GTD acceleration 2wd vs 4wd

[Sootchucker]

There's an interesting debate going on over the Audi Sport forum concerning the published figures for the A3 184ps Quattro vs the Golf GTD 184ps. According to the published figures, the Quattro Audi does the 0-100 Km/hr sprint in 6.9 seconds, whereas the GTD takes 7.5 secs for the same speed (obviously these are just VAG published figures). It seems both cars use the same engine in the same state of tune, however the Quattto is about 75kg heavier.

Now it stands to reason that the Quattro's advantage from a standing start is traction. My GTD easily just spins it's wheels in 1st and 2nd if I dial in too much accelerator (however a lot of that ccould be down ot the Bridgestone Tyres). Whilst the difference in the real world might be slight, and once rolling I'm sure any advantage in acceleration hands back to the 2wd car, but someone mentioned that this might be due to VW limiting power (torque) in 1st and 2nd to aid traction. I then remembered that VW advertised the GTI and GTD with an "Anti Tramp" feature which was never properly explained.

Is it possible then that not all the advantage (0.6 seconds) is due to 4wd, but more that the Golf has a limited torque value imposed during the first few MPH from a standing start which the Quattro doesn't have. Anyone any thoughts ?

[monkeyhanger]

Do you mean 6.9s for the Audi and not 7.9s? 

I actually read 6.8s on the current brochure for the 3 door variant. This has always been the case for Audi Quattros of a similar size compared to VW 2WD. My 170TDI Scirocco had quoted 0-62 of 8.1s, but the Audi TT TDI quattro was up for 7.5s.

That's got to be down to the traction in 1st and 2nd as the slight weight advantage the A3 2WD has over the Golf is eaten up on the Quattro version. The 2WD 184PS A3 sportback is quoted at 7.3s for the 3 door variant.

Traction in the GTD with Bridgestones is the worst I have experienced in any VAG car I have bought from new, just surpassing the MK5 170TDI GT Sport (which also came with Bridgestones on mine). Occasionally I do seem to feel what I assume is the "anti tramping" kicking in. It is usually when I am just on the cusp of losing grip, but if i've planted my foot down it spins and thumps wildly with nothing reining it back in until I ease off the throttle. Seems to me that torque isn't limited by any system until the car has detected a loss of traction.

Above 30mph I would assume there is absolutely no advantage in Quattro acceleration, except maybe holding a little more speed in the corners than a 2WD variant would dare to.

I did read somewhere in the promotional stuff for the A3's all LED headlight (optional) that fitment of these shaved 0.1s off the 0-62 time due to noticeably less demand placed on the alternator for the lights. This did seem like bullsh!t to me - 35W LED headlights vs 45W Xenons at night and pretty much everything you'd have on during the day on both cars is comparable (LED running lights, rear light clusters etc). I'm sure that it's a best case all LED vs worst case all halogen lighting to conjure up that 0.1s advantage.

I doubt there's 0.6s in it between an A3 Quattro shod with Bridgestones and a GTD shod with Michelin Pilotsport 3.

[Sootchucker]

Doh...thanks MH 

[Geomets]

A question arose after reading this thread. Do these cars have the same torque? The Quattros always had greater torque than the 2WD versions of the same car -in petrol though. Do the same thing happen to the diesel ones? The benefit in the petrols was huge: better acceleration and the same consumption as the 2WD version. I remember the A4 Quattro had better consumption than even the MK6 GTI! (official consumption to be fair) But then, it had the EA888 gen.2 with the valvelift system...

[monkeyhanger]

Same torque on the diesels. The 211ps unit with variable valve opening/valve-lift fitted in A5, then À4 sas considerably more advanced than the unit in the MK5 GTI when It was launched and still outdid the MK6 GTI unit for economy (43 mpg combined). The valvelift tech added too much bulk to fit under the bonnet of an A3 or Golf and so it was never considered for use there.  A3 184ps uses the exact same unit as the GTD.

Perhaps the valvelift version of the engine was only speccable with Quattro on the A4? Audi do this quite a bit - my cousin has the 177ps TDI Q3, was only available with S-tronic, current TT TDI is only available with Quattro etc.

[Geomets]

Same torque on the diesels. The 211ps unit with variable valve opening/valve-lift fitted in A5, then À4 sas considerably more advanced than the unit in the MK5 GTI when It was launched and still outdid the MK6 GTI unit for economy (43 mpg combined). The valvelift tech added too much bulk to fit under the bonnet of an A3 or Golf and so it was never considered for use there.  A3 184ps uses the exact same unit as the GTI.

Perhaps the valvelift version of the engine was only speccable with Quattro on the A4? Audi do this quite a bit - my cousin has the 177ps TDI Q3, was only available with S-tronic, current TT TDI is only available with Quattro etc.

Yes, it was available only in the Quattro. In 2009 when my brother bought his GTI he had other cars under consideration and we checked many cars. The A4 Quattro was one of them. He didn't buy it, naturally..!

Merry Christmas to everyone!