Who needs a VR6 when youve got a TDI....

I'm glad you don't write for evo mate, we'd have legions of ill-informed diesel-heads running around screaming "torque is teh win", who seem to think physics are wrong and they are right. I don't care about the forces at work within the engine - they aren't what provide the forward motion - it is the energy produced from these forces, which is converted into the car's kinetic energy - i.e it's speed. Like I said, Power is Energy divided by time i.e the rate that the engine produces this energy to be converted into KE. The faster it can increase its energy output, the faster the car will accelerate. Hence power dictates how fast the engine accelerates. It's not the extra torque that makes diesels so impressive in gear, it's the fact that the flat torque curves result in far smaller drop-offs in power around the power peak, resulting in a far more linear power delivery. And the final nail in your argument's coffin - compare the Mk3 8v and 16v. Very similar peak torque figures (133 vs 125), yet the 16v is leaps and bounds faster, thanks to it's extra 35bhp. If your argument held any water, the 8v and 16v would be far closer in ultimate performance.

A question. If power is so unimportant as you say, why is used as the universal measurement for the performance of a car in the form of power to weight ratios? I'm not simply talking about evo here, I'm talking about every other motoring publication, Gran Turismo (a game I know, but a damn realistic one at that), the F1 coverage and manufacturer's documentation. Surely if torque was so important they'd be talking about torque per ton? Torque is nice for driveability, but doesn't really matter for ultimate performance. Honda's VTEC engines prove a car with very little torque can still be made to perform excellently, simply by revving to a higher speed and producing more power.

Just noticed another nonsensical part of your post. Cars accelerate fastest at their peak torque point do they? I'll assume that's why my 16v provides a bigger kick in the back at 6000rpm (peak power) than at 4600rpm (peak torque). Man, the evidence really is mounting up for the power people...........
Edited by: Bodhi_16V

 

HAHAHA

You are a retard


So by your reasoning, if i were to exert a 10N force on a 1kg mass, there would be no motion on that mass??

And that Newtons law of F=MA would not hold???

My GOD i think you have just disproved all we know about motion!!!




or maybe not

 

Of course there would, because the energy you are exerting in producing the 10N force is being converted into Kinetic energy which causes the mass to move. All the forces tell you are the direction in which the energy is being exerted.

 

jesus, this still going?

f**k it diesel wins.


btw phat, i have seen you, you were at york last yr 27th of july, twas my birthday, i saw you.

 

Everyone seen the figures for the new Touran based Caddy??

http://www.uk-mkivs.net/forum/topic.asp?TOPIC_ID=32417

Quite impressive. Think i need to save for a 2.0 GT TDI!!

 

I may not know much but i know what I like

 

I think that settles it then.

Its definitly a "performance" engine if its involved in motorsport by default =), especially since im sure that its up against plenty of petrol engines, and still came 17th and 12th.

Yes it didn't come first, but they did basically use a road going engine for it

Nuff said Me Thinks.

 

Interesting terminology, never heard that beforec


....: Checks the applied mechanics text book sittin next to the computer :....


Nope, no refernece to exerting energy


Go read a mechanics text book, i've got a copy of Hannah and Hillier : Applied Mechanics sitting here in front of me, they seem to use an awful lot of forces in there, despite you not requiring them

 

*Snigger*

 

hang on all these diesels are turbo diesels being compared to NA petrol engines. turbo petrol engines also have huge amounts of torque dont they?

lets compare apples with apples - 1.8T vs 1.8 TDI 150bhp. Anyone got figures? and if so does anyone know if they run the same boost pressure? or which is greater?

I know one thing, without a turbo, a diesel is slooooow. I've driven them (even with turbos) and the pug I drove was still slow!

 

Valid argument, however diesels don't have the same fuel problems that petrols encounter with Turbo's so almost all diesels on the real market are turbo'ed.

I think the main point is even with a turbo, a diesel can be efficent and fast (although im sure that TDI racing-van doesn't get great MPG )

However, just as Bhodi keeps pointing out "Torque" isn't everything, so why don't we compare a TDI engine with equal BHP to a petrol engine, and then look at those performance figures?

Find a diesel and petrol with around 150Bhp, and around equal weight, and see which is faster? sounds fair to me.

 

The boost pressure is irrelevant, they are two entirely different designs of engine and therefore comparisons cant bbe made on aspects such as that.

The diesel will have loads more torque, but produced at lower revs, the petrol less torque at higher revs, giving same peak power outputs - thats not disputed.

What would be intersting are the plots of the torque graphs and the areas under them, this would be what you'd need to compare the two.

 

PD TD 150
vs
R32
vs
VR6

Can we please find the end of this dispute, even im getting tired of reading it and im usually well up for diesel vs petrol threads

 

Look at it from a basic molecular level. All a force is is the transfer of energy from one particle to another. Your textbook probably won't go into energies, as it makes the calculations look far too horrendous for a first-year university level. As is so typical in the sciences, in second year they disprove everything you've learned in first year and at A-level. Kinda why I said testicles to it and studied Management instead. Much less work and far fewer contradictions aswell.

 

Audi A3 1.8T 150bhp 155lb ft Torque 0-60 8.2 seconds Max speed 135mph 1175Kg

VW Golf GTi 16v Mk3 150bhp 133lb ft Torque 0-60 7.9 seconds max speed 134mph 1181Kg

Audi A3 figure taken from Top Gear mag, 16v taken from evo as the 16v isn't in Top Gear anymore.

I used two petrol cars, as the weight penalty of a diesel makes like for like comparisons difficult (and diesels not handle very well either, but that's a different argument).
Edited by: Bodhi_16V

 

Cant be arsed anymore, gotta be up early to drive.

Jus to clarify one point though, you do realise the calibre of the people you are arguing with??

Trendy Tramp was a lecturer, knows his stuff, and he said you were talkin crap

And as for Drew - well he's jus another one who knows his stuff about this aswell.

And what are you? Some sort of managerial student.... I rest my case

 

That's nice. Doesn't mean they know about cars tho does it?

 

Think you'll find that trendy tramp is a mechanical engineer, who works on car engines all the time

So yeah, i guess he does know about cars

As for drew, not sure what his background is, but he certainly knows it too

 

D on't mention heavy engines in the front, that'll turn Phat against you...




Far fewer contradictions in management?!



Btw, I'd like to run a diesel as a daily driver and have just had a petrol with lowly torque but short gearing. I've no idea what side of the fence I'm on but as I always seem to have more than car I'd hedge my bets with one of each

 

i dont know much about physicas apart from what i covered in my a-Level. Why is the engien converting enegery? from the piston crown onwards its all kenetic energy?

anyway, IIRC Andy graduated his Mech Eng Degree