i have a 1.9tdi octavia with 18inch wheels and a spoiler and remapped and it wil do a top speed of about 120 maybe a little more. Is this rite and if not what could be wrong?. Thought id post after looking at the other thread. Also is anyone doing this to a 1.9tdi as all the posts seem to be about vrs. Ill get one someday(more like the day i turn 25!!!!! )

What was the original power of the car? 90/110/130??? What was the power afterwards? Did you have it remapped or Chipped? Looking on Parkers the standard TDi top speed was 113mph for the 90bhp, 119mph for the 110bhp and 129mph for the 130bhp. TDi's have inherently more torque than power. This moves the car. I am thinking that if the remap has gone for greater torque over power then you will find that your acceleration may have improved rather than the top end. The 18's will improve the top end over the standard size wheel but cuts acceleration. (Something to do with the greater rolling radius)...

Here we go again.....

Power = Torque x speed.

You can't have 'more torque than power', they're different properties and quantified in different ways.

it is the 90bhp rmapped to 120bhp. It does accelerate really well and will head to the 100s in 4th which really wind up the guys in there done up cars lol:cool: so by the sound of it its doing ok then?

also remapped not chipped btw

also can i make it faster without spend huge amounts of money?

Here we go again.....

Power = Torque x speed.

You can't have 'more torque than power'' date=' they're different properties and quantified in different ways.[/quote']

Actually.....

Power = Torque * rpm / 5252

Where Torque is measured in lbft and power in bhp

That's why all RR graphs with a shared y axis show the 2 lines crossing at 5252rpm

It is possible (and normal on turbo cars) to have a higher peak torque figure than peak power figure, however for the purposes of top speed it's irrelevant.

Mid range torque (peak) accelerates a car... top end power (or top end torque if you prefer as torque defines the power) determines the top speed.

Torque and power are one and the same really, however it's the peaks of each which are most talked about really, which occur at different engine speeds.

People say that Hondas are torqueless... the difference is their peak is at about 5000rpm, meaning it's actually more effective.

But the question I ask is.... what does it matter what the top speed is? High speeds are boring. Accelerating is the fun bit.

True - top speed is pretty boring, hardly worth the ammount of effort you have to put into extra concentration (for very little gain). Its noisy too.

Actually, that could be misread.

It's not just the peak torque which acclerates a car... it's the torque curve. However the peak will occur within the significant part of that curve, and it's this which is talked about. The peak is unimportant really too.. it could spike up and back down again and be useless. What's the point of acclerating hard for 300rpm when the rest of the range is useless? But, if the curve is flat and still high then you're onto a winner.

i'd say 120Bhp in a 1.9TDi Octavia and acheiving 120mph is about right, perhaps a bit more if you held on for longer. It's a heavier car than the fabia and the fabia has 10bhp more and yet is only rated to a top speed of about 126mph. It's also has 6 gears and i'm assuming yours is 5? So yeah in real world sound about right.

i'd say 120Bhp in a 1.9TDi Octavia and acheiving 120mph is about right, perhaps a bit more if you held on for longer. It's a heavier car than the fabia and the fabia has 10bhp more and yet is only rated to a top speed of about 126mph. It's also has 6 gears and i'm assuming yours is 5? So yeah in real world sound about right.

Weight of the car is relatively unimportant tbh, it's the aerodynamics which will affect the top speed. Weight will only affect acceleration.

But yeah, 120mph for a 120bhp car sounds about right. You need around 140bhp to get to 130, 170bhp to get to 140 and 200bhp to get to 150mph.

The aerodynamics will affect those figures, but they're a reasonably good base.

Oh, that's for FWD manuals. Power losses due to different drivetrains will also affect it.

thats ok then but whatr could i do to accelerate faster as id like that stuck to your seat feeling that really high performance cars have

Actually.....

Power = Torque * rpm / 5252

Where Torque is measured in lbft and power in bhp

How is that different to my (deliberately) dimensionless statement? You're just multiplying Torque x speed by a constant' date=' '1/5252' to suit the archaic non-si units

It is possible (and normal on turbo cars) to have a higher peak torque figure than peak power figure

Eh?

If I defined my unit of power as a 'Bodge', where 1Bodge = 0.01bhp, then my power peak, if drawn on the same graph, would be 100 times 'bigger' than if I used bhp . As the 2 units express different things, the numbers are arbitrary depending on the units used!

....other than that you've just agreed with what I said originally....

Weight of the car is relatively unimportant tbh, it's the aerodynamics which will affect the top speed.

Correct, unless the gearing is too high or too low for the the engine to produce its peak power at a suitable speed.

as an aside:

something else to remember is that aerodynamic drag is often expressed as 'Cd' eg. 0.32, that's the 'drag' compared with a flat fronted block of the same cross-sectional area.

So a TDCi transit van may (and possibly does) have a lower Cd than a TDCi Mondeo, but when the frontal area is multiplied by the Cd, the air resistance may be higher at a given speed.

so can i make it accelerate any faster?

Actually.....

Power = Torque * rpm / 5252

Where Torque is measured in lbft and power in bhp

That's why all RR graphs with a shared y axis show the 2 lines crossing at 5252rpm

It is possible (and normal on turbo cars) to have a higher peak torque figure than peak power figure' date=' however for the purposes of top speed it's irrelevant.

Mid range torque (peak) accelerates a car... top end power (or top end torque if you prefer as torque defines the power) determines the top speed.

Torque and power are one and the same really, however it's the peaks of each which are most talked about really, which occur at different engine speeds.

People say that Hondas are torqueless... the difference is their peak is at about 5000rpm, meaning it's actually more effective.

But the question I ask is.... what does it matter what the top speed is? High speeds are boring. Accelerating is the fun bit.[/quote']

YEAH wot i said but put so elqua... elaqu... elequa . WOT he said

I knew it was something like that.

so can i make it accelerate any faster?

I think that you have probably gone as far as you can with out spending thousands. I believe, but I am sure somebody will correct me if wrong:D, that tuning DERVs is different from petrol engines due to it being compression combustion. You can't really advance/retard the ignition so doing the usual things such as cams or bigger turbo's don't really work as adding more lots of fuel and air will have an adverse effect rather than generate more power.