Torque - how does it affect towing a van?

Submitted: Thursday, Jul 24, 2014 at 15:49
ThreadID: 108861 Views:2563 Replies:11 FollowUps:8
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Hi
As newbies to caravanning, we've been asked about the torque of our car (Nissan Xtrail petrol 2.5 litre, 2013 model). I've looked up the details on the Nissan site and it says that the car has a maximum torque of 226@4.400.
That's great and we understand that it means 226 Newtons at 4,400rpm, but we don't know how that applies to towing a van.
The Xtrail whas a maximum towing capacity of 2,000kg and we tow an Avan which is 900kg dry with an ATM of 1200kg. We think this is well witin the capability of the car. If we wanted to buy a bigger van, how can we tell if the torque rating of the car will be sufficient to tow the van we choose?
Could anyone who can help please answer in plain English as I'm a mature female and just throwing these terms around like I know what I'm talking about

Thanks
Sandra


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Reply By: madfisher - Thursday, Jul 24, 2014 at 16:08

Thursday, Jul 24, 2014 at 16:08
Your xtrail will tow that weight fine. My friends tows a 1 ton boat with and xtrail and is very happy with it. However once you are towing above 1500kg I think you need at least 350nm .
We have and xtrail and a jackaroo, the Jack does most of the towing duties as it has 310nm. But we love the Xtrail for its comfy seats, refinement and economy. Wife will not let me put a tow bar on it yet, but I will get one on it eventually. lol
Cheers Pete
AnswerID: 536518

Reply By: Member - Rob D (NSW) - Thursday, Jul 24, 2014 at 16:46

Thursday, Jul 24, 2014 at 16:46
Torque is a measure of turning force and is measured in Newton Metres. More turning force (torque) at the rear wheels translates to more pulling force.

1 Newton is the force of a 1 kilogram mass subjected to gravity. I.e. it is the force on the surface of your measuring scales when a 1 kilogram mass is place on the scales.

1 Newton metre is the turning force that would be exerted on a horizontal lever one metre long with a mass of one kilogram sitting on the other end.

It is not so much the maximum torque that is important it is the torque distribution over the complete revolution range of the motor. For example a Landcruiser 200 V8 diesel has a maximum torque at 1600 rpm. Having good torque at low revolutions will generally make a better towing vehicle.

Hope this helps.
If you relax at a faster pace you can get more relaxation in for a given time.
Regards Rob

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Follow Up By: Member - Rob D (NSW) - Thursday, Jul 24, 2014 at 18:26

Thursday, Jul 24, 2014 at 18:26
Just out of interest, the relationship between power and torque is:

Power (kW) = Torque (N.m) x Speed (RPM) / 9.5488
If you relax at a faster pace you can get more relaxation in for a given time.
Regards Rob

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Reply By: Member - Rosco from way back - Thursday, Jul 24, 2014 at 17:09

Thursday, Jul 24, 2014 at 17:09
Rod D has given you an excellent description of what torque is.

As relates to vehicles towing, the higher the torque the better and max torque achieved at lower revs is equally important.

As long as you are towing within the manufacturers limits you should not have a problem, however you may find you need to work the gears more in a manual or it will drop down more often in an auto. This will be particularly noticeable on hills or when overtaking.

In your case this will be noticeable insomuch as you need reasonably high revs to arrive at your quoted figure, hence you will find the engine needs to work a bit harder.

Your Xtrail is a relatively small vehicle so I would approach the idea of towing a larger van with a measure of trepidation, however I can't see why you would have any problems with your current Avan.
AnswerID: 536522

Reply By: Tony H15 - Thursday, Jul 24, 2014 at 17:45

Thursday, Jul 24, 2014 at 17:45
If you watch a drag car/rail or a racing V8, you will notice when the engine is reved the car will list to one side momentarily: that is the engines massive torque in action: twisting the cars chassis and suspension. If you google ‘the difference between torque and HP’ you should find something that will explain both much better than I can, however, in simple terms torque is what helps you up hills and towing heavy items like caravans.

Your Xtrail for example delivers 226nm at 4400 rpm, so when your engine is spinning at less than 4400 rpm it will deliver less than maximum torque – how much less depends on the design of the engine and its displacement (size). The engine in most modern petrol engined cars, when cruising at say 100kph, will be spinning at around 2500rpm (give or take), certainly it won’t be spinning anywhere near 4400rpm where maximum torque is delivered, so it will be delivering less than the quoted 226nm.

A diesel engined vehicle on the other hand delivers maximum torque at relatively low revs (typically between 1700 and 2500rpm) and the torque band is relatively level. That means it will deliver close to maximum torque throughout it’s rev range; however, (typically) most diesel’s torque delivery drops off markedly once past a given point (rpm), some liken it to falling off a cliff. So, when cruising at the same speed (100kph) a modern diesel, generally, will be spinning somewhere within the 1700 – 2500rpm band where maximum torque is delivered.

To sum up, if you have two vehicles with identical torque outputs, at a crusiing speed of 100kph the diesel will be operating at maximum torque whilst the petrol engined vehicle will be operating at somewhat less that max torque.

Sounds simple, but it isn’t. There are a lot of other variables – not the least of which is HP.
AnswerID: 536523

Follow Up By: Allan B (Member, SunCoast) - Thursday, Jul 24, 2014 at 18:20

Thursday, Jul 24, 2014 at 18:20
Actually Tony, what you describe is not torque, it is mass acceleration and it produces an equal and opposite reaction which acts on the vehicle to twist the body on its suspension. When the acceleration reaches a plateau and maintains a constant rev speed, the force ceases and the body returns to its original position even though the revs continue.

Torque is a rotary action of force acting upon a restraint. If there is no restraint there is no transmission of force hence no torque, merely effortless rotation.
Cheers
Allan

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Reply By: Tony H15 - Thursday, Jul 24, 2014 at 18:32

Thursday, Jul 24, 2014 at 18:32
The lady asked for 'Simple English', I can't see any requests for people to stroke their egos!
AnswerID: 536524

Reply By: Ross M - Thursday, Jul 24, 2014 at 18:33

Thursday, Jul 24, 2014 at 18:33
Sandra
Torque can be present without power, When doing up a bolt with a spanner torque is applied and can be continually applied with out any power happening.

Torque is turning force
Power is a rate of doing work.

In a vehicle the two are combined and while your vehicle may have 226 rating for torque it is always the maximum which is stated.
The faster and engine revs the faster it does work and so faster generally means more power.ie KW
You won't be operating your engine at the 4,400rpm level where maximum torque is happening.
So the real torque which is happening in the normal engine operating speed range is what you will mostly be interested in.
Possibly at 2500rpm or a little above may be the realistic operating speed and at that rpm it may only be making 180 in the torque department.

A high powered petrol or diesel vehicle may make far more power than you will ever need, ie, You don't need the large power to tow the van at 200 kmh, so a respectable amount of torque is what will be really required, as that is what you really are using to drive the vehicle along and move the weight at sensible road speeds.

A diesel will provide quite a good deal of torque at normal expected rev operating range.
Often a petrol engine has to use gears to provide sufficient torque to the rear wheels.
After all, it is the torque happening at the wheels from the engine which is what drags the load along.
AnswerID: 536525

Follow Up By: Ross M - Thursday, Jul 24, 2014 at 19:49

Thursday, Jul 24, 2014 at 19:49
To deal with some replies.

Ego + some knowledge X google sqd = many talks. Often not related ie different language
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Reply By: Nutta - Thursday, Jul 24, 2014 at 18:35

Thursday, Jul 24, 2014 at 18:35
I'd be more worried about the gearbox if its a cvt, I dont think those things are designed for to much load.
AnswerID: 536526

Follow Up By: Sandrab58 - Thursday, Jul 24, 2014 at 18:45

Thursday, Jul 24, 2014 at 18:45
Its a manual gearbox.
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FollowupID: 820675

Follow Up By: Tony H15 - Thursday, Jul 24, 2014 at 19:18

Thursday, Jul 24, 2014 at 19:18
CVTs, autos and manuals all have different tow ratings. In Xtrail's case I think the CVT is rated the same as the manual and the auto considerably less. Or, could be the CVT rated at considerably less, not sure, ask google, he's a bit of a know all!
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Reply By: Rangiephil - Thursday, Jul 24, 2014 at 21:29

Thursday, Jul 24, 2014 at 21:29
The Xtrail manual is known to have a weak clutch . My son's ex's father ruined one at 20,000 K while reversing a caravan.
While it shouldn't be too worried by an A van, you should be careful not to slip the clutch .
The fact that a petrol Xtrail has weak torque at low revs and no low ratio means that you may have to slip the clutch a lot if starting on steep hills while towing, so this should be avoided.

Nobody seems to have made the point but the main effect that you will see while towing is that you will slow down quickly on hills and have to change down gears more often than if you have a car with torque at low revs. As long as you accept this and the fuel economy penalties that entails , then there is no real problem in towing.

Regards Philip A
AnswerID: 536534

Reply By: customline - Friday, Jul 25, 2014 at 09:32

Friday, Jul 25, 2014 at 09:32
G'day Sandra, to put an answer in simple terms Torque relates to how easily you can move the mass (car & van) from a standing start . Once you are moving at your speed limit Power is what keeps it going . Simple "EH" .
AnswerID: 536550

Follow Up By: kiwicol - Sunday, Jul 27, 2014 at 09:02

Sunday, Jul 27, 2014 at 09:02
Have to agree with customline, torque is what gets you going and power is what keeps you going. Col
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Reply By: The Bantam - Saturday, Jul 26, 2014 at 15:00

Saturday, Jul 26, 2014 at 15:00
There is lots said about Torque and towing.......well.

One thing that has been mentioned but needs to be absolutly clear...above all for comfortable towing you need power and plenty of it.

You can not have power without torque.

In the past people mostly towed with big slow reving motors that had to have lots of torque to achieve the power required at the low RPM that the motors where capable of.

Back in the day, no one would entertain any sort of serous towing with other than a big six or a V8, likewise pretty well all the trucks and commercial vehicles had either big sixes or V8s.

AND it was also a general rule that diesels had lots of torque and petrol motors had lots less.

While a lot of that may still be sort of true...things have changed.

back in the day the HQ holden came with a 253 V8, a little later the XF falcon came with a 4.1 litre six cylinder..both similar capacity both in petrol......both considered pretty fair tow vehicles in the day and there where plenty of em dragging round caravans and horse floats.....the 2.7 litre petrol motor in the 03 hilux produces more power than both those motors in a 4 cylinder........of course it produces marginally less torque, because it is a higher reving motor.

Back in the day, motors had pretty well fixed performance factors set by fixed physical items like cam & ignition timing and fixed fuel system......thus they had fairly narrow band of performance..if the motor produced lots of power it reved high and had poor low down torque...if it had lots of low down torque if reved poorly and had pretty modest high end power output.

these days with variable valve timimg, and electronic engine managment, engines can drive like a tractor at low revs and exceed what was once expected of racing vehicles for high end power of the past.

In the ute variant and assessed by the same criteriour, the hilux has a higher towing capacity and a greater load carrying capacity then either the HQ 1 tonner and the XF longreach.

Still many will not consider the petrol hilux a good towng vehicle.....harping on about the lack of torque.

But you will drive the hilux differently.

The same improvements can be found in desel powered vehicles......in the past most trucks on the lighter end of medium rigid had 6 cylinder diesels in them.....these days we are seeing more 4 cylinder common rail motors.....with more power that rev higher but of course have less torque.

then we move onto the gearboxes...in the past people towed in vehicles with 3 speed gearboxes.....they depended on the torque to lug away in higher gears because they would be revving their big fat ring out in lower gears.
Now we have moved thru 4 and 5 speed gearboxes into 6 or even 7 and 8 speed gearboxes that can keep the engine running right at the top of the torque and power curve...so massive low down torque is not as imperative as it was in the past.


people continue to harp on about engine torque and towing......what matters is the total package and how it works.


Now to SUVs.....most of the lighter SUVs like the RAV, Xtrail, CRV and the like are chasing the fuel economy, so they tend to be pretty high geared.
Even lightly loaded you have to give them some hurbs and slip the clutch to get them off the mark.
As far as I know all of them have issues with their clutches.....its common to see RAVs getting new clutches at 50 000 doing nothing but the school and shops run ( we have just sold one at about that).

So as mentioned I would have concerns about any of the light SUVs and towing near capacity.
The concern is not about the power or torque available or the actual ability of the vehicle to tow the load...but more the wear and tear on the transmission.

just some thaughts.

cheers
AnswerID: 536634

Follow Up By: Bigfish - Saturday, Jul 26, 2014 at 16:59

Saturday, Jul 26, 2014 at 16:59
Ford Australia had the 4.1 released here in 1970...about 130hp and 220 torque/lbs..
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FollowupID: 820823

Follow Up By: The Bantam - Saturday, Jul 26, 2014 at 22:52

Saturday, Jul 26, 2014 at 22:52
by the 80s and with the aloy head and electronic ignition it did a little bit better than that.

the 3RZ 2.7 litre toyota motor from around 2003 does about 150Hp and around 180ft/lb of torque.

The similar current motor with variable valve timimg does a bit better.

cheers
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FollowupID: 820838

Reply By: mikehzz - Sunday, Jul 27, 2014 at 08:40

Sunday, Jul 27, 2014 at 08:40
In my 4wd club there are quite a few soft roaders. We run a trip every year to a place with some super steep fire trails to test them out. The difference between a petrol and diesel XTrail is the torque as they both have around the same power (125-127 kw). The diesel has 360 Bert Newtons of torque, considerably more than the petrol. I can tell you that a petrol XTrail has never made it up the hill, while the diesel has absolutely no trouble. The petrol XTrails get half way up the hill and the force on the wheels causes the engine to stall. Therefore, simply put, I see torque as the ability of the car to keep the wheels turning using the same amount of power. You can liken towing to continually driving up a hill as far as the car is concerned.
AnswerID: 536658

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