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Torque to weight?

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Just read a post in the tuning/tuners section regarding power to weight , but i've always wondered why there isn't a torque to weight figure quoted by manufacturers or car mags or anywhere else for that matter.

Surely, wouldn't it be beneficial to diesel car sales to promote their torque/weight ratio, as this would even up the tables a bit with regard to the fact that the bhp/tonne figure doesn't always look that great on paper for alot of diesels.

It's real world performance figures that we want and a fairer reflection of a cars overall power to weight (i.e. torque) not how much power has been generated through the rev-range by thrashing the engine to within an inch of it's life! (especially as after a certain point in the rev-range the torque drops off but you still keep getting 'horsepowers' 'til the red line)

Can any friendly folk here shed any light as to why the tq/tonne figure isn't used?

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Anyone?

Surely someone must know why torque to weight figues aren't used??

Anyway, seeing as i didn't get any replies, i did a bit of 'Googling' and found this page:

http://www.mouthshut.com/review/Petrol_Vs._Diesel_car-68253-1.html

which kinda demonstrates what i'm saying about hp vs. torque.

I mean, take my golf for example. 130hp sounds fairly impressive for a diesel, but the torque figure sounds much more impressive.

I simply want to know why torque/tonne figure is not used (by diesel manufacturers especially).

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I think (from distant physics A level lessons) that torque may not be an SI unit and therefore does not "translate" into torque/weight.

If it does, I currently have a "family estate" that kicks out a much better torque/weight than my R32.

Of course it's bhp/tonne is much worse!

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Just been doing some number crunching.

I have 232lbs/ft and the car weighs 1290kg.

So I have the SAME torque/weight as an S4 saloon (more than an Avant) and more than an M3, Impreza STI and a Boxster S.

So maybe the figure is a bit irrelevant (my power/weight is the same as an A4 1.8T saloon)!

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The problem is, what can you really do with Torque? a car with 100bhp will be a lot slower than a car with 200bhp, but the difference between 100lbs/ft and 200lbs/ft is a lot more difficult to quantify.

Im sure bhp is irrelevent on lorries, but torque is important, because they dont really require acceleration, but need pulling power from torque.

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So I can tow a caravan as effectively as an S4 (with less traction)?!

I'm sure there's some formula you could use to work out performance involving bhp, weight, a torque "conversion factor" and a coefficient of drag and gearing adjustment for good measure.

Might leave that to someone else though!

Basically there seems to be a direct correlation between bhp and weight but torque appears to affect performance in a non linear way.

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I know what torque is (Engineering graduate) but not a lot explains it's relationship to performance which, unlike bhp, seems to have a much smaller effect.

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well then you'll know power is a function of torque and engine speed!

Torque has a massive effect if it's maintained throughout the rev range. For this reason, I'd expect bi-turbo diesels to be the way forward!

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My V70 D5 has so much torque, I can spin the wheels in the dry with new tyres in 1st, 2nd and 3rd, and thats with the traction control ON ! Yeehaaa !

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I make your torque/weight 295/1.580 = 186lb/ft/tonne.

6lbs/ft/tonne more than me and rather healthy!

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[ QUOTE ]

I make your torque/weight 295/1.580 = 186lb/ft/tonne.

6lbs/ft/tonne more than me and rather healthy!

[/ QUOTE ]

Interesting stuff ! I have the latest one with 185 bhp and 400Nm, not the old 163 bhp model. What did you base your figures on ?

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I did a quick Google search tbh and got the figure from there.

It said it was the latest 185bhp model so assume that's yours?

Off the top of my head mine's 310NM (232lbs/ft) so 400NM is about 295lbs/ft.

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