Why the bad 0-100MPh time for 2.0TDi?

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SideShowBob

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Just curious really, I understand that for one reason or another a diesel doesnt post great 0 - 60 times, so we're looking at around 9.2s for the DSG model, and apparently this is made up for once moving, but when looking about at performance figures, the 0 - 100MPh times seem to be reported at about 26 seconds, ie, about what you'd expect from smaller engined basic hatchbacks.

Thing is, reading a few reviews, they go on about the diesel being almost as quick as a 3.2 between 30 - 50/50 - 70, so then theoretically, between 30 - 70Mph, its a very quick car, so its got to be outside of those figures that it loses a bunch of time.

Does it run out of steam rapidly after 70? is 0-30 so comparitevly slow that it costs a lot of time?
A 3.2 should be around 17 or 18 seconds to 100, and a difference of about 8 or 9 seconds to the 2.0TDi is quite significant, especially as it only gives away approx 3 seconds 0-60.
That means it loses another 5 seconds somewhere from 60-100, which seems a lot.

I know all this comparison stuff is nonsense, and holds very little water on the open road, but Im interested to find out where its losing out if the 30-70 times are very close.

I in no way have bought a TDi with illusions that ive bought a performance hatch, and im not even concerned greatly with the performance, as I bought the car for other reasons, but be good to know how and where the car lacks performance.
 
In a word 'Torque'

The car may not be fast 0-60 or 0-100, but when moving it is the torque that pulls you.

I am not going to go into it in a big way, but for example we have both had CTRs which had good BHP but crap Torque. So off the line the CTR would beat the A3 but if you were side by side doing 50 and both sunk the foot the A3 would beat the CTR. It's swings and roundabouts.

Your either like Traffic light grand prix or motorway muncher. Unless that is you have a car with Big BHP and Torque and then you get the best of both worlds /ubbthreads/images/graemlins/grin.gif
 
Your right in that once it's moving it's a quick car.

Last night, in a bid to get to my friends house and break between Top Gear and LOST I was 'pushing on' shall we say.

Anyway, on the return leg I was behind an Evo VI. Don't get me wrong, I know my cars not in the same league as the EVO (coz mine will be worth something after 3 years /ubbthreads/images/graemlins/grin.gif)
However, coming off the roundabout and up to about 70 there really was nothing in it. After that he predictably pulled away. However, from about 20-70 I was just about hanging on.

The best bit? Him looking at the Diesel badge on the back as I passed him in the Q at the roundabout /ubbthreads/images/graemlins/fuck_you.gif

So yes, it's a quick car, allbeit in a narrow(ish) mph band.
 
I would suspect the 0-100 time is crap because of the gearchange that takes place around the 60 mark.
It's been discussed on here before,but the DSG does have quite a marked ratio step between 3rd and 4th.
My car goes flat as a fart for a wee while at that point,then picks up again.
Definitely a few seconds lost there.
Strange that they've done this when they have six gears to play with.
You'd have thought they would have 'evened out' the ratios a bit more.
It's only a problem at the traffic light GP though.
 
Does sport mode rectify the large ratio step?
Im not hugely bothered with traffic light GP's, happy to let anyone who's trying to prove something go flying off, but didnt know about the marked gap between 3rd and 4th.

I would guess any acceleration tests are done in D mode, so would be more noticeable?
 
[ QUOTE ]
Does sport mode rectify the large ratio step?
Im not hugely bothered with traffic light GP's, happy to let anyone who's trying to prove something go flying off, but didnt know about the marked gap between 3rd and 4th.

I would guess any acceleration tests are done in D mode, so would be more noticeable?

[/ QUOTE ]

Ratios are ratios,regardless of what mode you're in.
The DSG has more of a marked step from 3rd to 4th than the manual.
Audi were obviously chasing an impressive 0-60 time,so geared 1st,2nd and 3rd quite close.
 
True, but as I understand it, Sport mode allows the engine to rev higher before changing, which should in theory go some way to making the effect of a large ratio change less damaging to aceleration, as you wont drop as far down the rev range (ie below the rev range that provides decent power), as prior to the change you would have been rev'ing higher.

I would imagine if the ratio step is significant enough, it'd still cause a noticeable drop, but Sport mode should help in some way?
 
The rev range has got nothing to do with it. It's a diesel and will start to run out of puff from about 3.5k onwards, ideally your shifts want to land you somewhere around 2.5k in the new gear if you want to get the best acceleration.
 
[ QUOTE ]
True, but as I understand it, Sport mode allows the engine to rev higher before changing, which should in theory go some way to making the effect of a large ratio change less damaging to aceleration, as you wont drop as far down the rev range (ie below the rev range that provides decent power), as prior to the change you would have been rev'ing higher.

I would imagine if the ratio step is significant enough, it'd still cause a noticeable drop, but Sport mode should help in some way?

[/ QUOTE ]

It's hard to put into words,but I'll try.
Letting it rev out in 3rd (sport or manual) just makes the change into 4th feel that much flatter,IMO.
I'm sure (without checking) that the change knocks you down from around 4600rpm to around 2500rpm,and the car seems to take a while to pick up again from those revs.
You're actually better short shifting into 4th and letting the torque pull you through the 2500rpm zone without any noticeable 'dropping off'.
I let the car rev out in all the other gears,but not 3rd.

I hope that makes sense !
 
audi upgrades
Okay, but we're saying acceleration is blunted by a large ratio change, and this would surely be attributed to dropping too far down the rev range when the change occurs to be making suitable power?
So when in Sport mode, the engine revs you drop down to at the change should be higher than the revs you drop down to when in D mode, so the effect of the ratio change should be reduced.

Edit: thanks bowfer, I do get the jist of it, so ultimately it'd use the paddles to avoid landing in the flat spot.
Would you say acceleration to 100MPh is improved a lot by doing that? and im guessing any tests would be done using the auto in D mode, to give a good representation of performance.
 
Like you say thou bowfer, seems strange that the flatspot exists at all, with 6 ratios to play with, sounds like they could have improved performance significantly, thou no doubt at the expense of fuel economy.
 
[ QUOTE ]
Okay, but we're saying acceleration is blunted by a large ratio change, and this would surely be attributed to dropping too far down the rev range when the change occurs to be making suitable power?


[/ QUOTE ]

Not necessarily too far down the rev range.
Just to an unsuitable point within the rev range.
 
Right, makes more sense, cheers, and it seems that the on paper figures dont have much bearing on the actual driving experience at all, as the car certainly didnt feel as slow as straight 0-100MPh figures might make you believe.
I did notice a flat spot a few times on the test drive, but it is very brief, and didnt affect general driving.
 
[ QUOTE ]
Like you say thou bowfer, seems strange that the flatspot exists at all, with 6 ratios to play with, sounds like they could have improved performance significantly, thou no doubt at the expense of fuel economy.

[/ QUOTE ]

Flatspot is not really the right term,so I apologise for using it in the first place.
The car just takes a while to recover from the change from max revs in 3rd to 4th.
Once it 'raises it's skirt' in 4th,it's fine though.
70-100 acceleration is fine.
You can leave a lot of cars grappling for gears behind you on the motorway.
 
I would dispute those figures - there is no way the tdi is that slow.

I know top speed is all about bhp but a CTR will break 100 in around 16.5s. I can't believe the audi gets there 10 secs later.

I personally beieve that the tdi figure are deeply conservative, both in terms of torque, subsequently bhp and performance.

I have heard rumours of people having rolling roaded their tdis and they kick out just north of 250 lb/ft.- thats as much as a lightly modded scooby.

I also believe that boost is cut in 1st gear in the tdi - mine is flat as anything in 1st but 2nd and beyond has 'full beans' - anyone else experience this?

Its all a conspiracy - can't have the diesel as quick as the petrols now can we !!!
 
The CTR doesnt need high torque figures to be quick, power at the wheels is a relationship between torque and rpm. The CTR looks ike its low on power because of the torque figure isn't that high but you have to factor in unlike most petrol cars that are developiong max torque between 2.5k-5kish the ctr is up the 7k area. Multiply with its low torque figure and you have a machine with lots of power at the wheels. The deisel A3 is a very nice machine but its certainly no match for powerful petrol cars like the EVO or CTR even from a moving start, unless they are in the wrong gear or not trying.

I thought the 2.0TDI was quick but it was nowhere near the speed of my Volvo T4 and thats in the same area as the CTR for speed and nowhere near an EVO.
 
"SideShowBob", those 30-50 figures and such are nice for TDI in the magazines, because they're tested at the same gear. And that already makes those figures biased and pretty useless.

And optimum gear any CTR/3,2/EVO will just shred the 2,0TDI into pieces. There's a huge difference in maximum power. Lots of torque just means there's a lot of power available in the lower rpms, that however isn't the point with the petrol engines, since they make high power at higher rpm.

- Yak
 
Thank you Yak - exactly.

Sorry to upset the torque theorists here, but acceleration is all about power, whether the car is already moving or not.

(The "get it moving first" thing about diesels is actually turbo lag, nothing more.)

Therefore it would be strange to expect anything else than a marked difference between a car with 225 bhp and one with 140bhp.

Torque is present in all engines. Torque x Revs (with a bit of jiggery pokery involving the number 5252) gives power.

Fortunately for the typical unhurried driver, a 2.0TDi makes an awful ot of it between 1750 and 3000 revs, so you get a lot of power at relatively low revs. However, this does not translate to any immense acceleration, just the illusion of "impressive acceleration from an engine that isn't even trying" if you know what I mean.

Hence, get a petrol car and a 2.0TDi both at 2000 revs and the diesel clears off. As this is roughly the scenario for in gear overtaking times, diesels appear quicker than they are.

In fact, the engine with the most power is often the one with the most revs, as other efficiencies between powerplants vary by a surprisingly small amount.

So although we can argue all night about which engine is best for "real world" driving, the fact is that the car with the most outright horsepower will accelerate quicker (unless that car has a power curve which is peakier than anything that has ever gone into mass production).

This will be true of acceleration from a standing start or overtaking, providing the driver uses the gears to maximise thrust at the tyres.

From previous experience I would expect this thread to run and run, but these facts will not change.
 
Thats right - all these 30-50 and 30-70 etc runs are all in Top (or a stated gear) thats why diesels fair well at them.

Also, any 'speed' runs in a DSG would be quicker in manual mode as D or S (when flat out) have the same change points which just over rev past optimum change up point.

+/- mode shifts quicker IMO also.
 
[ QUOTE ]


(The "get it moving first" thing about diesels is actually turbo lag, nothing more.)



[/ QUOTE ]

I dount that's true any more. It's the lack of traction and inappropriate gearing because of a low rev limit.

I haven't got a dog's chance of beating a petrol car with the same power as mine (especially in this weather) as I lose my advantage of loads of torque (therefore power) at low revs because I just can't put it down. The petrol engine then get's the advantage as the power arrives at the higher revs, while I start to lose out. Then the same again in second gear.

I think I should be able to make 100 in 17 seconds with my chipped A3. A standard car should do it in less than 20 seconds. If it takes 10 seconds to 60, and 50-70 in 4 seconds, 20 should be acheivable. No way 26 seconds, unless it's in 5th from standstill /ubbthreads/images/graemlins/grin.gif
 
Great post, bunny. Sums it up nicely.

And to balance what you've said (I think), I recall my old Puma 1.7 used to reach 60mph in 8.6 seconds and 100mph in 27. The 2.0TDI takes 9.2 seconds to 60mph and 26 to 100mph, so although the first time is a touch slower, the extra torque combined with longer gearing seems to make its presence felt.
 
All I know is that in my personal experience if you compare a 2.0 TDI with a 2.0 FSI the FSI feels dead at normal driving speeds, especially in country lanes. In the TDI, come out of a corner and put your foot on the floor and it just goes. Do the same in an FSI and... well nothing. Thats not to say that the difference is one is a diesel and one petrol. I think the main difference is one has a turbo and one does not. My previous 1.8T behaved in just the same way as my current TDI and that was petrol of course. It only took a few minutes of the test drive of the 2.0 FSI for me to discount it compared with my 1.8T.
 
[ QUOTE ]
[ QUOTE ]
Like you say thou bowfer, seems strange that the flatspot exists at all, with 6 ratios to play with, sounds like they could have improved performance significantly, thou no doubt at the expense of fuel economy.

[/ QUOTE ]

Flatspot is not really the right term,so I apologise for using it in the first place.
The car just takes a while to recover from the change from max revs in 3rd to 4th.
Once it 'raises it's skirt' in 4th,it's fine though.
70-100 acceleration is fine.
You can leave a lot of cars grappling for gears behind you on the motorway.

[/ QUOTE ]


Careful Bowfer, I don't want to start reading posts that imply that you might like the DSG...... /ubbthreads/images/graemlins/smile.gif.
 
I don't dispute that the petrol cars are faster - I had an impreza sti and then an M3, the impreza felt loadsd ker but wasn't - thats down to the deception of a turbo delivery more than anything.

What I still dispute is the 0-100 time of 26 secs. if it takes 9.2 to reach 60 then from 60 to 100 takes 16.8 secs to get from 60 to 100. I just don't believe that. Low 20's maybe but not 26
 
Right,tried a few experiments on a straight country road (no junctions) near my house.
There was only me in the car and I was running on fumes,so no high fuel load to blame.

Best acceleration times were in sport mode and the best times I got were as follows;

0-60 8.82 seconds
0-100 24.18 seconds

I was right yesterday,it's the change from 3rd to 4th,at just about bang on 60mph,that absolutely kills the acceleration.
The car takes a comparitive age to pick up from that gearchange.

It was an indicated 100mph,which is obviously not a true 100mph,so perhaps the 0-true 100mph time would be around 26 seconds after all. /ubbthreads/images/graemlins/blush.gif
 
Be interested to find out how how the remap changes the driving characteristics of the car MikeP, particullaly with a DSG box.

All good info about this, and as no one would buy a 2l diesel because they want performance, I suppose a slow 0-100MHp time isnt particullaly important.

Edit: Nice work bowfer, and a decent 0-60 time there, I suppose unless you're at santa pod, the car does perform in line with a car that does the 0-100 in under 20 seconds, simply because it has good in gear acceleration.
 
I'm at Revo now, we've tried the first iteration of the map and just about to test v2.

Initial feelings from the first map are impressive, the low down response is much better.

Should have some figures from the rollers later today.

Watch this space.......

BTW the DSG gearbox is much stronger than some threads have indicated, the stock maps for the manual and DSG show the DSG has more power not less.
 
Keep us informed Mike - if I end up keeping my car and my new house purchase looks like a change of car will be delayed I'm looking at getting Revo's at christmas time /ubbthreads/images/graemlins/laugh.gif

J.
 
audi upgrades
They're confident the increased power and torque wont damage or shorten the life of a DSG box? also, is the code removable for warranty?

Ill probably wait till warranty runs out anyway (about 8 months or something), but be interesting to see what the resultant 0-60/100MPh times are like.
 
Actually, what am I saying!! I bought the car predominantely for the economy and quality it offered, and im already thinking about remapping it!!

Not good....must...........resist....
 
Don't forget (as Bowfer has already said) speedo inaccuaracy - mine is running 10% optimistic, so unless you have satnav test for 0-110.
 
Depends if I have an open day for the 'group buy', which is the only way Revo allow 'discounts'. Anyone for a trip to Suffolk?

On the speedo front, I have TomTom for the road runs and a very accurate system on the RR.
 
[ QUOTE ]
Don't forget (as Bowfer has already said) speedo inaccuaracy - mine is running 10% optimistic, so unless you have satnav test for 0-110.

[/ QUOTE ]

If I'd bothered letting it run to 110 on the speedo,it would have been well over the 24.18 seconds I recorded (obviously).

I'm guessing,but I reckon it would have taken another 4 or 5 seconds at the very least.

So perhaps the quoted 26 seconds to a true 100mph is quite kind to the car.
 
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