05evo

is it true that Audi's AWD (quattro) system is the best and puts everyone else to shame? also how does Mitsubishis AWD system in the evo stack up with the rest? Please try to stay away from biased answers because MOST of us have Evos. I'd like to know that truth.

Thanks

Evoegg

iTrader: (8)

have you seen Quattro in WRC ???


my 2cp

giumela

iTrader: (1)

Audi probably the best and Porsche closely behind....

Silk

iTrader: (4)

Skoda is owned by VW and i think the system is a lil similar but to answer yuor question, no. BUt audi did wipe up in rallying back in the day

EVILutionVIII

iTrader: (6)

ATTESA ETS:

"ATTESA-ETS distributes the torque to the rear-wheels, but when slip is detected on one of those rear-wheels, it can distribute up to 50% of the torque to the front wheels, i.e. it can adjust the front/rear torque-split from anything between 0:100 to 50:50. Among the rear-wheels, an active LSD can further distribute the torque from one wheel to the other if necessary."

Gstuck

iTrader: (1)

I have read that VW and Audi is very front biased only putting power to the back wheels if the fronts start to slip. Sport Compact Car said that the Audi system felt like it was tuned by a group of lawyers

osunick

iTrader: (8)

Depends. The Haldex coupling on the R32 and Audi TT is decidedly inferior to a true AWD system that has a mechanical center differential with either a mechanical (torsen or Viscous) lock or an electronic clutchpack like the ACD. This is because, despite the electronic control, it can only react to slipping and is not always sending torque to the rear axle. Haldex has come up with a bandaid that precharges the coupling to provide a few hp of instant torque to alleviate the lag.

The Porsche system is actually extremely simple. After experimenting with complex electronic diffs in the 80's with the 959 and Carrera 4, they went with just a VCU for the front axle that sends some torque to the front when the rears slip. Porsche doesn't even use a center differential in their newest awd cars (except for the Cayenne). Porsche has moved towards electronic driver aids like PSM which work extremely well with the simple awd system.

It's important to note the difference between a VCU and a VLSD. A VCU is just the coupling by itself. Think of a tube of syrup with a propeller on both ends. If you spin the propeller on one end, the other end will slowly start to turn as the syrup spins. As the syrup gets churned, it thickens and the second propeller starts to approach the speed of the first propeller but it will never be exactly the same. Some energy is lost in the coupling. Now in a car, imagine that you have this thing with the engine + one axle on one side and the remaining axle on the other side. Since on a dry road both axles are already turning at the same speed, no problem, but when it slips, that syrup thickens and both axles are connected. Sicne there is some slipping it's not very efficient but useful when you want to have most of your power on one end of the car.

A VLSD is a mechanical diff with a vcu connecting both halves. So whatever you put into the diff is split in two, so torque loss is minimal. The VCU limits the speed difference between the two sides of the diff so if one axle is spinning much faster than the other, it will lock up and force them to spin at close to the same speed.

The Quattro IV system on the A4's and higher uses an expensive torsen diff which works very well but theoretically would act like an open diff if one axle is completely in the air.

The Evo system (either the VLSD or the ACD) are rally proven and great "true" awd systems that send power to all four wheels all the time. Many of the "active torque split" solutions are slow to respond and are poor performers at the track.

MaxR

iTrader: (3)

Why is it always VC or Computer controled center diff for Mitsubishi and Subaru? The Evo rear diff is just a clutch and plate type diff without computer control. Why not that type as a center diff?


How is that? An electric motor for one axle and an engine for the other?

osunick

iTrader: (8)

Because it would be impossible to drive on the street. Kaaz does make this kind of diff for the evo but the major problem is that a mechanical plated diff would react even when turning in a parking lot. A VCU can be tuned to allow enough speed difference in a lot at low speeds to allow for parking maneuvers. And the ACD is smart enough to disengage the clutch packs in this situation by examining steering wheel angle and speed.


They just have the VCU but no true geared differential.

dubbleugly01

iTrader: (24)

so is any of this related to the poor turning radius of the car? Or is the poor turning radius just a design flaw?

osunick

iTrader: (8)

No. And it's not really a design flaw, it's due to several factors, mainly the wide tires, long wheelbase, and transverse engine. It's a compromise which results in high performance but poor turning radius.

Arithmetic

iTrader: (9)

+1

Doesn't get any better than what nissan brings. The SH-AWD from honda is a very close second.

honda-guy

iTrader: (55)

i was under the impression that the Skyline R34 awd system was pretty high tech. any body knows how this system works?

EVO-8-Nate

I thought that the EVO especially the J-spec and Euro-spec EVO's were ahead of there time with the VCD and Super AYC?!?!

-Nate

Stealth-Ghost

Reviews and Top Gear say that the Evos is the most high tech, quoted from Top Gear, "[quattro] it's not as high tech as the mitsubishis, but it gets the job done" something like that.

I don't know much about the Skylines, you can switch to just RWD right?, that's pretty high tech =p