Joined
·
17,998 Posts
Discussion Starter · #1 ·


Like most markets, Audi Canada operates its own driving experience and, not surprisingly, the Canuck take includes lots of snow and ice. That it’s focus is Audi’s prowess on the slipper stuff is to be expected though when we were offered the chance to drive the company’s all-new Euro-only RS 3 Sportback we found its temporary presence in Canada quite unexpected. Eh?

Full Story
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #8 ·
First of all, it's not fair that we don't get anything remotely this cool in the US. The fact that this car is in its last year makes it even more insane.

Secondly, I find it interesting that this car has the Sport Seats...no Recaro action? I think maybe only the two doors have Recaros for some reason?

Thirdly, who is going to make some of these parts available. I want:
1) Rear Spoiler
2) Leather covered Interior center console buttresses (unless they're more expensive than the Osir carbon ones)
3) Complete body shell, drive-train and chassis. :D

Lastly, this car epitomizes why I love Germans and the cars they build. The only cars that come close in their pure insanity are:
GT-R (let's face it, this car can't be profitable)
CTS-V Coupe and the SRT-8 Cherokee (insane)
Various hi-spec V8 powered Aussie Holdens and Fords (mad)

All praise quattro gmbh!
Read the piece. It is being considered for USA. That doesn't mean it's been confirmed but the fact that it's being considered is welcome news to me.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #17 ·
Thanks George. Must have been nice to get in the rs3 and ttrs back to back.

I'm suspect that we will see this car since we'd also likely get the s3 at that point as well.
I doubt the S3 will happen. If RS 3 does happen it'll be a parting shot. Plus, S3 would be effectively the same drivetrain as Golf R and I'm not sure that'd be a smart move.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #18 ·
HOT DAMN!!! I want this car. At first I was pretty stoked on the TTRS, but needs will be eventually changing so a five door would be optimal. Plus it's 5 cyl with decent mileage, DSG, high fun factor! I want this car. I hope audi brings it over!!! 7 Speed DSG please. Makes sense since the TTRS will be the manual choice.
This is a question of economies of scale. TT RS with MT6 is already federalized. I5 wiht 7-speed DSG is not. If it comes it will likely be MT6.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #121 ·
Whoever said it uses torsen is just plan making it up. The race division is given a platform and told to tweak it, so they got the 2.5, beefed it up and added a turbo to it. They don't have the R&D to redesign a whole AWD system, let alone adopt something that is impossible to fit without redesigning the chassis/engine/transmission block. The question is whether they threw in the Haldex sports controller in.
Yeah maybe they installed an aftermarket type Haldex controller to achieve the 50:50. I read it on Top Gear blog when it first came out:

"Using the same Haldex-equipped quattro drivetrain as the TT RS, the RS3 doesn’t get a rearward torque bias like the R8, unfortunately. Instead, power is split 50:50, although the system can apportion muscle to the wheel with the most grip."

http://topgearnew.blogspot.com/2010/11/audis-rs3-storms-in.html
The system is Haldex for sure. Torsen style system is only used on cars with longitudinally mounted engines, which is A4 on up pretty much. Cars with transversely mounted engines (A3 and TT) get Haldex which is a front-wheel drive based system that uses a hydraulic clutch center differential to send power to the rear as needed.

There are advantages to both I suppose. Torsen drives around at 40:60 while Haldex drives around as FWD but reacts more quickly. Torsen is mechanical while Haldex is controlled by software so different cars with Haldex might feel different in their driving dynamic based on what software they're running. Aftermarket Haldex controllers offer even more aggressive locking of the system but, as you might expect, a clutch-based system may likely wear out faster if you're driving around in 50:50 all the time so while most aftermarket setups are more aggressive they're likely not driving around all the time with the clutch engaged.

There are other versions of Haldex worth mentioning. When Volvo went to their XC90 V8 they were the first to implement a non-return valve that allowed the diff to lock while stationary so that it could launch with 50:50 much as Torsen does. I'm not clear as to which Audis may benefit from this upgrade.

Next is XWD as seen in the Saab Turbo X. Basically, this setup uses a hydraulic clutch rear diff that apportions power to the inner and outer rear wheel and this is basically the same functionality you see in the Sport Differential in the S4. No Audis yet use this iteration of Haldex which'd require a re-tooling of floorpan stampings in order to make it fit... likely the reason we haven't seen it yet.

Without a Sport Differential (XWD to Haldex) you still need to flick the car or at least let off and let the weight come around before you can oversteer. It's not a throttle-on oversteer experience as one would encounter in a Sport Differential-equipped S4.

Audi doesn't need to go to the aftermarket for Haldex software. They develop their own as needed and work with Haldex the OE supplier, etc. The Volkswagen Group is one of Haldex's biggest customers (if not THE biggest) and Haldex is now owned by Borg Warner. I believe companies like HPA in the aftermarket also work with Haldex though I'm not clear whether their software is HPA proprietary or if it is Haldex developed.

I hope this clears things up on the car's AWD.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #132 ·
Thanks for the info. I thought Torsen does not need to react given that the diff locks as soon as one axle tries to apply a twisting force to the differential, causing the worm gear to bind. Hence no slipping has yet to occur before diff locks.
We're probably talking semantics here. If my B8 S4 slips at the front wheels it sends torque to the rear via the mechanical differential. In the case of Torsen slip must first occur for torque to be shifted front to rear or rear to front. In the case of Haldex, most operational software parameters also use slip as the factor for torque transfer (to the rear because it's operating FWD under normal conditions). I say "Haldex is faster" because I seem to remain (and I'd have to re-check this) that torque transfer happens in a shorter degree of wheel rotation before torque is actually transferred. Haldex may be faster but the torque is already split on Torsen so it's not a wash but it's not as simple as one being faster. Another key difference is that software can be used to proactively send torque and this can be set to other parameters beyond ABS wheel spin sensors such as yaw sensor in the ESP system or steering angle, etc.

Isn't XWD a single clutchpack that locks the rear axle together, hence more like limited slip diff than a sport diff (with dual clutchpacks) that could overdrive either wheel above what the rear diff is providing, hence giving that oversteering feeling?
From what I understand, no. It can overdrive a given wheel. Here's a reference.

http://en.wikipedia.org/wiki/Saab_XWD

Here's quote.

To ensure immediate traction, torque distribution can be transferred to the wheel with the most grip in fractions of a second, and using the two couplings the XWD system can send 85% of available torque to a single rear wheel. The ability to transfer torque laterally between the rear wheels is similar to Mitsubishi's Super Active Yaw Control or Honda/Acura's Super Handling-All Wheel Drive.

It's also similar to the S4's Sport Differential and actually when I had my S4 on the lift over at APTuning this week, they remarked how similar the rear Sport Differential looked to the Haldex unit on an R32.

I also asked Stefan Reil about this once. Stefan is basically head of quattro GmbH. I asked more about why the TT RS did not have Haldex Generation 4 (a.k.a. XWD). I was told that this was largely to floorpan stampings of cars like the TT RS and A3 already being in place and that they'd have to be modified to accept XWD. Based on that conversation I'd bet upcoming transverse cars such as next-gen A3 and TT will use it or something like it.


So the haldex controller would be different on different cars? Such as the A3 to S3 to RS3? If so, gotta go to the junkyard to look for a TT-S or TT-RS haldex unit.
I'm not positive it'd be physically different. I'd imagine the differences are software... maybe that the non-return valve in the diff itself ***might*** be a physical difference but they all might be using that setup by now. Changing to a controller/software from a TT RS or RS 3 would likely be more aggressive than an A3/S3/TT/TTS setup and more streetable than the more aggressive and more racing oriented aftermarket controllers... though I must admit I have no practical experience with aftermarket controllers and don't know how aggressive they are. Assessment of that would be better left to those who own them and have logged miles. I've driven TT RS, TTS, TT, RS 3, S3 and A3 but none with the aftermarket controllers.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #133 ·
There could be an interesting article opportunity here for Fourtitude, comparing and contrasting the standard VW 2.5 with this new 2.5T engine. Would make great reference material for those of us who find themselves needing to explain it to the "whatever, it's just a Golf with a turbo" crowd. :)
I'll see if I can find some time to work something in. In the meantime, use the search particularly in the Car Lounge for threads on this subject. I know I've participated in several with Shomare who is an engineer at Audi and has quoted interesting facts about that motor. I think there are two foundries in the world who can make that alloy block. I know I recently compared power levels (in the article this thread points to) and the motor in less-powerful RS 3 guise is still second only to the Bugatti Veryron SuperSports in hp per liter under the VAG umbrella. That means all Lambos, Bentleys and even the more pedestrian Bugatti Veyron (non SuperSports) are less efficient in terms of power in regards to displacement.

Just because the engines may share some geometry means very little. Even suggesting this car is half a Gallardo engine is simplifying things quite a bit.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #134 ·
I am not saying the RS3's engine is a low end 2.5 with a turbo. Obviously much of it is redesigned, but i don't think Quattro GmBH has the ability to design something from scratch. Although it does do a bit more work than many of these super tuners that strips an engine and replace many OEM parts with beefed up ones, but not having the ability to make changes like the sump system, casting method or variable timing/lift cams.

They could have thrown in a flat plane crank though.
Actually it's not that simple. First, they don't start with the Rabbit 2.5 and say "okay, let's modify this". VAG does use modular design principals in its engine design so a W8 is really two VR4s, which are done by cutting one cylinder off of each bank of a VR6... but even then it's not that simple. This is done more for shared parts or part designs (not always materials) across a range. There are savings to be had in lower costs of developing a whole range of engines depending on power of efficiency needs.

If you're not an engine person or an engineer, think about it like their chassis development. The lowest A4 and the highest A8 W12 are all now MLB. This means certain shared geometries (mainly steering hardware as it relates to engine placement) are shared. Other things like fiber optic data transfer, etc. can be shared or cost can be minimized in taking an existing part and re-speccing it for a new application rather than designing a new part. The A4 shows Audi's best ability to cost save in a more price conscious segment where the A8 makes use of expensive materials such as magnesium, aluminum (space frame) and higher grade leathers in a less conscious application where performance and luxury are a higher priority than cost and of course there's the push to want to show off what Audi can do with the A8 and represent the brand in the public eye.

In many ways that TT RS engine represents the brand and even VAG. It is an exotic engine (more hp per liter than Bugatti Veyron) in a down-sized and more efficient package. The block is a different alloy. Nearly every part must be of much higher tolerances than that of the Jetta's 2.5 because of the power levels on hand here. You might say it's half an RS 6 but even that is a misnomer because the RS 6 does not have to deal with these sorts of inertial stresses. On the other hand, the 2.5 in the Jetta has been designed mainly to keep costs down and keep the Jetta in a price point. While one's been engineered up for performance, the other has been engineered down for price.

As for quattro GmbH, they are fully integrated into the Volkswagen Group. An engine developed by quattro GmbH goes through the same testing, endurance evaluation, etc. as any other engine. Picture Piech, Winterkorn and Stadler driving these cars in far off African locales just as they would the more widely sold 2.0T or 3.0T. Picture these engines on dynos for as many hours as those higher volume engines. You get the idea. quattro GmbH doesn't modify engines as a tuner would. They develop engines fully as Audi or Volkswagen do because they are in fact part of Audi and thus part of the Volkswagen Group.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #135 ·
So the main question is for the Tim and George When will we hear news that Audi is bringing this sweet ride to the USA?
It is currently under evaluation. That doesn't mean it'll happen but we've confirmed they're considering it and that's a step in the right direction. I'd expect to hear something by summer if it's going to happen.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #143 ·
With the Torsen system for new Audi's the normal torque split is 40:60 front to rear so there is no reacting to send torque to the rear. Under normal conditions with the Haldex it doesn't send any torque to the rear unless it thinks there is a reason. I would think at the minimum it would affect steering as the Haldex will drive like a FWD car unless there is some reason to change.
Yes and no. You're right, the torque is already split under normal conditions. However, if there is wheel spin at the front then more than 60% is pushed to the rear. That's what I mean by "reaction".
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #144 ·
Regarding Haldex XWD: read this info carefully, and explore the site to find the truth...

http://www.haldex-xwd.com/

From my reading, the XWD is a modular add-on to the Gen4 Haldex coupling, sharing the electronics and hydraulic pump with the center coupling. Gen4 or Gen4+XWD option (saab, now volvo... but not audi)

The XWD is an eLSD, or electronic limited slip for the REAR diff, functioning as a locking LS clutch for the left and right rear axles, and can be controlled very precisely by the computer, in little bursts, to stabilize the car. There is a great read on the math involved with yaw cotnrol..

This is different from the electronic "fake" limited slip which uses the abs/esp/braking to control wheel slip, either front or rear. Its a real hydraulic coupling.

XWD is very different from the Audi sport rear diff.

The audi sport diff has TWO electronic controlled hydraulic couplings, one on each side, with hollow shafts and overdrive gearing that can be engaged under computer control, like the ones banned in rally racing, and on Ferrari 430 production cars. This provides more torque to the needed wheel, to go around a corner faster. The XWD cant do that.
There is a great writeup with diagrams and torque flow charts that appeared in AUDI DRIVER magazine (Aug 2009), but short of scanning my copy, I cant find a link.
Good stuff. I'll check it out. I'd heard the Volvo setup used brakes to apply to the inner rear wheel while sending torque to the rear (thus sending to the outer rear wheel). It's sort of Haldex augmented by creative use of ABS and much like slip control in a FWD car might operate. My understanding of XWD was that it could drive a given rear wheel. I'll have to read up after your link and dig up that back issue of Audi Driver. Thanks for the tip.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #145 ·
Isn't torsen based on torque sensing, instead of slip sensing? It locks when there is a difference in torque applied to the the axles.
Yes, the Haldex senses slip. They still both react to variances and thus "slip".

They do alot more performance upgrades than even super tuners that does extensive mods (e.g. tuners can never recast the block), but their mods seems to be beefing up of parts and could only be within the confines of what VAG dictates. I mean CGI is an improvement, but it was pulled from the TDI bin. They could have gone with aluminum block, but that would probably meant a redesign of the whole block to take into account of the weakness of aluminum. Flat plane crank? probably out of the scope. Dry sump? probably out of the scope, especially when the chassis can't allow a lower engine mount. I do see they use Audi's valvelift on it, something not on the stock 2.5.
These engines are signed off on by the board. At the time of this engine (and the R8 4.2, V10, etc.) this was managed by Wolfgang Hatz who was the board member in charge of engine development. Hatz was involved in this engine and the high-rev concepts and they can and do add what they need as dictated by costs, expected volumes, etc. as they would with any engine Audi or VW build. 4.2 high-rev got dry sump in the R8 and RS 5 applications but was not included in RS 4... maybe a performance evaluation, maybe one of cost... not sure. They pick and choose but any engines developed by quattro GmbH are developed with as much of the VAG resources as any other Audi engine.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #146 ·
I found an article on the TT RS with the development history of the RS 2.5 and it came from the NA 2.5. That just goes to show that I'm not an engine designer....:)

As for fog lights--it doesn't matter to me but what will those who drive with them on at night all the time do without them?? ;)
There have been a LOT of articles on the TT RS that say it's built from the Jetta engine. There are also many that say it's half a Gallardo or half an RS 6. In actuality it's not really any of these. It's got FSI and valvelift so it might be closer to the Gallardo LP560 or RS 6 and and development costs were probably saved based on shared design parameters with all three but saying it's just a Jetta or just half a Gallardo/RS 6 is a huge oversimplification.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #151 ·
The RS5 got a dry sump because it was developed for the R8 already. I don't think the Quattro division would have been able to re-engineer the engine to take that. Same as aluminum block, probably not re-engineerable given that the block design would have to be completely different.
.
I'm not sure why the impression keeps remaining that quattro GmbH is somehow just a factory tuner. quattro GmbH produces the R8 FYI. They were in charge of the car's development. They are a team within Audi that focuses on the highest-performance cars but that doesn't mean they have access to less resources. I've toured the R8 facility and I've seen their other production facilities. They're part of the Neckarsulm plant.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #153 ·
I believe the Typ42 chassis (R8, Gallardo) was evaluated across the group. Remember the VW W12 Nardo concept or the Bentley Hunaudieres... probably evaluation concepts used to determine if there was potential for the chassis under these brands as well.

Once the go ahead was given I'm sure it was up to Audi's lightweight design group (also in Neckarsulm) to develop the structure. Designs by each brand (Luc Donkerwolke I think did the Gallardo and I'm not sure who specifically did the R8 design) tailored the exterior and chassis development (suspension, brake, etc. settings and hardware finalization) then went to Lamborghini and quattro GmbH though quattro likely uses developmental teams in Neckarsulm... I don't know this for sure though it would make sense. These cars all go out to remote testing where top VAG executives drive each of them.

I say this because the 2.5T FSI is much the same. This engine was signed off on at the highest levels and I wouldn't be surprised to see it in various states of tune and at various costs of components. It could go into something of the highest price (production quattro Concept) or maybe be de-tuned and used in transverse applications like a Volkswagen CC R (nothing to do with Creedence Clearwater ;) ).
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #161 ·
I doubt you'll see this engine in VW. Just look at what they're doing to the Jetta and the new Passat. I think audi would be better off keeping this engine to themselves as a differentiator.
Never say never. Look at the V10. That engine debuted rather exotically in the Gallardo. Further updates saw it gain various states of tune with various states of cost and component differentiation - FSI, FSI high-rev, biturbo and fitted in various price ranges of VAG products from the S6 on up to the Gallardo LP560-4. If VAG wants to maximize their investment, they'll do more. For now you have extremes - this very low cost and low hp 2.5 and this very high cost and high performance TT RS engine.
 

· Registered
Joined
·
17,998 Posts
Discussion Starter · #176 ·
the question is, whether they custom coded the haldex unit, or did they just put fatter tires in the front to cure the understeer. if they left the quattro as stock, it would be pretty lame given the rs5 has a completely new crown differential.
They don't just one software setup. TTS is more aggressive for instance than TT.
 
1 - 20 of 21 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top