How different will the new GTD engine be compared to the current 177PS unit?

[Hawaii-Five-O]

As above.

Any ideas how much different the new 184PS unit will be compared to say the Scirocco fitted with the 177PS?

On paper they look almost identical:

184PS v 177PS
280 Lbs.ft v 280 Lbs.ft
380 Nm v 380 Nm
7.5 sec v 8.1 sec 0-62mph
143 mph v 138 mph Top speed
67.3 mpg v 53.3 mpg
109 grms/km v 139 grms/km CO2 emissions
1377kg v 1395kg Unladen weight


Interesting to note that the pounds foot of torque are exactly the same. Makes you wonder what, if anything, they've done with the new GTD unit apart from focusing on dramatically improving CO2 and MPG.

[mcmaddy]

The mk7 with less unladen weight will be slightly quicker even with the same torque figures. On paper looks the same but little differences should help.

[Bill_the_Bear]

Interesting to note that the pounds foot of torque are exactly the same. Makes you wonder what, if anything, they've done with the new GTD unit apart from focusing on dramatically improving CO2 and MPG.

I am an engineer, but I know little about the engineering of cars, so correct me if I'm wrong here!  Torque is basically the length of your spanner, whereas power is how hard you are pushing on it.  So, if they don't change the dimensions or layout of the engine, gears etc and just adjust or replace some parts it makes sense for the power output to change but torque to remain similar (identical?).

I might be hugely off here, can anyone confirm?

[monkeyhanger]

The mk7 with less unladen weight will be slightly quicker even with the same torque figures. On paper looks the same but little differences should help.

18kg difference won't add up to 0.6s off the 0-62 time, I think there's more telling than that and the 2 cars aren't directly comparable (although similar in weight).

There is a huge difference in power delivery between the 170TDI PD and the 170TDI CR, maybe a similar story with the new unit. I gauged this by what speed I pass a certain signpost when entering the coast road from Billy Mill at mine. My old 140 PD Golf got to 70mph at the signpost, the 170 PD I had next got to 80mph, the 140 CR Roc managed 76mph and the current 170 CR does about 83mph to the same point under same acceleration. Better traction may be part of the better 0-62 times. The TT 170TDI was 0.6s quicker on the sprint than the same Roc, despite being about the same weight, although they all come with Quattro which helps get all of the powwer down early, my 170PD Golf was awful for "tramping" under load.

Maybe a decision not to up the torque was made so they didn't have to put in a beefier clutch (or uprate other components), or maybe there's been a compromise between power and torque to keep the CO2 levels just within their respective bands for taxation (although 5 door DSG gaining 3g CO2/km over the 3 door when the same doesn't happen with the manual is a mystery to me).

[monkeyhanger]

Bill: Yep, as an engineer you'll know that torque is turning force. A simple demonstration is that it's easier to loosen off a wheel nut with a longer wheel brace handle than a shorter one. How that translates to the internals of an engine is unknown to me - piston and lever lengths vs rotation diameter on joints maybe?

[Bill_the_Bear]

Bill: Yep, as an engineer you'll know that torque is turning force. A simple demonstration is that it's easier to loosen off a wheel nut with a longer wheel brace handle than a shorter one. How that translates to the internals of an engine is unknown to me - piston and lever lengths vs rotation diameter on joints maybe?

I believe its the pin offset on the crankshaft.  This means torque will vary depending on how far through a stroke the piston is.  So max torque will be when the pin is perpendicular relative to the axis the piston moves on.  Of course we have more than one piston so this will average out.  This is the kind of thing that I assume is rarely changed without completely redesigning the engine.

EDIT:
Actually not perpendicular to the piston movement, its perpendicular to the connecting rod.

[tuscan]

As far I as understand torque in term of a car engine...

Yes it is measured in the way you describe using a spanner.  Imagine holding a 1lb weight off the end of a 1ft spanner and that is 1lb/ft of torque.  What that means in real terms is the ability to actually use the power of the car.

E.g.  A 125cc 2 stroke motorbike has very little torque and has a tiny power band where the hp is useable say bewteen 9k and 9.5k revs and nothing anywhere else.  A car with large toque means that it can use the optimum hp through a larger spectrum of revs.  Say 1500 revs to 4000 revs. Hence low down grunt.

I may not of explained that very well but thats how i understand it 

[mjh_056]

It took a bit of getting used to when first drove my 170BHP Diesel in how that power is delivered, as it is different, a real 'surge' but now 2 cars and 5 years on it is something I have grown to love and I would very much miss, hence moving from A3 to GTD so can retain the performance/economy combination

So I just think the difference will be even greater improved experience over what already happy with in power aspect

The thing that I am really looking to see difference on is the handling given I am losing the Quattro?

The Golf is going to be a whole lot lighter than my 8P has the XDS system, progressive steering, improved suspension with added ACC so it could be a very differing driver experience?

Anyone gone from a Quattro to GTi previously can comment?

[monkeyhanger]

mjh_056: The power delivery of the CR TDI engines is a lot smoother than that of the PD versions, and the power band is a lot wider. For those coming from a 170 Roc or MK6 GTD the difference won't be that big apart from the extra power I would imagine, but for someone coming from a MK5 GT 170TDI the difference in power delivery will be quite big.

I have XDS on my Roc, it does make it easier to fling the car around a bend at speed without worry of sliding around.

[mjh_056]

Not sure what engine mine would compare to there given from same stable, CR or PD? present is 2010 A3 Sline 170BHP with the Quattro

The Golf is lighter on new frame and more so removing Quattro and with all the other features mentioned including the XDS
then just feel I am heading to an improved experience across the board, particularly handling, and that only maybe in extreme wet conditions I will have to remember not driving a Quattro.

Feel a little guilty in anticipating the GTD so much as my poor A3 is now being seen as past sell by date!