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Some interesting observations...

Discussion in 'A3/S3/Sportback (8P Chassis)' started by steve184, Jan 7, 2007.

  1. steve184
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    steve184 Active Member

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    Bit sad but just been having a look at power curves for the two 2.0 TDIs and the 2.0 TFSI engines (from the superchips website) - i opened the pdfs and overlaid them on each other.

    Noticed some interesting things:

    1. The 170 TDI has awfully low torque at very low engine speeds, ie, tickover and just over - in fact up to 1200rpm the 2.0 petrol has higher torque - guess this would mean the 170 would be easier to stall than the 140 or even the petrol! (if it were manual)

    2.The 170 TDI over the rev range 1200-4500 is far more powerful to the 2.0 Petrol in every way, torque and power - only reason petrol is faster is because at that point you dont need to make a gear change and the petrol goes a bit further up to 6000. If you had a rev limit of 5000 on the petrol it would not be able to out-accelerate a 170 TDI. (yeh yeh stupid thing to say because it doesnt! lol)

    3. The raw power figures between the 170 TDI and 200 ps petrol are not as far apart as the figures suggest (30) as the superchips curve shows the petrol makes exactly the manufacturers quoted power 196bhp and the TDI makes more 179bhp - which means actual difference between the two is only 17bhp - strange why this would be the case that audi under quote power on diesel but not on petrol?

    I know not a very scientific way as the figures may not be accurate and may not be the same for all cars - but as a quick overview... hmmmmm
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  2. TDI-line
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    TDI-line Uber Post Whore

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    Interesting Steve.

    So what engine is the best?
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  3. steve184
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    steve184 Active Member

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    well thats stii a matter of opinion, as you still have other tings in the equation such as noise, fuel consumption, other running costs, tax, insurance etc
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  4. Vertigo1
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    Vertigo1 Well-Known Member

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    Well I have the 170 TDI (used to have the 140) and I have to say these findings don't surprise me that much.

    Back when comparisons were drawn between the 140 TDI and 2.0 FSI it was said that, although the petrol had slightly more power and a better 0-60 figure, in reality the diesel was way faster in everyday driving.

    Whilst I don't think the 170 TDI is "way faster" than the 2.0 TFSI in everyday driving, I do think the same thing applies when it comes to performance stats (i.e. 0-60, standing quarter) versus "normal" driving - they're much closer than the stats would suggest imo. Bear in mind the petrol has 18% more power whilst the diesel has 25% more torque, so they're fairly closely matched really.

    I was tanking it back down the M6 last night and I have to say the pickup of the 170 in the 70-90mph range in 6th is unbelievable, you just prod the pedal and it's off. Even compared to my old 140 it's far faster than a mere extra 30bhp would suggest. This car is going to get me into a lot of trouble :)

    As for the discrepancy in quoted power figures twixt petrol and diesel, I'm guessing here but it could be that, due to the variations in manufacturing, their margin of error on power output is far lower on petrols than it is on diesels? If this were the case then they'd presumably target a slightly higher power figure for the diesels so that even those which came in under target would still achieve the quoted nominal output.
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  5. trims
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    trims Member

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    Thanks for pointing us to the web site. You might wish to compare with the 163PS BMW diesel while you're there. If anything the torque on the Audi 170PS comes in at slightly lower revs.

    I have to say that the sudden 'rush' of torque as you hit about 1800rpm appears to be a feature of all the VAG diesels I've driven. What I liked about the Audi 170PS I test drove was the sensation that the 'rush' was sustained beyond 2500 - 3000 rpm, rather than just fizzling out.

    The petrol v. diesel is a personal preference thing I guess. I prefer the low end power / torque (how often do you red-line in real traffic?), the 450 - 500 mile tank range, and the fact that my new A3 170PS TDI Quattro will be the same insurance group as my six year old A4 115PS TDI SE. :)
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  6. RobinA3
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    RobinA3 Active Member

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    Each engine will produce slightly different power figures, not every 2TFSI will produce 196bhp, some will create more and some will create less.

    Most manufactures, including the one i work for, have a target BHP and torque to aim for and this figure is usually +-5% for power and +-10% for torque at a certain engine speed.

    Also the superchips graph could have been created using a quattro petrol and a 2WD diesel which would not help matters in trying to calculate the flywheel power.

    I think it would be interesting for a 2TFSI and a 170Diesel to have a bash down the strip at santa pod to see what real difference there is on a striaght line thrash

    out on the open road i would think that the petrol and diesel will be very well matched until the petrol pulls into the petrol station to fill up! :)
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  7. Vertigo1
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    Vertigo1 Well-Known Member

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    Actually, the original torque graphs for the 140 and 170 diesels make for very very interesting reading.

    The 140 peaks at 336Nm, 16 over quoted, but tails off really badly from 3000rpm onwards. By 4000rpm it's down to about 260Nm.

    The 170 peaks at 371Nm, 21 over quoted, but doesn't fall off at higher revs anything like as much as the 140. It only starts to tail off at around 3500rpm and even then falls away much more gradually. By 4000rpm, it's still make around 320Nm, which is the peak nominal output of the 140!

    I think this alone is what makes it feel so much faster than the 140. When I first drove one I was astonished at how much quicker it felt, considering it had "only" another 30bhp. As trims said, where as the 140 starts running out of steam between 3500 and 4000rpm, the 170 just keeps on pulling.
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  8. Dandle
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    Dandle Member

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    The overeading power/torque figeres mean nothing unless they were all carried out on the same dyno for a comparision. Revo qoute stock power of their test 2.0TFSI at 216bhp and the qoute above is 196bhp, either could be right or both wrong.
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  9. h5djr
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    h5djr Well-Known Member

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    I'm looking forward to March when I get my new 170 even more now.

    I'm also be looking forward to June when I will be taking it across Germany on some un-restricted sections of autobahn. I'll have betweem early March and mid June to make sure it's nicely run in.
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  10. steve184
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    steve184 Active Member

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    well yeh i accept these figures may or may not be accurate as i said in my original statement.

    i've got a 170 on order and im looking forward to march - however when i test drove it originally it didnt really feel much faster than my 140 but again thats prob becasue the 140 is like an on/off switch whereas the 170 is more gradual going up and down which tends to mask performance. I remmeber saying the easy way for me to describe it was it was like an engine which was half petrol and half diesel (obviously not possible i know) but if it were this would be it
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  11. Vertigo1
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    Vertigo1 Well-Known Member

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    Seriously, you will not believe how fast it picks up speed at around 70-80mph compared to the 140.
    Mine will be hitting the autobahns before then with a bit of luck :)

    (Downside is I'll be trying to keep up with a de-restricted M5 - sorry but the TDI 170 ain't that good :) )
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  12. beerglass
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    beerglass Member

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    How does the TDI 170 compare to a older golf mkiv TDI PD150 running revo
    so a claimed 190 plus....

    I only ask because I owned a PD150 with revo and found it very fast. I know my A3 is only 140 but its much much slower and do feel the pull towards a remap again
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  13. Vertigo1
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    Vertigo1 Well-Known Member

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    As I said above, I think the main difference with the 170 is the way the torque curve doesn't tail off nearly as badly as it does with the 140. This gives you more revs to play with and you can let it pull right round to 4000rpm and beyond without feeling a pressing need to change up as the engine is running out of puff (as was the case with the 140).

    I suspect the Revo you had resulted in a similar torque curve which is what made it also feel very fast.
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  14. trims
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    trims Member

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    Readers of this list are probably too young to remember when VW stuck a 16v head on the Mk II GTI engine and upped the bhp from 112 to 136. The Mk II weighed less than 900kg, so even the 8v was on a par with the current A3 170 TDI / TFSI in terms of power / weight (though the modern turbos have more than double the torque).

    It felt like the 140 to 170 PS TDI upgrade: at lower speeds the two cars felt similar, but at higher revs and high speed the 16v came into its own. Possibly the best GTI ever?
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  15. Russky
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    Russky New Member

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    Hi All,

    Been reading these forums for a while and have been trying to choose between TDi170 and 2.0TFSI so quite relevant for my first post to be here!!

    I have been looking at the pros and cons of each for a while but ended up taking both the TDI170 and 2.0TFSI Sportbacks for a drive yesterday, Back to back an on the same route (Usual mix of roads).

    I have to say that speed-wise there didnt seem to be much in it! Both accelerated well and both were smooth and refined at motorway speeds (Even the TDI). The power delivery was much smoother in the petrol, whereas in the Diesel there was not much till about 1850 revs then you took off. 1st Gear on the TDI is interesting as you've hit the limiter before you know it and have to change up. The petrol did "Feel" faster simply because it felt more eager due to the higher revs.

    Whilst travelling at speed both engines were responsive when accelerating from 70 - the Diesel may have pulled more strongly but to be honest it wasnt that noticeable from the TFSI.

    Must say I was very impressed with the TDI - it seem to be a very good engine and the economy is definately a bonus.

    But for me - and this is only a personal view (Obviously) - the petrol gave the "Smile Factor" right away and I wanted to saty out longer than I did in the TDI - it was just more exciting to drive whilst the Diesel felt a bit dull. And for me thats what made me decide to go for the petrol.

    So - order placed for a 2.0TFSI Sline Sportback with some toys. Its a bit different from my 3.2 (yes its a bit slower but the engine felt like it had more life in it!) but I cant wait till March.

    Cheers,

    Russky
    ----------
    54 A3 3.2 Sport
    07 2.0TFSI Sline Sportback on order!
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  16. Russky
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    Russky New Member

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    Oh - and yes, the TDI170 is Very easy to stall!!!

    Russky
    ----------
    54 A3 3.2 Sport
    07 2.0TFSI Sline Sportback on order!
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  17. BrianM
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    BrianM BrianM

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    I'd love to understand what the 140TDi with DSG would look like alongside the 170Tdi, and also the comparison between a chipped 140tdi with DSG. Thinking of having my 140Tdi DSG Superchipped so that it can be removed easily. Anyone odne this?
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  18. steve184
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    steve184 Active Member

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  19. Vertigo1
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    Vertigo1 Well-Known Member

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    BrianM: by all means look into getting your 140 chipped but are you saying you're wondering how a standard 140 DSG would fare against a 170 non-DSG? If so then I'm sorry but it wouldn't stand a chance :)

    Russky: Interesting observations and I too looked at the 2.0TFSI myself but as a company car I worked out that it would have cost me more than £100 extra per month in tax and fuel. No doubt the petrol is the better engine but it's very close and certainly not worth another £1200 a year!
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  20. steve184
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    steve184 Active Member

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    oo i dunno vertigo - a chipped 140 DSG against a 170 manual?? i think it would trounce it to be honest - those rapid gear changes cancel out the fact you need to change gear three times ot get to 60 in the diesel dont forget
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  21. southpaw66
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    southpaw66 Member

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    I'd have to agree with the no torque at low revs as trying to pull away from junctions in 2nd from a rolling start can be a slow process.

    And also the sustained torque at higher revs, I don't really feel any loss of push all the way to 4500rpm.

    Does anyone know the final drive ratio for the 170TDI and 2.0TFSI, as if they're different (which I suspect they are) then you can't compare rev limits between the two engines as the rotational speed of the wheels is altered and therefore the requirement to change up at a given speed is not based purely on revs. Consequently, it would be wrong to say you have to change gears more often due to limited rev range, but you may have to change more often if the power/torque is limited within the rev range which was more common on older diesels, but less so on the 170TDI.
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  22. Russky
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    Russky New Member

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    Hi Vertigo1 - Yep they are close, but I found the petrol much more fun to drive. If economy was a major factor it would have been the Diesel, but it wasnt so I got the petrol. Heart ruling head etc.

    Cheers,

    Russky
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  23. Vertigo1
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    Vertigo1 Well-Known Member

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    I didn't say that. I said that a standard 140 DSG wouldn't be a match for a non-DSG 170 as, IMO, the speed of the gear changes wouldn't be anywhere near enough to compensate for the extra speed.

    As for a chipped 140, I think that'd easily be a match for the 170 even if neither (or both) had DSG, as most chips for the 140 I've seen give more power and torque than the 170 offers as standard. Then again, if we're talking chipping, superchips do one for the 170 that gives 209bhp and 416Nm!!!
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  24. BrianM
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    BrianM BrianM

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    Sorry I didn't make myself that clear, I menat to compare a chipped 140 Tdi DSG to a standard 170, either with or without DSG. Interested to see if the 140 with something like Superchip or AMD would be comparable. Guess it depends on just how far you go with the remap. Need to keep it reliable and as undetectable as poss due to warranty of course.
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  25. steve184
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    steve184 Active Member

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    sorry vertigo right you are - i mis-read
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  26. Vertigo1
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    Vertigo1 Well-Known Member

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    Well, as well as raising the peak power of the 140 to around the same level as the 170, the chip/remap would also have to rectify the tail-off in the torque curve IMO. If it simply raised the torque curve but left the tail-off then I think it'd have trouble keeping up with a 170.

    From what I know, the ability of the 170 to rev more freely and maintain torque until 4000rpm and beyond is down to the improved piezo injectors. You could well find that a simple chip or remap wouldn't be able to do this, which could hand the 170 the edge. It's not just about peak torque, it's about torque throughout the rev range - as I said above, the fact that the 170 exceeds the peak torque of the 140 all the way from 2000-4000rpm is very telling.
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  27. marriedblonde
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    marriedblonde Moderator

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    I think you would find the 170 would defo beat the chipped 140tdi off the line. Would the chipped car have enough to claw it back once up and running I'm not sure.

    I'm not 100% certain but I reckon the power is limited on the Revo map in first gear. At inters last year my car was only recording similar 0-60 figures as a standard one.

    You can feel the power in second gear that isn't available in first.

    Thats not taking into accound the dreaded delay with DSG off the line.

    Not sure about the ni gear times between the 2 though.

    J.
    #27

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