What IS torque?!

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imported_monkeytrousers

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The recent S3 vs TDI vs Civic Type R threads have led me to ask "What is torque, and how does it affect performance?".

I did a definition search on Google but it wasn't much help:

http://www.google.co.uk/search?hl=en&q=define%3A+torque&meta=

My thoughts:

Torque is not the same as acceleration, but has an effect on it.
However, a TDI has bags of torque but cannot accelerate like a VXR220 which has low torque.
Torque affects a car's ability to tow a load - I think.

Can anyone offer a simple explanation that doesn't involve too much physics?
 
Torque turns wheels...power keeps them spinning when they are up to speed.

Torque is pulling power...grunt, if you like.
You roll along in 3rd at 30mph and plant the foot...torque is what you feel...or don't if you are in an Integra Type-R!


Acceleration is different again...it's a function of gearing, mass, torque, power and grip...and at higher speeds aerodynamics.

There are too many variables to make an easy comparison...but in general high torque cars pull better in gears...whereas low torque cars require more effort, gearchanges and revs to get the best out of them.
 
my understanding is it's kinda like electricity. Volts and current, the current is the strength that the voltage is forced, so to me the torque is the strength the power is delivered. The higher torque will find it easier to push a heavier mass than a car with the same power but less torque. I could be talking crap though LOL
 
copy and paste..

The concept of torque in physics, also called moment or couple, originated with the work of Archimedes on levers. Informally, torque can be thought of as "rotational force". The rotational analogues of force, mass and acceleration are torque, moment of inertia and angular acceleration. The force applied to a lever, multiplied by its distance from the lever's , is the torque. For example, a force of three newtons applied two metres from the fulcrum exerts the same torque as one newton applied six
 
Torque is turning force. In the case of lb.ft, imagine holding one end of a 1ft ruler. Now imagine placing a 1lb weight at the other end of the ruler. The force you feel trying to pull the ruler from your grip is 1lb.ft.

There is some very useful information on Wikipedia.
 
So what are the effects of each in the real world, and apologies if this has already been covered in the other posts but I'm still not 100% on it.

Take 3 cars, say they have...

1. 150bhp 250Nm
2. 200bhp 250Nm
3 150bhp 320Nm

Not real figures but an example. What would each be like?
 
I always understood it as torque being the amount of force exerted on the 'twist' (imagine undoing a nut with a large wrench, and the force you apply to doing it), and the BHP effectively defining the rate (how fast) at which you can apply that force..
 
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in a nutshell;

bhp is how fast you can go
torque is how quick you get there

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See this is the bit that confuses me. If BHP is just how fast you can go (top speed?) and torque is how quick you get to that speed then that would give high torque cars a quicker 0 -60, but it doesn't.

Maybe its that high torque is good for acceleration but on diesels you only get it within a narrow range. With higher BHP do you just get a longer range at which max torque is applied?
 
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See this is the bit that confuses me. If BHP is just how fast you can go (top speed?) and torque is how quick you get to that speed then that would give high torque cars a quicker 0 -60, but it doesn't.


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It's just not that simple.

If each car had only one gear and weighed the same...then the car with the higher torque would accelerate faster - assuming it could put the torque down to the road.

Gearing is the big factor...gears are only torque multipliers, after all.

Race cars tend to have lots of top end power but little torque below 5000RPM...but they aren't slow at accelerating. Why?
Because they are geared low.

My Integra Type-R would easily match an S3 from 0-100MPH with only 133lb-ft of torque and FWD. Why?
Because it was very low geared, and you flew through the rev band quickly to get the engine into the meaty part of the rev range.


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Maybe its that high torque is good for acceleration


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I think this should read:
"high torque is good for in gear acceleration" ...this is regardless of the gearing of the car...high torque cars will always accelarate faster than the same car, with the same gearing, being accelerated by less torque. That's obvious.


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but on diesels you only get it within a narrow range.


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Which is ideal for in gear acceleration, when you can't be bothered changing gear...


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With higher BHP do you just get a longer range at which max torque is applied?

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No as simple as that either...
With peak power being produced at higher RPM you get a larger speard of power...larger spread of power and torque gives a completely different power and torque graph curve...
The more area under the curve...the faster the car has the potential to be - in both acceperation and top speed - assuming you match the gearing to the torque/power curves.
 
Ok..

Lets assume the following.

All cars are the same shape (same drag coefficient), same weight same gearing. Torque (lb.ft/nm) is accelerative force, Power (bhp/kw) is top speed. BHP is relative to revs. Theoretically, a car that revs to 8000rpm will have twice the power than one that revs to 4000rpm (compare diesel to petrol where the torque figure is similar). Diesel engines for example have high torque figures, but low power figures... This is becasue they dont have a long rev rabge like petrol engines do so a car with all things mentioned above the same but one diesel and one petrol, and the torque values the same, the petrol engine will be able to achieve a much higher top speed than that of the diesel.

This make sense to anyone?

Rich
 
Richa3turbo - yes, good article..

so for our purposes the torque is the twisting force applied to turn the various components of the drivetrain.

The overall power is a function of this force, multiplied by the revs per min figure.. (a simplification)

Diesels usually have high torque figures, but lower rev limits, still giving a good overall power figure.

Petrols often have a lower figure for this twisting force, but because of the higher rev limits they can apply this force faster, giving a more effective top end result, and a higher overall power figure.

is that right?
 
I remember from school an electric motor has its maximum torque at 0 rpm but its max horse power at its running rpm. The torque is therefore at its highest when it starts it turning.

I was told a good explanation was that torque is in relation to getting something moving faster and horse power in relation to the point at which the most force is needed to slow it back down. I think this is where 'brake' horse power comes in to it.

Kinda makes sense to me.
 
You know what Rich...that explains things perfectly!
I was struggling to put things down to illustrate that exact point.

I have an example which shows exactly what you state:

Take two cars:

A Golf GT TDI - say chipped to 165 BHP and 280 lb-ft...revs usefully to 4500

...and a Porsche 911 - say 330 BHP and 280 lb-ft, revving usefully to 7500

Same torque...similar weight...different gearing though so not directly comparable...although compare 5 speed Golf ratios (rather than the later 6 speed 'box) to the 911's first 5 ratios, and you arn't worlds apart.

One has twice the power of the other.

The Golf has lots of torque low down...this will show by it being very quick out of slow corners (as proven on the road) and excellent for overtaking without changing gear (also proven on the road).
The 911 will be MUCH faster though when using all the revs (proven on the road) and far faster top end.

This isn't the best - or a definitive example - but illustrates rev range, power delivery etc..

Especially obvious if you study the relevant power and torque curves and measure the area under the graph.
 
[ QUOTE ]
You know what Rich...that explains things perfectly!
I was struggling to put things down to illustrate that exact point.

I have an example which shows exactly what you state:

Take two cars:

A Golf GT TDI - say chipped to 165 BHP and 280 lb-ft...revs usefully to 4500

...and a Porsche 911 - say 330 BHP and 280 lb-ft, revving usefully to 7500

Same torque...similar weight...different gearing though so not directly comparable...although compare 5 speed Golf ratios (rather than the later 6 speed 'box) to the 911's first 5 ratios, and you arn't worlds apart.

One has twice the power of the other.

The Golf has lots of torque low down...this will show by it being very quick out of slow corners (as proven on the road) and excellent for overtaking without changing gear (also proven on the road).
The 911 will be MUCH faster though when using all the revs (proven on the road) and far faster top end.

This isn't the best - or a definitive example - but illustrates rev range, power delivery etc..

Especially obvious if you study the relevant power and torque curves and measure the area under the graph.

[/ QUOTE ]

A good example! shows in real terms what i was trying to get across!
 
excellent! think thats finally cleared that up.
 
so if a diesel was to rev to 8K then it would annihilate a petrol eq. to the same revvin power?

Having more torque over a longer period, or not?
 
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so if a diesel was to rev to 8K then it would annihilate a petrol eq. to the same revvin power?

Having more torque over a longer period, or not?

[/ QUOTE ]

If a diesel could rev to 8000rpm, then it would be something very special and insanely quick, but would need a special turbo to maintain bottom end performance whilst being able to sustain boost at high RPM.

RIch
 
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So thats a YES then?

[/ QUOTE ] I think so... /ubbthreads/images/graemlins/noidea.gif lol
 
Glen, your view on this, lol, it sounds like it would be tho, now that would be great 8k revving diesel, ohhh soo much torque/bhp, lol. Mind you didnt Honda develope a diesel powered motor bike that was high revving?
 
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So thats a YES then?

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I would say yes...

But, as Rich says...such a Diesel would be a masterpiece to be able to make a compression ignition enginer that runs at 8000RPM would be something else...but it would weigh a metric tonne!

The whole issue of rev range is the problem with compression ignition engines in general...
You either have a high torque, low revving diesel,
Or a high revving, lower torque but much higher power petrol engine.

You pays yer money, and takes yer choice. /ubbthreads/images/graemlins/tongue.gif
 
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[ QUOTE ]
So thats a YES then?

[/ QUOTE ]
You pays yer money, and takes yer choice. /ubbthreads/images/graemlins/tongue.gif

[/ QUOTE ]


And its petrol all the way!! /ubbthreads/images/graemlins/grin.gif Until it runs out anyway! /ubbthreads/images/graemlins/crazy.gif
 
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[ QUOTE ]
You pays yer money, and takes yer choice. /ubbthreads/images/graemlins/tongue.gif

[/ QUOTE ]


And its petrol all the way!! /ubbthreads/images/graemlins/grin.gif Until it runs out anyway! /ubbthreads/images/graemlins/crazy.gif

[/ QUOTE ]

Me too!
Until it gets too expensive and the money runs out...
Then I'll stop eating...
Then I'll stop drinking...
 
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
You pays yer money, and takes yer choice. /ubbthreads/images/graemlins/tongue.gif

[/ QUOTE ]


And its petrol all the way!! /ubbthreads/images/graemlins/grin.gif Until it runs out anyway! /ubbthreads/images/graemlins/crazy.gif

[/ QUOTE ]

Me too!
Until it gets too expensive and the money runs out...
Then I'll stop eating...
Then I'll stop drinking...

[/ QUOTE ]

Lol. Its too expensive now! But im still willing to pay for the pleasure of luxury.
 
lets not turn this into a diesel bashing thread... /ubbthreads/images/graemlins/confused.gif I might be selling my car and getting a diesel... /ubbthreads/images/graemlins/shocked2.gif can't believe I'm saying that never liked the ****** things.

and a TVR / Corvette / Caterham to go with it in the next year or two. /ubbthreads/images/graemlins/idea.gif
 
[ QUOTE ]
The whole issue of rev range is the problem with compression ignition engines in general...
You either have a high torque, low revving diesel,
Or a high revving, lower torque but much higher power petrol engine.

[/ QUOTE ]

Ah now I see the light, that's why diesel is more economical as it revs lower and burns less fuel.....
 
[ QUOTE ]

Ah now I see the light, that's why diesel is more economical as it revs lower and burns less fuel.....

[/ QUOTE ]

That's certainly part of it...
Compression ignition engines are more efficient than spark ignition engines anyway...so that helps too - although in these new hi-tech diesels, they aren't as economical as they used to be!
 
Wow, thanks all for the replies!

Some of it was way too technical for me but RichA3Turbo and Ess_Three get the vote for putting it in layman's terms.

Cheers.
 
[ QUOTE ]
[ QUOTE ]

Ah now I see the light, that's why diesel is more economical as it revs lower and burns less fuel.....

[/ QUOTE ]

That's certainly part of it...
Compression ignition engines are more efficient than spark ignition engines anyway...so that helps too - although in these new hi-tech diesels, they aren't as economical as they used to be!

[/ QUOTE ]

Maybe so, but it would be due to the fact diesels of today now have CAT's.

Mine is good enought for me at average of 50mpg
 
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