[Jay.B]

Hi,

cars have never really interested me but now that I have a Cooper S I turned fanatic! :-)

Thinking about getting the JCW in there but I'm having trouble interpreting all the tech talk. One thing I can't figure out though, what is the meaning of 'torque'? What are the consequences/benefits of 'Max. torque/revs: 220 Nm at 4000 rpm' ? Only thing I know is that you need horsepower to go fast...lots of it.

oh wait - just found a thread on it, see if it gets me anywhere. Thanks for the heads-up anyway! :-)

thanks...
Jay.

[Mon the fish]

Torque is hard to explain, its the physical turning force in the crankshaft (the force of the piston going down multiplied by the length of the crank)

Best way I've found to explain it is torque is how hard an engine punches (torquey diesely weasly), and power is how fast it punches (Honda VTEC 8000rpm screamer)

[Grimbo]

Good old http://www.howstuffworks.com to the rescue

Torque and horsepower info overload!

http://science.howstuffworks.com/fpte.htm
http://auto.howstuffworks.com/horsepower.htm
http://auto.howstuffworks.com/question622.htm
http://auto.howstuffworks.com/question381.htm

[Mooyer]

Good explaination I heard from somewhere a bit ago,

Think of BHP as the size of your bicep and the torque as the size of your wrench

[bimini]

torque for acceleration, bhp for top speed

think of torque as the power that helps you pull up the hill and accelerate without changing down a gear, and bhp as how fast you go up it if you do drop a gear.

when things are equal, a more torquey engine will pull you out of a corner better and faster than a less torquey one,...but a vehicle with more bhp may overtake you down the straight afterwards.

Generally people feel torque rather than bhp.

[mattE]

I'm like you, Jay B, I just started reading up on this stuff since getting interested in the MINI. Bimi's explanation was the best for the non-techies like us. My understnading is that BHP is the power of your engine and torque tells you how much it will accelerate your car given its weight. A heavy car with 168bhp will not accelerate like a ligher car with the same bhp and that difference is reflected in the torque. Someone correcte me if I'm wrong.

[Eelke]

Close, but not quite, because both power *and* torque are engine characteristics; neither are dependent on the weight of the car (and if I understand your post correctly, you thought torque *is* dependent on the weight of the car - if not, forget what I said ).

What is dependent on all three is the performance of the car, obviously, where torque and weight have more influence on acceleration (getting the car at a certain speed), and power and air resistance have more influence on top speed (keeping the car at a certain speed).

BTW, to complicate matters further, torque and power are dependant on each other. But I'm sure the howstuffworks-links posted above do a wonderful job of explaining that.

[Tommy_Gun]

So lets compare two cars here, the MCS and the civic type R.
The mcs has 170bhp and 220Nm of torque, the Type R has 186bhp and 196Nm of torque. The civic is also heavier at 1204kg with the mcs 1140kg.

Why is the civic so much quicker 0-60 than the mcs then as it is heavier and only a slight bhp advantage and lower torque?

Also if we were looking at the 50-70 dash who would be quicker? Would it be the mcs with its higher torque to drag it along?

[crooksm]

You also need to throw gear ratios into the mix when comparing accelaration times (and top speeds)...

[Mon the fish]

0-60 depends on so many factors outside of the engine, such as gearing, tyres, suspension setup etc

But yes, the extra torque should make it quicker from 50-70, thats where diesels really score, the in-gear times, ie 4th or 5th, measuring the flexibility of the engine.

But 50-70 is done in 3rd in my S...

[bimini]

Quote: Originally Posted by Tommy_Gun

So lets compare two cars here, the MCS and the civic type R.
The mcs has 170bhp and 220Nm of torque, the Type R has 186bhp and 196Nm of torque. The civic is also heavier at 1204kg with the mcs 1140kg.

Why is the civic so much quicker 0-60 than the mcs then as it is heavier and only a slight bhp advantage and lower torque?

Also if we were looking at the 50-70 dash who would be quicker? Would it be the mcs with its higher torque to drag it along?

gearing is a big factor...quite a few manufacturers make 2nd gear suite maximum 0-60 times so the stats look good.

[twouptons]

The annoying thing about torque is that a single number is useless.
I can get 1500lb-ft of torque at the wheels by simply standing on the end of a 6 foot long wrench connected to the hub (I'm a big guy...), but our MINI accelerates much more quickly with the motor rather than my pushing...
While I can make a ton of torque myself, I can't spin that 6 foot wrench around at any respectable rpm, since I can't make that much power. Doing that is what makes you accelerate.

To make any sense in the context of performance, a torque value must be paired with an rpm value. This, of course, is where power comes from. But the power numbers you get by calculating torque*rpm are at any rpm – and will probably be very different from the peak number.

Those slow-spinning diesels that make gigantic torque at low rpms also make a lot of power at those rpms when compared to the traditional "Hondaesque" fast-spinning motor. That low rpm power is also now where we tend to use it most in normal driving, so the car feels a lot faster than it may actually be.

Putting all this into a single performance measure is really tricky because of the aforementioned gearing, etc. There is a reason, though, that diesel engines have never really been very popular among racers, just as there's a reason that fast-turning gasoline motors have never caught on with the long-haul trucking types...

-Eric

[Squire]

Quote: Originally Posted by Mon the fish

But 50-70 is done in 3rd in my S...

50-70 is done in 3rd in my Cooper too.......and in my astra van as well

[cook1e]

This got me thinking, as I have two cars that drive totally differently, my 18 month old Cooper and my 34 year old Triumph GT6.

The Cooper has more power than the Triumph but the Cooper is however heavier and much less torquey than the GT6 so I did some calculations to compare.

Cooper kicks out 115bhp weighs in at 1150kg and that calculates out at exactly 100bhp/tonne. Torque wise the Cooper produces 149Nm of Torque so that's 129Nm/Tonne.

The GT6 kicks out 104BHP and weighs in at 922Kg and that calculates out at 112bhp/tonne. Torque is 158Nm so that's 171 Nm/Tonne. A better Torque to weight ratio than a Cooper S .

So power to weight ratio and torque to weight ratio wise the GT6 is much better than the Cooper, however it's about 1 sec slower on 0-60 and about 10 mph slower on top speed. I would have expected the GT6 to be somewhat more aerodynamic than the Cooper as well as it's so low and has very sleek lines.

When it comes to drive-ability the GT6 is much easier to drive fast providing the roads are not too twisty (after all the suspension design is over 30 years old and not exactly state of the art). Overtaking say 40 - 70mph is also appreciably more rapid in the GT6 and it really pulls like a train from low revs. Having said that, keep the Cooper on the boil by keeping the Revs up and it's definitely the quicker of the two cars.

So my conclusion is that Torque makes a car more easy to drive fast.....

I do enjoy being able to drive both of my cars, the character is so different and both are really good for posing

[justbob]

torgue is horsepower and horsepower is torgue.

the difference is that horsepower is torgue doing work over time.

torgue gets you started. horsepower keeps you going. that's why you want torque in the low rpm bands and horsepower at high rpms.

an illustration: an electric motor with current applied to it and braked to zero rpm is putting out 100 percent of its possible torgue. unbrake it, and as it spins up in rpms it will increase its horsepower output but the amount of torque it produces will decrease.

the illustration only partially applies to internal combustion engines, but that is a mechanical difference not a theoretical one.

hope this helps.

[Jay.B]

thanks for all the feedback...starting to get it now.

Just one more thing...if torque causes acceleration, how come it feels like you get better acceleration when you shift back a gear to higher revs? Maximum torque of the mini decreases after 4000 rpm which would mean you get less pull and better shift up after that....

Or still missing the point?

Jay.

[obehave]

Quote: Originally Posted by Jay.B

thanks for all the feedback...starting to get it now.

Just one more thing...if torque causes acceleration, how come it feels like you get better acceleration when you shift back a gear to higher revs? Maximum torque of the mini decreases after 4000 rpm which would mean you get less pull and better shift up after that....

Or still missing the point?

Jay.

Now you're getting into torque applied through mechanical ratios.
That's a whole new topic

[Squire]

Quote: Originally Posted by Jay.B

thanks for all the feedback...starting to get it now.

Just one more thing...if torque causes acceleration, how come it feels like you get better acceleration when you shift back a gear to higher revs? Maximum torque of the mini decreases after 4000 rpm which would mean you get less pull and better shift up after that....

Or still missing the point?

Jay.

Except its not until 4000rpm that the cooper starts to do anything lol

its a lil bit lifeless at times untill it reach's 4000rpm, then it kicks in and pulls better

Don't know why, i just know how to drive cars, not how they work

[twouptons]

Quote: Originally Posted by cook1e

This got me thinking, as I have two cars that drive totally differently, my 18 month old Cooper and my 34 year old Triumph GT6.

So power to weight ratio and torque to weight ratio wise the GT6 is much better than the Cooper, however it's about 1 sec slower on 0-60 and about 10 mph slower on top speed. I would have expected the GT6 to be somewhat more aerodynamic than the Cooper as well as it's so low and has very sleek lines.

Of course, you have to figure that :
1) The torque/power calculations done in 1971 were done the same way as in 2004 (in the US, they were not)
2) The 34 year-old car is still making all the power it says it is

That, and aerodynamics are much trickier than they look. Some of the most fabulously streamlined cars of the 1930s have the some of the worst aerodynamic characteristics going.

The whole "what makes my car go fast" problem is more complicated than just a few numbers, and that makes the whole thing a mess...

-Eric

[bimini]

thats cos the mini dont have a great deal of torque...thats largely due to its small engine size and higher reving engine. The bigger the engine, the more torque it naturally develops. You can design engines to provide more torque over another engine of the same size, but the two design roads confilct after a while...the easy way is just to make the engine bigger (you'll here the american brethren often quoting "there's no substitute for cubes"...which is what they measure their engine sizes in)

You get more acceleration because even though you are past the peak torque you now have the bhp now being developed as well.

Another way of thinking about it is torque = pull, bhp = speed...with two vehicles developing the same bhp and capable of going the same speed down the motorway, the one with more torque will be faster under loads like going up hills or carrying passengers, or god forbid towing something like a caravan ...or better at getting the power down coming out of low speed corners without the wheels spinning.

Torque is very useful in scenarios where you dont want wheelspin due to too much power...ie accelerating from wet hair pins, off road, or ploughing your farm