Torque, displacement or horsepower?

[ahmadbila]

horsepower is how hard you hit the wall,... torque is how far you move it

is that how manufacturers check the specs of their newly built cars ?

[mehrozniazi1]

another one

8) which situation is better, when an engine is producing max hp at lower rpm or at higher rpm? and why?

at higher

1 yes you can

2 v8 will have more

3 correct

4 second 1 will be quick in terms of ACC

5 depands on track...its torque doing the wheeli

6 no idea ny expert

7 no idea

i may be wrong ..experts

[ahmadbila]

at higher

sorry, wanted to ask about torque actually edited the original post.

[mehrozniazi1]

in race terms...

torque is needed to start the race and the rest is done by HP(power)

vigo will out run the 1.3 vtec in first gear but then in 3rd it will be the opposite way

[Storm]

thanx everyone for taking out time and explaining me torque n hp... im really gratefull. specially @vcheng. you used very simple language and examples to illustrate eveything.

i opened the tread yesterday, read the long replies in a hurry as i had to log off soon.so today, just got an ice cream frm the freezer and clicked this thread, read everything slowly and tried to understand. i ve got most of it, but still, im afraid mr.vcheng, your writing practice isnt over yet as i ve got new questions now

here they are...

1) you cannot get more torque from an engine by throwing in a turbo or other mods, u will get hp this way, but not torque.which means that over all power of the car will remain the same but u will reach the peak faster.correct?

2) if you need more torque, the only way is to switch to a bigger displacement engine, bcuz a modified b18c 250bhp engine wud'nt be giving as much torque as a toyota 3.5l v8, bcuz by modifying, you are making it rev faster, but the torque remains the same because the displacement and bore stroke etc are the same.

3) a 2.0D may be slower while climbing mountains, but it will be going up easily.while a 1.3L vtec with more hp may be faster but it wud be screaming badly. right?

4) consider 2 cars, everything else same. one is 150bhp and 130ft lbs of torque, the other one has 150ft lb of torque but 130bhp, which will be faster? my guess is the first one.bcuz it wud do lesser work but in lesser time too, the 2nd one would be a little slower bcuz it has less bhp.

5) on a race track, which car will be faster? one with more hp or one with more torque? i ve seen vdos of sum real dragsters which wud lift their nose of launch, is that due to hp or torque?

6) i read sumwhere that when a car touches its peak torque, it gets difficult for it to accelerate further bcuz peak torque is reached. how true is it? or am i missing sumthing?

7) maximum hp is found on max rpm (as far as the engine can go) but maximum torque is usually sumwhere below that level.whats the reason for that? and when at 5252 rpms, both are same, does that mean that the instantaneous acceleration at this point would be maximum?

so far, my rusty little mind could squeese out these questions.sorry if they are stupid or if they reflect that i ve not understood sumthing they way u tried to make me understand .... once again, thanx to vcheng and all others who replied.

looking forward for the answers...

1. turbos increase torque as well. the formula for HP is (torque x rpm)/5252

2. high revving small capacity japanese engines are tailored for specific uses, large capacity american V8s are for other uses. usually high revving engines have high stroke and small bores (easier to rev) and lazy large capacity engines have large bores and shorter strokes. this is also why they hev different charachteristics. take for example a hayabusa engine and an XLi engine,... both are 1.3 (as far as i know) buy it'd make no sense to use either engine in the other vehicle...

3. the 2.0D is geared to use the bottom end torque delivery of the engine to better use.

4. see the above equation and then keep in mind that it's torque which moves the mass of the car,.. compare the 530i Vs the 530d,.. the 530i should be faster through the gears,.. but it isn't.

5. on a race track there are too many variables,.. but do look into the story of audis disel lemans car. dragsters lift their noses due to torque.

6. in an ideal world you should change up at peak torque, but nowdays cars don't develop "peak" torque,.. most engines are now designed to have flat torque curves rather than spikes liek the engines in the 60s (and before) did.

7. peak power is almost never at peak rpms, to explain why, please refer to the equation i posted above. as for the idea of them being equal at 5252rpm,.. it's not true. try the equation i gave you, try one with 200lb/ft at 3000rpm (will give 114hp) and another one with 100lb/ft at 6000rpm (also 114hp). clearly torque is decreasing as rpms rise but HP remains constant (flat powerband).

[mehrozniazi1]

sorry, wanted to ask about torque actually edited the original post.

''It is better to make torque at high rpm than at low rpm''

@TP
SEiGHT - Torque vs. Horespower

this will help

[Storm]

in race terms...

torque is needed to start the race and the rest is done by HP(power)

vigo will out run the 1.3 vtec in first gear but then in 3rd it will be the opposite way

question: what would be faster in a drag race from 0-100km/h? a 3.0L D4D manual (5speed) vigo or a 3.4L auto (4speed) surf?

answer: they are EXACTLY equal somehow (speaking from experience - many tries).

the higher torque of the turbodiesel, lighter weight and (5) shorter ratios help the vigo get moving, whereas the 3.4L with a 4speed auto requires less gearshifts but doesn't maximise the powerband.

another one

8) which situation is better, when an engine is producing max torque at lower rpm or at higher rpm? and why?

peak torque should be produced down low and then stay near the peak till the rev limit. however modern small jap engines produce peak torque up high and people think that is normal. the truth is that these cars are designed to make HP, which is moe of a marketing thing. real engines make torque down low and don't need to spool up to 11000rpm to make power.

for example i'd rather have a VR6 powering my car than a B18.

I'm a fan of torque, but differnt people would choose different engines depending on thier requirements and preferences.

[VCheng]

Excellent comments by all. I am on the road and will answer in detail as soon as I get the chance. In the meantime please carry on!

thanx everyone for taking out time and explaining me torque n hp... im really gratefull. specially @vcheng. you used very simple language and examples to illustrate eveything.

i opened the tread yesterday, read the long replies in a hurry as i had to log off soon.so today, just got an ice cream frm the freezer and clicked this thread, read everything slowly and tried to understand. i ve got most of it, but still, im afraid mr.vcheng, your writing practice isnt over yet as i ve got new questions now

here they are...

1) you cannot get more torque from an engine by throwing in a turbo or other mods, u will get hp this way, but not torque.which means that over all power of the car will remain the same but u will reach the peak faster.correct?

2) if you need more torque, the only way is to switch to a bigger displacement engine, bcuz a modified b18c 250bhp engine wud'nt be giving as much torque as a toyota 3.5l v8, bcuz by modifying, you are making it rev faster, but the torque remains the same because the displacement and bore stroke etc are the same.

3) a 2.0D may be slower while climbing mountains, but it will be going up easily.while a 1.3L vtec with more hp may be faster but it wud be screaming badly. right?

4) consider 2 cars, everything else same. one is 150bhp and 130ft lbs of torque, the other one has 150ft lb of torque but 130bhp, which will be faster? my guess is the first one.bcuz it wud do lesser work but in lesser time too, the 2nd one would be a little slower bcuz it has less bhp.

5) on a race track, which car will be faster? one with more hp or one with more torque? i ve seen vdos of sum real dragsters which wud lift their nose of launch, is that due to hp or torque?

6) i read sumwhere that when a car touches its peak torque, it gets difficult for it to accelerate further bcuz peak torque is reached. how true is it? or am i missing sumthing?

7) maximum hp is found on max rpm (as far as the engine can go) but maximum torque is usually sumwhere below that level.whats the reason for that? and when at 5252 rpms, both are same, does that mean that the instantaneous acceleration at this point would be maximum?

so far, my rusty little mind could squeese out these questions.sorry if they are stupid or if they reflect that i ve not understood sumthing they way u tried to make me understand .... once again, thanx to vcheng and all others who replied.

looking forward for the answers...

Thank you for the kind words. Let me try to answer your new questions.

here they are...

1) you cannot get more torque from an engine by throwing in a turbo or other mods, u will get hp this way, but not torque.which means that over all power of the car will remain the same but u will reach the peak faster.correct?

A1: You can get more torque by adding suitable modifications. Consider that the rotational force is produced by burning fuel as efficiently as possible. You increase the amount of fuel burnt by increasing displacement in a naturally aspirated engine or by forcing more fuel/air into the same displacement by using forced induction.
<FONT color=black><FONT face=Arial><?xml:namespace prefix = o ns = "urn:schemas-microsoft-comhttp://www.tpub.com/content/automotiveenginemechanics/TM-9-8000/

another one

8) which situation is better, when an engine is producing max torque at lower rpm or at higher rpm? and why?

Please define the "situation" better. Is this a car or truck? Type of fuel? etc. etc.

[JuGnO]

nice replies

[2468]

@VCheng

You said Torque and HP intersect at 5252 RPM

@Storm

You said intersection concept of Torque and HP at 5252 RPM is not true

[Bilaltq]

Bilaltq, daniyalahmad, 2468: Thank you for your comments.

Please recite this 100 times before going to bed each night for the next month:

"There is no replacement for displacement."

Don't worry. That's been tattoed on the back of my retinae

[Storm]

@VCheng

You said Torque and HP intersect at 5252 RPM

@Storm

You said intersection concept of Torque and HP at 5252 RPM is not true

in that case i'm not going to argue with VCheng...

[waqas34]

i just remembered a very nice quote of someone here at pakwheel, i don't remember who he was but the quote is
"Horse power is about how fast you hit a wall and torque is about how far you drag the wall after hitting it"(H)

[VCheng]

in that case i'm not going to argue with VCheng...

We are all friends here, so there will be no arguments, only intelligent discussion.

I wrote:

Torque and Horsepower are related by this equation:

Horsepower = [Torque x rpm] / 5252

This means that below 5252 rpm any engine's torque will always be higher than its horsepower, and above 5252 rpm horsepower will always be higher than its torque. At 5252 rpm both will be exactly the same.

Storm wrote:

7. peak power is almost never at peak rpms, to explain why, please refer to the equation i posted above. as for the idea of them being equal at 5252rpm,.. it's not true. try the equation i gave you, try one with 200lb/ft at 3000rpm (will give 114hp) and another one with 100lb/ft at 6000rpm (also 114hp). clearly torque is decreasing as rpms rise but HP remains constant (flat powerband).

Let's start with the basic position that both agree upon:

Horsepower = [Torque x rpm] / 5252

Now let's see what happens at 5252 rpm:

Horsepower = [Torque x 5252] /5252

Horsepower = Torque at 5252 rpm.

Graphically, it means that both the horsepower and torque curves will intersect at 5252 rpm because they are equal at this point, for the same engine of course.

Storm however brings up an interesting point. His intuition is along the right track, and it is related to the shape of the torque and horsepower curves, which are not flat in real life. However, please note that I am talking about the behaviour of a single engine across the rpm range, and not comparing two different engines. That is a whole another discussion.

The ideal torque curve is flat from idle to redline. With this ideal curve, horsepwer will rise linearly with rpm, will be less than the torque until 5252 rpm, intersect the torque line at 5252 rpm, and then continue to rise above the torque value for all rpm values greater than 5252 until the redline.

However, the torque curve is never totally flat, and rises until peak efficiency is reached, and then begins to fall as limitations of the combustion process set in coupled with engineering considerations. This of course will change the shape of the horsepower curves as well.

Think of it this way: It is the total area under the torque curve that is important.

Don't worry. That's been tattoed on the back of my retinae

That means that you are a true car nut!

[ahmadbila]

1. turbos increase torque as well. the formula for HP is (torque x rpm)/5252

2. high revving small capacity japanese engines are tailored for specific uses, large capacity american V8s are for other uses. usually high revving engines have high stroke and small bores (easier to rev) and lazy large capacity engines have large bores and shorter strokes. this is also why they hev different charachteristics. take for example a hayabusa engine and an XLi engine,... both are 1.3 (as far as i know) buy it'd make no sense to use either engine in the other vehicle...

3. the 2.0D is geared to use the bottom end torque delivery of the engine to better use.

4. see the above equation and then keep in mind that it's torque which moves the mass of the car,.. compare the 530i Vs the 530d,.. the 530i should be faster through the gears,.. but it isn't.

5. on a race track there are too many variables,.. but do look into the story of audis disel lemans car. dragsters lift their noses due to torque.

6. in an ideal world you should change up at peak torque, but nowdays cars don't develop "peak" torque,.. most engines are now designed to have flat torque curves rather than spikes liek the engines in the 60s (and before) did.

7. peak power is almost never at peak rpms, to explain why, please refer to the equation i posted above. as for the idea of them being equal at 5252rpm,.. it's not true. try the equation i gave you, try one with 200lb/ft at 3000rpm (will give 114hp) and another one with 100lb/ft at 6000rpm (also 114hp). clearly torque is decreasing as rpms rise but HP remains constant (flat powerband).

Once again, everyone, thankyou for your replies.will reply to every post seperately.

as for this post by @storm bhai. i ve got another question again

1) if turbos etc increase torque, why a heavily modified b18c or h22 honda engine doesnt have enough torque compared to the toyota v8 engine? and then wats the myth behind this "no replacement for displacement" theory?

will read about the audi's le man cars too...

@TP
SEiGHT - Torque vs. Horespower

this will help

thats seems to have a very nice explanation.will read in a few minutes though thanx mehroz bhai.

peak torque should be produced down low and then stay near the peak till the rev limit. however modern small jap engines produce peak torque up high and people think that is normal. the truth is that these cars are designed to make HP, which is moe of a marketing thing. real engines make torque down low and don't need to spool up to 11000rpm to make power.

for example i'd rather have a VR6 powering my car than a B18.

I'm a fan of torque, but differnt people would choose different engines depending on thier requirements and preferences.

thanx, this part is 100% clear to me now.

in that case i'm not going to argue with VCheng...

Im sure there must be a reason of you saying that they dont cut each other on 5252rpm, but i searched for many dyno results of random cars and found that this 5252 thing DOES happen.

can you shed some light on why you suggest theres nothing like it?

Thank you for the kind words. Let me try to answer your new questions.

here they are...

1) you cannot get more torque from an engine by throwing in a turbo or other mods, u will get hp this way, but not torque.which means that over all power of the car will remain the same but u will reach the peak faster.correct?

A1: You can get more torque by adding suitable modifications. Consider that the rotational force is produced by burning fuel as efficiently as possible. You increase the amount of fuel burnt by increasing displacement in a naturally aspirated engine or by forcing more fuel/air into the same displacement by using forced induction.ffice:office" /><?xml:namespace prefix = o ns = "urn:schemas-microsoft-comhttp://www.tpub.com/content/automotiveenginemechanics/TM-9-8000/<o:p></o:p>
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looking forward for the answers... <o:p></o:p>
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If there are any more questions, please keep them coming.<o:p></o:p>

once again i appreciate the time and effort u put into this thread... thankyou

1) first question is the same as that i asked from @storm bhai.if turbos can increase performance, why a turbo charged 1800cc honda motor lacks in torque compared to toyota v8 engine? or am i again missing a lot of factors? if i am, plz consider them same for both engines (if thats possible). and whats the story behind the replacemnt for displacement statement if you CAN get more torque and hp from lesser disp. engine bu modifying it accordingly.

2) so as far as i ve understood at the moment is that torque is what once pushes your car and hp is what supports that PUSH.everything else considered same, a faster car on a track will be the one with proper mix of hp and torque.a car with more hp but less torque might accelerate faster after its in motion but will be slow on the launch.and a car with more torque and lesser hp will be quicker on launch but will get slow after sometime.but there are factors like where does the peak torque comes in for both cars and how much revs the engine is doing etc etc.... correct? somewhat?

yes please take your time and reply to these questions when you are in relax mood and free, bcuz i also take my time reading replies and asking new questions

regards.

We are all friends here, so there will be no arguments, only intelligent discussion.

I wrote:

Torque and Horsepower are related by this equation:

Horsepower = [Torque x rpm] / 5252

This means that below 5252 rpm any engine's torque will always be higher than its horsepower, and above 5252 rpm horsepower will always be higher than its torque. At 5252 rpm both will be exactly the same.

Storm wrote:

7. peak power is almost never at peak rpms, to explain why, please refer to the equation i posted above. as for the idea of them being equal at 5252rpm,.. it's not true. try the equation i gave you, try one with 200lb/ft at 3000rpm (will give 114hp) and another one with 100lb/ft at 6000rpm (also 114hp). clearly torque is decreasing as rpms rise but HP remains constant (flat powerband).

Let's start with the basic position that both agree upon:

Horsepower = [Torque x rpm] / 5252

Now let's see what happens at 5252 rpm:

Horsepower = [Torque x 5252] /5252

Horsepower = Torque at 5252 rpm.

Graphically, it means that both the horsepower and torque curves will intersect at 5252 rpm because they are equal at this point, for the same engine of course.

Storm however brings up an interesting point. His intuition is along the right track, and it is related to the shape of the torque and horsepower curves, which are not flat in real life. However, please note that I am talking about the behaviour of a single engine across the rpm range, and not comparing two different engines. That is a whole another discussion.

The ideal torque curve is flat from idle to redline. With this ideal curve, horsepwer will rise linearly with rpm, will be less than the torque until 5252 rpm, intersect the torque line at 5252 rpm, and then continue to rise above the torque value for all rpm values greater than 5252 until the redline.

However, the torque curve is never totally flat, and rises until peak efficiency is reached, and then begins to fall as limitations of the combustion process set in coupled with engineering considerations. This of course will change the shape of the horsepower curves as well.

Think of it this way: It is the total area under the torque curve that is important.

By flat torque curve you mean to say that torque at all rpms should be more or less same, this would give you the advantage because u always have peak torque working for u no matter what ever rpm the engine is at. while hp will increase by the increasing revs.

and that like u posted in your previous reply, maaannn thats a huge chunk of knowledge will read few topics everyday and will also try to find the same in a downloadable version thanks for it.

[Automotorsport_Lover]

Oh yaar simple si baat ha...

a TOURQUEY Engine is one with more Power..

A higher BHP engine is one with more speed..

Jeeps have more tourque and less BHP, cars have have more BHPs..
Choopers have more tourque, heavy bike have more BHP..

There are fans 4 both! Some ppl like raww power, some like speed..

Eg. 2800cc Turbo diesel pejaro is 110BHP( i think this info is exact as far as i remember)

A honda civic is eagle eye is 127 Bhp... but pajero is far better at hill climbing than civic, plus at lower Rpms a pajero's response to the accelarator wud be gr8... and civic wud usually show its power at all Rpms levels, especially doing btter in the higher Rpms..

For an effortless drive in which u wonna feel power and some quick accelaration.. a nice SUV wud do it.
For a drive in which u ill have 2 take care of proper gear shifts to let urself "FEEL" the power of engine...a car wud do it.

A 3400cc Parado wud have less BHP than a camry or markX etc...

[ahmadbila]

another of my very strange question.

if i let u drive a car, you dont know which engine it has, petrol or diesel, how many hp how much torque etc etc.u are just allowed to drive and test the car.is there any way u can determine that the car has more torque or more hp? or is there anything u can anticipate about the specs of the engine just by driving it? is there any way to FEEL the power?

[v8]

thread has got pretty informative... many concepts are crystal clear now

thanks for sharing guys

[mehrozniazi1]

another of my very strange question.

if i let u drive a car, you dont know which engine it has, petrol or diesel, how many hp how much torque etc etc.u are just allowed to drive and test the car.is there any way u can determine that the car has more torque or more hp? or is there anything u can anticipate about the specs of the engine just by driving it? is there any way to FEEL the power?

cant u?

[Devastator]

is that how manufacturers check the specs of their newly built cars ?

:Si just got to know the secret which lies behind Car Safety Crash Tests!
its actually chekin the torque i guess;)

Yes the Thread is truely informative!
i personally browsed many webpages to clarify this same concept, but hats off to VCheng for provision of information especially getting it all down to our level of understanding (i refer it as an art) for conveying your superior knowledge to ppl like us in a simpler manner omittin the technical terms!
More than Thankful to you!
Still Thangs To You!