It's the torque that makes you move not the power in a Diesel engine.

Torque is the turning effect that throws you back in the seat not the power

In my experience of modern diesels, you do not need to rely on torque to get you going and changing early and using the torque uses more fuel and is slower than using the full rev range and making use of the "top-end" power

Chris

In my experience of modern diesels, you do not need to rely on torque to get you going and changing early and using the torque uses more fuel and is slower than using the full rev range and making use of the "top-end" power

Chris

Using the torque doesn't use more fuel, thats what it's there for, or the manufacturers wouldn't give it so much. The lower the engine revs, the less fuel is injected.

I never go above 3500 on the clock and I make rapid progress.

Power of a diesel engine is relativly insignificant compared to the torque output, thats what makes the wheels spin in the first place and the revs continue it when they have built up enough.

Try it for a week, do both and see which is the better.

Petrol, engines rely on power output, Diesels rely mostly on Torque, hence they don't rev as high because they don't need too.

Skoda stick a smaller power Diesel engine in the Octavia vRS but it's near as damnit as fast as the petrol one and you don't need to rev the hell out of it.

Using the torque doesn't use more fuel, thats what it's there for, or the manufacturers wouldn't give it so much. The lower the engine revs, the less fuel is injected.

Changing up to go through peak torque each time uses more fuel in my experience as my foot is flat to the floor trying to make up for lost momentum There was a detailed thread on this a couple of years back and someone posted the overlapped torque curves for each gear to show the optimum change points - IIRC it was circa 4.1k rpm

I tried both methods for several weeks after that and found that using the full rev range worked better, was quicker (despite feeling slower because of the lack of a shove in the back) and was more economical too! Seems to be true on the Mondeo too

Of course, what do I know!!!

Chris

Petrol, engines rely on power output, Diesels rely mostly on Torque, hence they don't rev as high because they don't need too.

All engines rely on power output...it's a measure of "work done"!

And the reason diesel engines don't rev high is because they can't efficiently...

Rob.

Very odd style of driving a TDI especially the very peaky 1.9PD engine. I could understand it with the Duratec (but only in certain circumstances).

Reving your car to 4,500 rpm or 4100 rpm on every gear change.....! With me driving a petrol which has a redline on 7,500rpm in day to day driving I hardly ever need to rev beyond 3-3500rpm.

As said higher up if your changing at 4500rpm then 3rd gear you getting into 3500-3700rpm already miles past peak torque and a few hundred revs below peak power.

Anyone who thinks having the engine constantly spinning up to 4500rpm vs spinning up to 2500rpm and claims the fuel usage is the same or better for the higher reving style is very incorrect.

High engine speed = greater number of injections fact.

Very odd style of driving a TDI especially the very peaky 1.9PD engine. I could understand it with the Duratec (but only in certain circumstances).

I'll bow down to your superior knowledge - as stated above I know very little about driving a car properly and am always willing to learn

Chris

It just seems so odd to drive a car to the red line on EVERY gear change surely common sense tells you it will wear out parts sooner than if driven in a more gentle way & save you a packet in fuel at the same time.

I also find it highly amusing when someone has to rev their engines so hard to pass / attempt to pass me and Im there with very low revs easily keeping up. Dont you prefer the Q car appeal low noise and fly past?

Note also drive like that and you'll never pass your advanced driving licence

Note also drive like that and you'll never pass your advanced driving licence

Is that right?! :eek:

Chris

High engine speed = greater number of injections fact.

And the engine will be closer to it's peak power output...hence you're getting more power out of the engine for the fuel you're using.

Rob.

Is that right?! :eek:

Rob.

Let that be a lesson to you young man. Learn to drive properly :nono:

And the engine will be closer to it's peak power output...hence you're getting more power out of the engine for the fuel you're using.

Rob.

Well at 4500rpm you about 700rpm over peak power so you may as well be @3100rpm & with the added benefit of having some torque to accelerate you down the road.:eek:

Let that be a lesson to you young man. Learn to drive properly :nono:

Well exactly anyone who drives to the red line on EVERY gear change is killing their car & really hurting their pocket. If your on a circuit driving a racing car then yes thats what its designed for & they are serviced far more frequently with engine rebuilds.

Im not sure who it was on here previously who stated they would never buy an x hire car due to it being driven in a certain manner then please dont buy either of these chaps cars as you have seen this is how they treat it.

Also it must be added that this is a very boy racer hcav style of driving are you within that subset?:P

http://www.superchips.co.uk/curves/vagpd130.pdf

This proves that driving up to 4500rpm is the incorrect thing to do as anything above 3800rpm and the car has less power than it would in the next gear so your accelerating at a slower rate.

Surely going from A-B in the quickest & most efficient manner is the ultimate goal?

I'm not sure where I said I red-lined the car, just that I make use of the full power band rather than changing up at 2.5-3k rpm and relying on the torque (cos that really isn't a smooth way of getting anywhere fast). This is actively encouraged by the advanced driving community I believe......

If that makes me a boy racer or ch@v then so be it

Chris

I certainly wouldn't buy Chris's car :eek: the brakes are rubbish for a start :P

The 4500 rpm change up point was raised by the thread starter.

Its a shame that the vRS wasnt available as CVT as if that were the case you'd be constantly driving at 1,900rpm at peak torque.

I drove once a Nissan Primera with a 1st Gen CVT went out on a te4st drive and the petrol went to the red line and stayed there making a lot of noise and only a gradual increase in speed - rubbish car (although the brakes with brake assist were the best Ive ever used).

This proves that driving up to 4500rpm is the incorrect thing to do as anything above 3800rpm and the car has less power than it would in the next gear so your accelerating at a slower rate.

It doesn't really prove that - it just proves that the peak power output is a 4k rpm.

So the way to achieve optimum performance would be to keep the engine at 4k rpm. If you change at 4.5k rpm, you're more likely to be closer to 4k rpm in the next gear...

Rob.

Are you an advanced driver, Welshy? Perhaps you'd be able to give Chris some tuition - his driving could certainly do with some improvement ...

It doesn't really prove that - it just proves that the peak power output is a 4k rpm.

So the way to achieve optimum performance would be to keep the engine at 4k rpm. If you change at 4.5k rpm, you're more likely to be closer to 4k rpm in the next gear...

Rob.

Why would you want to change gear and be in the next gear right at peak power - as doing this power falls so acceleration falls beyond that point you need to change up gear so that there is more power available.

It doesn't really prove that - it just proves that the peak power output is a 4k rpm.

So the way to achieve optimum performance would be to keep the engine at 4k rpm. If you change at 4.5k rpm, you're more likely to be closer to 4k rpm in the next gear...

Rob.

Did you also notice that between 3-4krpm power is level/increases however 4-4700rpm the power graph replicates lemmings

Why would you want to change gear and be in the next gear right at peak power - as doing this power falls so acceleration falls beyond that point you need to change up gear so that there is more power available.

Whether the power drop or not is largely irrelevant - the power output is higher, and that's why it's a Good Thing to keep the engine at this point.

Rob.

But as soon as you go beyond 4000rpm power drops whereas changing up sooner would mean your increasing power & your totally excluding the fact that at those revs Torque is low however changing up sooner you have the blend of torque & power increasing.

Plus no black smoke out of the exhaust & pedestrians not requiring ear plugs as you go by.

Note also drive like that and you'll never pass your advanced driving licence

Hear, hear! :grumpy:

Let that be a lesson to you you Chris.

I actually tried it on track, use the torque and use the power - power was quicker but less serene. Made about 5-10 mph difference along thestraight and about 4-5 seconds difference to a 1.6 mile lap. Either that or I'm not a very smooth or consistent driver. :(

Regardless of power vs torque, with a remap and/or hybrid turbo or similar, you can definitely use more revs higher up the range (on the Fabia vRS for sure).

I gained almost 1000 rpm strong-pulling range at the top end and a bit more at the lower end too I suppose