In my experience it's not about rpm. Both standard the TFSI off the mark will be faster than the TDI. On the move i doubt there would be a lot of difference between the 2. If the TDI was remapped to say 200bhp and was put against a standard 200bhp TFSI it would at least be even even though the TDI revs to 4750 rpm. Just because a car revs higher does not mean it's faster because the TDI will have more torque and longer gearing.

Sorry Mickey, I still don't agree with you re revs.

Because the TFSI can rev higher it can be geared differently to the TDI (or use 3rd instead of 4th). The different gearing allows the TFSI to put out more torque at the wheels (because it has a higher multiplier effect) than the TDI.

Even though the TDI has more torque at the engine, this advantage isn't maintained at the wheels because it has to have higher gear ratios (due to its lesser revving ability) and therefore a lower mechanical advantage (compared with the TFSI).

Another way of looking at it would be if they both had identical gearboxes (ie the same gear ratios in each gear), then you would normally drive in one gear higher in the TDI than in the TFSI, so you could see the TFSI pull better in 4th gear than the TDI would in 5th at the same speed. The TFSI would have a significantly higher top speed in each gear.

I know I still haven't explained it very well, maybe someone else can clarify what I am saying better.

Anyway, it is still horses for courses, and we are lucky to have the choice in the vRS

I thought both models used the same 'Boxes?

Well that's not exactly the way i saw it i'm afraid. My old PD 130 ( tuned to 220bhp) was as fast as my TFSI with a stage 1 remapp ( 237bhp) and yet the redline is 6500 in the TFSI and the diesel had 4750 redline, so sorry it's not all about rpm. I should know i have had both. A diesel with equivalent bhp as an equivelant petrol with the same bhp will be just as fast. Also i could get the same speed in each gear 6 speed vs 6 speed as my TFSI

Edited 9 December, 200817 yr by Micky 32

I thought both models used the same 'Boxes?

They have different ratios.

Anyway, it is still horses for courses, and we are lucky to have the choice in the vRS

Sums it up rather well, it's all down to personal preferrence and driving style.

After 3 weeks in a PD TDI after a TFSI, I'm still missing the TFSI.. the low down pull of the TFSI is just as impressive as the TDI (in my opionion), but I am starting to enjoy the TDI.

Overall I still think a Bluefin remap will be required on the TDI to bring it up to the same levels of enjoyment as I got out of my standard TFSI - but again that's just down to me and what I like

But I supose I've only driven 1k miles in the TDI and 16k miles in the TFSI, so not really in a position to make a ralistic comparison !!

Both are spot on cars IMHO

Overall I still think a Bluefin remap will be required on the TDI to bring it up to the same levels of enjoyment as I got out of my standard TFSI - but again that's just down to me and what I like

Bluefin and K&N 57i intake.

The effect of the 57i is to (relatively) flatten the power/torque curve of the TDi, giving you not quite as much a thump in the back at low-mid revs but making it stronger at the upper end 3,500 - 4,500. It gives the engine a more petrolesque feeling.

My old PD 130 ( tuned to 220bhp) was as fast as my TFSI with a stage 1 remapp ( 237bhp) and yet the redline is 6500 in the TFSI and the diesel had 4750 redline, so sorry it's not all about rpm. I should know i have had both. A diesel with equivalent bhp as an equivelant petrol with the same bhp will be just as fast. Also i could get the same speed in each gear 6 speed vs 6 speed as my TFSI

I don't recall ever saying acceleration was "all about rpm". I did say that the ability of a petrol engine to rev higher than a diesel gave petrols some advantages in getting the maximum possible acceleration.

Was your old PD130 the same weight as the newer TFSI, or was it lighter ? As I said earlier acceleration is about power to weight. And to be more precise, power (for acceleration purposes) is defined as the area under the power curve at the revs to be used during the measurement (not just the peak figure).

And what sort of acceleration comparison are we talking about ? The fastest possible acceleration from a standing start by each vehicle (the one I prefer), or the low(ish) starting rev higher gear rolling start comparison that is often preferred by diesel enthusiasts (for obvious reasons) ? Both are valid measures of acceleration, but I note that standing start figures are far more widely tested for and published.

All else being equal (weight, traction etc), I would expect that if a diesel and a petrol had the same peak power then the diesel would accelerate faster, as the diesel would normally have more torque at lower revs, giving it a greater area under the power curve. Of course sometimes the diesel may need extra gear changes to reach certain speeds (depending on gearing).

As far as comparing two modified cars goes, you are then rarely comparing an apple with an apple. If you want a good indication of which type of engine can produce the most power when modified, take a look at any sanctioned drag racing association - once you get into the seriously modified classes you will find very few diesels on the podium.

I am happy to agree to hold different opinions, you obviously like your diesels better than petrols, I see virtues in both. But if you want to continue this debate, may I suggest we take it off line (via PM ? ), as other readers may be starting to get glazed eyes by now

But if you want to continue this debate, may I suggest we take it off line (via PM ? ), as other readers may be starting to get glazed eyes by now

How about creating a new thread about it, as this is now totally off-topic and has nothing to do with the original thread, about a member receiving his new car!

That said, this has all been discussed before anyway, so a new thread might well be counter-productive.

Steve