I dont want to dwell on it but Lutz on this one i dont get your logic.The truck engine example (below) contradicts every thing you say.
1, Low horse power (relatively speaking)
2, Low engine speeds.
3, Torque curve is irrelevent.
4, High torque figures.
Non of these are any different to a modern engine fitted in a passenger vehicle,and yet the modern truck performs very well.
I only wish i had the brain power to be able to copy and paste a calibration page from one of our industrial engines that we upload to the ECM showing two different cals for the same engine,one with 250hp less than the other but with 300 lbs ft torque more showing nowadays torque and hp dont go hand in hand.
1, Low horse power (relatively speaking)
2, Low engine speeds.
3, Torque curve is irrelevent.
4, High torque figures.
Non of these are any different to a modern engine fitted in a passenger vehicle,and yet the modern truck performs very well.
I only wish i had the brain power to be able to copy and paste a calibration page from one of our industrial engines that we upload to the ECM showing two different cals for the same engine,one with 250hp less than the other but with 300 lbs ft torque more showing nowadays torque and hp dont go hand in hand.
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If i was considing of buying a Zafira 2009 or 2010 1.9 diesel and a Hyundai Tucson 4 wd 2.0 diesel the choice i would go for is the Hyundia Santa Fe 2.2 190 bph or the Tucson 4 wheel drive and you will have no problems . I use to have a Zafira 1.8 auto towing a Bailey 460/2 and the juice we got throught was a joke we were always at the pumps so now i will always have a diesel .....but the choice is yours .
I'd like to know the individual weights of each make, before making a chioce of which is more ralaxed...Lutz said:Perhaps, to get back on to the rails, here's the comparative data for the Zafira and TucsonParksy - Moderator said:Have you reached any conclusions based on the 'advice' given so far Marie?
....................Thought not!
Zafira
Max. torque 320Nm at 2000 to 2750rpm
Max. power 110kW (150PS) at 4000rpm
Tucson
Max. torque 305Nm at 1800 to 2500rpm
Max. power 103kW (140PS) also at 4000rpm
The Zafira therefore has both more horsepower and more torque. The only point where the Tucson scores is that its max. torque is developed at slightly lower rpm so, at least in theory, it should be a little more relaxing to drive and possibly a little more economical, too. But for performance, even as a towcar, the Zafira is undoubtedly the better alternative.
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The "relatively low horsepower" that you refer to is the reason why quite a lot of trucks start to struggle uphill, especially when fully laden. Despite their high torque, their engines simply can't rev fast enough to provide the power needed to maintain the same cruising speed as on level ground. However, a car towing a caravan is expected to be able to hold 60mph even on quite significant gradients. Also, cars are expected to accelerate a lot better than trucks. Hence, the conditions under which car engines operate cannot be compared directly with those of trucks.seth said:
You are comparing two truck engines, one with 250hp less but with 300ftlb torque more than the other, but this comparison is meaningless without stating at what engine speeds both these maxima occur. As max. torque occurs at a lower engine speed than max. horsepower, all that tells us is that the truck with 300ftlb more will be quicker off the mark from standstill, but its lower horsepower output will result in its top speed being cut drastically when confronted by a hill.
That is just it Lutz there not reving at all,infact they are probably attacking the hill at the same engine speed as they would be on the flat.The engine would not increase speed,for instance on a motorway gradient,most HGV,S would be on the road speed limiter at 90 kmh,most would attempt to climb at that speed,so were would the increase in engine speed come from?OK if there is enough power your going over without changing down,no increase in engine speed,this is were torque comes into play.
The actual comparison i made earlier was of two identical engines but with different ratings just to show that not allways does torque raise in proportion to hp which is were i recall one of your posts pointing to if im not correct.
I would say this-if we had two cars both with the same torque but one with 40 hp more both would climb at the same speed but if both cars were to speed up from 50mph to 70mph the greater car would gain speed quicker but both cars would still maintain the 70mph figure.That to me is a simple understanding of the difference.
The actual comparison i made earlier was of two identical engines but with different ratings just to show that not allways does torque raise in proportion to hp which is were i recall one of your posts pointing to if im not correct.
I would say this-if we had two cars both with the same torque but one with 40 hp more both would climb at the same speed but if both cars were to speed up from 50mph to 70mph the greater car would gain speed quicker but both cars would still maintain the 70mph figure.That to me is a simple understanding of the difference.
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As I've said before, hp and torque are interrelated. Horsepower is basically torque times engine speed. If you raise torque you will also raise horsepower unless you drop engine speed. When comparing engines it is therefore always important to state at which engine speeds max. torque and max. power are developed.seth said:
NO! The one with more horsepower would outperform the the one with the same torque but less hp. It would also be more likely to be able to maintain 70mph depending on how steep the hill is.seth said:
Horsepower determines performance, not torque. That's why one has to change down when climbing a hill. The engine is unable to develop any more torque so to get more power, one changes down which increases the engine speed and consequently also raises the power. If engine torque were the only factor in determining performance there would be no reason to change down.
A high torque figure only enables the engine to rev slower to achieve the same performance.
ps: I'm sorry if this thread which started about the relative merits of Zafira and Tucson has been hi-jacked for other purposes, but I just wanted to get something straight. Perhaps we can now return to the roots.
Yep, i am sorry too, its seems all that is happening is we are coming from different angles.
Sorry Lutz both you and the professor are mis leading new caravanner's about choice of vehicles that most consider "the better "option for the job of towing. Indeed you go on about raising torque will raise horsepower! Not entirely true. with modern turbo cars, so many now have "overboost" facilities which gives a dramatic raise in "TORQUE! for 5 to 7 seconds but if you use the equation Torque x revs over 5252, you will see many cars do not comply with that therory.They have more torque than the equation states is possible or rather less bhp than they should have. my own car mondeo 2.2. has almost 300 lb of torque and a max of 152ps at 3800 rpm/. The book also quotes aprox 270lb of torque without the overboost facility and again 152ps at 3800rpm.and it still doesnt add up.
classroom physics is one thing, but on the road is another. BHP is NOT POWER. put your foot down you are feeling the torque in the seat of your pants.You cannot physically feel bhp, hence the equation. You do need both the torque and the revs [bhp] sure but its wrong to quote bhp as a means of pulling power, towing. That misleads people.into thinking a tow car with more BHP would be better,it is foolish to dismiss the not to small matter of torque and where it is developed as being key to a good towcar
Sorry Lutz both you and the professor are mis leading new caravanner's about choice of vehicles that most consider "the better "option for the job of towing. Indeed you go on about raising torque will raise horsepower! Not entirely true. with modern turbo cars, so many now have "overboost" facilities which gives a dramatic raise in "TORQUE! for 5 to 7 seconds but if you use the equation Torque x revs over 5252, you will see many cars do not comply with that therory.They have more torque than the equation states is possible or rather less bhp than they should have. my own car mondeo 2.2. has almost 300 lb of torque and a max of 152ps at 3800 rpm/. The book also quotes aprox 270lb of torque without the overboost facility and again 152ps at 3800rpm.and it still doesnt add up.
classroom physics is one thing, but on the road is another. BHP is NOT POWER. put your foot down you are feeling the torque in the seat of your pants.You cannot physically feel bhp, hence the equation. You do need both the torque and the revs [bhp] sure but its wrong to quote bhp as a means of pulling power, towing. That misleads people.into thinking a tow car with more BHP would be better,it is foolish to dismiss the not to small matter of torque and where it is developed as being key to a good towcar
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But neither the 300ftlb nor the 270ftlb of torque which you mention occur at 3800rpm. What torque is being developed at 3800rpm?JonnyG said:
Of course it is. After all, it already says so in the word "brake horsepower"! By defintion, brake horsepower is 550ftlb (of torque) per second, or in metric terms, 735 Newton metres (of torque) per second.JonnyG said:
You don't feel torque, either. You feel acceleration. Power = work divided by time. If the time required to cover a certain distance is less due to the acceleration, then the power must be greater. Hence, you indirectly feel power, not torque.JonnyG said:
http://www.revsearch.com/dynamometer/torque_vs_horsepower.html
In the case of my individual car, the piont is the torque value and BHP values will not add up to the scientific calculations. i believe max torque is around 1800 rpm, if you want to do the numbers.but remember i have 300 ft/lb on over boost and 270 ish off. the calculations for Max bhp will be based on the 270ish the car develops and not the 300 ft/lbs on over boost! Many modern turbo diesels now have that concept
The link hopefully works, and whilst i know you know your stuff, exactly what power do you feel? Oh thats right the power developed from the torque directly. more torque more power available. after all the power [thrust]one feels coming in on a turbo diesel at 1800 rpm, feels far greater than the feel of power one can get from an engine that has half the torque but is working twice as hard.which in theory is the same effect.And i repeat your notion only works under controlled laboratory conditions that finds both vehicles sitting at their equivalent "work loads" ie the weak peaky motor will have to be already set up to be revving substantially higher in the right gear to match the values of the stronger low revs torque equivalent.
That does not happen in road conditions, it cannot, we humans are not enhanced with a foresight great enough to be able to accurately judge things so, nor do most drivers have the inclination to even try.
On the road, when people ask which is a better tow vehicle,its all subjective to what people find important size weight handling ect ect. But if power is added to that list then torque and its availability lower down the rev range far far outweighs high revs BHP.
Tell me that is not so......
In the case of my individual car, the piont is the torque value and BHP values will not add up to the scientific calculations. i believe max torque is around 1800 rpm, if you want to do the numbers.but remember i have 300 ft/lb on over boost and 270 ish off. the calculations for Max bhp will be based on the 270ish the car develops and not the 300 ft/lbs on over boost! Many modern turbo diesels now have that concept
The link hopefully works, and whilst i know you know your stuff, exactly what power do you feel? Oh thats right the power developed from the torque directly. more torque more power available. after all the power [thrust]one feels coming in on a turbo diesel at 1800 rpm, feels far greater than the feel of power one can get from an engine that has half the torque but is working twice as hard.which in theory is the same effect.And i repeat your notion only works under controlled laboratory conditions that finds both vehicles sitting at their equivalent "work loads" ie the weak peaky motor will have to be already set up to be revving substantially higher in the right gear to match the values of the stronger low revs torque equivalent.
That does not happen in road conditions, it cannot, we humans are not enhanced with a foresight great enough to be able to accurately judge things so, nor do most drivers have the inclination to even try.
On the road, when people ask which is a better tow vehicle,its all subjective to what people find important size weight handling ect ect. But if power is added to that list then torque and its availability lower down the rev range far far outweighs high revs BHP.
Tell me that is not so......
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You feel neither power nor torque but acceleration. To accelerate you need power, i.e. torque AND engine speed. OK, the more torque that is available the less speed is required.JonnyG said:
I think what you are trying to get at in the real live situation is that if maximum horsepower is developed at a much higher engine speed than maximum torque then the engine needs to react a lot quicker to putting your foot on the accelerator than if it has a relatively flat performance curve. Among other things, this also depends on how many gear changes you have to go through in the process.
Lutz im sorry but your working on at best characteristics of old engines,as i said in todays situations torque does not always go up in proportion to hp.
Using my example of the lorry situation of low hp and high torque but good climbing capibilitys how do you explain it because it contradicts what you say?
Perhaps we should refraise the terminology and say a vehicle with high torque and low hp will climb gradients without the need to change gear as much as a vehicle with low torque and high hp as it is the engine speed that is carrying it over the hill.
As an example,earlier on this year we came back from Cornwall with friends,them with their outfit and us with ours.we were probably 300 kgs heavier.
Their vehicle measured in at 260 hp and 230 lbs ft torque respectively roughly(turbo petrol)
We measured in at 220 hp and 370 lbs ft torque which i know is correct because i watched it on a dyno two weeks earlier to find a split intercooler hose(turbo diesel)
Yet consistently we passed our friends at half way on every hill out of cornwall(a30) and this was by no means a race,not with three children on board but we just couldnt go any slower.Both autos,and in my opinion mine isnt the best and could be alot better.
Yes i understand were comparing diesel agaist petrol but its the torque and hp figures im interested in.
?
Using my example of the lorry situation of low hp and high torque but good climbing capibilitys how do you explain it because it contradicts what you say?
Perhaps we should refraise the terminology and say a vehicle with high torque and low hp will climb gradients without the need to change gear as much as a vehicle with low torque and high hp as it is the engine speed that is carrying it over the hill.
As an example,earlier on this year we came back from Cornwall with friends,them with their outfit and us with ours.we were probably 300 kgs heavier.
Their vehicle measured in at 260 hp and 230 lbs ft torque respectively roughly(turbo petrol)
We measured in at 220 hp and 370 lbs ft torque which i know is correct because i watched it on a dyno two weeks earlier to find a split intercooler hose(turbo diesel)
Yet consistently we passed our friends at half way on every hill out of cornwall(a30) and this was by no means a race,not with three children on board but we just couldnt go any slower.Both autos,and in my opinion mine isnt the best and could be alot better.
Yes i understand were comparing diesel agaist petrol but its the torque and hp figures im interested in.
?
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Firstly, the same laws of physics that say power and not torque is a measure of performance apply to both old and modern engines.
I cannot comment on the rest of what you have written because you have not given enough details to enable anyone to do so. Simply quoting relative maximum torque and maximum horsepower figures of the two vehicles is not enough. Most important, but by no means decisive, is the relative engine speeds at which these occur. Other variables can also cloud the picture. For instance, did both vehicles have the same gearbox and final drive ratios?
Going back to your statement about lorries with low horsepower but high torque having good climbing ability, I have my doubts whether a 40 tonner can accelerate from, say, 50mph to 60mph on a typical 6% motorway gradient (which is something one would expect from a car, even when towing a caravan). The 40 tonner would be lucky to be able to hold its speed.
The reason why truck engines have 'relatively' low horsepower although they develop substantial torques is that they are slow revving engines. Maximum horsepower of the MAN engine that I mentioned in an earlier post is developed at only 1900rpm which is less than half that of a typical car engine. They need such a high torque in order to provide adequate performance because they are unable to rev as high as a car engine.
I cannot comment on the rest of what you have written because you have not given enough details to enable anyone to do so. Simply quoting relative maximum torque and maximum horsepower figures of the two vehicles is not enough. Most important, but by no means decisive, is the relative engine speeds at which these occur. Other variables can also cloud the picture. For instance, did both vehicles have the same gearbox and final drive ratios?
Going back to your statement about lorries with low horsepower but high torque having good climbing ability, I have my doubts whether a 40 tonner can accelerate from, say, 50mph to 60mph on a typical 6% motorway gradient (which is something one would expect from a car, even when towing a caravan). The 40 tonner would be lucky to be able to hold its speed.
The reason why truck engines have 'relatively' low horsepower although they develop substantial torques is that they are slow revving engines. Maximum horsepower of the MAN engine that I mentioned in an earlier post is developed at only 1900rpm which is less than half that of a typical car engine. They need such a high torque in order to provide adequate performance because they are unable to rev as high as a car engine.
- Mar 14, 2005
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For goodness sake, ........
I am not discussing the relative merits or torque, BHP or Hp or even rabbit power!!!
The point is that a more powerfull car is more than likely able to tow a given caravan more briskly them a less powerfull one. However just becasue its a brisk tower does not necesarily make it a better tower.
I am not discussing the relative merits or torque, BHP or Hp or even rabbit power!!!
The point is that a more powerfull car is more than likely able to tow a given caravan more briskly them a less powerfull one. However just becasue its a brisk tower does not necesarily make it a better tower.
There you are Lutz,you,ve just said it yourself"you doubt a 40 tonner could accelerate from 50 to 60mph on a 6%gradient"
So with that satement you,ll have hands on experiance to back it up.
But hold on a minute was that not what i was saying in my deffinition of the two cars with equal torque,but oposing hp figures.
The two vehicles in question,mine and my friends are two different makes,but either way the gear ratios and final drive ratio could not have as much impact as the difference in effort it took to climb the hills.
So with that satement you,ll have hands on experiance to back it up.
But hold on a minute was that not what i was saying in my deffinition of the two cars with equal torque,but oposing hp figures.
The two vehicles in question,mine and my friends are two different makes,but either way the gear ratios and final drive ratio could not have as much impact as the difference in effort it took to climb the hills.
- Mar 14, 2005
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I don't know why you keep on questioning the laws of physics. Under these circumstances and until you are able to offer some explanation that would reconcile your claims with these basics, there is no further point in me commenting any further to this thread.seth said:
You are correct on both pionts, Only when you replace your understanding of power [bhp] with torque! as per your original post.Prof John L said:
And there is no point in pedantics because the caravan fraternity mainly moved over to cars that, guess what had high torque outputs at low revs and not 16 valve screamers with xxxx bhp...................And the same applies to lorries, they have to move great loads and guess what that industry deems the better option for towing a trailer or carrying on its back? Answer "torque"! and not Excessive revs/bhp.
I would be interested to know what yours and lutz experience is of dyno measurements and vehicle set up is?
BHP wins?
Watched le mans over the last 6 years? well lets goback to 2004 and taurus motorsport ran a lola-caterpillar prototype.It was powered by a mountune prepared v10 vw toureg unit producing 530 bhp but a whopping 740 IL ft of torque. the car was quick competitive economical [for a racing car] alas didny last the distance but 530 bhp wasnt considered a huge figurer for 2004 le mans racing cars.
The torque on the otherhand was massive..........
2005/2006. F1 Renaults all conquering grand prix cars was less powerful than the Ferrari's, in terms of "bhp" but had more torque from a little lower, they were quicker out of the slower to medium corners always able to pull a substantial gap down any short straight and usually hold off the Ferrari's down longer straights because of it! better lowdown pulling power,not just traction nor was it chassis as without the Renault in its way the Ferrari was quicker around the actual circuit, but for all its revs bhp being in the right gear or using ant graphs of time against revs, fundamentally even in this high BHP high revving scenario, there was something to be said for a car with less bhp but more torque at a slightly lower rev band.
OK so we are not racing, we were discussing real life on the road towing, but you two are still in the classroom and not looking at real life towing secarios.
- Jun 20, 2005
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This is better than Motorsport
Our MX-5 is all BHP and not much torque. To achieve performance the engine has to go right up to 6000rpm and beyond for max BHP. Stirring the stick is good fun but my god does it drink the fuel and all that high speed cylinder wear!
The Sorento, a good old plodder ,develops all its torque and most of its BHP very low don the rev range. Very relaxing and for it's size and weight probably a better mpg to weight ratio than the Mazda.
Jonny and Seth's pages on torque makes intelligent sense to me. If BHP was so important then you would expect high mileage heavy haulers to use different types of engines than those currently in use.
I don't know how it is today but years back we were told long stroke engines developed bags of torque whilst their short stroke relations were high speed revvers with loads of BHP and not much torque.
I can say when the Mazda engine is in full flow the exhaust is music to the ears. The Sorie just keeps tugging effortlesly but with no exhaust burble or rev counter red lining. For my needs I must conclude that a high torque low revving engine suits my needs best .
Our MX-5 is all BHP and not much torque. To achieve performance the engine has to go right up to 6000rpm and beyond for max BHP. Stirring the stick is good fun but my god does it drink the fuel and all that high speed cylinder wear!
The Sorento, a good old plodder ,develops all its torque and most of its BHP very low don the rev range. Very relaxing and for it's size and weight probably a better mpg to weight ratio than the Mazda.
Jonny and Seth's pages on torque makes intelligent sense to me. If BHP was so important then you would expect high mileage heavy haulers to use different types of engines than those currently in use.
I don't know how it is today but years back we were told long stroke engines developed bags of torque whilst their short stroke relations were high speed revvers with loads of BHP and not much torque.
I can say when the Mazda engine is in full flow the exhaust is music to the ears. The Sorie just keeps tugging effortlesly but with no exhaust burble or rev counter red lining. For my needs I must conclude that a high torque low revving engine suits my needs best .
ok then to put it an otherway,present day 1000cc sports bikes are now putting out 200hp out the crate.That is 50hp more that the 1.9jtdm i have just parted with.On these beliefs if it was possible to tow a caravan with a bike it would outperform the car due to the higher hp, and by the way last week i saw a kawasaki zx10r towing a trailer on the m6.Quite right DD in what you say,the only draw back with long stroke engines was/is a small valve area due to a small bore size leading to bad breathing and high mean piston speeds.
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Hello JonnyG,
I do not normally personalise comments, but I feel I need to on this occasion.
As I write this, the posting count on this thread is 44 I have made three replies in which I have not contradicted one of your views (however that does not mean I necessarily agree with them).
In your last post you quote my earlier one and thus I have to assume that when you write:-
"I would be interested to know what yours and lutz experience is of dyno measurements and vehicle set up is?
BHP wins?"
I have to assume that the "yours" you use refers to me.
I realise that my first reply on this topic introduced the principal of comparing towing vehicles by BHP, and perhaps that was a too blinkered approach for the petrolheads on the forum, but as I have said in later comments it was the concept that a more powerful car does not necesarily mean a better tow car. which was the answer that is appropriate to the opening question - and no one has contradicted that proposition.
My experience or otherwise of dynometers has no relevance to the opening question and is not up for discussion.
Again because you quote my post in your header, I have to assume that one of the "TWO" you refer to is me!
I take exception to your final comment:-
"OK so we are not racing, we were discussing real life on the road towing, but you two are still in the classroom and not looking at real life towing secarios."
May I point out that I did not raise the issue of racing cars, nor have I engaged in the debate you have driven about engine performance. I therfore can see no justification for you to make assumptions about me or my expertese on the matters that I have not written about.
I get the distinct impression that you also think there is some connection between Lutz and I. Whilst we may often share a perspective about a topic, we arrive at those positions through entirely independent thought processess and the fact that we do is pure coincidence. I should also point out there are areas where our views diverge.
I cannot answer for Lutz, but for my self you have absolutely know idea of the wealth of experience both practical or theoretical that I have. As for towing experience I have more than my fair share with a variety of vehicles and trailers.
By standing on your soap box and shouting louder or longer does not automatically make you right. Just like everyone else on this forum you use a nickname, which means that no one has any means to confirm you or I as a bone-fide expert or equally as novices on any subject.
I will not be drawn into any further off topic discussion on this thread.
I do not normally personalise comments, but I feel I need to on this occasion.
As I write this, the posting count on this thread is 44 I have made three replies in which I have not contradicted one of your views (however that does not mean I necessarily agree with them).
In your last post you quote my earlier one and thus I have to assume that when you write:-
"I would be interested to know what yours and lutz experience is of dyno measurements and vehicle set up is?
BHP wins?"
I have to assume that the "yours" you use refers to me.
I realise that my first reply on this topic introduced the principal of comparing towing vehicles by BHP, and perhaps that was a too blinkered approach for the petrolheads on the forum, but as I have said in later comments it was the concept that a more powerful car does not necesarily mean a better tow car. which was the answer that is appropriate to the opening question - and no one has contradicted that proposition.
My experience or otherwise of dynometers has no relevance to the opening question and is not up for discussion.
Again because you quote my post in your header, I have to assume that one of the "TWO" you refer to is me!
I take exception to your final comment:-
"OK so we are not racing, we were discussing real life on the road towing, but you two are still in the classroom and not looking at real life towing secarios."
May I point out that I did not raise the issue of racing cars, nor have I engaged in the debate you have driven about engine performance. I therfore can see no justification for you to make assumptions about me or my expertese on the matters that I have not written about.
I get the distinct impression that you also think there is some connection between Lutz and I. Whilst we may often share a perspective about a topic, we arrive at those positions through entirely independent thought processess and the fact that we do is pure coincidence. I should also point out there are areas where our views diverge.
I cannot answer for Lutz, but for my self you have absolutely know idea of the wealth of experience both practical or theoretical that I have. As for towing experience I have more than my fair share with a variety of vehicles and trailers.
By standing on your soap box and shouting louder or longer does not automatically make you right. Just like everyone else on this forum you use a nickname, which means that no one has any means to confirm you or I as a bone-fide expert or equally as novices on any subject.
I will not be drawn into any further off topic discussion on this thread.
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